Entanglement via atomic coherence induced by two strong classical fields
Lü, Xin-You; Huang, Pei; Yang, Wen-Xing; Yang, Xiaoxue
2009-09-01
Based on the standard criteria [P. van Loock and A. Furusawa, Phys. Rev. A 67, 052315 (2003)], we propose a scheme to achieve the fully tripartite continuous-variable (CV) entanglement in a Y -type atomic system driven by two strong classical fields. By numerically simulating the dynamics of system, we show that the generation of entanglement does not depend intensively on the initial condition of cavity field and the time for which the cavity modes remain entangled can be prolonged via enhancing the intensities of classical fields in our scheme. Moreover, our numerical results also show that a tripartite entanglement amplifier can be realized in the present scheme. The present research provides an efficient approach to achieve fully tripartite CV entangled state even when the three entangled modes have different frequencies and initial states, which may be useful for the progress of quantum information networks with many nodes.
Classical trajectory perspective of atomic ionization in strong laser fields semiclassical modeling
Liu, Jie
2014-01-01
The ionization of atoms and molecules in strong laser fields is an active field in modern physics and has versatile applications in such as attosecond physics, X-ray generation, inertial confined fusion (ICF), medical science and so on. Classical Trajectory Perspective of Atomic Ionization in Strong Laser Fields covers the basic concepts in this field and discusses many interesting topics using the semiclassical model of classical trajectory ensemble simulation, which is one of the most successful ionization models and has the advantages of a clear picture, feasible computing and accounting for many exquisite experiments quantitatively. The book also presents many applications of the model in such topics as the single ionization, double ionization, neutral atom acceleration and other timely issues in strong field physics, and delivers useful messages to readers with presenting the classical trajectory perspective on the strong field atomic ionization. The book is intended for graduate students and researchers...
Finding quantum effects in strong classical potentials
Hegelich, B. Manuel; Labun, Lance; Labun, Ou Z.
2017-06-01
The long-standing challenge to describing charged particle dynamics in strong classical electromagnetic fields is how to incorporate classical radiation, classical radiation reaction and quantized photon emission into a consistent unified framework. The current, semiclassical methods to describe the dynamics of quantum particles in strong classical fields also provide the theoretical framework for fundamental questions in gravity and hadron-hadron collisions, including Hawking radiation, cosmological particle production and thermalization of particles created in heavy-ion collisions. However, as we show, these methods break down for highly relativistic particles propagating in strong fields. They must therefore be improved and adapted for the description of laser-plasma experiments that typically involve the acceleration of electrons. Theory developed from quantum electrodynamics, together with dedicated experimental efforts, offer the best controllable context to establish a robust, experimentally validated foundation for the fundamental theory of quantum effects in strong classical potentials.
Renormalization in classical field theory
International Nuclear Information System (INIS)
Corbo, Guido
2010-01-01
We discuss simple examples in which renormalization is required in classical field theory. The presentation is accessible to undergraduate students with a knowledge of the basic notions of classical electromagnetism. (letters and comments)
Classical field theory with fermions
International Nuclear Information System (INIS)
Borsanyi, Sz.; Hindmarsh, M.
2009-01-01
Classical field theory simulations have been essential for our understanding of non-equilibrium phenomena in particle physics. In this talk we discuss the possible extension of the bosonic classical field theory simulations to include fermions. In principle we use the inhomogeneous mean field approximation as introduced by Aarts and Smit. But in practice we turn from their deterministic technique to a stochastic approach. We represent the fermion field as an ensemble of pairs of spinor fields, dubbed male and female. These c-number fields solve the classical Dirac equation. Our improved algorithm enables the extension of the originally 1+1 dimensional analyses and is suitable for large-scale inhomogeneous settings, like defect networks.
Embedding classical fields in quantum field theories
International Nuclear Information System (INIS)
Blaha, S.
1978-01-01
We describe a procedure for quantizing a classical field theory which is the field-theoretica analog of Sudarshan's method for embedding a classical-mechanical system in a quantum-mechanical system. The essence of the difference between our quantization procedure and Fock-space quantization lies in the choice of vacuum states. The key to our choice of vacuum is the procedure we outline for constructing Lagrangians which have gradient terms linear in the field varialbes from classical Lagrangians which have gradient terms which are quadratic in field variables. We apply this procedure to model electrodynamic field theories, Yang-Mills theories, and a vierbein model of gravity. In the case of electrodynamics models we find a formalism with a close similarity to the coherent-soft-photon-state formalism of QED. In addition, photons propagate to t = + infinity via retarded propagators. We also show how to construct a quantum field for action-at-a-distance electrodynamics. In the Yang-Mills case we show that a previously suggested model for quark confinement necessarily has gluons with principle-value propagation which allows the model to be unitary despite the presence of higher-order-derivative field equations. In the vierbein-gravity model we show that our quantization procedure allows us to treat the classical and quantum parts of the metric field in a unified manner. We find a new perturbation scheme for quantum gravity as a result
2008-01-01
Since the invention of the laser in the 1960s, people have strived to reach higher intensities and shorter pulse durations. High intensities and ultrashort pulse durations are intimately related. Recent developments have shown that high intensity lasers also open the way to realize pulses with the shortest durations to date, giving birth to the field of attosecond science (1 asec = 10-18s). This book is about high-intensity lasers and their applications. The goal is to give an up to date introduction to the technology behind these laser systems and to the broad range of intense laser applications. These applications include AMO (atomic molecular and optical) physics, x-ray science, attosecond science, plasma physics and particle acceleration, condensed matter science and laser micromachining, and finally even high-energy physics.
Quantum electrodynamics of strong fields
International Nuclear Information System (INIS)
Greiner, W.
1983-01-01
Quantum Electrodynamics of Strong Fields provides a broad survey of the theoretical and experimental work accomplished, presenting papers by a group of international researchers who have made significant contributions to this developing area. Exploring the quantum theory of strong fields, the volume focuses on the phase transition to a charged vacuum in strong electric fields. The contributors also discuss such related topics as QED at short distances, precision tests of QED, nonperturbative QCD and confinement, pion condensation, and strong gravitational fields In addition, the volume features a historical paper on the roots of quantum field theory in the history of quantum physics by noted researcher Friedrich Hund
From classical to quantum fields
Baulieu, Laurent; Sénéor, Roland
2017-01-01
Quantum Field Theory has become the universal language of most modern theoretical physics. This introductory textbook shows how this beautiful theory offers the correct mathematical framework to describe and understand the fundamental interactions of elementary particles. The book begins with a brief reminder of basic classical field theories, electrodynamics and general relativity, as well as their symmetry properties, and proceeds with the principles of quantisation following Feynman's path integral approach. Special care is used at every step to illustrate the correct mathematical formulation of the underlying assumptions. Gauge theories and the problems encountered in their quantisation are discussed in detail. The last chapters contain a full description of the Standard Model of particle physics and the attempts to go beyond it, such as grand unified theories and supersymmetry. Written for advanced undergraduate and beginning graduate students in physics and mathematics, the book could also serve as a re...
Classical field approach to quantum weak measurements.
Dressel, Justin; Bliokh, Konstantin Y; Nori, Franco
2014-03-21
By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical field is itself a weak value of the corresponding quantum field operator and satisfies equations of motion that extremize an effective action. Weak measurements perturb this effective action, producing measurable changes to the classical field dynamics. As such, weakly measured effects always correspond to an effective classical field. This general result explains why these effects appear to be robust for pre- and postselected ensembles, and why they can also be measured using classical field techniques that are not weak for individual excitations of the field.
Rydberg atoms in strong fields
International Nuclear Information System (INIS)
Kleppner, D.; Tsimmerman, M.
1985-01-01
Experimental and theoretical achievements in studying Rydberg atoms in external fields are considered. Only static (or quasistatic) fields and ''one-electron'' atoms, i.e. atoms that are well described by one-electron states, are discussed. Mainly behaviour of alkali metal atoms in electric field is considered. The state of theoretical investigations for hydrogen atom in magnetic field is described, but experimental data for atoms of alkali metals are presented as an illustration. Results of the latest experimental and theoretical investigations into the structure of Rydberg atoms in strong fields are presented
Quantum simulation of the general semi-classical Rabi model in regimes of arbitrarily strong driving
Dai, Kunzhe; Wu, Haiteng; Zhao, Peng; Li, Mengmeng; Liu, Qiang; Xue, Guangming; Tan, Xinsheng; Yu, Haifeng; Yu, Yang
2017-12-01
We propose and experimentally demonstrate a scheme to simulate the interaction between a two-level system and a classical light field. Under the transversal driving of two microwave tones, the effective Hamiltonian in an appropriate rotating frame is identical to that of the general semi-classical Rabi model. We experimentally realize this Hamiltonian with a superconducting transmon qubit. By tuning the strength, phase, and frequency of the two microwave driving fields, we simulate the quantum dynamics from the weak to extremely strong driving regime. Under these conditions, we observe that, as a function of increased Rabi drive strength, the qubit evolution gradually deviates from the normal sinusoidal Rabi oscillation, in accordance with the predictions of the general semi-classical Rabi model far beyond the weak driving limit. Our scheme provides an effective approach to investigate the extremely strong interaction between a two-level system and a classical light field. Such strong interactions are usually inaccessible in experiments.
Semiclassical Quantization of Classical Field Theories
Cattaneo, A.; Mnev, P.; Reshetikhin, N.; Calaque, D.; Strobi, Th.
2015-01-01
Abstract These lectures are an introduction to formal semiclassical quantization of classical field theory. First we develop the Hamiltonian formalism for classical field theories on space time with boundary. It does not have to be a cylinder as in the usual Hamiltonian framework. Then we outline
Thomson scattering in strong external fields
Varró, S.; Ehlotzky, F.
1992-09-01
In the present paper we shall investigate relativistic Thomson scattering in two external fields. A free classical electron will be embedded in a strong, constant and homogeneous magnetic field and in a powerful electromagnetic field. Both fields will be considered in the Redmond configuration, in which case the electromagnetic wave is circularly polarized and propagates in the direction of the homogeneous magnetic field. The electron will be allowed to have arbitrary initial conditions and the electromagnetic wave will be switched on either suddenly or adiabatically. We shall present the exact solution of the Lorentz equation of motion in the above external field configuration and we shall evaluate the spectrum and cross sections of the scattered radiation. In particular, we shall consider scattering close to resonance and we shall compare our results with the findings of earlier work.
International Nuclear Information System (INIS)
L'Huillier, A.
2002-01-01
When a high-power laser focuses into a gas of atoms, the electromagnetic field becomes of the same magnitude as the Coulomb field which binds a 1s electron in a hydrogen atom. 3 highly non-linear phenomena can happen: 1) ATI (above threshold ionization): electrons initially in the ground state absorb a large number of photons, many more than the minimum number required for ionization; 2) multiple ionization: many electrons can be emitted one at a time, in a sequential process, or simultaneously in a mechanism called direct or non-sequential; and 3) high order harmonic generation (HHG): efficient photon emission in the extreme ultraviolet range, in the form of high-order harmonics of the fundamental laser field can occur. The theoretical problem consists in solving the time dependent Schroedinger equation (TDSE) that describes the interaction of a many-electron atom with a laser field. A number of methods have been proposed to solve this problem in the case of a hydrogen atom or a single-active electron atom in a strong laser field. A large effort is presently being devoted to go beyond the single-active approximation. The understanding of the physics of the interaction between atoms and strong laser fields has been provided by a very simple model called ''simple man's theory''. A unified view of HHG, ATI, and non-sequential ionization, originating from the simple man's model and the strong field approximation, expressed in terms of electrons trajectories or quantum paths is slowly emerging. (A.C.)
Classical theory of electric and magnetic fields
Good, Roland H
1971-01-01
Classical Theory of Electric and Magnetic Fields is a textbook on the principles of electricity and magnetism. This book discusses mathematical techniques, calculations, with examples of physical reasoning, that are generally applied in theoretical physics. This text reviews the classical theory of electric and magnetic fields, Maxwell's Equations, Lorentz Force, and Faraday's Law of Induction. The book also focuses on electrostatics and the general methods for solving electrostatic problems concerning images, inversion, complex variable, or separation of variables. The text also explains ma
On incompleteness of classical field theory
Sardanashvily, G.
2009-01-01
Classical field theory is adequately formulated as Lagrangian theory on fibre bundles and graded manifolds. One however observes that non-trivial higher stage Noether identities and gauge symmetries of a generic reducible degenerate Lagrangian field theory fail to be defined. Therefore, such a field theory can not be quantized.
Classical Ising chain in transverse field
International Nuclear Information System (INIS)
Cuccoli, A.; Taiti, A.; Vaia, R.; Verrucchi, P.
2007-01-01
The spin 12 Ising chain in transverse field is considered the prototypical system for quantum phase transitions. However, very little is apparently known in literature about its classical counterpart, not to be confused with the standard classical Ising model: while the latter is constructed from classical discrete variables, the model we consider is a chain of classical vectors of modulus 1, interacting via an Ising-like Hamiltonian. When an uniform field is applied perpendicular to the exchange interaction, both the quantum model and its classical counterpart get to be characterized by a critical field separating a ferromagnetically ordered state of minimal energy from a paramagnetic one. The properties of the classical model, and especially the behaviour of the correlation length, are investigated at low temperature around the critical field and compared with those of the quantum model, in order to single out the role played by quantum and classical fluctuations at finite temperature; the possibility to experimentally observe peculiar quantum critical effects in Ising spin chains is discussed
Classical Fields Derived from Quantum Sources.
Morris, Fred Gordon
The Clifford algebra C(,4) is shown to be a suitable formalism for classical and quantum physics, and enables classical electromagnetic and gravitational field equations to be derived from the quantum conservation laws for electric charge and energy-momentum. The resulting linear theory of gravitation is shown to make predictions in agreement with the results of the classic weak field tests of gravitation theories. The C(,4) formalism is a physically intuitive, unifying, and mathematically powerful formalism. It can be developed as a geometric algebra in which its elements and operations have direct geometrical interpretations. The Dirac algebra of 4 x 4 matrices is a matrix representation of C(,4). C(,4) also contains the Pauli algebra, the generators of the Lorentz group, tensors, and differential forms. Because of these features C(,4) is both unifying, effectively merging tensor formulations of classical physics with the Dirac and Pauli algebras of quantum physics, and mathematically powerful, as its simple rules allow a wide variety of mathematical operations and structures to be defined. The unified treatment of classical and quantum physics permits a straightforward discussion of the classical limit of quantum field equations and conservation laws. Electromagnetic and gravitational field equations are derived from the local conservation laws for electric charge and energy-momentum by using the Poincare lemma from differential forms theory. The electromagnetic field equations thereby obtained are the usual Maxwell equations. The gravitational field equations obtained have an analogous mathematical form to the Maxwell equations and describe a linear gravitational field. The resulting theory provides a relativistic treatment of the motion of particles in a central gravitational field. The theory makes predictions in agreement with the predictions of general relativity for the classic weak field tests so can be considered a valid theory in problems in which the
Classical and quantum mechanics of non-abelian gauge fields
International Nuclear Information System (INIS)
Savvidy, G.K.
1984-01-01
Classical and quantum mechanics of non-abelian gauge fields are investigated both with and without spontaneous symmetry breaking. The fundamental subsystem (FS) of Yang-Mills classical mechanics (YMCM) is considered. It is shown to be a Kolmogorov K-system, and hence to have strong statistical properties. Integrable systems are also found, to which in terms of KAM theory Yang-Mills-Higgs classical mechanics (YMHCM) is close. Quantum-mechanical properties of the YM system and their relation to the problem of confinement are discussed. (orig.)
Atoms and clusters in strong laser fields
Marchenko, T.
2008-01-01
This thesis describes experimental and theoretical studies on the interaction of strong infrared laser fields with atoms and atomic clusters. Part I provides an overview of the main strong-field phenomena in atoms, molecules and clusters and describes the state-of-the-art in strong-field science.
Classical limit of relativistic dynamical fields
Hruška, Ondřej
2013-01-01
In this work, we summarise existing results concerning the absence of "gravitational aberration" in Einstein's general theory of relativity, i.e., the fact that the gravitational "force" points towards the instantaneous position of objects with mass, although the field propagates at the speed of light. The electromagne- tic interaction behaves similarly. Thanks to that, the classical limit with infinite speed of propagation of electricity and gravitation is a good approximation of relativisti...
Special relativity and classical field theory
Susskind, Leonard
2017-01-01
Physicist Leonard Susskind and data engineer Art Friedman are back. This time, they introduce readers to Einstein's special relativity and Maxwell's classical field theory. Using their typical brand of real math, enlightening drawings, and humor, Susskind and Friedman walk us through the complexities of waves, forces, and particles by exploring special relativity and electromagnetism. It's a must-read for both devotees of the series and any armchair physicist who wants to improve their knowledge of physics' deepest truths.
Classical gravity and quantum matter fields in unified field theory
von Borzeszkowski, Horst-Heino; Treder, Hans-Jürgen
1996-01-01
The Einstein-Schrödinger purely affine field theory of the non-symmetric field provides canonical field equations without constraints. These equations imply the Heisenberg-Pauli commutation rules of quantum field theory. In the Schrödinger gauging of the Einstein field coordinatesU {/kl i }=Γ{/kl i }-δ{/l i }Γ{/km m }, this unified geometric field theory becomes a model of the coupling between a quantized Maxwellian field in a medium and classical gravity. Therefore, independently of the question as to the physical truth of this model, its analysis performed in the present paper demonstrates that, in the framework of a quantized unified field theory, gravity can appear as a genuinely classical field.
Quantum scattering from classical field theory
International Nuclear Information System (INIS)
Gould, T.M.; Poppitz, E.R.
1995-01-01
We show that scattering amplitudes between initial wave packet states and certain coherent final states can be computed in a systematic weak coupling expansion about classical solutions satisfying initial-value conditions. The initial-value conditions are such as to make the solution of the classical field equations amenable to numerical methods. We propose a practical procedure for computing classical solutions which contribute to high energy two-particle scattering amplitudes. We consider in this regard the implications of a recent numerical simulation in classical SU(2) Yang-Mills theory for multiparticle scattering in quantum gauge theories and speculate on its generalization to electroweak theory. We also generalize our results to the case of complex trajectories and discuss the prospects for finding a solution to the resulting complex boundary value problem, which would allow the application of our method to any wave packet to coherent state transition. Finally, we discuss the relevance of these results to the issues of baryon number violation and multiparticle scattering at high energies. ((orig.))
Introduction to classical and quantum field theory
International Nuclear Information System (INIS)
Ng, Tai-Kai
2009-01-01
This is the first introductory textbook on quantum field theory to be written from the point of view of condensed matter physics. As such, it presents the basic concepts and techniques of statistical field theory, clearly explaining how and why they are integrated into modern quantum (and classical) field theory, and includes the latest developments. Written by an expert in the field, with a broad experience in teaching and training, it manages to present such substantial topics as phases and phase transitions or solitons and instantons in an accessible and concise way. Divided into three parts, the first part covers fundamental physics and the mathematics background needed by students in order to enter the field, while the second part introduces more advanced concepts and techniques. Part III discusses applications of quantum field theory to a few basic problems. The emphasis here lies on how modern concepts of quantum field theory are embedded in these approaches, and also on the limitations of standard quantum field theory techniques in facing, 'real' physics problems. Throughout there are numerous end-of-chapter problems, and a free solutions manual is available for lecturers. (orig.)
Strong and superstrong pulsed magnetic fields generation
Shneerson, German A; Krivosheev, Sergey I
2014-01-01
Strong pulsed magnetic fields are important for several fields in physics and engineering, such as power generation and accelerator facilities. Basic aspects of the generation of strong and superstrong pulsed magnetic fields technique are given, including the physics and hydrodynamics of the conductors interacting with the field as well as an account of the significant progress in generation of strong magnetic fields using the magnetic accumulation technique. Results of computer simulations as well as a survey of available field technology are completing the volume.
Atom collisions in a strong electromagnetic field
International Nuclear Information System (INIS)
Smirnov, V.S.; Chaplik, A.V.
1976-01-01
It is shown that the long-range part of interatomic interaction is considerably altered in a strong electromagnetic field. Instead of the van der Waals law the potential asymptote can best be described by a dipole-dipole R -3 law. Impact broadening and the line shift in a strong nonresonant field are calculated. The possibility of bound states of two atoms being formed in a strong light field is discussed
Synchrotron radiation in strongly coupled conformal field theories
Athanasiou, Christiana; Chesler, Paul M.; Liu, Hong; Nickel, Dominik; Rajagopal, Krishna
2010-06-01
Using gauge/gravity duality, we compute the energy density and angular distribution of the power radiated by a quark undergoing circular motion in strongly coupled N=4 supersymmetric Yang-Mills theory. We compare the strong coupling results to those at weak coupling, finding them to be very similar. In both regimes, the angular distribution of the radiated power is in fact similar to that of synchrotron radiation produced by an electron in circular motion in classical electrodynamics: the quark emits radiation in a narrow beam along its velocity vector with a characteristic opening angle α˜1/γ. To an observer far away from the quark, the emitted radiation appears as a short periodic burst, just like the light from a lighthouse does to a ship at sea. Our strong coupling results are valid for any strongly coupled conformal field theory with a dual classical gravity description.
Thermodynamical instabilities under strong magnetic fields
Chen, Y. J.
2017-03-01
The thermodynamical instabilities of low densities in the n p matter and n p e matter are studied within several relativistic nuclear models under some values of magnetic fields. The results are compared between each other and the effects of the symmetry energy slope at saturation density on the instability are investigated. The instability regions can exhibit bands due to the presence of Landau levels for very strong magnetic fields of the order of 1017 G, while for weaker magnetic fields, the bands are replaced by many diffused or scattered pieces. It also shows that the proton fraction in the inner crust of neutron stars may be complex under strong magnetic fields.
Classical gluon fields of relativistic color charges
International Nuclear Information System (INIS)
Zadora, A. S.
2016-01-01
The objective of the present study is to consider in more detail the exotic color-charge-glow effect discovered recently and to analyze its possible physical manifestations associated with the treatment of ensembles of color-charged particles at a classical level. The ways in which this effect may appear in arbitrary systems consisting of pointlike massive particles and admitting the partition into elementary configurations like color charges and color dipoles are studied. The possible influence of this effect on particle dynamics (in particular, on gluon distributions) is also examined. Particle collisions at a given impact parameters are considered for a natural regularization of emerging expressions. It is shown that, in the case of reasonable impact-parameter values, collisions may proceed in the electrodynamic mode, in which case the charge-glow contribution to field strengths is suppressed in relation to what we have in the electrodynamic picture. From an analysis of the color-echo situation, it follows that the above conclusion remains valid for more complicated particle configurations as well, since hard gluon fields may arise only owing to a direct collision rather than owing to any echo-like effects.
Quantum theory of strong-field frustrated tunneling
Popruzhenko, S. V.
2018-01-01
We show how the strong-field approximation, widely used for description of multiphoton and tunneling ionization, can be extended to analyse the excitation of bound states in intense low-frequency laser pulses. The proposed theory is based on the formalism of quantum trajectories and fills the gap between the numerical solution of the time-dependent Schrödinger equation and classical simulations. In particular, it allows identifying non-adiabatic and interference effects in strong-field excitation of Rydberg states.
Super-strong Magnetic Field in Sunspots
Okamoto, Takenori J.; Sakurai, Takashi
2018-01-01
Sunspots are the most notable structure on the solar surface with strong magnetic fields. The field is generally strongest in a dark area (umbra), but sometimes stronger fields are found in non-dark regions, such as a penumbra and a light bridge. The formation mechanism of such strong fields outside umbrae is still puzzling. Here we report clear evidence of the magnetic field of 6250 G, which is the strongest field among Stokes I profiles with clear Zeeman splitting ever observed on the Sun. The field was almost parallel to the solar surface and located in a bright region sandwiched by two opposite-polarity umbrae. Using a time series of spectral data sets, we discuss the formation process of the super-strong field and suggest that this strong field region was generated as a result of compression of one umbra pushed by the horizontal flow from the other umbra, such as the subduction of the Earth’s crust in plate tectonics.
Experimental investigation of strong field trident production
Esberg, J.; Kirsebom, K.; Knudsen, H.; Thomsen, H.D.; Uggerhøj, E.; Uggerhøj, U.I.; Sona, P.; Mangiarotti, A.; Ketel, T.J.; Ditzdar, A.; Dalton, M.M.; Ballestrero, S.; Connell, S.H.
2010-01-01
We show by experiment that an electron impinging on an electric field that is of critical magnitude in its rest frame, may produce an electron-positron pair. Our measurements address higher-order QED, using the strong electric fields obtainable along particular crystallographic directions in single
Experimental investigation of strong field trident production
Esberg, J; Knudsen, H; Thomsen, H D; Uggerhøj, E; Uggerhøj, U I; Sona, P; Mangiarotti, A; Ketel, T J; Dizdar, A; Dalton, M M; Ballestrero, S; Connell, S H
2010-01-01
We show by experiment that an electron impinging on an electric field that is of critical magnitude in its rest frame, may produce an electron-positron pair. Our measurements address higher-order QED, using the strong electric fields obtainable along particular crystallographic directions in single crystals. For the amorphous material our data are in good agreement with theory, whereas a discrepancy with theory on the magnitude of the trident enhancement is found in the precisely aligned case where the strong electric field acts.
Semicalssical quantization of interacting anyons in a strong magnetic field
International Nuclear Information System (INIS)
Levit, S.; Sivan, N.
1992-01-01
We represent a semiclassical theory of charged interacting anyons in strong magnetic fields. We apply this theory to a number of few anyons systems including two interacting anyons in the presence of an impurity and three interacting anyons. We discuss the dependence of their energy levels on the statistical parameter and find regions in which this dependence follows very different patterns. The semiclassical arguments allow to correlate these patterns with the change in the character of the classical motion of the system. (author)
Electromagnetic processes in strong crystalline fields
2007-01-01
We propose a number of new investigations on aspects of radiation from high energy electron and positron beams (10-300 GeV) in single crystals and amorphous targets. The common heading is radiation emission by electrons and positrons in strong electromagnetic fields, but as the setup is quite versatile, other related phenomena in radiation emission can be studied as well. The intent is to clarify the role of a number of important aspects of radiation in strong fields as e.g. observed in crystals. We propose to measure trident 'Klein-like' production in strong crystalline fields, 'crystalline undulator' radiation, 'sandwich' target phenomena, LPM suppression of pair production as well as axial and planar effects in contributions of spin to the radiation.
Electromagnetic Processes in strong Crystalline Fields
2007-01-01
We propose a number of new investigations on aspects of radiation from high energy electron and positron beams (10-300 GeV) in single crystals and amorphous targets. The common heading is radiation emission by electrons and positrons in strong electromagnetic fields, but as the setup is quite versatile, other related phenomena in radiation emission can be studied as well. The intent is to clarify the role of a number of important aspects of radiation in strong fields as e.g. observed in crystals. We propose to measure trident 'Klein-like' production in strong crystalline fields, 'crystalline undulator' radiation, 'sandwich' target phenomena, LPM suppression of pair production as well as axial and planar effects in contributions of spin to the radiation.
Beyond Quantum Fields: A Classical Fields Approach to QED
Directory of Open Access Journals (Sweden)
Chafin C.
2015-07-01
Full Text Available A classical field theory is introduced that is defined on a tower of dimensionally in- creasing spaces and is argued to be equivalent to QED. The domain of dependence is discussed to show how an equal times picture of the many coordinate space gives QED results as part of a well posed initial value formalism. Identical particle symmetries are not, a priori, required but when introduced are clearly propagated. This construc- tion uses only classical fields to provide some explanation for why quantum fields and canonical commutation results have been successful. Some old and essential questions regarding causality of propagators are resolved. The problem of resummation, gener- ally forbidden for conditionally convergent series, is dis cussed from the standpoint of particular truncations of the infinite tower of functions an d a two step adiabatic turn on for scattering. As a result of this approach it is shown that the photon inherits its quantization ~ ω from the free lagrangian of the Dirac electrons despite the fact that the free electromagnetic lagrangian has no ~ in it. This provides a possible explanation for the canonical commutation relations for quantum operators , [ ˆ P , ˆ Q ] = i ~ , without ever needing to invoke such a quantum postulate. The form of the equal times conservation laws in this many particle field theory suggests a simplification of the radiation reaction process for fields that allows QED to arise from a sum of path integrals in the various particle time coordinates. A novel method of unifying this theory with gravity, but that has no obvious quantum field theoretic computational scheme , is introduced.
Hydrogen atoms in a strong magnetic field
International Nuclear Information System (INIS)
Santos, R.R. dos.
1975-07-01
The energies and wave functions of the 14 lowest states of a Hydrogen atom in a strong magnetic field are calculated, using a variational scheme. The equivalence between the atomic problem and the problems related with excitons and impurities in semiconductors in the presence of a strong magnetic field are shown. The calculations of the energies and wave functions have been divided in two regions: the first, for the magnetic field ranging between zero and 10 9 G; in the second the magnetic field ranges between 10 9 and 10 11 G. The results have been compared with those obtained by previous authors. The computation time necessary for the calculations is small. Therefore this is a convenient scheme to obtain the energies and wave functions for the problem. Transition probabilities, wavelengths and oscillator strengths for some allowed transitions are also calculated. (Author) [pt
Controlling Josephson dynamics by strong microwave fields
Chesca, B.; Savel'ev, E.; Rakhmanov, A.L.; Smilde, H.J.H.; Hilgenkamp, Johannes W.M.
2008-01-01
We observe several sharp changes in the slope of the current-voltage characteristics (CVCs) of thin-film ramp-edge Josephson junctions between YBa2Cu3O7−delta and Nb when applying strong microwave fields. Such behavior indicates an intriguing Josephson dynamics associated with the switching from a
Bound states in a strong magnetic field
International Nuclear Information System (INIS)
Machado, C. S.; Navarra, F. S.; Noronha, J.; Oliveira, E. G.; Ferreira Filho, L. G.
2013-01-01
We expect a strong magnetic field to be produced in the perpendicular direction to the reaction plane, in a noncentral heavy-ion collision . The strength of the magnetic field is estimated to be eB∼m 2 π ∼ 0.02 GeV 2 at the RHIC and eB∼ 15m 2 π ∼ 0.3 GeV 2 at the LHC. We investigate the effects of the magnetic field on B 0 and D 0 mesons, focusing on the changes of the energy levels and of the mass of the bound states.
Quantum electrodynamics in strong external fields
International Nuclear Information System (INIS)
Mueller, B.; Rafelski, J.; Kirsch, J.
1981-05-01
We review the theoretical description of quantum electrodynamics in the presence of strong and supercritical fields. In particular, the process of the spontaneous vacuum decay accompanied by the observable positron emission in heavy ion collisions is described. Emphasis is put on the proper formulation of many-body aspects in the framework of quantum field theory. The extension of the theory to the description of Bose fields and many-body effects is presented, and the Klein paradox is resolved. Some implications of the theoretical methods developed here are presented concerning non-abelian gauge theories and the quark confinement puzzle. (orig.)
Description of collisionless plasmas by classical field equations
International Nuclear Information System (INIS)
Fraley, G.S.
1975-10-01
Classical field equations are derived from quantum fields to obtain a different and possibly simpler description of a collisionless plasma. The method is to take the simultaneous limit, Dirac constant, e, m → 0, of charged scalar fields and the electromagnetic field. Laplace transforms for perturbations in a uniform relativistic plasma are compared with corresponding results from the Maxwell--Vlasov equations. For the nonlinear case, a distribution function defined on the classical fields is shown to satisfy the Vlasov equation
Violation of quantum inequalities with classical fields
International Nuclear Information System (INIS)
Barros, J. Acacio de; Sant'Anna, Adonai S.
1997-01-01
We use as experimental configuration two classical sources α 1 (θ 1 ) with θ 1 phase, and α 2 (θ 2 ) with θ 2 phase, and a third one u(θ) with unknown phase, to be studied. The configuration has two homodyne detections (D 1 , D 2 ) and (D 3 , D 4 ). We compute the correlation functions which violate the inequalities. We calculate the classical intensities for the four detectors used in configuration. These intensities are conditioned in the θ variable. For obtaining the unconditional intensities we assume an uniform distribution for θ, and integrate the expressions for all the possible θ values
Approximation for a Coulomb-Volkov solution in strong fields
Reiss, H. R.; Krainov, V. P.
1994-08-01
A simple analytical approximation is found for the wave function of an electron simultaneously exposed to a strong, circularly polarized plane-wave field and an atomic Coulomb potential. The approximation is valid when α0>>1, where α0 is the classical radius of motion of a free electron in the plane-wave field. This constraint is sufficiently mild at low frequencies that it makes possible a major extension of the lower bound of laser intensities for which Volkov-solution-based approximations are useful.
Generalized classical mechanics and field theory
International Nuclear Information System (INIS)
De Leon, M.; Rodrigues, P.R.
1985-01-01
The aim of this book is to build up a large panel of the present situation of Lagrangian and Hamiltonian formalisms involving higher order derivatives. The achievements of differential geometry in formulating a more modern and powerful treatment of these theories are developed. An extensive review of the development of these theories in classical language is also given. (Auth.)
Classical and quantum Big Brake cosmology for scalar field and tachyonic models
Energy Technology Data Exchange (ETDEWEB)
Kamenshchik, A. Yu. [Dipartimento di Fisica e Astronomia and INFN, Via Irnerio 46, 40126 Bologna (Italy) and L.D. Landau Institute for Theoretical Physics of the Russian Academy of Sciences, Kosygin str. 2, 119334 Moscow (Russian Federation); Manti, S. [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy)
2013-02-21
We study a relation between the cosmological singularities in classical and quantum theory, comparing the classical and quantum dynamics in some models possessing the Big Brake singularity - the model based on a scalar field and two models based on a tachyon-pseudo-tachyon field . It is shown that the effect of quantum avoidance is absent for the soft singularities of the Big Brake type while it is present for the Big Bang and Big Crunch singularities. Thus, there is some kind of a classical - quantum correspondence, because soft singularities are traversable in classical cosmology, while the strong Big Bang and Big Crunch singularities are not traversable.
Classical and quantum Big Brake cosmology for scalar field and tachyonic models
International Nuclear Information System (INIS)
Kamenshchik, A. Yu.; Manti, S.
2013-01-01
We study a relation between the cosmological singularities in classical and quantum theory, comparing the classical and quantum dynamics in some models possessing the Big Brake singularity - the model based on a scalar field and two models based on a tachyon-pseudo-tachyon field . It is shown that the effect of quantum avoidance is absent for the soft singularities of the Big Brake type while it is present for the Big Bang and Big Crunch singularities. Thus, there is some kind of a classical - quantum correspondence, because soft singularities are traversable in classical cosmology, while the strong Big Bang and Big Crunch singularities are not traversable.
Frictional Coulomb drag in strong magnetic fields
DEFF Research Database (Denmark)
Bønsager, Martin Christian; Flensberg, Karsten; Hu, Ben Yu-Kuang
1997-01-01
A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21) is eval......A treatment of frictional Coulomb drag between two two-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity rho(21......) is evaluated using diagrammatic techniques. The transresistivity is given by an integral over energy and momentum transfer weighted by the product of the screened interlayer interaction and the phase space for scattering events. We demonstrate, by a numerical analysis of the transresistivity, that for well...
Neutrino oscillations in strong magnetic fields
International Nuclear Information System (INIS)
Likhachev, G.G.; Studenikin, A.I.
1994-07-01
Neutrino conversion processes between two neutrino species and the corresponding oscillations induced by strong magnetic fields are considered. The value of the critical strength of magnetic field B cr as a function of characteristics of neutrinos in vacuum (Δm 2 ν , mixing angle θ), effective particle density of matter n eff , neutrino (transition) magnetic moment μ-tilde and energy E is introduced. It is shown that the neutrino conversion and oscillations effects induced by magnetic fields B ≥ B cr are important and may result in the depletion of the initial type of ν's in the bunch. A possible increase of these effects in the case when neutrinos pass through a sudden decrease of density of matter (''cross-boundary effect'') and applications to neutrinos from neutron stars and supernova are discussed. (author). 25 refs
Stable states in a strong IR field
Zhong, Changchun; Robicheaux, Francis
2015-05-01
It is found that 10% of atoms stay in the quasi-stable states after being exposed to intense laser or microwave (MW) pulses, even though the pulses' intensity is much stronger than that needed for static fields ionization. The reason why atoms survive those strong pulses has attracted growing attentions. A. Arakelyan et al. have observed the optical spectra of the surviving Lithium atoms after interaction with intense 38-GHz MW fields for more than 1000 cycles, and the spectra exhibit a periodic train of peaks 38 GHz apart. It suggests that those weakly bound Rydberg electrons seldom go back to the ionic core, where the cycle average energy exchange happens. In this study, we are interested in the electron behavior in the presence of intense infrared fields with a much shorter wavelength (1000 nm). By solving the full 3D time dependent Schrodinger equation, we calculate the spectra of the surviving atoms under intense IR fields. Our numerical calculations show atoms survive the intense field in quasi-stable states for a long time, and the optical spectra are obviously modulated by the IR frequency. Through tuning the ponderomotive energy, we see how field parameters affect the behavior of electrons. Different atoms, such as Hydrogen, Helium, Lithium, and Sodium, are tested to see how atom's energy structures influence the results.
Strong-field short-pulse nondipole dynamics
DEFF Research Database (Denmark)
Dimitrovski, Darko; Førre, Morten; Madsen, Lars Bojer
2009-01-01
We present a quantitative investigation of strong-field short-pulse nondipole dynamics in laser-matter interactions. We find excellent agreement between ab initio numerical and analytic results obtained using the Magnus expansion. We show that in the short-pulse limit, ultrafast transfer and cont......We present a quantitative investigation of strong-field short-pulse nondipole dynamics in laser-matter interactions. We find excellent agreement between ab initio numerical and analytic results obtained using the Magnus expansion. We show that in the short-pulse limit, ultrafast transfer...... and control of population can be achieved using nondipole effects. The relative importance of nondipole to dipole effects depends on the displacement imparted to a free classical electron....
Haba, Naoyuki; Yamada, Toshifumi
2017-06-01
We investigate the scenario where the standard model is extended with classical scale invariance, which is broken by chiral symmetry breaking and confinement in a new strongly coupled gauge theory that resembles QCD. The standard model Higgs field emerges as a result of the mixing of a scalar meson in the new strong dynamics and a massless elementary scalar field. The mass and scalar decay constant of that scalar meson, which are generated dynamically in the new gauge theory, give rise to the Higgs field mass term, automatically possessing the correct negative sign by the bosonic seesaw mechanism. Using analogy with QCD, we evaluate the dynamical scale of the new gauge theory and further make quantitative predictions for light pseudo-Nambu-Goldstone bosons associated with the spontaneous breaking of axial symmetry along chiral symmetry breaking in the new gauge theory. A prominent consequence of the scenario is that there should be a standard model gauge singlet pseudo-Nambu-Goldstone boson with mass below 220 GeV, which couples to two electroweak gauge bosons through the Wess-Zumino-Witten term, whose strength is thus determined by the dynamical scale of the new gauge theory. Other pseudo-Nambu-Goldstone bosons, charged under the electroweak gauge groups, also appear. Concerning the theoretical aspects, it is shown that the scalar quartic coupling can vanish at the Planck scale with the top quark pole mass as large as 172.5 GeV, realizing the flatland scenario without being in tension with the current experimental data.
Grassmann expansion of the classical N=2 supergravity field equations
International Nuclear Information System (INIS)
Embacher, F.
1984-01-01
The classical field equations of N=2 supergravity are expanded with respect to an infinite dimensional Grassmann algebra. The general freedom in constructing classical solution is exhibited. As an application, a uniqueness theorem for supersymmetric extreme black holes is given. (Author)
Theoretical Femtosecond Physics Atoms and Molecules in Strong Laser Fields
Grossmann, Frank
2008-01-01
Theoretical femtosecond physics is a new field of research. Theoretical investigations of atoms and molecules interacting with pulsed or continuous wave lasers of up to atomic field strengths are leading to an understanding of many challenging experimental discoveries. Laser-matter interaction is treated on a nonperturbative level in the book using approximate and numerical solutions of the time-dependent Schrödinger equation. The light field is treated classically. Physical phenomena, ranging from ionization of atoms to the ionization and dissociation of molecules and the control of chemical reactions are presented and discussed. Theoretical background for experiments with strong and short laser pulses is given. Several exercises are included in the main text. Some detailed calculations are performed in the appendices.
Asymptotic Conservation Laws in Classical Field Theory
International Nuclear Information System (INIS)
Anderson, I.M.; Torre, C.G.
1996-01-01
A new, general, field theoretic approach to the derivation of asymptotic conservation laws is presented. In this approach asymptotic conservation laws are constructed directly from the field equations according to a universal prescription which does not rely upon the existence of Noether identities or any Lagrangian or Hamiltonian formalisms. The resulting general expressions of the conservation laws enjoy important invariance properties and synthesize all known asymptotic conservation laws, such as the Arnowitt-Deser-Misner energy in general relativity. copyright 1996 The American Physical Society
Quantum and Classical Strong Direct Product Theorems and Optimal Time-Space Tradeoffs
Klauck, H.; Spalek, R.; de Wolf, R.M.
2004-01-01
A strong direct product theorem says that if we want to compute k independent instances of a function, using less than k times the resources needed for one instance, then our overall success probability will be exponentially small in k. We establish such theorems for the classical as well as quantum
Quantum and Classical Strong Direct Product Theorems and Optimal Time-Space Tradeoffs
Klauck, H.; Špalek, R.; de Wolf, R.
2007-01-01
A strong direct product theorem says that if we want to compute k independent instances of a function, using less than k times the resources needed for one instance, then our overall success probability will be exponentially small in k. We establish such theorems for the classical as well as quantum
Lectures on classical and quantum theory of fields
Arodz, Henryk
2017-01-01
This textbook addresses graduate students starting to specialize in theoretical physics. It provides didactic introductions to the main topics in the theory of fields, while taking into account the contemporary view of the subject. The student will find concise explanations of basic notions essential for applications of the theory of fields as well as for frontier research in theoretical physics. One third of the book is devoted to classical fields. Each chapter contains exercises of varying degree of difficulty with hints or solutions, plus summaries and worked examples as useful. It aims to deliver a unique combination of classical and quantum field theory in one compact course.
Classical and quantum electrodynamics and the B(3) field
Evans, Myron W
2001-01-01
It is well known that classical electrodynamics is riddled with internal inconsistencies springing from the fact that it is a linear, Abelian theory in which the potentials are unphysical. This volume offers a self-consistent hypothesis which removes some of these problems, as well as builds a framework on which linear and nonlinear optics are treated as a non-Abelian gauge field theory based on the emergence of the fundamental magnetizing field of radiation, the B(3) field. Contents: Interaction of Electromagnetic Radiation with One Fermion; The Field Equations of Classical O (3) b Electrodyn
Classical Solutions in Quantum Field Theory
International Nuclear Information System (INIS)
Mann, Robert
2013-01-01
Quantum field theory has evolved from its early beginnings as a tool for understanding the interaction of light with matter into a rather formidable technical paradigm, one that has successfully provided the mathematical underpinnings of all non-gravitational interactions. Over the eight decades since it was first contemplated the methods have become increasingly more streamlined and sophisticated, yielding new insights into our understanding of the subatomic world and our abilities to make clear and precise predictions. Some of the more elegant methods have to do with non-perturbative and semiclassical approaches to the subject. The chief players here are solitons, instantons, and anomalies. Over the past three decades there has been a steady rise in our understanding of these objects and of our ability to calculate their effects and implications for the rest of quantum field theory. This book is a welcome contribution to this subject. In 12 chapters it provides a clear synthesis of the key developments in these subjects at a level accessible to graduate students that have had an introductory course to quantum field theory. In the author's own words it provides both 'a survey and an overview of this field'. The first half of the book concentrates on solitons-–kinks, vortices, and magnetic monopoles-–and their implications for the subject. The reader is led first through the simplest models in one spatial dimension, into more sophisticated cases that required more advanced topological methods. The author does quite a nice job of introducing the various concepts as required, and beginning students should be able to get a good grasp of the subject directly from the text without having to first go through the primary literature. The middle part of the book deals with the implications of these solitons for both cosmology and for duality. While the cosmological discussion is quite nice, the discussion on BPS solitons, supersymmetry and duality is
Classical field configurations and infrared slavery
Swanson, Mark S.
1987-09-01
The problem of determining the energy of two spinor particles interacting through massless-particle exchange is analyzed using the path-integral method. A form for the long-range interaction energy is obtained by analyzing an abridged vertex derived from the parent theory. This abridged vertex describes the radiation of zero-momentum particles by pointlike sources. A path-integral formalism for calculating the energy of the radiation field associated with this abridged vertex is developed and applications are made to determine the energy necessary for adiabatic separation of two sources in quantum electrodynamics and for an SU(2) Yang-Mills theory. The latter theory is shown to be consistent with confinement via infrared slavery.
Lectures on classical and quantum theory of fields
Energy Technology Data Exchange (ETDEWEB)
Arodz, Henryk; Hadasz, Leszek [Jagiellonian Univ., Krakow (Poland). Inst. Physics
2010-07-01
This textbook on classical and quantum theory of fields addresses graduate students starting to specialize in theoretical physics. It provides didactic introductions to the main topics in the theory of fields, while taking into account the contemporary view of the subject. The student will find concise explanations of basic notions essential for applications of the theory of fields as well as for frontier research in theoretical physics. One third of the book is devoted to classical fields. Each chapter contains exercises of varying degree of difficulty with hints or solutions, plus summaries and worked examples as useful. The textbook is based on lectures delivered to students of theoretical physics at Jagiellonian University. It aims to deliver a unique combination of classical and quantum field theory in one compact course. (orig.)
Achieving the classical Carnot efficiency in a strongly coupled quantum heat engine
Xu, Y. Y.; Chen, B.; Liu, J.
2018-02-01
Generally, the efficiency of a heat engine strongly coupled with a heat bath is less than the classical Carnot efficiency. Through a model-independent method, we show that the classical Carnot efficiency is achieved in a strongly coupled quantum heat engine. First, we present the first law of quantum thermodynamics in strong coupling. Then, we show how to achieve the Carnot cycle and the classical Carnot efficiency at strong coupling. We find that this classical Carnot efficiency stems from the fact that the heat released in a nonequilibrium process is balanced by the absorbed heat. We also analyze the restrictions in the achievement of the Carnot cycle. The first restriction is that there must be two corresponding intervals of the controllable parameter in which the corresponding entropies of the work substance at the hot and cold temperatures are equal, and the second is that the entropy of the initial and final states in a nonequilibrium process must be equal. Through these restrictions, we obtain the positive work conditions, including the usual one in which the hot temperature should be higher than the cold, and a new one in which there must be an entropy interval at the hot temperature overlapping that at the cold. We demonstrate our result through a paradigmatic model—a two-level system in which a work substance strongly interacts with a heat bath. In this model, we find that the efficiency may abruptly decrease to zero due to the first restriction, and that the second restriction results in the control scheme becoming complex.
Dynamics of classical and quantum fields an introduction
Setlur, Girish S
2014-01-01
Dynamics of Classical and Quantum Fields: An Introduction focuses on dynamical fields in non-relativistic physics. Written by a physicist for physicists, the book is designed to help readers develop analytical skills related to classical and quantum fields at the non-relativistic level, and think about the concepts and theory through numerous problems. In-depth yet accessible, the book presents new and conventional topics in a self-contained manner that beginners would find useful. A partial list of topics covered includes: Geometrical meaning of Legendre transformation in classical mechanics Dynamical symmetries in the context of Noether's theorem The derivation of the stress energy tensor of the electromagnetic field, the expression for strain energy in elastic bodies, and the Navier Stokes equation Concepts of right and left movers in case of a Fermi gas explained Functional integration is interpreted as a limit of a sequence of ordinary integrations Path integrals for one and two quantum particles and for...
Solitons and their interactions in classical field theory
International Nuclear Information System (INIS)
Belova, T.I.; Kudryavtsev, A.E.
1997-01-01
Effects of nonlinearity in the classical field theory for non-integrated systems are considered, such as soliton scattering, soliton bound states, the fractal nature of resonant structures, kink scattering by inhomogeneities, and domain bladder collapse. The results are presented in both (1 + 1) and higher dimensions. Both neutral and charged scalar fields are considered. Possible applications areas for the nonlinearity effects are discussed
Modern Classical Electrodynamics and Electromagnetic Radiation - Vacuum Field Theory Aspects
Bogolubov, N. N.; Prykarpatsky, A. K.
2012-01-01
The work is devoted to studying some new classical electrodynamics models of interacting charged point particles and related with them physical aspects. Based on the vacuum field theory no-geometry approach, developed in \\cite{BPT,BPT1}, the Lagrangian and Hamiltonian reformulations of some alternative classical electrodynamics models are devised. A problem closely related to the radiation reaction force is analyzed aiming to explain the Wheeler and Feynman reaction radiation mechanism, well ...
Strong-field ionization of polar molecules: Stark-shift-corrected strong-field approximation
DEFF Research Database (Denmark)
Dimitrovski, Darko; Martiny, Christian P. J.; Madsen, Lars Bojer
2010-01-01
We extend the molecular strong-field approximation for ionization, in the tunneling limit, to include systematically the linear and quadratic static Stark shifts of the ionizing molecular orbital. This approach, simple to implement, is capable of describing the essential physics of the process of...
Second quantization of classical nonlinear relativistic field theory. Pt. 2
International Nuclear Information System (INIS)
Balaban, T.
1976-01-01
The construction of a relativistic interacting local quantum field is given in two steps: first the classical nonlinear relativistic field theory is written down in terms of Poisson brackets, with initial conditions as canonical variables: next a representation of Poisson bracket Lie algebra by means of linear operators in the topological vector space is given and an explicit form of a local interacting relativistic quantum field PHI is obtained. (orig./BJ) [de
Classical-field model of the hydrogen atom
Rashkovskiy, Sergey A.
2017-06-01
It is shown that all of the basic properties of the hydrogen atom can be consistently described in terms of classical electrodynamics if instead of considering the electron to be a particle, we consider an electrically charged classical wave field—an "electron wave"—which is held by the electrostatic field of the proton. It is shown that quantum mechanics must be considered not as a theory of particles but as a classical field theory in the spirit of classical electrodynamics. In this case, we are not faced with difficulties in interpreting the results of the theory. In the framework of classical electrodynamics, all of the well-known regularities of the spontaneous emission of the hydrogen atom are obtained, which is usually derived in the framework of quantum electrodynamics. It is shown that there are no discrete states and discrete energy levels of the atom: the energy of the atom and its states change continuously. An explanation of the conventional corpuscular-statistical interpretation of atomic phenomena is given. It is shown that this explanation is only a misinterpretation of continuous deterministic processes. In the framework of classical electrodynamics, the nonlinear Schrödinger equation is obtained, which accounts for the inverse action of self-electromagnetic radiation of the electron wave and completely describes the spontaneous emissions of an atom.
Classical field isomorphisms in two-fluid plasmas
International Nuclear Information System (INIS)
Thompson, Richard J.; Moeller, Trevor M.
2012-01-01
Previous work recognized a new framework for the equations of a multifluid plasma, wherein each species can be described by a set of equations remarkably similar to the Maxwell equations of classical electrodynamics. This paper extends the previous effort to form an exact isomorphism between the multifluid theory and classical electrodynamics. The major benefits of the new formulation are that the explicit coupling between different species is minimized, and theorems and techniques of classical electrodynamics can be immediately applied to the new multifluid formulation. We introduce the exact isomorphism and investigate some of the immediate consequences from classical electrodynamics. To provide a visualization of the isomorphism, previous 1D and 2D numerical simulations are postprocessed and presented to illustrate the generalized fields and source terms.
Indian Academy of Sciences (India)
and how the related ideas of relativity affect our formulation of field theories, form the ... problem. While relativity is a strong tool provided by physicists for dealing with the cosmological problem, its early orgins are actually to be found in cosmology. .... dynamical relations of physics is provided by tensor analysis, for the lan-.
Coherence and quasistable states in a strong infrared field
Zhong, Changchun; Robicheaux, F.
2016-03-01
We study the quasistability of UV-pulse-train-excited H atoms in a strong infrared (IR) laser as a function of the phase delay of the UV pulse train relative to the IR laser. The UV pulse train contains two frequency components. When the two components have frequencies separated by two IR photons, the population of surviving electrons is modulated by up to ten percent. When electrons are excited to right above or below the threshold, the survival probabilities have inverted phase delay dependence, which can be explained classically. When the two frequencies are one IR photon apart, the angular symmetry of the quasistable electrons is broken, and the asymmetry is also controlled by the phase delay. The asymmetrical distribution can be observed while the IR is on and smoothly evolves to a nonzero asymmetry that only weakly depends on the duration of the IR field.
Construction of classical and quantum integrable field models ...
Indian Academy of Sciences (India)
85, No. 5. — journal of. November 2015 physics pp. 899–913. Construction of classical and quantum integrable field models unravelling hidden possibilities .... It is interesting to note that the infinite set of conserved quantities associated with an inte- ..... that taking c2 as the Hamiltonian would lead to a NLS-type equation.
Linear classical stability from three coupled real scalar fields
International Nuclear Information System (INIS)
Rodrigues, R. de Lima; Silva Filho, Pedro Barbosa da; Vaidya, A.N.
1997-01-01
We investigate the linear classical stability of static solitons for a system of three coupled real scalar fields in 1+1 dimensions. We consider a general positive potential with a square form and show that the associated three-component normal modes are non-negatives. (author)
Constrained variational calculus for higher order classical field theories
International Nuclear Information System (INIS)
Campos, Cedric M; De Leon, Manuel; De Diego, David MartIn
2010-01-01
We develop an intrinsic geometrical setting for higher order constrained field theories. As a main tool we use an appropriate generalization of the classical Skinner-Rusk formalism. Some examples of applications are studied, in particular to the geometrical description of optimal control theory for partial differential equations.
Correlated electron-ion collisions in a strong laser field
International Nuclear Information System (INIS)
Ristow, T.
2007-01-01
Electron-ion-collisions in plasmas in the presence of an ultra-short intensive laser pulse can cause high energy transfers to the electrons. During the collision the oscillation energy of the electron in the laser field is changed into drift energy. In this regime, multi-photon processes, known from the ionization of neutral atoms (Above-Threshold Ionization), and successive, so called correlated collisions, are important. The subject of the thesis is a study of binary Coulomb collisions in strong laser fields. The collisions are treated both in the context of classical Newtonian mechanics and in the quantum-mechanical framework by the Schroedinger equation. In the classical case a simplified instantaneous collision model and a complete dynamical treatment are discussed. Collisions can be treated instantaneously, if the ratio of the impact parameter to the quiver amplitude is small. The energy distributions calculated in this approximation show an elastic peak and a broad plateau due to rescattered electrons. At incident velocities smaller than the quiver velocity, correlated collisions are observed in the electron trajectories of the dynamical model. This effect leads to characteristic momentum distributions of the electrons, that are explicitly calculated and compared with the results of the instantaneous model. In addition, the time-dependence of the collisions is discussed in the framework of a singular perturbation theory. The complete description of the Coulomb scattering requires a quantum-mechanical description. A time-dependent method of wave-packet scattering is used and the corresponding time-dependent three-dimensional Schroedinger equation is solved by an implicit ADImethod on a spatial grid. The momentum and the energy distributions of the scattered electrons are calculated by the Fourier transformation of the wavefunction. A comparison of the scattering from a repulsive and an attractive potential is used to distinguish between simple collisions and
Classical electromagnetic field theory in the presence of magnetic sources
Chen, Wen-Jun; Li, Kang; Naón, Carlos
2001-01-01
Using two new well defined 4-dimensional potential vectors, we formulate the classical Maxwell's field theory in a form which has manifest Lorentz covariance and SO(2) duality symmetry in the presence of magnetic sources. We set up a consistent Lagrangian for the theory. Then from the action principle we get both Maxwell's equation and the equation of motion of a dyon moving in the electro-magnetic field.
International Nuclear Information System (INIS)
Chaturvedi, D.K.; Senatore, G.; Tosi, M.P.
1980-10-01
An analytic theory is presented for the static structure factor of the one-component classical plasma at strong couplings. The theory combines the hard-core model of Gillan for short-range correlations in the Coulomb fluid with a semiempirical representation of intermediate-range correlations, through which the requirement of thermodynamic consistency on the ''compressibility'' and the known equation of state of the system are satisfied. Excellent agreement is found with the available computer simulation data on the structure of the fluid. The approach becomes inapplicable at intermediate and weak couplings where effects of penetration in the Coulomb hole of each particle become important. (author)
Indian Academy of Sciences (India)
Volume 4 Issue 11 November 1999 pp 88-88 Classics. Introduction to Classics Essay · Max Delbrück · More Details Fulltext PDF. Volume 4 Issue 11 November 1999 pp 89-102 Classics. A Physicist Looks at Biology · Max Delbrück · More Details Fulltext PDF. Volume 5 Issue 3 March 2000 pp 105-105 Classics. Introduction.
Theoretical femtosecond physics atoms and molecules in strong laser fields
Grossmann, Frank
2018-01-01
This textbook extends from the basics of femtosecond physics all the way to some of the latest developments in the field. In this updated edition, the chapter on laser-driven atoms is augmented by the discussion of two-electron atoms interacting with strong and short laser pulses, as well as by a review of ATI rings and low energy structures in photo-electron spectra. In the chapter on laser-driven molecules a discussion of 2D infrared spectroscopy is incorporated. Theoretical investigations of atoms and molecules interacting with pulsed lasers up to atomic field strengths on the order of 10^16 W/cm² are leading to an understanding of many challenging experimental discoveries. The presentation starts with a brief introduction to pulsed laser physics. The basis for the non-perturbative treatment of laser-matter interaction in the book is the time-dependent Schrödinger equation. Its analytical as well as numerical solution are laid out in some detail. The light field is treated classically and different possi...
Waves in strong centrifugal fields: dissipationless gas
Bogovalov, S. V.; Kislov, V. A.; Tronin, I. V.
2015-04-01
Linear waves are investigated in a rotating gas under the condition of strong centrifugal acceleration of the order 106 g realized in gas centrifuges for separation of uranium isotopes. Sound waves split into three families of the waves under these conditions. Dispersion equations are obtained. The characteristics of the waves strongly differ from the conventional sound waves on polarization, velocity of propagation and distribution of energy of the waves in space for two families having frequencies above and below the frequency of the conventional sound waves. The energy of these waves is localized in rarefied region of the gas. The waves of the third family were not specified before. They propagate exactly along the rotational axis with the conventional sound velocity. These waves are polarized only along the rotational axis. Radial and azimuthal motions are not excited. Energy of the waves is concentrated near the wall of the rotor where the density of the gas is largest.
Strongly Interacting Matter in Magnetic Field
Mao, Shijun; Wu, Youjia; Zhuang, Pengfei
Inverse magnetic catalysis effect on the chiral phase transition is investigated in the frame of SU(2) NJL model with Pauli-Villars regularization scheme. We consider two scenarios, the chiral chemical potential μ5 caused by sphalerons and magnetic inhibition of mesons π0. With different chiral chemical potential, we always obtain magnetic catalysis in the mean field calculation, due to the enhancement of Fermi surface of the pairing fermions by μ5. On the other hand, when going beyond the mean field approximation by including the feed-down from mesons to quarks, the competition between the magnetic catalysis effect of quarks and magnetic inhibition effect of mesons leads to the transition from inverse magnetic catalysis to delayed magnetic catalysis with increasing magnetic field.
Difference of observability between classical electromagnetic and gravitational gauge fields
International Nuclear Information System (INIS)
Asorey, M.; Boya, L.J.
1979-01-01
An analysis of the observability of the classical electromagnetic gauge field based in its quantum effects shows that this is physically determined up to equivalences. By contrast a similar analysis of the gravitational gauge field from Einstein's General Relativity theory shows that this field is univocally determined by the trajectories of material particles provided they feel only that gravitational field, and its proper gravitational and quantum effects are negligible. This difference of observability in both kinds of gauge fields is caused by the attachment of the gravitational field in the Einstein theory to the space-time, and this difference must be taken into account to formulate unified gauge theories with both kinds of fields. (author)
Strong terahertz field generation, detection, and application
Energy Technology Data Exchange (ETDEWEB)
Kim, Ki-Yong [Univ. of Maryland, College Park, MD (United States)
2016-05-22
This report describes the generation and detection of high-power, broadband terahertz (THz) radiation with using femtosecond terawatt (TW) laser systems. In particular, this focuses on two-color laser mixing in gases as a scalable THz source, addressing both microscopic and macroscopic effects governing its output THz yield and radiation profile. This also includes the characterization of extremely broad THz spectra extending from microwaves to infrared frequencies. Experimentally, my group has generated high-energy (tens of microjoule), intense (>8 MV/cm), and broadband (0.01~60 THz) THz radiation in two-color laser mixing in air. Such an intense THz field can be utilized to study THz-driven extremely nonlinear phenomena in a university laboratory.
Strong terahertz field generation, detection, and application
Energy Technology Data Exchange (ETDEWEB)
Kim, Ki-Yong [Univ. of Maryland, College Park, MD (United States)
2016-05-15
This report describes the generation and detection of high-power, broadband terahertz (THz) radiation with using femtosecond terawatt (TW) laser systems. In particular, this focuses on two-color laser mixing in gases as a scalable THz source, addressing both microscopic and macroscopic effects governing its output THz yield and radiation profile. This also includes the characterization of extremely broad THz spectra extending from microwaves to infrared frequencies. Experimentally, my group has generated high-energy (tens of microjoule), intense (>8 MV/cm), and broadband (0.01~60 THz) THz radiation in two-color laser mixing in air. Such an intense THz field can be utilized to study THz-driven extremely nonlinear phenomena in a university laboratory.
Quantum mechanics from statistical mechanics of classical fields
Khrennikov, Andrei
2007-05-01
We show that QM can be represented as a natural projection of a classical statistical model on the phase space Ω = H × H, where His the real Hilbert space. Statistical states are given by Gaussian measures on Ω having zero mean value and dispersion of very small magnitude α (which is considered as a small parameter of the model). Such statistical states can be interpreted as fluctuations of the background field, cf. with SED and Nelson's mechanics. Physical variables (e.g., energy) are given by maps f: Ω → R (functions of classical fields). The conventional quantum representation of our prequantum classical statistical model is constructed on the basis of the Taylor expansion (up to the terms of the second order at the vacuum field point ψvacuum ≡ 0) of variables f: Ω → R with respect to the small parameter √α The complex structure of QM is induced by the symplectic structure on the infinite-dimensional phase space Ω. A Gaussian measure (statistical state) is represented in QM by its covariation operator. Equations of Schrödinger, Heisenberg and von Neumann are images of Hamiltonian dynamics on Ω. The main experimental prediction of our prequantum model is that experimental statistical averages can deviate from ones given by QM.
Electromagnetic processes in strong crystalline fields
Uggerhoj, U I; Esberg, J; Knudsen, H; Lund, M; Møller, S P; Sørensen, A H; Thomsen, A H; Uggerhøj, U I; Geissel, H; Scheidenberger, C; Weick, H; Winfield, J; Sona, P; Connell S; Ballestrero, S; Ketel, T; Dizdar, A; Mangiarotti, A
2009-01-01
As an addendum to the NA63 proposal cite{Ande05}, we propose to measure 1) the Landau-Pomeranchuk-Migdal (LPM) effect in low-$Z$ targets, 2) Magnetic suppression of incoherent bremsstrahlung resulting from exposure to an external field during the emission event, and 3) the bremsstrahlung emission from relativistic ($gamma=170$), fully stripped Pb nuclei penetrating various amorphous targets. Concerning the LPM effect, both the 'traditional' Migdal approach and the modern treatment by Baier and Katkov display inaccuracies, i.e. a possible lack of applicability in low-$Z$ targets. Moreover, the LPM effect has been shown to have a significant impact on giant air showers for energies in the EeV range - evidently processes in a low-$Z$ material. A measurement of magnetic suppression is demanding in terms of necessary accuracy (an expected $lesssim$15% effect), but would prove the existence of a basic interplay between coherent and incoherent processes, also believed to be significant in beamstrahlung emission. For...
Classical Spin Liquid Instability Driven By Off-Diagonal Exchange in Strong Spin-Orbit Magnets
Rousochatzakis, Ioannis; Perkins, Natalia B.
2017-04-01
We show that the off-diagonal exchange anisotropy drives Mott insulators with strong spin-orbit coupling to a classical spin liquid regime, characterized by an infinite number of ground states and Ising variables living on closed or open strings. Depending on the sign of the anisotropy, quantum fluctuations either fail to lift the degeneracy down to very low temperatures, or select noncoplanar magnetic states with unconventional spin correlations. The results apply to all 2D and 3D tricoordinated materials with bond-directional anisotropy and provide a consistent interpretation of the suppression of the x-ray magnetic circular dichroism signal reported recently for β -Li2IrO3 under pressure.
Nonequilibrium statistical field theory for classical particles: Basic kinetic theory.
Viermann, Celia; Fabis, Felix; Kozlikin, Elena; Lilow, Robert; Bartelmann, Matthias
2015-06-01
Recently Mazenko and Das and Mazenko [Phys. Rev. E 81, 061102 (2010); J. Stat. Phys. 149, 643 (2012); J. Stat. Phys. 152, 159 (2013); Phys. Rev. E 83, 041125 (2011)] introduced a nonequilibrium field-theoretical approach to describe the statistical properties of a classical particle ensemble starting from the microscopic equations of motion of each individual particle. We use this theory to investigate the transition from those microscopic degrees of freedom to the evolution equations of the macroscopic observables of the ensemble. For the free theory, we recover the continuity and Jeans equations of a collisionless gas. For a theory containing two-particle interactions in a canonical perturbation series, we find the macroscopic evolution equations to be described by the Born-Bogoliubov-Green-Kirkwood-Yvon hierarchy with a truncation criterion depending on the order in perturbation theory. This establishes a direct link between the classical and the field-theoretical approaches to kinetic theory that might serve as a starting point to investigate kinetic theory beyond the classical limits.
BOOK REVIEW: Classical Solutions in Quantum Field Theory Classical Solutions in Quantum Field Theory
Mann, Robert
2013-02-01
Quantum field theory has evolved from its early beginnings as a tool for understanding the interaction of light with matter into a rather formidable technical paradigm, one that has successfully provided the mathematical underpinnings of all non-gravitational interactions. Over the eight decades since it was first contemplated the methods have become increasingly more streamlined and sophisticated, yielding new insights into our understanding of the subatomic world and our abilities to make clear and precise predictions. Some of the more elegant methods have to do with non-perturbative and semiclassical approaches to the subject. The chief players here are solitons, instantons, and anomalies. Over the past three decades there has been a steady rise in our understanding of these objects and of our ability to calculate their effects and implications for the rest of quantum field theory. This book is a welcome contribution to this subject. In 12 chapters it provides a clear synthesis of the key developments in these subjects at a level accessible to graduate students that have had an introductory course to quantum field theory. In the author's own words it provides both 'a survey and an overview of this field'. The first half of the book concentrates on solitons--kinks, vortices, and magnetic monopoles--and their implications for the subject. The reader is led first through the simplest models in one spatial dimension, into more sophisticated cases that required more advanced topological methods. The author does quite a nice job of introducing the various concepts as required, and beginning students should be able to get a good grasp of the subject directly from the text without having to first go through the primary literature. The middle part of the book deals with the implications of these solitons for both cosmology and for duality. While the cosmological discussion is quite nice, the discussion on BPS solitons, supersymmetry and duality is rather condensed. It is
Motion of small bodies in classical field theory
International Nuclear Information System (INIS)
Gralla, Samuel E.
2010-01-01
I show how prior work with R. Wald on geodesic motion in general relativity can be generalized to classical field theories of a metric and other tensor fields on four-dimensional spacetime that (1) are second-order and (2) follow from a diffeomorphism-covariant Lagrangian. The approach is to consider a one-parameter-family of solutions to the field equations satisfying certain assumptions designed to reflect the existence of a body whose size, mass, and various charges are simultaneously scaled to zero. (That such solutions exist places a further restriction on the class of theories to which our results apply.) Assumptions are made only on the spacetime region outside of the body, so that the results apply independent of the body's composition (and, e.g., black holes are allowed). The worldline 'left behind' by the shrinking, disappearing body is interpreted as its lowest-order motion. An equation for this worldline follows from the 'Bianchi identity' for the theory, without use of any properties of the field equations beyond their being second-order. The form of the force law for a theory therefore depends only on the ranks of its various tensor fields; the detailed properties of the field equations are relevant only for determining the charges for a particular body (which are the ''monopoles'' of its exterior fields in a suitable limiting sense). I explicitly derive the force law (and mass-evolution law) in the case of scalar and vector fields, and give the recipe in the higher-rank case. Note that the vector force law is quite complicated, simplifying to the Lorentz force law only in the presence of the Maxwell gauge symmetry. Example applications of the results are the motion of 'chameleon' bodies beyond the Newtonian limit, and the motion of bodies in (classical) non-Abelian gauge theory. I also make some comments on the role that scaling plays in the appearance of universality in the motion of bodies.
Quantum averaging and resonances: two-level atom in a one-mode classical laser field
Directory of Open Access Journals (Sweden)
M. Amniat-Talab
2007-06-01
Full Text Available We use a nonperturbative method based on quantum averaging and an adapted from of resonant transformations to treat the resonances of the Hamiltonian of a two-level atom interacting with a one-mode classical field in Floquet formalism. We illustrate this method by extraction of effective Hamiltonians of the system in two regimes of weak and strong coupling. The results obtained in the strong-coupling regime, are valid in the whole range of the coupling constant for the one-photon zero-field resonance.
Electron Dynamics in Nanostructures in Strong Laser Fields
Energy Technology Data Exchange (ETDEWEB)
Kling, Matthias
2014-09-11
The goal of our research was to gain deeper insight into the collective electron dynamics in nanosystems in strong, ultrashort laser fields. The laser field strengths will be strong enough to extract and accelerate electrons from the nanoparticles and to transiently modify the materials electronic properties. We aimed to observe, with sub-cycle resolution reaching the attosecond time domain, how collective electronic excitations in nanoparticles are formed, how the strong field influences the optical and electrical properties of the nanomaterial, and how the excitations in the presence of strong fields decay.
First-order discrete Faddeev gravity at strongly varying fields
Khatsymovsky, V. M.
2017-11-01
We consider the Faddeev formulation of general relativity (GR), which can be characterized by a kind of d-dimensional tetrad (typically d = 10) and a non-Riemannian connection. This theory is invariant w.r.t. the global, but not local, rotations in the d-dimensional space. There can be configurations with a smooth or flat metric, but with the tetrad that changes abruptly at small distances, a kind of “antiferromagnetic” structure. Previously, we discussed a first-order representation for the Faddeev gravity, which uses the orthogonal connection in the d-dimensional space as an independent variable. Using the discrete form of this formulation, we considered the spectrum of (elementary) area. This spectrum turns out to be physically reasonable just on a classical background with large connection like rotations by π, that is, with such an “antiferromagnetic” structure. In the discrete first-order Faddeev gravity, we consider such a structure with periodic cells and large connection and strongly changing tetrad field inside the cell. We show that this system in the continuum limit reduces to a generalization of the Faddeev system. The action is a sum of related actions of the Faddeev type and is still reduced to the GR action.
Nonlinear quantum electrodynamic and electroweak processes in strong laser fields
Energy Technology Data Exchange (ETDEWEB)
Meuren, Sebastian
2015-06-24
Various nonlinear electrodynamic and electroweak processes in strong plane-wave laser fields are considered with an emphasis on short-pulse effects. In particular, the momentum distribution of photoproduced electron-positron pairs is calculated numerically and a semiclassical interpretation of its characteristic features is established. By proving the optical theorem, compact double-integral expressions for the total pair-creation probability are obtained and numerically evaluated. The exponential decay of the photon wave function in a plane wave is included by solving the Schwinger-Dyson equations to leading-order in the quasistatic approximation. In this respect, the polarization operator in a plane wave is investigated and its Ward-Takahashi identity verified. A classical analysis indicates that a photoproduced electron-positron pair recollides for certain initial conditions. The contributions of such recollision processes to the polarization operator are identified and calculated both analytically and numerically. Furthermore, the existence of nontrivial electron-spin dynamics induced by quantum fluctuations is verified for ultra-short laser pulses. Finally, the exchange of weak gauge bosons is considered, which is essential for neutrino-photon interactions. In particular, the axial-vector-vector coupling tensor is calculated and the so-called Adler-Bell-Jackiw (ABJ) anomaly investigated.
Prequantum classical statistical field theory: background field as a source of everything?
Khrennikov, Andrei
2011-07-01
Prequantum classical statistical field theory (PCSFT) is a new attempt to consider quantum mechanics (QM) as an emergent phenomenon, cf. with De Broglie's "double solution" approach, Bohmian mechanics, stochastic electrodynamics (SED), Nelson's stochastic QM and its generalization by Davidson, 't Hooft's models and their development by Elze. PCSFT is a comeback to a purely wave viewpoint on QM, cf. with early Schrodinger. There is no quantum particles at all, only waves. In particular, photons are simply wave-pulses of the classical electromagnetic field, cf. SED. Moreover, even massive particles are special "prequantum fields": the electron field, the neutron field, and so on. PCSFT claims that (sooner or later) people will be able to measure components of these fields: components of the "photonic field" (the classical electromagnetic field of low intensity), electronic field, neutronic field, and so on. At the moment we are able to produce quantum correlations as correlations of classical Gaussian random fields. In this paper we are interested in mathematical and physical reasons of usage of Gaussian fields. We consider prequantum signals (corresponding to quantum systems) as composed of a huge number of wave-pulses (on very fine prequantum time scale). We speculate that the prequantum background field (the field of "vacuum fluctuations") might play the role of a source of such pulses, i.e., the source of everything.
Electrodynamics of a hydrogenlike atom in a strong electromagnetic field
International Nuclear Information System (INIS)
Kovarskij, V.A.; Perel'man, N.F.
1974-01-01
The quasienergy spectrum of the hydrogen atom in strong electromagnetic radiation is studied, the luminescence of the atom under these conditions is considered. It is shown that in a strong field the atom, being even in the ground state, radiates a spectrum of frequencies corresponding to transitions from the ground state into excited states, the strong field photons being involved. The intensity of such a luminescence is basically a non-linear function of the strong field. The exposure of the atom to two strong electromagnetic fields Ω and ω (Ω>>ω) is considered, the Ω coinciding with one of the natural frquencies of the atom. The effct of modulation of the resonance shift for an atomic level by the ω-field strength is predicted. The dependence of Ω-absorption in the ω-field on the statistic properties of the latter is investigated. (author)
On the mathematical theory of classical fields and general relativity
Klainerman, S
1993-01-01
From the perspective of an analyst, like myself, the General Theory of Relativity provides an extrordinary rich and vastly virgin territory. It is the aim of my lecture to provide, ﬁrst, an account of those aspects of the theory which attract me most and second a perspective of what has been accomplished so far in that respect. In trying to state our main objectives it helps to view General Relativity in the broader context of Classical Field Theory. EinsteiniVacuum equations, or shortly E—V, is already sufﬁciently complicated. I will thus restrict my attention to them.
Enhancing Quantum Discord in Cavity QED by Applying Classical Driving Field
International Nuclear Information System (INIS)
Qian Yi; Xu Jing-Bo
2012-01-01
We investigate the quantum discord dynamics in a cavity quantum electrodynamics system, which consists of two noninteracting two-level atoms driven by independent optical fields and classical fields, and find that the quantum discord vanishes only asymptotically although entanglement disappears suddenly during the time evolution in the absence of classical fields. It is shown that the amount of quantum discord can be increased by adjusting the classical driving fields because the increasing degree of the amount of quantum mutual information is greater than classical correlation by applying the classical driving fields. Finally, the influence of the classical driving field on the fidelity of the system is also examined. (general)
Mamo, Kiminad A.
2013-08-01
We calculate the DC conductivity tensor of strongly coupled = 4 super-Yang-Mills (SYM) plasma in a presence of a strong external magnetic field B ≫ T 2 by using its gravity dual and employing both the RG flow approach and membrane paradigm which give the same results. We find that, since the magnetic field B induces anisotropy in the plasma, different components of the DC conductivity tensor have different magnitudes depending on whether its components are in the direction of the magnetic field B. In particular, we find that a component of the DC conductivity tensor in the direction of the magnetic field B increases linearly with B while the other components (which are not in the direction of the magnetic field B) are independent of it. These results are consistent with the lattice computations of the DC conductivity tensor of the QCD plasma in an external magnetic field B. Using the DC conductivity tensor, we calculate the soft or low-frequency thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in the presence of the strong external magnetic field B ≫ T 2. We find that the strong magnetic field B enhances both the thermal photon and dilepton production rates of the strongly coupled = 4 SYM plasma in a qualitative agreement with the experimentally observed enhancements at the heavy-ion collision experiments.
Directory of Open Access Journals (Sweden)
Maruyama Tomoyuki
2016-01-01
Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum-field approach do not agree with those obtained in the semi-classical approach. Furthermore, we also find that the anomalous magnetic moment of the proton greatly enhances the production rate about by two orders of magnitude, and that the polar angle of an emitted pion is the same as that of an initial proton.
Principles of physics from quantum field theory to classical mechanics
Jun, Ni
2014-01-01
This book starts from a set of common basic principles to establish the formalisms in all areas of fundamental physics, including quantum field theory, quantum mechanics, statistical mechanics, thermodynamics, general relativity, electromagnetic field, and classical mechanics. Instead of the traditional pedagogic way, the author arranges the subjects and formalisms in a logical-sequential way, i.e. all the formulas are derived from the formulas before them. The formalisms are also kept self-contained. Most of the required mathematical tools are also given in the appendices. Although this book covers all the disciplines of fundamental physics, the book is concise and can be treated as an integrated entity. This is consistent with the aphorism that simplicity is beauty, unification is beauty, and thus physics is beauty. The book may be used as an advanced textbook by graduate students. It is also suitable for physicists who wish to have an overview of fundamental physics. Readership: This is an advanced gradua...
Geometry of Lagrangian first-order classical field theories
International Nuclear Information System (INIS)
Echeverria-Enriquez, A.; Munoz-Lecanda, M.C.; Roman-Roy, N.
1996-01-01
We construct a lagrangian geometric formulation for first-order field theories using the canonical structures of first-order jet bundles, which are taken as the phase spaces of the systems in consideration. First of all, we construct all the geometric structures associated with a first-order jet bundle and, using them, we develop the lagrangian formalism, defining the canonical forms associated with a lagrangian density and the density of lagrangian energy, obtaining the Euler-Lagrange equations in two equivalent ways: as the result of a variational problem and developing the jet field formalism (which is a formulation more similar to the case of mechanical systems). A statement and proof of Noether's theorem is also given, using the latter formalism. Finally, some classical examples are briefly studied. (orig.)
Strong-field-ionization suppression by light-field control
DEFF Research Database (Denmark)
Räsänen, Esa; Madsen, Lars Bojer
2012-01-01
in the intensity and thus preventing tunneling. In contrast, at high frequencies in the extreme ultraviolet regime the optimized pulses strongly couple with the (de)-excitations of the system, which leads to different pulse characteristics. Finally, we show that the applied target functional works, to some extent...
Ionization of atoms in strong low-frequency electromagnetic field
International Nuclear Information System (INIS)
Krainov, V. P.
2010-01-01
The ionization of atoms in a low-frequency linearly polarized electromagnetic field (the photon energy is much lower than the ionization potential of an atom) is considered under new conditions, in which the Coulomb interaction of an electron with the atomic core in the final state of the continuum cannot be considered in perturbation theory in the interaction of the electron with the electromagnetic field. The field is assumed to be much weaker that the atomic field. In these conditions, the classical motion of the electron in the final state of the continuum becomes chaotic (so-called dynamic chaos). Using the well-known Chirikov method of averaging over chaotic variations of the phase of motion, the problem can be reduced to non-linear diffusion on the energy scale. We calculate the classical electron energy in the final state, which is averaged over fast chaotic oscillations and takes into account both the Coulomb field and the electromagnetic field. This energy is used to calculate the probability of ionization from the ground state of the atom to a lower-lying state in the continuum using the Landau-Dykhne approximation (to exponential accuracy). This ionization probability noticeably depends on the field frequency. Upon a decrease in frequency, a transition to the well-known tunnel ionization limit with a probability independent of the field frequency is considered.
Probing strong field ionization of solids with a Thomson parabola ...
Indian Academy of Sciences (India)
2014-01-11
Jan 11, 2014 ... large electric field drives the electrons to a very high energy. These hot electrons quickly move out of the solid surface, long before the ions move and the electron drift creates a strong quasistatic charge separation sheath electric field. Ions are then accelerated in this sheath field preferentially along the ...
Electron dynamics in metals and semiconductors in strong THz fields
DEFF Research Database (Denmark)
Jepsen, Peter Uhd
2017-01-01
Semiconductors and metals respond to strong electric fields in a highly nonlinear fashion. Using single-cycle THz field transients it is possible to investigate this response in regimes not accessible by transport-based measurements. Extremely high fields can be applied without material damage...
Mechanism and Simulation of Generating Pulsed Strong Magnetic Field
Yang, Xian-Jun; Wang, Shuai-Chuang; Deng, Ai-Dong; Gu, Zhuo-Wei; Luo, Hao
2014-10-01
A strong magnetic field (over 1000 T) was recently experimentally produced at the Academy of Engineering Physics in China. The theoretical methods, which include a simple model and MHD code, are discussed to investigate the physical mechanism and dynamics of generating the strong magnetic field. The analysis and simulation results show that nonlinear magnetic diffusion contributes less as compared to the linear magnetic diffusion. This indicates that the compressible hydrodynamic effect and solid imploding compression may have a large influence on strong magnetic field generation.
Statistical methods in quantum optics 2 non-classical fields
Carmichael, H J
2007-01-01
Statistical Methods in Quantum Optics 2 - Non-Classical Fields continues the development of the methods used in quantum optics to treat open quantum systems and their fluctuations. Its early chapters build upon the phase-space methods introduced in the first volume Statistical Methods in Quantum Optics 1 - Matter Equations and Fokker-Planck Equations: the difficulties these methods face in treating non-classical light are exposed, where the regime of large fluctuations – failure of the system size expansion – is shown to be particularly problematic. Cavity QED is adopted as a natural vehicle for extending quantum noise theory into this regime. In response to the issues raised, the theory of quantum trajectories is presented as a universal approach to the treatment of fluctuations in open quantum systems. This book presents its material at a level suitable for beginning researchers or students in an advanced course in quantum optics, or a course in quantum mechanics or statistical physics that deals with o...
Gauge-fields and integrated quantum-classical theory
Energy Technology Data Exchange (ETDEWEB)
Stapp, H.P.
1986-01-01
Physical situations in which quantum systems communicate continuously to their classically described environment are not covered by contemporary quantum theory, which requires a temporary separation of quantum degrees of freedom from classical ones. A generalization would be needed to cover these situations. An incomplete proposal is advanced for combining the quantum and classical degrees of freedom into a unified objective description. It is based on the use of certain quantum-classical structures of light that arise from gauge invariance to coordinate the quantum and classical degrees of freedom. Also discussed is the question of where experimenters should look to find phenomena pertaining to the quantum-classical connection. 17 refs.
Energy Technology Data Exchange (ETDEWEB)
Rosenberg, Danna [Los Alamos National Laboratory; Peterson, Charles G [Los Alamos National Laboratory; Dallmann, Nicholas [Los Alamos National Laboratory; Hughes, Richard J [Los Alamos National Laboratory; Mccabe, Kevin P [Los Alamos National Laboratory; Nordholt, Jane E [Los Alamos National Laboratory; Tyagi, Hush T [Los Alamos National Laboratory; Peters, Nicholas A [TELCORDIA TECHNOLOGIES; Toliver, Paul [TELCORDIA TECHNOLOGIES; Chapman, Thomas E [TELCORDIA TECHNOLOGIES; Runser, Robert J [TELCORDIA TECHNOLOGIES; Mcnown, Scott R [TELCORDIA TECHNOLOGIES
2008-01-01
To move beyond dedicated links and networks, quantum communications signals must be integrated into networks carrying classical optical channels at power levels many orders of magnitude higher than the quantum signals themselves. We demonstrate transmission of a 1550-nm quantum channel with up to two simultaneous 200-GHz spaced classical telecom channels, using ROADM (reconfigurable optical <1dd drop multiplexer) technology for multiplexing and routing quantum and classical signals. The quantum channel is used to perform quantum key distribution (QKD) in the presence of noise generated as a by-product of the co-propagation of classical channels. We demonstrate that the dominant noise mechanism can arise from either four-wave mixing or spontaneous Raman scattering, depending on the optical path characteristics as well <1S the classical channel parameters. We quantity these impairments and discuss mitigation strategies.
On the construction of classical superstring field theories
Energy Technology Data Exchange (ETDEWEB)
Konopka, Sebastian Johann Hermann
2016-07-01
This thesis describes the construction of classical superstring field theories based on the small Hilbert space. First we describe the traditional construction of perturbative superstring theory as an integral over the supermoduli space of type II world sheets. The geometry of supermoduli space dictates many algebraic properties of the string field theory action. In particular it allows for an algebraisation of the construction problem for classical superstring field theories in terms of homotopy algebras. Next, we solve the construction problem for open superstrings based on Witten's star product. The construction is recursive and involves a choice of homotopy operator for the zero mode of the η-ghost. It turns out that the solution can be extended to the Neveu-Schwarz subsectors of all superstring field theories. The recursive construction involves a hierarchy of string products at various picture deficits. The construction is not entirely natural, but it is argued that different choices give rise to solutions related by a field redefinition. Due to the presence of odd gluing parameters for Ramond states the extension to full superstring field theory is non-trivial. Instead, we construct gauge-invariant equations of motion for all superstring field theories. The realisation of spacetime supersymmetry in the open string sector is highly non-trivial and is described explicitly for the solution based on Witten's star product. After a field redefinition the non-polynomial equations of motion and the small Hilbert space constraint become polynomial. This polynomial system is shown to be supersymmetric. Quite interestingly, the supersymmetry algebra closes only up to gauge transformations. This indicates that only the physical phase space realizes N=1 supersymmetry. Apart from the algebraic constraints dictated by the geometry of supermoduli space the equations of motion or action should reproduce the traditional string S-matrix. The S-matrix of a field
On the construction of classical superstring field theories
International Nuclear Information System (INIS)
Konopka, Sebastian Johann Hermann
2016-01-01
This thesis describes the construction of classical superstring field theories based on the small Hilbert space. First we describe the traditional construction of perturbative superstring theory as an integral over the supermoduli space of type II world sheets. The geometry of supermoduli space dictates many algebraic properties of the string field theory action. In particular it allows for an algebraisation of the construction problem for classical superstring field theories in terms of homotopy algebras. Next, we solve the construction problem for open superstrings based on Witten's star product. The construction is recursive and involves a choice of homotopy operator for the zero mode of the η-ghost. It turns out that the solution can be extended to the Neveu-Schwarz subsectors of all superstring field theories. The recursive construction involves a hierarchy of string products at various picture deficits. The construction is not entirely natural, but it is argued that different choices give rise to solutions related by a field redefinition. Due to the presence of odd gluing parameters for Ramond states the extension to full superstring field theory is non-trivial. Instead, we construct gauge-invariant equations of motion for all superstring field theories. The realisation of spacetime supersymmetry in the open string sector is highly non-trivial and is described explicitly for the solution based on Witten's star product. After a field redefinition the non-polynomial equations of motion and the small Hilbert space constraint become polynomial. This polynomial system is shown to be supersymmetric. Quite interestingly, the supersymmetry algebra closes only up to gauge transformations. This indicates that only the physical phase space realizes N=1 supersymmetry. Apart from the algebraic constraints dictated by the geometry of supermoduli space the equations of motion or action should reproduce the traditional string S-matrix. The S-matrix of a field
Rhie-Chow interpolation in strong centrifugal fields
Bogovalov, S. V.; Tronin, I. V.
2015-10-01
Rhie-Chow interpolation formulas are derived from the Navier-Stokes and continuity equations. These formulas are generalized to gas dynamics in strong centrifugal fields (as high as 106 g) occurring in gas centrifuges.
Spectral confinement and current for atoms in strong magnetic fields
DEFF Research Database (Denmark)
Fournais, Søren
2007-01-01
e study confinement of the ground state of atoms in strong magnetic fields to different subspaces related to the lowest Landau band. Using the results on confinement we can calculate the quantum current in the entire semiclassical region B<3......e study confinement of the ground state of atoms in strong magnetic fields to different subspaces related to the lowest Landau band. Using the results on confinement we can calculate the quantum current in the entire semiclassical region B
Directory of Open Access Journals (Sweden)
Maruyama Tomoyuki
2016-01-01
Full Text Available We study pion production from proton synchrotron radiation in the presence of strong magnetic fields by using the exact proton propagator in a strong magnetic field and explicitly including the anomalous magnetic moment. Results in this exact quantum approach do not agree with those obtained in the semi-classical approach. Then, we find that the anomalous magnetic moment of the proton greatly enhances the production rate by about two orders magnitude, and that the decay width satisfies a robust scaling law.
Dynamic polarizability of a complex atom in strong laser fields
International Nuclear Information System (INIS)
Rapoport, L.P.; Klinskikh, A.F.; Mordvinov, V.V.
1997-01-01
An asymptotic expansion of the dynamic polarizability of a complex atom in a strong circularly polarized light field is found for the case of high frequencies. The self-consistent approximation of the Hartree-Fock type for the ''atom+field'' system is developed, within the framework of which a numerical calculation of the dynamic polarizability of Ne, Kr, and Ar atoms in a strong radiation field is performed. The strong field effect is shown to manifest itself not only in a change of the energy spectrum and the character of behavior of the wave functions of atomic electrons, but also in a modification of the one-electron self-consistent potential for the atom in the field
Colloquium: Strong-field phenomena in periodic systems
Kruchinin, Stanislav Yu.; Krausz, Ferenc; Yakovlev, Vladislav S.
2018-04-01
The advent of visible-infrared laser pulses carrying a substantial fraction of their energy in a single field oscillation cycle has opened a new era in the experimental investigation of ultrafast processes in semiconductors and dielectrics (bulk as well as nanostructured), motivated by the quest for the ultimate frontiers of electron-based signal metrology and processing. Exploring ways to approach those frontiers requires insight into the physics underlying the interaction of strong high-frequency (optical) fields with electrons moving in periodic potentials. This Colloquium aims at providing this insight. Introduction to the foundations of strong-field phenomena defines and compares regimes of field-matter interaction in periodic systems, including (perfect) crystals as well as optical and semiconductor superlattices, followed by a review of recent experimental advances in the study of strong-field dynamics in crystals and nanostructures. Avenues toward measuring and controlling electronic processes up to petahertz frequencies are discussed.
Classical study of the rovibrational dynamics of a polar diatomic molecule in static electric fields
Energy Technology Data Exchange (ETDEWEB)
Inarrea, Manuel, E-mail: manuel.inarrea@unirioja.e [Area de Fisica, Universidad de la Rioja, E-26006 Logrono (Spain); Salas, J. Pablo [Area de Fisica, Universidad de la Rioja, E-26006 Logrono (Spain); Gonzalez-Ferez, Rosario [Instituto ' Carlos I' de Fisica Teorica y Computacional, Universidad de Granada, E-18071 Granada (Spain); Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Schmelcher, Peter [Theoretische Chemie, Physikalisch-Chemisches Institut, D-69120 Heidelberg (Germany); Physikalisches Institut, Universitaet Heidelberg, D-69120 Heidelberg (Germany)
2010-01-04
We study the classical dynamics of a polar diatomic molecule in the presence of a strong static homogeneous electric field. Our full rovibrational investigation includes the interaction with the field due to the permanent electric dipole moment and the polarizability of the molecule. Using the LiCs molecule as a prototype, we explore the stability of the equilibrium points and their bifurcations as the field strength is increased. The phase space structure and its dependence on the energy and field strength are analyzed in detail. We demonstrate that depending on the field strength and on the energy, the phase space is characterized either by regular features or by small stochastic layers of chaotic motion.
Radial oscillations of neutron stars in strong magnetic fields
Indian Academy of Sciences (India)
Abstract. The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained from the relativistic nuclear mean field theory is taken and ...
Resonances of the helium atom in a strong magnetic field
DEFF Research Database (Denmark)
Lühr, Armin Christian; Al-Hujaj, Omar-Alexander; Schmelcher, Peter
2007-01-01
We present an investigation of the resonances of a doubly excited helium atom in a strong magnetic field covering the regime B=0–100 a.u. A full-interaction approach which is based on an anisotropic Gaussian basis set of one-particle functions being nonlinearly optimized for each field strength...
Attosecond Electron Wave Packet Dynamics in Strong Laser Fields
International Nuclear Information System (INIS)
Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier, A.; Lopez-Martens, R.; Valentin, C.; Balcou, Ph.; Kazamias, S.; Mauritsson, J.; Gaarde, M. B.; Schafer, K. J.; Mairesse, Y.; Wabnitz, H.; Salieres, P.
2005-01-01
We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy (∼20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes
Vortex-lattice states at strong magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Akera, H.; MacDonald, A.H.; Girvin, S.M. (Department of Physics, Indiana University, Bloomington, Indiana (USA)); Norman, M.R. (Materials Science Division, Argonne National Laboratory, Argonne, Illinois (USA))
1991-10-21
At strong magnetic fields, Landau quantization invalidates the semiclassical approximations which underly the Ginzburg-Landau (GL) theory of the mixed states of type-II superconductors. We have solved the {ital microscopic} mean-field equations for the case of a two-dimensional electron system in the strong magnetic-field limit. For delta-function attractive interactions there exist {ital n}+1 pairing channels in the {ital n}th Landau level. For {ital n}{gt}0, two channels share the maximum {ital T}{sub {ital c}}, and the order parameter differs markedly from expectations based on GL theory.
NATO Advanced Study Institute on Atoms in Strong Fields
Clark, Charles; Nayfeh, Munir
1990-01-01
This book collects the lectures given at the NATO Advanced Study Institute on "Atoms in Strong Fields", which took place on the island of Kos, Greece, during the two weeks of October 9-21,1988. The designation "strong field" applies here to an external electromagnetic field that is sufficiently strong to cause highly nonlinear alterations in atomic or molecular struc ture and dynamics. The specific topics treated in this volume fall into two general cater gories, which are those for which strong field effects can be studied in detail in terrestrial laboratories: the dynamics of excited states in static or quasi-static electric and magnetic fields; and the interaction of atoms and molecules with intense laser radiation. In both areas there exist promising opportunities for research of a fundamental nature. An electric field of even a few volts per centimeter can be very strong on the atom ic scale, if it acts upon a weakly bound state. The study of Rydberg states with high reso lution laser spectroscop...
Carrier envelope phase effects in molecular dissociation by few-cycle strong laser fields
Energy Technology Data Exchange (ETDEWEB)
Dimitriou, K I [Hellenic Army Academy, Department of Natural Science and Applications, Vari (Greece); Constantoudis, V [Institute of Microelectronics, NCSR ' Demokritos' , Athens (Greece); Mercouris, Th [Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens (Greece); Nicolaides, C A, E-mail: dimi@eie.g [Physics Department, National Technical University, Athens (Greece)
2009-11-01
Multiphoton molecular dissociation produced by few-cycle strong laser fields of mid-infrared wave lengths is studied theoretically. The dependence of the carrier envelope phase (CEP) on the photodissociation dynamics is investigated using both quantum and classical nonperturbative approaches. Our results show that dissociation is affected by the changes of the CEP. A detailed analysis shows that this dependence is sensitive to the duration and to the shape of the pulse.
Interaction of neutral particles with strong laser fields
Energy Technology Data Exchange (ETDEWEB)
Meuren, Sebastian; Keitel, Christoph H.; Di Piazza, Antonino [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
2013-07-01
Since the invention of the laser in the 1960s the experimentally available field strengths have continuously increased. The current peak intensity record is 2 x 10{sup 22} W/cm{sup 2} and next generation facilities such as ELI, HiPER and XCELS plan to reach even intensities of the order of 10{sup 24} W/cm{sup 2}. Thus, modern laser facilities are a clean source for very strong external electromagnetic fields and promise new and interesting high-energy physics experiments. In particular, strong laser fields could be used to test non-linear effects in quantum field theory. Earlier we have investigated how radiative corrections modify the coupling of a charged particle inside a strong plane-wave electromagnetic background field. However, a charged particle couples already at tree level to electromagnetic radiation. Therefore, we have now analyzed how the coupling between neutral particles and radiation is affected by a very strong plane-wave electromagnetic background field, when loop corrections are taken into account. In particular, the case of neutrinos is discussed.
On covariant Poisson brackets in classical field theory
International Nuclear Information System (INIS)
Forger, Michael; Salles, Mário O.
2015-01-01
How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem—as testified by the extensive literature on “multisymplectic Poisson brackets,” together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls–De Witt bracket and whose construction in a geometrical setting is now well understood. Here, we show how the basic “multisymplectic Poisson bracket” already proposed in the 1970s can be derived from the Peierls–De Witt bracket, applied to a special class of functionals. This relation allows to trace back most (if not all) of the problems encountered in the past to ambiguities (the relation between differential forms on multiphase space and the functionals they define is not one-to-one) and also to the fact that this class of functionals does not form a Poisson subalgebra
Classical particles with spin in electromagnetic and gravitational fields
International Nuclear Information System (INIS)
Amorim, R.M. de.
1977-02-01
Following a review of several problems connected with classical particles with intrinsic angular momentum are reproduced the Frenkel equations (with the condition S sup(μν)U sub(ν)=0) by means of a holonomic variational principle, and have related them to Bargann, Michel and Tededgie equations. The treatment is then generalized to the case in wich S sup(μν)U sub(ν)=0 and the resulting equation coincide in the linearized limit with those obtained by Suttorp and de Groot. Also, by using variational principles, the generalizations to Frenkel equations are obtained, as well as to those of Suttorp and de Groot when electromagnetic and gravitational interactions are considered. Finally, those equations are analysed according to a scheme proposed by Oliveira and Tiommo where the gravitational interactions are described by gravielectric and gravimagnetic fields. The analogies in these equations of motion between the gravitational and eletromagnetic interactions, in the case in which the particle has a giromagnetic factor g=1, are shown. The last results complete a previous study by wald. (Author) [pt
On covariant Poisson brackets in classical field theory
Energy Technology Data Exchange (ETDEWEB)
Forger, Michael [Instituto de Matemática e Estatística, Universidade de São Paulo, Caixa Postal 66281, BR–05315-970 São Paulo, SP (Brazil); Salles, Mário O. [Instituto de Matemática e Estatística, Universidade de São Paulo, Caixa Postal 66281, BR–05315-970 São Paulo, SP (Brazil); Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Campus Universitário – Lagoa Nova, BR–59078-970 Natal, RN (Brazil)
2015-10-15
How to give a natural geometric definition of a covariant Poisson bracket in classical field theory has for a long time been an open problem—as testified by the extensive literature on “multisymplectic Poisson brackets,” together with the fact that all these proposals suffer from serious defects. On the other hand, the functional approach does provide a good candidate which has come to be known as the Peierls–De Witt bracket and whose construction in a geometrical setting is now well understood. Here, we show how the basic “multisymplectic Poisson bracket” already proposed in the 1970s can be derived from the Peierls–De Witt bracket, applied to a special class of functionals. This relation allows to trace back most (if not all) of the problems encountered in the past to ambiguities (the relation between differential forms on multiphase space and the functionals they define is not one-to-one) and also to the fact that this class of functionals does not form a Poisson subalgebra.
Atomic and Free Electrons in a Strong Light Field
International Nuclear Information System (INIS)
Fedorov, Mikhail V.
1998-02-01
This book presents and describes a series of unusual and striking strong-field phenomena concerning atoms and free electrons. Some of these phenomena are: multiphoton stimulated Bremsstrahlung, free-electron lasers, ave-packet physics, above-threshold ionization, and strong-field stabilization in Rydberg atoms. The theoretical foundations and causes of the phenomena are described in detail, with all the approximations and derivations discussed. All the known and relevant experiments are described oo, and their results are compared with those of the existing theoretical models. An extensive general theoretical introduction gives a good basis for subsequent parts of the book and is an independent and self-sufficient description of the most efficient theoretical methods of the strong-field and multiphoton physics. This book can serve as a textbook for graduate students
Relativistic nonlinear electrodynamics the QED vacuum and matter in super-strong radiation fields
Avetissian, Hamlet K
2016-01-01
This revised edition of the author’s classic 2006 text offers a comprehensively updated review of the field of relativistic nonlinear electrodynamics. It explores the interaction of strong and super-strong electromagnetic/laser radiation with the electromagnetic quantum vacuum and diverse types of matter – including free charged particles and antiparticles, acceleration beams, plasma and plasmous media. The appearance of laser sources of relativistic and ultra-relativistic intensities over the last decade has stimulated investigation of a large class of processes under such super-strong radiation fields. Revisions for this second edition reflect these developments and the book includes new chapters on Bremsstrahlung and nonlinear absorption of superintense radiation in plasmas, the nonlinear interaction of relativistic atoms with intense laser radiation, nonlinear interaction of strong laser radiation with Graphene, and relativistic nonlinear phenomena in solid-plasma targets under supershort laser pul...
Construction of classical and quantum integrable field models ...
Indian Academy of Sciences (India)
The aims, scopes and the methods of the integrable classical and quantum systems how- ever, are different ... aim of the classical integrable systems is to focus mainly on evolution equations, investi- gate their various ...... waves, where we also include the effect of a nonconstant ocean current term I(x,y,t) = −iUcqx to get the ...
Vaccinology of classical swine fever: from lab to field
Oirschot, van J.T.
2003-01-01
There are two types of classical swine fever vaccines available: the classical live and the recently developed E2 subunit vaccines. The live Chinese strain vaccine is the most widely used. After a single vaccination, it confers solid immunity within a few days that appears to persist lifelong. The
Atomic and free electrons in a strong light field
Fedorov, Mikhail V
1997-01-01
This book presents and describes a series of unusual and striking strong-field phenomena concerning atoms and free electrons. Some of these phenomena are: multiphoton stimulated bremsstrahlung, free-electron lasers, wave-packet physics, above-threshold ionization, and strong-field stabilization in Rydberg atoms. The theoretical foundations and causes of the phenomena are described in detail, with all the approximations and derivations discussed. All the known and relevant experiments are described too, and their results are compared with those of the existing theoretical models.An extensive ge
Discriminative deep inelastic tests of strong interaction field theories
International Nuclear Information System (INIS)
Glueck, M.; Reya, E.
1979-02-01
It is demonstrated that recent measurements of ∫ 0 1 F 2 (x, Q 2 )dx eliminate already all strong interaction field theories except QCD. A detailed study of scaling violations of F 2 (x, Q 2 ) in QCD shows their insensitivity to the gluon content of the hadron at presently measured values of Q 2 . (orig.) [de
Near-field strong coupling of single quantum dots.
Groß, Heiko; Hamm, Joachim M; Tufarelli, Tommaso; Hess, Ortwin; Hecht, Bert
2018-03-01
Strong coupling and the resultant mixing of light and matter states is an important asset for future quantum technologies. We demonstrate deterministic room temperature strong coupling of a mesoscopic colloidal quantum dot to a plasmonic nanoresonator at the apex of a scanning probe. Enormous Rabi splittings of up to 110 meV are accomplished by nanometer-precise positioning of the quantum dot with respect to the nanoresonator probe. We find that, in addition to a small mode volume of the nanoresonator, collective coherent coupling of quantum dot band-edge states and near-field proximity interaction are vital ingredients for the realization of near-field strong coupling of mesoscopic quantum dots. The broadband nature of the interaction paves the road toward ultrafast coherent manipulation of the coupled quantum dot-plasmon system under ambient conditions.
Dynamic chaos in the tunnelling ionization produced by a strong low-frequency electromagnetic field
International Nuclear Information System (INIS)
Krainov, V P
2014-01-01
Ionization of atoms by a strong low-frequency linearly polarized electromagnetic field (the photon energy is small compared to the atomic ionization potential) is considered under new conditions compared to the well known Keldysh approach. The field strength is supposed to be small in comparison to the atomic field strength. But the Coulomb interaction of an electron with atomic core is assumed to be of the same order of magnitude as the interaction between an electron and the external electromagnetic field. It was shown that then classical electron motion in the continuum becomes chaotic (this is so-called dynamic chaos). Using the averaging procedure of Chirikov about the chaotic variation of the phase of motion, the considered Newton problem is transformed into the problem of nonlinear electron diffusion over energy scale. In this work we derive the classical electron energy averaged over fast chaotic oscillations of an electron in the final continuum state which takes into account both the Coulomb field and electromagnetic field. This energy is used for analytic calculation of the ionization rate of the ground atomic state into the low lying continuum state based on the Landau–Dykhne approximation (with exponential accuracy). We found that the ionization rate depends significantly on the field frequency. When field frequency decreases, the well known tunnelling limit has been obtained, and then the ionization rate does not depend on the field frequency. (paper)
Chidume, C E; Bello, A U; Usman, B
2015-01-01
Let [Formula: see text], [Formula: see text], and [Formula: see text] be a strongly monotone and Lipschitz mapping. A Krasnoselskii-type sequence is constructed and proved to converge strongly to the unique solution of [Formula: see text]. Furthermore, our technique of proo f is of independent interest.
Statistical relationship of strong earthquakes with planetary geomagnetic field activity
Pogrebnikov, M. M.; Komarovski, N. I.; Kopytenko, Y. A.; Pushel, A. P.
1984-12-01
Earlier studies reported a significant decrease in the geomagnetic field before strong earthquakes. Possible relationships between earthquakes with magnitude greater than 7 (Soviet scale) and planetary terrestrial magnetic field activity as characterized by the K sub p index were investigated. A total of 100 cases of strong earthquakes on magnetically quiet days in 1965 to 1975 were studied. The K sub p indexes were studied for two days before and two days after the earthquakes. The dispersion curve shows a significant decrease one day before each event. The relationship of the planetary K sub p index with seismic activity indicates that the period of preparation for an earthquake and at the moment of the shock are reflected in the terrestrial magnetic field.
Magnetic properties of a classical XY spin dimer in a “planar” magnetic field
Energy Technology Data Exchange (ETDEWEB)
Ciftja, Orion, E-mail: ogciftja@pvamu.edu [Department of Physics, Prairie View A& M University, Prairie View, TX 77446 (United States); Prenga, Dode [Department of Physics, Faculty of Natural Sciences, University of Tirana, Bul. Zog I, Tirana (Albania)
2016-10-15
Single-molecule magnetism originates from the strong intra-molecular magnetic coupling of a small number of interacting spins. Such spins generally interact very weakly with the neighboring spins in the other molecules of the compound, therefore, inter-molecular spin couplings are negligible. In certain cases the number of magnetically coupled spins is as small as a dimer, a system that can be considered the smallest nanomagnet capable of storing non-trivial magnetic information on the molecular level. Additional interesting patterns arise if the spin motion is confined to a two-dimensional space. In such a scenario, clusters consisting of spins with large-spin values are particularly attractive since their magnetic interactions can be described well in terms of classical Heisenberg XY spins. In this work we calculate exactly the magnetic properties of a nanomagnetic dimer of classical XY spins in a “planar” external magnetic field. The problem is solved by employing a mathematical approach whose idea is the introduction of auxiliary spin variables into the starting expression of the partition function. Results for the total internal energy, total magnetic moment, spin–spin correlation function and zero-field magnetic susceptibility can serve as a basis to understand the magnetic properties of large-spin dimer building blocks. - Highlights: • Exact magnetic properties of a dimer system of classical XY spins in magnetic field. • Partition function in nonzero magnetic field obtained in closed-form. • Novel exact analytic results are important for spin models in a magnetic field. • Result provides benchmarks to gauge the accuracy of computational techniques.
Matter in strong fields: from molecules to living cells
International Nuclear Information System (INIS)
Mathur, D
2007-01-01
Strong optical fields induce multiple ionization in irradiated molecules. The ionization dynamics are governed by optical-field-induced distortions of molecular potential energy surfaces and molecular dissociation is the expected by-product. Recent experiments have even shown, quite counter-intuitively, that strong optical fields may even induce bond formation processes in molecules. All such processes are all manifestations of how intense light affects matter. In turn, matter also affects intense light. A visually dramatic manifestation of matter affecting light is obtained when ultrashort pulses of intense light propagate though condensed matter. The temporal and spatial properties of the incident light pulse are modified, and such modifications manifest themselves in an enlarged optical frequency sweep, resulting in the generation of broadband radiation (white light) known as supercontinuum production. Although the physics that governs supercontinuum generation is not properly understood, some recent progress is summarized. Novel applications of strong field phenomena are reported that are of relevance in the biomedical and life sciences
Nonlinear dynamics of semiconductors in strong THz electric fields
DEFF Research Database (Denmark)
Tarekegne, Abebe Tilahun
weak THz and near infrared pulses as probes. Firstly, an intense THz pulse is used to study THz-induced impact ionization (IMI) dynamics in silicon. Local field enhancement by metallic dipole antenna arrays has been used to generate strong electric fields of several MV/cm in the hot spots near...... uniquely. Finally it is demonstrated for the first time that SiC can be tailored to have extremely fast THz-induced nonlinear behavior in moderate THz electric fields by addition of appropriate dopants. A 4H-SiC sample with high concentrations of nitrogen and boron dopants shows a nonlinear THz......In this thesis, we investigate nonlinear interactions of an intense terahertz (THz) field with semiconductors, in particular the technologically relevant materials silicon and silicon carbide. We reveal the time-resolved dynamics of the nonlinear processes by pump-probe experiments that involve...
Annular billiard dynamics in a circularly polarized strong laser field
Kamor, A.; Mauger, F.; Chandre, C.; Uzer, T.
2012-01-01
We analyze the dynamics of a valence electron of the buckminsterfullerene molecule (C60) subjected to a circularly polarized laser field by modeling it with the motion of a classical particle in an annular billiard. We show that the phase space of the billiard model gives rise to three distinct trajectories: “whispering gallery orbits,” which hit only the outer billiard wall; “daisy orbits,” which hit both billiard walls (while rotating solely clockwise or counterclockwise for all time); and orbits that only visit the downfield part of the billiard, as measured relative to the laser term. These trajectories, in general, maintain their distinct features, even as the intensity is increased from 1010 to 1014Wcm-2. We attribute this robust separation of phase space to the existence of twistless tori.
Ion Motion in a Plasma Interacting with Strong Magnetic Fields
International Nuclear Information System (INIS)
Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtmant, A.
1999-01-01
The interaction of a plasma with strong magnetic fields takes place in many laboratory experiments and astrophysical plasmas. Applying a strong magnetic field to the plasma may result in plasma displacement, magnetization, or the formation of instabilities. Important phenomena in plasma, such as the energy transport and the momentum balance, take a different form in each case. We study this interaction in a plasma that carries a short-duration (80-ns) current pulse, generating a magnetic field of up to 17 kG. The evolution of the magnetic field, plasma density, ion velocities, and electric fields are determined before and during the current pulse. The dependence of the plasma limiting current on the plasma density and composition are studied and compared to theoretical models based on the different phenomena. When the plasma collisionality is low, three typical velocities should be taken into consideration: the proton and heavier-ion Alfven velocities (v A p and v A h , respectively) and the EMHD magnetic-field penetration velocity into the plasma (v EMHD ). If both Alfven velocities are larger than v EMHD the plasma is pushed ahead of the magnetic piston and the magnetic field energy is dissipated into ion kinetic energy. If v EMHD is the largest of three velocities, the plasma become magnetized and the ions acquire a small axial momentum only. Different ion species may drift in different directions along the current lines. In this case, the magnetic field energy is probably dissipated into electron thermal energy. When vs > V EMHD > vi, as in the case of one of our experiments, ion mass separation occurs. The protons are pushed ahead of the piston while the heavier-ions become magnetized. Since the plasma electrons are unmagnetized they cannot cross the piston, and the heavy ions are probably charge-neutralized by electrons originating from the cathode that are 'born' magnetized
Two-level atom in a strong polychromatic field
International Nuclear Information System (INIS)
Kazakov, A.Ya.
1991-01-01
The quasienergy spectrium of a two-level atom in a polychromatic electromagnetic field can be expressed in terms of the Floquet indexes of a linear set of ordinary differential equations with periodic coefficients. An analytic expression for the quasienergy spectrum is obtained by the asymptotic technique for the case of a strong polychromatic field. It is shown that on deep modulation of the radiation incident on the atom forbidden bands for the quasilevels may arise. The Stark effect for the physical system under consideration is described
Strong field transient manipulation of electronic states and bands
Directory of Open Access Journals (Sweden)
I. Crassee
2017-11-01
Full Text Available In the present review, laser fields are so strong that they become part of the electronic potential, and sometimes even dominate the Coulomb contribution. This manipulation of atomic potentials and of the associated states and bands finds fascinating applications in gases and solids, both in the bulk and at the surface. We present some recent spectacular examples obtained within the NCCR MUST in Switzerland.
Radiative electron-atom collision in a strong laser field
International Nuclear Information System (INIS)
Faisal, F.H.M.
1984-01-01
The comment is concerned with certain current problems and prospects in the theory of electron-atom collision in a strong radiation field. High energy off-shell electron-photon excitation of atoms; low-energy e-atom radiative scattering; steady state input distribution; typical distribution; low energy phenomena; and extensions of the close coupling and the algebraic methods, are all discussed. (U.K.)
Experiments on plasma turbulence induced by strong, steady electric fields
International Nuclear Information System (INIS)
Hamberger, S.M.
1975-01-01
The author discusses the effect of applying a strong electric field to collisionless plasma. In particular are compared what some ideas and prejudices lead one to expect to happen, what computer simulation experiments tell one ought to happen, and what actually does happen in two laboratory experiments which have been designed to allow the relevant instability and turbulent processes to occur unobstructed and which have been studied in sufficient detail. (Auth.)
Quantum and classical strong direct product theorems and optimal time-space tradeoffs
H. Klauck (Hartmut); R. Spalek (Robert); R. M. de Wolf (Ronald)
2007-01-01
textabstractA strong direct product theorem says that if we want to compute $k$ independent instances of a function, using less than $k$ times the resources needed for one instance, then our overall success probability will be exponentially small in $k$. We establish such theorems for the
Classical theory of high intensity collisional absorption in a constant magnetic field
Pieruccini, M.; Ferrante, G.; Nuzzo, S.; Zarcone, M.
The problem of gain and loss of kinetic energy by electrons colliding off ions, in the presence of a strong e.m. radiation and of a steady homogeneous magnetic field B, has been investigated within the framework of the classical non relativistic theory. The analysis is first restricted to the elementary process of the electron stimulated direct and inverse bremsstrahlung. The rate of change of the time averaged electron kinetic energy is numerically evaluated for the special cases when the radiation field is either linearly polarized along B, or circularly polarized in a plane perpendicular to B. For the former case, the appropriate Langevin equations are also derived, in order to describe the average motion of test electrons in velocity space.
Spin effects in strong-field laser-electron interactions
International Nuclear Information System (INIS)
Ahrens, S; Bauke, H; Müller, T-O; Villalba-Chávez, S; Müller, C
2013-01-01
The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation.
Theoretical femtosecond physics atoms and molecules in strong laser fields
Grossmann, Frank
2013-01-01
Theoretical investigations of atoms and molecules interacting with pulsed or continuous wave lasers up to atomic field strengths on the order of 10^16 W/cm² are leading to an understanding of many challenging experimental discoveries. This book deals with the basics of femtosecond physics and goes up to the latest applications of new phenomena. The book presents an introduction to laser physics with mode-locking and pulsed laser operation. The solution of the time-dependent Schrödinger equation is discussed both analytically and numerically. The basis for the non-perturbative treatment of laser-matter interaction in the book is the numerical solution of the time-dependent Schrödinger equation. The light field is treated classically, and different possible gauges are discussed. Physical phenonema, ranging from Rabi-oscillations in two-level systems to the ionization of atoms, the generation of high harmonics, the ionization and dissociation of molecules as well as the control of chemical reactions are pre...
Asymptotic behaviour of classical Yang-Mills fields in Minkowski space
International Nuclear Information System (INIS)
Luescher, M.
1978-05-01
It is shown how to define incoming and outgoing asymptotic fields for classical solutions of the Yang-Mills field equations without fixing the gauge. It is seen that the Gribov ambiguities for putting the field in the Coulomb gauge reduce asymptotically to a field independent, infinite parameter group of gauge transformations. This obscures the notion of color charge already at the classical level. (Auth.)
Experimental observation of strong radiation reaction in the field of an ultra-intense laser
Sarri, G.; Poder, K.; Tamburini, M.; di Piazza, A.; Keitel, C. H.; Zepf, M.
2017-10-01
Describing radiation reaction in an electromagnetic field is one of the most fundamental outstanding problems in electrodynamics. It consists of determining the dynamics of a charged particle fully taking into account self-forces (loosely referred to as radiation reaction) resulting from the radiation fields generated by the particle whilst it is accelerated. Radiation reaction has only been invoked to explain the radiative properties of powerful astrophysical objects, such as pulsars and quasars. From a theoretical standpoint, this phenomenon is subject of fervent debate and this impasse is worsened by the lack of experimental data, due to extremely high fields required to trigger these effects. Here, we report on the first experimental evidence of strong radiation reaction during the interaction of an ultra-relativistic electron beam with an intense laser field, beyond a purely classical description.
Dynamics of dissociation versus ionization in strong laser fields
International Nuclear Information System (INIS)
In this paper, experimental results are presented which clearly demonstrate the effectiveness that an external field has in altering the dissociation dynamics. The experiment examines the strong-field dissociation dynamics of molecular hydrogen ions and its deuterated isotopes. These studies involve multiphoton excitation in the intensity regime of 10 11-14 W/cm 2 with the fundamental and second harmonic of a ND:YAG or ND:YLF laser system. Measurements include energy resolved electron and mass spectroscopy which provide useful probes in elucidating the interaction dynamics predicted by existing models. The example this in this paper, examines the strong-field dissociation of H 2 + , HD + , and D 2 + at green (0.5 μm) and (1μm) frequencies. The diatomic ions are formed via multiphonon ionization of the neutral precursor which is physically separable from the dissociation process. This study provides the first observation of the dynamics associated with the above threshold dissociation (ATD) process and analogies will be made with the more familiar above threshold ionization (ATI) phenomenon
A course in mathematical physics 1 and 2 classical dynamical systems and classical field theory
Thirring, Walter
1992-01-01
The last decade has seen a considerable renaissance in the realm of classical dynamical systems, and many things that may have appeared mathematically overly sophisticated at the time of the first appearance of this textbook have since become the everyday tools of working physicists. This new edition is intended to take this development into account. I have also tried to make the book more readable and to eradicate errors. Since the first edition already contained plenty of material for a one semester course, new material was added only when some of the original could be dropped or simplified. Even so, it was necessary to expand the chap ter with the proof of the K-A-M Theorem to make allowances for the cur rent trend in physics. This involved not only the use of more refined mathe matical tools, but also a reevaluation of the word "fundamental. " What was earlier dismissed as a grubby calculation is now seen as the consequence of a deep principle. Even Kepler's laws, which determine the radii of the ...
Classical calculation of radiative lifetimes of atomic hydrogen in a homogeneous magnetic field
International Nuclear Information System (INIS)
Horbatsch, M.W.; Hessels, E.A.; Horbatsch, M.
2005-01-01
Radiative lifetimes of hydrogenic atoms in a homogeneous magnetic field of moderate strength are calculated on the basis of classical radiation. The modifications of the Keplerian orbits due to the magnetic field are incorporated by classical perturbation theory. The model is complemented by a classical radiative decay calculation using the radiated Larmor power. A recently derived highly accurate formula for the transition rate of a field-free hydrogenic state is averaged over the angular momentum oscillations caused by the magnetic field. The resulting radiative lifetimes for diamagnetic eigenstates classified by n,m and the diamagnetic energy shift C compare well with quantum results
Cooper Pair Breakup in YBCO under Strong Terahertz Fields
Glossner, Andreas; Zhang, Caihong; Kikuta, Shinya; Kawayama, Iwao; Murakami, Hironaru; Müller, Paul; Tonouchi, Masayoshi
2012-01-01
We show that strong electric fields of ~ 30 kV cm^(-1) at terahertz frequencies can significantly weaken the superconducting characteristics of cuprate superconductors. High-power terahertz time-domain spectroscopy (THz-TDS) was used to investigate the in-plane conductivity of YBa2Cu3O7-delta (YBCO) with highly intense single-cycle terahertz pulses. Even though the terahertz photon energy (~ 1.5 meV) was significantly smaller than the energy gap in YBCO (~ 20-30 meV), the optical conductivity...
Confinement and αs in a strong magnetic field
Directory of Open Access Journals (Sweden)
Yu.A. Simonov
2015-07-01
Full Text Available Hadron decay widths are shown to increase in strong magnetic fields as Γ(eB∼eBκΓ(0. The same mechanism is shown to be present in the production of the sea quark pair inside the confining string, which decreases the string tension with the growing eB parallel to the string. On the other hand, the average energy of the qq¯ holes in the string world sheet increases, when the direction of B is perpendicular to the sheet. These two effects stipulate the spectacular picture of the B dependent confinement and αs, discovered on the lattice.
Quark-gluon plasma in strong magnetic fields
International Nuclear Information System (INIS)
Kalaydzhyan, Tigran
2013-04-01
One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.
Helium atoms and molecules in strong magnetic fields
Mori, K.
Recent theoretical studies have shown that the neutron star surface may be composed of helium or heavier elements as hydrogen may be quickly depleted by diffuse nuclear burning Chang Bildsten However while Hydrogen atmospheres have been studied in great details atomic data for helium is available only for He ion Pavlov Bezchastnov 2005 We performed Hartree-Fock type calculation for Helium atom and molecules and computed their binding ionization and dissociation energies in strong magnetic fields B sim10 12 -- 10 15 G We will present ionization balance of Helium atmospheres at typical magnetic field strengths and temperatures to radio-quiet neutron stars and AXPs We will also discuss several implications of helium atmosphere to X-ray data of isolated neutron stars focusing on the detected spectral features
Quark-gluon plasma in strong magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Kalaydzhyan, Tigran
2013-04-15
One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.
Electron-positron-photon cascades in the strong laser field
Legkov, Maxim; Fedotov, Alexander
2012-06-01
At nearest future several ambitious projects (such as ELI and HiPER) may provide laser filed intensity up to 10^23--10^24 W/cm^2. In such strong fields quantum effects are essential. The most important among them is production of QED cascades. In this paper external field intensity is considered as ultra-relativistic but subcritical. Using a model of two colliding counter-propagating laser beams it was shown that the number of particles during the process is growing exponentially in time. This leads to vast formation of electron-positron-photon plasma. According to numerical simulations, this plasma quickly absorbs an essential part of the energy of the laser field thus leading to its depletion. Numerical simulation has been also performed for a case of high-energetic particle and laser beam collision. Probability rates of direct and recombination processes have been theoretically studied. Under some conditions, recombination may come into play and suppress cascade development. Using approximation of radiation in forward direction, system of kinetic equations, which describes plasma evaluation, was constructed. According to qualitative estimations based on kinetic equations, it was shown that recombination processes can be neglected for optical frequencies range of external field.
Quantum correlations and dynamics from classical random fields valued in complex Hilbert spaces
International Nuclear Information System (INIS)
Khrennikov, Andrei
2010-01-01
One of the crucial differences between mathematical models of classical and quantum mechanics (QM) is the use of the tensor product of the state spaces of subsystems as the state space of the corresponding composite system. (To describe an ensemble of classical composite systems, one uses random variables taking values in the Cartesian product of the state spaces of subsystems.) We show that, nevertheless, it is possible to establish a natural correspondence between the classical and the quantum probabilistic descriptions of composite systems. Quantum averages for composite systems (including entangled) can be represented as averages with respect to classical random fields. It is essentially what Albert Einstein dreamed of. QM is represented as classical statistical mechanics with infinite-dimensional phase space. While the mathematical construction is completely rigorous, its physical interpretation is a complicated problem. We present the basic physical interpretation of prequantum classical statistical field theory in Sec. II. However, this is only the first step toward real physical theory.
Strong-field control landscapes of coherent electronic excitation
Bayer, Tim; Wollenhaupt, Matthias; Baumert, Thomas
2008-04-01
We report on physical mechanisms behind resonant strong-field coherent control. To this end, we study multi-photon ionization of potassium atoms using intense shaped femtosecond laser pulses. The measured photoelectron spectra are discussed in terms of selective population of dressed states (SPODS). A physically motivated pulse parameterization is introduced which opens up two-dimensional parameter spaces comprising pulse sequences as well as chirped pulses. The control topologies of these subspaces are mapped out experimentally and are presented in the form of strong-field control landscapes (SFCLs). In the SFCLs, complementary realizations of SPODS via photon locking and rapid adiabatic passage are observed. Moreover, the combined effect, termed Multi-RAP, arises when both mechanisms are at play simultaneously. In order to better understand the performance of adaptive optimization procedures, we experimentally study their capability to find optimal solutions on a given parameter space. The evolution of different optimization procedures is visualized by means of control trajectories on the surface of the measured SFCL.
Richert, Micah David
2008-01-01
This dissertation is organized into two main parts: physiology and new techniques. The physiology is organized into classical receptive fields, surround properties and global object selectivity of area MT. The first two physiology chapters used a novel sparse motion stimulus to drive MT cells and used reverse correlation to analyze the data. For the classical receptive field the spike triggered average was used as an estimate of the field. For the surround, maximally informative dimension ana...
Stable classical orbits for atomic hydrogen in magnetic and rotating electric fields
International Nuclear Information System (INIS)
Kazanskij, A.K.
1989-01-01
A hydrogen atom, being in a magnetic field and in a field of circulation-polarized electromagnetic wave propagating along the magnetic field is considered. Classical orbits in the hydrogen atom, being in various external fields, were investigated to find stable orbits. Determination of a stationary region for considering conditions is the result of invesigation
k-Cosymplectic Classical Field Theories: Tulczyjew and Skinner–Rusk Formulations
International Nuclear Information System (INIS)
Rey, Angel M.; Román-Roy, Narciso; Salgado, Modesto; Vilariño, Silvia
2012-01-01
The k-cosymplectic Lagrangian and Hamiltonian formalisms of first-order classical field theories are reviewed and completed. In particular, they are stated for singular and almost-regular systems. Subsequently, several alternative formulations for k-cosymplectic first-order field theories are developed: First, generalizing the construction of Tulczyjew for mechanics, we give a new interpretation of the classical field equations. Second, the Lagrangian and Hamiltonian formalisms are unified by giving an extension of the Skinner–Rusk formulation on classical mechanics.
k-Cosymplectic Classical Field Theories: Tulczyjew and Skinner-Rusk Formulations
Rey, Angel M.; Román-Roy, Narciso; Salgado, Modesto; Vilariño, Silvia
2012-06-01
The k-cosymplectic Lagrangian and Hamiltonian formalisms of first-order classical field theories are reviewed and completed. In particular, they are stated for singular and almost-regular systems. Subsequently, several alternative formulations for k-cosymplectic first-order field theories are developed: First, generalizing the construction of Tulczyjew for mechanics, we give a new interpretation of the classical field equations. Second, the Lagrangian and Hamiltonian formalisms are unified by giving an extension of the Skinner-Rusk formulation on classical mechanics.
Field theory and weak Euler-Lagrange equation for classical particle-field systems.
Qin, Hong; Burby, Joshua W; Davidson, Ronald C
2014-10-01
It is commonly believed as a fundamental principle that energy-momentum conservation of a physical system is the result of space-time symmetry. However, for classical particle-field systems, e.g., charged particles interacting through self-consistent electromagnetic or electrostatic fields, such a connection has only been cautiously suggested. It has not been formally established. The difficulty is due to the fact that the dynamics of particles and the electromagnetic fields reside on different manifolds. We show how to overcome this difficulty and establish the connection by generalizing the Euler-Lagrange equation, the central component of a field theory, to a so-called weak form. The weak Euler-Lagrange equation induces a new type of flux, called the weak Euler-Lagrange current, which enters conservation laws. Using field theory together with the weak Euler-Lagrange equation developed here, energy-momentum conservation laws that are difficult to find otherwise can be systematically derived from the underlying space-time symmetry.
Anomalous electrodynamics of neutral pion matter in strong magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Brauner, Tomáš [Department of Mathematics and Natural Sciences, University of Stavanger,N-4036 Stavanger (Norway); Kadam, Saurabh V. [Indian Institute of Science Education and Research (IISER),Pune 411008 (India)
2017-03-03
The ground state of quantum chromodynamics in sufficiently strong external magnetic fields and at moderate baryon chemical potential is a chiral soliton lattice (CSL) of neutral pions https://arxiv.org/abs/1609.05213. We investigate the interplay between the CSL structure and dynamical electromagnetic fields. Our main result is that in presence of the CSL background, the two physical photon polarizations and the neutral pion mix, giving rise to two gapped excitations and one gapless mode with a nonrelativistic dispersion relation. The nature of this mode depends on the direction of its propagation, interpolating between a circularly polarized electromagnetic wave https://www.doi.org/10.1103/PhysRevD.93.085036 and a neutral pion surface wave, which in turn arises from the spontaneously broken translation invariance. Quite remarkably, there is a neutral-pion-like mode that remains gapped even in the chiral limit, in seeming contradiction to the Goldstone theorem. Finally, we have a first look at the effect of thermal fluctuations of the CSL, showing that even the soft nonrelativistic excitation does not lead to the Landau-Peierls instability. However, it leads to an anomalous contribution to pressure that scales with temperature and magnetic field as T{sup 5/2}(B/f{sub π}){sup 3/2}.
Strong-field relativistic processes in highly charged ions
Energy Technology Data Exchange (ETDEWEB)
Postavaru, Octavian
2010-12-08
In this thesis we investigate strong-field relativistic processes in highly charged ions. In the first part, we study resonance fluorescence of laser-driven highly charged ions in the relativistic regime by solving the time-dependent master equation in a multi-level model. Our ab initio approach based on the Dirac equation allows for investigating highly relativistic ions, and, consequently, provides a sensitive means to test correlated relativistic dynamics, bound-state quantum electrodynamic phenomena and nuclear effects by applying coherent light with x-ray frequencies. Atomic dipole or multipole moments may be determined to unprecedented accuracy by measuring the interference-narrowed fluorescence spectrum. Furthermore, we investigate the level structure of heavy hydrogenlike ions in laser beams. Interaction with the light field leads to dynamic shifts of the electronic energy levels, which is relevant for spectroscopic experiments. We apply a fully relativistic description of the electronic states by means of the Dirac equation. Our formalism goes beyond the dipole approximation and takes into account non-dipole effects of retardation and interaction with the magnetic field components of the laser beam. We predicted cross sections for the inter-shell trielectronic recombination (TR) and quadruelectronic recombination processes which have been experimentally confirmed in electron beam ion trap measurements, mainly for C-like ions, of Ar, Fe and Kr. For Kr{sup 30}+, inter-shell TR contributions of nearly 6% to the total resonant photorecombination rate were found. (orig.)
International Nuclear Information System (INIS)
Gelis, Francois; Venugopalan, Raju
2006-01-01
We develop a formalism for particle production in a field theory coupled to a strong time-dependent external source. An example of such a theory is the color glass condensate. We derive a formula, in terms of cut vacuum-vacuum Feynman graphs, for the probability of producing a given number of particles. This formula is valid to all orders in the coupling constant. The distribution of multiplicities is non-Poissonian, even in the classical approximation. We investigate an alternative method of calculating the mean multiplicity. At leading order, the average multiplicity can be expressed in terms of retarded solutions of classical equations of motion. We demonstrate that the average multiplicity at next-to-leading order can be formulated as an initial value problem by solving equations of motion for small fluctuation fields with retarded boundary conditions. The variance of the distribution can be calculated in a similar fashion. Our formalism therefore provides a framework to compute from first principles particle production in proton-nucleus and nucleus-nucleus collisions beyond leading order in the coupling constant and to all orders in the source density. We also provide a transparent interpretation (in conventional field theory language) of the well-known Abramovsky-Gribov-Kancheli (AGK) cancellations. Explicit connections are made between the framework for multi-particle production developed here and the framework of reggeon field theory
Korobkin, V. V.; Romanovsky, M. Yu.
1992-12-01
It is shown that in a strong circularly polarized laser field a classical electron motion around ions can occur. The scattering of these electrons in a plasma has the Thompson cross section in the limit of strongs field only and for a subrelativistic motion of the electrons. There are non-ion satellites apart from the basic frequency in the scattering spectrum.
Point splitting regularization of classical string field theory
International Nuclear Information System (INIS)
Strominger, A.
1987-01-01
We regulate Witten's star algebra using point splitting and conformal field theory techniques. Certain products of nonassociative operators and states are defined. This involves a refinement of star that exists in cases where Witten's star is ill-defined. A simple derivation of a recently discovered associativity anomaly is given. It is shown that there is no anomaly obstructing the equivalence of Witten's string theory action and the cubic action for string fields in the open string Fock space. (orig.)
International Nuclear Information System (INIS)
Arbo, D.G.; Toekesi, K.; Miraglia, J.E.; FCEN, University of Buenos Aires
2008-01-01
Complete text of publication follows. We presented a theoretical study of the ionization of hydrogen atoms as a result of the interaction with an ultrashort external electric field. Doubly-differential momentum distributions and angular momentum distributions of ejected electrons calculated in the framework of the Coulomb-Volkov and strong field approximations, as well as classical calculations are compared with the exact solution of the time dependent Schroedinger equation. We have shown that the Coulomb-Volkov approximation (CVA) describes the quantum atomic ionization probabilities exactly when the external field is described by a sudden momentum transfer [1]. The velocity distribution of emitted electrons right after ionization by a sudden momentum transfer is given through the strong field approximation (SFA) within both the CVA and CTMC methods. In this case, the classical and quantum time dependent evolutions of an atom subject to a sudden momentum transfer are identical. The difference between the classical and quantum final momentum distributions resides in the time evolution of the escaping electron under the subsequent action of the Coulomb field. Furthermore, classical mechanics is incapable of reproducing the quantum angular momentum distribution due to the improper initial radial distribution used in the CTMC calculations, i.e., the microcanonical ensemble. We find that in the limit of high momentum transfer, based on the SFA, there is a direct relation between the cylindrical radial distribution dP/dρ and the final angular momentum distribution dP/dL. This leads to a close analytical expression for the partial wave populations (dP/dL) SFA-Q given by dP SFA-Q / dL = 4Z 3 L 2 / (Δp) 3 K 1 (2ZL/Δp) which, together with the prescription L = l + 1/2, reproduces quite accurately the quantum (CVA) results. Considering the inverse problem, knowing the final angular momentum distribution can lead to the inference of the initial probability distribution
International Nuclear Information System (INIS)
Multiple scale methods are used to treat several ingredients of the theory of atoms in strong electromagnetic fields. First, a focused electromagnetic field is expanded. Second, a classical electron is described giving the ponderomotive potential. Third, the quantum electron is treated in the WKB approximation. Fourth, the one dimensional quantum harmonic oscillator is solved; and last the one dimensional square well, showing the low intensity limit of the theory
An integral-field spectroscopic strong lens survey
Energy Technology Data Exchange (ETDEWEB)
Bolton, Adam S [Harvard-Smithsonian Center for Astrophysics, 60 Garden St. MS-20, Cambridge, MA 02138 (United States); Burles, Scott [Department of Physics and Kavli Institute, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139 (United States)
2007-12-15
We present the observational results of a survey for strong gravitational lens systems consisting of extended emission-line galaxies lensed by intervening early-type galaxies, conducted using integral field units (IFUs) of the Magellan IMACS and Gemini GMOS-N spectrographs. These data are highly valuable for corroborating the lensing interpretation of Hubble Space Telescope imaging data. We show that in many cases, ground-based IFU spectroscopy is in fact competitive with space-based imaging for the measurement of the mass model parameters of the lensing galaxy. We demonstrate a novel technique of three-dimensional gravitational lens modeling for a single lens system with a resolved lensed rotation curve. We also describe the details of our custom IFU data analysis software, which performs optimal multi-fiber extraction, relative and absolute wavelength calibration to a few hundredths of a pixel RMS and nearly Poisson-limited sky subtraction.
Virtual detector theory for strong-field atomic ionization
Wang, Xu; Tian, Justin; Eberly, J. H.
2018-04-01
A virtual detector (VD) is an imaginary device located at a fixed position in space that extracts information from the wave packet passing through it. By recording the particle momentum and the corresponding probability current at each time, the VDs can accumulate and build the differential momentum distribution of the particle, in a way that resembles real experiments. A mathematical proof is given for the equivalence of the differential momentum distribution obtained by the VD method and by Fourier transforming the wave function. In addition to being a tool for reducing the computational load, VDs have also been found useful in interpreting the ultrafast strong-field ionization process, especially the controversial quantum tunneling process.
Mechanics of magnetic fluid column in strong magnetic fields
International Nuclear Information System (INIS)
Polunin, V.M.; Ryapolov, P.A.; Platonov, V.B.
2017-01-01
Elastic-and magnetic properties of magnetic fluid confined by ponderomotive force in a tube fixed in horizontal position are considered. The system is placed in a strong magnetic field under the influence of external static and dynamic perturbations. An experimental setup has been developed. A theoretical basis of the processes of magnetic colloid elastic deformation has been proposed. The values of the static ponderomotive elasticity coefficient and the elasticity coefficient under dynamic action are experimentally determined. The calculations of the saturation magnetization for two magnetic fluid samples, carried out according to the equation containing the dynamic elasticity coefficient, are in good agreement with the experimental magnetization curve. The described method is of interest when studying magnetophoresis and aggregation of nanoparticles in magnetic colloids.
The ESRg matrix for strong field d5 systems
Directory of Open Access Journals (Sweden)
McGarvey Bruce R.
1998-01-01
Full Text Available This review has tried to collect and correlate all the various equations for the g matrix of strong field d5 systems obtained from different basis sets using full electron and hole formalism calculations. It has corrected mistakes found in the literature and shown how the failure to properly take in symmetry boundary conditions has produced a variety of apparently inconsistent equations in the literature. The review has reexamined the problem of spin-orbit interaction with excited t4e states and finds that the earlier reports that it is zero in octahedral symmetry is not correct. It has shown how redefining what x, y, and z are in the principal coordinate system simplifies, compared to previous methods, the analysis of experimental g values with the equations.
An integral-field spectroscopic strong lens survey
International Nuclear Information System (INIS)
Bolton, Adam S; Burles, Scott
2007-01-01
We present the observational results of a survey for strong gravitational lens systems consisting of extended emission-line galaxies lensed by intervening early-type galaxies, conducted using integral field units (IFUs) of the Magellan IMACS and Gemini GMOS-N spectrographs. These data are highly valuable for corroborating the lensing interpretation of Hubble Space Telescope imaging data. We show that in many cases, ground-based IFU spectroscopy is in fact competitive with space-based imaging for the measurement of the mass model parameters of the lensing galaxy. We demonstrate a novel technique of three-dimensional gravitational lens modeling for a single lens system with a resolved lensed rotation curve. We also describe the details of our custom IFU data analysis software, which performs optimal multi-fiber extraction, relative and absolute wavelength calibration to a few hundredths of a pixel RMS and nearly Poisson-limited sky subtraction
Probing strong-field general relativity near black holes
CERN. Geneva; Alvarez-Gaumé, Luís
2005-01-01
Nature has sprinkled black holes of various sizes throughout the universe, from stellar mass black holes in X-ray sources to supermassive black holes of billions of solar masses in quasars. Astronomers today are probing the spacetime near black holes using X-rays, and gravitational waves will open a different view in the near future. These tools give us an unprecedented opportunity to test ultra-strong-field general relativity, including the fundamental theorem of the uniqueness of the Kerr metric and Roger Penrose's cosmic censorship conjecture. Already, fascinating studies of spectral lines are showing the extreme gravitational lensing effects near black holes and allowing crude measurements of black hole spin. When the ESA-NASA gravitational wave detector LISA begins its observations in about 10 years, it will make measurements of dynamical spacetimes near black holes with an accuracy greater even than that which theoreticians can reach with their computations today. Most importantly, when gravitational wa...
Self-Organization of Polymeric Fluids in Strong Stress Fields
Directory of Open Access Journals (Sweden)
A. V. Semakov
2015-01-01
Full Text Available Analysis of literature data and our own experimental observations have led to the conclusion that, at high deformation rates, viscoelastic liquids come to behave as rubbery materials, with strong domination by elastic deformations over flow. This can be regarded as a deformation-induced fluid-to-rubbery transition. This transition is accompanied by elastic instability, which can lead to the formation of regular structures. So, a general explanation for these effects requires the treatment of viscoelastic liquids beyond critical deformation rates as rubbery media. Behaviouristic modeling of their behaviour is based on a new concept, which considers the medium as consisting of discrete elastic elements. Such a type of modeling introduces a set of discrete rotators settled on a lattice with two modes of elastic interaction. The first of these is their transformation from spherical to ellipsoidal shapes and orientation in an external field. The second is elastic collisions between rotators. Computer calculations have demonstrated that this discrete model correctly describes the observed structural effects, eventually resulting in a “chaos-to-order” transformation. These predictions correspond to real-world experimental data obtained under different modes of deformation. We presume that the developed concept can play a central role in understanding strong nonlinear effects in the rheology of viscoelastic liquids.
A course in mathematical physics 2 classical field theory
Thirring, Walter
1978-01-01
In the past decade the language and methods ofmodern differential geometry have been increasingly used in theoretical physics. What seemed extravagant when this book first appeared 12 years ago, as lecture notes, is now a commonplace. This fact has strengthened my belief that today students of theoretical physics have to learn that language-and the sooner the better. Afterall, they willbe the professors ofthe twenty-first century and it would be absurd if they were to teach then the mathematics of the nineteenth century. Thus for this new edition I did not change the mathematical language. Apart from correcting some mistakes I have only added a section on gauge theories. In the last decade it has become evident that these theories describe fundamental interactions, and on the classical level their structure is suffi cientlyclear to qualify them for the minimum amount ofknowledge required by a theoretician. It is with much regret that I had to refrain from in corporating the interesting developments in Kal...
International Nuclear Information System (INIS)
Thierry-Mieg, J.
1985-01-01
The reinterpretation of the BRS equations of Quantum Field Theory as the Maurer Cartan equation of a classical principal fiber bundle leads to a simple gauge invariant classification of the anomalies in Yang Mills theory and gravity
Sound absorption in a field of a strong electromagnetic wave in a quantizied magnetic field
International Nuclear Information System (INIS)
Chajkovskij, I.A.
1974-01-01
A coefficient of sound absorption GAMMA in a semiconductor and semi-metal in the quantized magnetic field is calculated for a system exposed to a field of strong electromagnetic radiation. The cases E parallel H and E orthogonal H are considered. Along with the already known strong oscillations of sound absorption in magnetic fields, the absorption spectrum GAMMAsub(par) and GAMMAsub(orth) shows new oscillations representing a manifestation of the quasi-energetic electron spectrum in the field of a strong electromagnetic wave. The oscillation height at E parallel H is modulated by the electromagnetic field. It is shown that the ratio GAMMAsub(par)/GAMMAsub(orth) allows the determination of the effective mass of the carriers
Theory of strong-field attosecond transient absorption
International Nuclear Information System (INIS)
Wu, Mengxi; Chen, Shaohao; Camp, Seth; Schafer, Kenneth J; Gaarde, Mette B
2016-01-01
Attosecond transient absorption is one of the promising new techniques being developed to exploit the availability of sub-femtosecond extreme ultraviolet (XUV) pulses to study the dynamics of the electron on its natural time scale. The temporal resolution in a transient absorption setup comes from the control of the relative delay and coherence between pump and probe pulses, while the spectral resolution comes from the characteristic width of the features that are being probed. In this review we focus on transient absorption scenarios where an attosecond pulse of XUV radiation creates a broadband excitation that is subsequently probed by a few cycle infrared (IR) laser. Because the attosecond XUV pulses are locked to the IR field cycle, the exchange of energy in the laser–matter interaction can be studied with unprecedented precision. We focus on the transient absorption by helium atoms of XUV radiation around the first ionization threshold, where we can simultaneoulsy solve the time-dependent Schrödinger equation for the single atom response and the Maxwell wave equation for the collective response of the nonlinear medium. We use a time-domain method that allows us to treat on an equal footing all the different linear and nonlinear processes by which the medium can exchange energy with the fields. We present several simple models, based on a few-level system interacting with a strong IR field, to explain many of the novel features found in attosecond transient absorption spectrograms. These include the presence of light-induced states, which demonstrate the ability to probe the dressed states of the atom. We also present a time-domain interpretation of the resonant pulse propagation features that appear in absorption spectra in dense, macroscopic media. We close by reviewing several recent experimental results that can be explained in terms of the models we discuss. Our aim is to present a road map for understanding future attosecond transient absorption
Classical and Quantum Chaos in a quantum dot in time-periodic magnetic fields
Badrinarayanan, R.; José, Jorge V.
1996-01-01
We investigate the classical and quantum dynamics of an electron confined to a circular quantum dot in the presence of homogeneous $B_{dc}+B_{ac}$ magnetic fields. The classical motion shows a transition to chaotic behavior depending on the ratio $\\epsilon=B_{ac}/B_{dc}$ of field magnitudes and the cyclotron frequency ${\\tilde\\omega_c}$ in units of the drive frequency. We determine a phase boundary between regular and chaotic classical behavior in the $\\epsilon$ vs ${\\tilde\\omega_c}$ plane. I...
Non-Noetherian symmetries for oscillators in classical mechanics and in field theory
Hojman, Sergio A.; Delajara, Jamie; Pena, Leda
1995-01-01
Infinitely many new conservation laws both for free fields as well as for test fields evolving on a given gravitational background are presented. The conserved currents are constructed using the field theoretical counterpart of a recently discovered non-Noetherian symmetry which gives rise to a new way of solving the classical small oscillations problem. Several examples are discussed.
A model of Bremsstrahlung: classical orbits coupled to quantized field
International Nuclear Information System (INIS)
Mayer, G.
1989-01-01
A charged particle velocity variation induces a displacement of the equilibrium point of the electromagnetic field oscillators. Projecting the displaced initial wave function on the oscillators eigenstates we get a straightforward calculation of various multiphotonic Bremsstrahlung effects. The model is realistic only if the velocity change occurs in a time small versus the oscillators periods. Our results which are in substantial agreement with previous calculations may help to clarify a few points [fr
International Nuclear Information System (INIS)
Sivan, N.; Levit, S.
1992-01-01
We present a semiclassical theory of charged interacting anyons in a strong magnetic field. We derive the appropriate generalization of the WKB quantization conditions and determine the corresponding wave functions for non separable integrable anyonic systems. This theory is applies to a system of two interacting anyons, two interacting anyons in the presence of an impurity and three interacting anyons. We calculate the dependence of the semiclassical energy levels on the statistical parameter and find regions in which dependence follows very different patterns. The semiclassical treatment allows to find the correlation between these patterns and the change in the character of the classical motion of the system. We also test the accuracy of the mean field approximation for low and high energy states of the three anyons. (author)
Eccentric binaries of compact objects in strong-field gravity
International Nuclear Information System (INIS)
Gold, Roman
2011-01-01
In this thesis we study the dynamics as well as the resulting gravitational radiation from eccentric binaries of compact objects in the non-linear regime of General Relativity. For this purpose we solve Einstein's field equation numerically in a 3+1 decomposition using the moving-puncture technique. We focus our study on very particular orbits, arising as a purely relativistic phenomenon of the two-body problem in General Relativity, which are associated with unstable circular orbits. They are governed by a fast, nearly circular revolution at a short distance followed by a slow, radial motion on a nearly elliptic trajectory. Due to the unique features of their orbital trajectories they are called zoom-whirl orbits. We analyze how the peculiar dynamics manifests itself in the emitted gravitational radiation and to which extent one can infer the orbital properties from observations of the gravitational waves. In the first part, we consider black hole binaries. We perform a comprehensive parameter study by varying the initial eccentricity, computing and characterizing the resulting gravitational waveforms. We address aspects, which can only be obtained from non-perturbative methods, and which are crucial to the astrophysical relevance of these orbits. In particular, our results imply a fairly low amount of fine-tuning necessary to spot zoom-whirl effects. We find whirl orbits for values of the eccentricities, which fall in disjunct intervals extending to rather low values. Furthermore, we show that whirl effects just before merger cause a signal with significant amplitude. In the second part, we investigate neutron star binaries on eccentric orbits in full General Relativity, which has not been studied so far. We explore their phenomenology and study the consequences for the matter after the neutron stars have merged. In these evolutions the merged neutron stars sooner or later collapse to form a black hole. During the collapse most of the matter is accreted on to the
Eccentric binaries of compact objects in strong-field gravity
Energy Technology Data Exchange (ETDEWEB)
Gold, Roman
2011-09-27
In this thesis we study the dynamics as well as the resulting gravitational radiation from eccentric binaries of compact objects in the non-linear regime of General Relativity. For this purpose we solve Einstein's field equation numerically in a 3+1 decomposition using the moving-puncture technique. We focus our study on very particular orbits, arising as a purely relativistic phenomenon of the two-body problem in General Relativity, which are associated with unstable circular orbits. They are governed by a fast, nearly circular revolution at a short distance followed by a slow, radial motion on a nearly elliptic trajectory. Due to the unique features of their orbital trajectories they are called zoom-whirl orbits. We analyze how the peculiar dynamics manifests itself in the emitted gravitational radiation and to which extent one can infer the orbital properties from observations of the gravitational waves. In the first part, we consider black hole binaries. We perform a comprehensive parameter study by varying the initial eccentricity, computing and characterizing the resulting gravitational waveforms. We address aspects, which can only be obtained from non-perturbative methods, and which are crucial to the astrophysical relevance of these orbits. In particular, our results imply a fairly low amount of fine-tuning necessary to spot zoom-whirl effects. We find whirl orbits for values of the eccentricities, which fall in disjunct intervals extending to rather low values. Furthermore, we show that whirl effects just before merger cause a signal with significant amplitude. In the second part, we investigate neutron star binaries on eccentric orbits in full General Relativity, which has not been studied so far. We explore their phenomenology and study the consequences for the matter after the neutron stars have merged. In these evolutions the merged neutron stars sooner or later collapse to form a black hole. During the collapse most of the matter is accreted on
International Nuclear Information System (INIS)
Brandt, R.A.; Neri, F.; Zwanziger, D.
1979-01-01
We establish the Lorentz invariance of the quantum field theory of electric and magnetic charge. This is a priori implausible because the theory is the second-quantized version of a classical field theory which is inconsistent if the minimally coupled charged fields are smooth functions. For our proof we express the generating functional for the gauge-invariant Green's functions of quantum electrodynamics: with or without magnetic charge: as a path integral over the trajectories of classical charged point particles. The electric-electric and electric-magnetic interactions contribute factors exp(JDJ) and exp(JD'K), where J and K are the electric and magnetic currents of classical point particles and D is the usual photon propagator. The propagator D' involves the Dirac string but exp(JD'K) depends on it only through a topological integer linking string and classical particle trajectories. The charge quantization condition e/sub i/g/sub j/ - g/sub i/e/sub j/ = integer then suffices to make the gauge-invariant Green's functions string independent. By implication our formulation shows that if the Green's functions of quantum electrodynamics are expressed as usual as functional integrals over classical charged fields, the smooth field configurations have measure zero and all the support of the Feynman measure lies on the trajectories of classical point particles
Probing Strong-field General Relativity with Gravitational Waves
Pretorius, Frans
We are on the verge of a new era in astrophysics as a world-wide effort to observe the universe with gravitational waves takes hold---ground based laser interferometers (Hz to kHz), pulsar timing (micro to nano Hz), measurements of polarization of the cosmic microwave background (sub-nano Hz), and the planned NASA/ESA mission LISA (.1 mHz to .1 Hz). This project will study the theoretical nature of gravitational waves (GWs) emitted by two sources in the LISA band, namely supermassive-black-hole (SMBH) binary mergers, and extreme-mass-ratio-inspirals (EMRI's)---the merger of a stellar mass black hole, neutron star, or white dwarf with a SMBH. The primary goal will be to ascertain how well LISA, by observing these sources, could answer the following related questions about the fundamental nature of strong-field gravity: Does Einstein's theory of general relativity (GR) describe the geometry of black holes in the universe? What constraints can GW observations of SMBH mergers and EMRIs place on alternative theories of gravity? If there are deviations from GR, are there statistics that could give indications of a deviation if sources are detected using a search strategy based solely on GR waveforms? The primary reasons for focusing on LISA sources to answer these questions are (a) binary SMBH mergers could be detected by LISA with exquisitely high signal-to- noise, allowing enough parameters of the system to be accurately extracted to perform consistency checks of the underlying theory, (b) EMRIs will spend numerous orbits close to the central black hole, and thus will be quite sensitive to even small near-horizon deviations from GR. One approach to develop the requisite knowledge and tools to answer these questions is to study a concrete, theoretically viable alternative to GR. We will focus on the dynamical variant of Chern-Simons modified gravity (CSMG), which is interesting for several reasons, chief among which are (1) that CSMG generically arises in both string
Classical understanding of electron vortex beams in a uniform magnetic field
Energy Technology Data Exchange (ETDEWEB)
Han, Yeong Deok [Department of Computer Science and Engineering, Woosuk University, Wanju, Cheonbuk, 565-701 (Korea, Republic of); Choi, Taeseung, E-mail: tschoi@swu.ac.kr [Division of Applied Food System, College of Natural Science, Seoul Women' s University, Seoul 139-774 (Korea, Republic of); School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-012 (Korea, Republic of)
2017-04-25
Recently, interesting observations on electron vortex beams have been made. We propose a classical model that shows vortex-like motion due to suitably-synchronized motion of each electron's cyclotron motion in a uniform magnetic field. It is shown that some basic features of electron vortex beams in a uniform magnetic field, such as azimuthal currents, the relation between energy and kinetic angular momentum, and the parallel-axis theorem are understandable by using this classical model. We also show that the time-dependence of kinetic angular momentum of electron vortex beams could be understood as an effect of a specific nonuniform distribution of classical electrons. - Highlights: • A classical model for electron vortex beams is proposed. • The basic features of azimuthal currents could be understood by using this model. • The kinetic angular momentum of electron vortex beams is intuitively understandable.
Towards strong field tests of beyond Horndeski gravity theories
Sakstein, Jeremy; Babichev, Eugeny; Koyama, Kazuya; Langlois, David; Saito, Ryo
2017-03-01
Theories of gravity in the beyond Horndeski class encompass a wide range of scalar-tensor theories that will be tested on cosmological scales over the coming decade. In this work, we investigate the possibility of testing them in the strong field regime by looking at the properties of compact objects—neutron, hyperon, and quark stars—embedded in an asymptotically de Sitter space-time, for a specific subclass of theories. We extend previous works to include slow rotation and find a relation between the dimensionless moment of inertia (I ¯ =I c2/GNM3 ) and the compactness C =GNM /R c2 (an I ¯-C relation), independent of the equation of state, that is reminiscent of but distinct from the general relativity prediction. Several of our equations of state contain hyperons and free quarks, allowing us to revisit the hyperon puzzle. We find that the maximum mass of hyperon stars can be larger than 2 M⊙ for small values of the beyond Horndeski parameter, thus providing a resolution of the hyperon puzzle based on modified gravity. Moreover, stable quark stars exist when hyperonic stars are unstable, which means that the phase transition from hyperon to quark stars is predicted just as in general relativity (GR), albeit with larger quark star masses. Two important and potentially observable consequences of some of the theories we consider are the existence of neutron stars in a range of masses significantly higher than in GR and I ¯-C relations that differ from their GR counterparts. In the former case, we find objects that, if observed, could not be accounted for in GR because they violate the usual GR causality condition. We end by discussing several difficult technical issues that remain to be addressed in order to reach more realistic predictions that may be tested using gravitational wave searches or neutron star observations.
Ionization, photoelectron dynamics and elastic scattering in relativistic, ultra-strong field
Luo, Sui
Ultrastrong laser-matter interaction has direct bearing to next generation technologies including plasma acceleration, laser fusion and attosecond X-ray generation. The commonly known physics in strong field becomes different as one progress to ultrastrong field. The works presented in this dissertation theoretically study the influence of relativistic effect and magnetic component of the laser field on the ionization, photoelectron dynamics and elastic scattering processes. The influence of magnetic component (B laser) of circularly polarized (CP) ultrastrong fields (up to3 x 1022 W/cm2) on atomic bound state dynamics is investigated. The Poincare plots are used to find the changes in trajectory energies are on the order of a few percent for intensities up to1 x 1022 W/cm2. It is found that at intensities where ionization approaches 50% for the bound state, the small changes from Blaser of the circular polarized light can actually result in a several-fold decrease in ionization probability. The force on the bound electron exerted by the Lorentz force from B laser is perpendicular to the rotating plane of the circular polarized light, and this nature makes those trajectories which are aligned away from the minimum in the potential barrier stabilized against tunneling ionization. Our results provide a classical understanding for ionization in ultrastrong fields and indicate that relativistic effects in ultrastrong field ionization may most easily be seen with CP fields. The photoelectron energy spectra from elastic rescattering in ultrastrong laser fields (up to 2x1019 W/cm2) is studied by using a relativistic adaption of a semi-classical three-step recollision model. The Hartree-Fock scattering potentials are used in calculating the elastic rescattering for both hydrogenlike and noble gas species. It is found that there is a reduction in elastic rescattering for intensities beyond 6 x 1016 W/cm2 when the laser Lorentz deflection of the photoelectron exceeds its
Colored, spinning classical particle in an external non-Abelian gauge field
International Nuclear Information System (INIS)
Arodz, H.
1982-04-01
Classical non-relativistic equations of motion are derived for a colored, spinning point-like particle in an external SU(2) gauge field from Dirac equation. It is found that in addition to the classical spin and color spin vectors, S, I, it is necessary to introduce a new classical dynamical variable [Jsup(ab)], a,b = 1,2,3, describing a mixing of the spin and color. The constraint relations between [Jsup(ab)], S, I are also found. (Auth.)
Note on Inverse Bremsstrahlung in a Strong Electromagnetic Field
Bethe, H. A.
1972-09-01
The collisional energy loss of an electron undergoing forced oscillation in an electromagnetic field behaves quite differently in the low and high intensity limits. ... It is shown that in the case of an electromagnetic field v {sub o} >> v {sub t} the rate of transfer is much slower, and actually decreases with the strength of the field.
Synchrotron radiation in strongly coupled conformal field theories
Athanasiou, Christiana; Chesler, Paul M.; Liu, Hong; Nickel, Dominik; Rajagopal, Krishna
2010-01-01
Using gauge/gravity duality, we compute the energy density and angular distribution of the power radiated by a quark undergoing circular motion in strongly coupled ${\\cal N}=4$ supersymmetric Yang-Mills (SYM) theory. We compare the strong coupling results to those at weak coupling, and find the same angular distribution of radiated power, up to an overall prefactor. In both regimes, the angular distribution is in fact similar to that of synchrotron radiation produced by an electron in circula...
Lower Bound on the Energy Density in Classical and Quantum Field Theories.
Wall, Aron C
2017-04-14
A novel method for deriving energy conditions in stable field theories is described. In a local classical theory with one spatial dimension, a local energy condition always exists. For a relativistic field theory, one obtains the dominant energy condition. In a quantum field theory, there instead exists a quantum energy condition, i.e., a lower bound on the energy density that depends on information-theoretic quantities. Some extensions to higher dimensions are briefly discussed.
Critical behavior in a random field classical Heisenberg model for amorphous systems
International Nuclear Information System (INIS)
Albuquerque, Douglas F. de; Alves, Sandro Roberto L.; Arruda, Alberto S. de
2005-01-01
By using the differential operator technique and the effective field theory scheme, the critical behavior of amorphous classical Heisenberg ferromagnet of spin-1/2 in a random field is studied. The phase diagram in the T-H and T-α planes on a simple cubic lattice for a cluster with two spins is obtained. Tricritical points, reentrant phenomena and influence of the random field and amorphization on the transition temperature are discussed
Ion H2+ can dissociate in a strong magnetic field
International Nuclear Information System (INIS)
Turbiner, A.V.; Lopez, J.C.; Flores-Riveros, A.
2001-01-01
In framework of a variational method the molecular ion H 2 + in a magnetic field is studied. An optimal form of the vector potential corresponding to a given magnetic field is chosen. It is shown that for any magnetic field strength as well as for any orientation of the molecular axis the system (ppe) possesses a minimum in the potential energy. The stable configuration always corresponds to elongation along the magnetic line. However, for magnetic fields B ≥ 5 x 10 11 G and some orientations the ion H 2 + becomes instable decaying to H-atom + p [ru
Some non-perturbative semi-classical methods in quantum field theory (a pedagogical review)
International Nuclear Information System (INIS)
Rajaraman, R.
1975-01-01
A pedagogical introduction is given to non-perturbative semi-classical methods for finding solutions to quantum theories. Both the weak coupling method based on a time-dependent classical solution, and the WKB method based on all periodic orbits are developed in detail, proceeding from elementary quantum mechanics to field theory in stages. Both methods are then illustrated in model field theories. The [lambdaphi 4 ] 2 theory to which weak coupling is applied yields a new family of kink states whose properties are discussed. (Auth.)
International Nuclear Information System (INIS)
Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo
2011-01-01
Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields. (author)
Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo
2011-01-01
Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields.
Effective Field Theories and Strong Interactions. Final Technical Report
International Nuclear Information System (INIS)
Fleming, Sean
2011-01-01
The framework of Effective Field Theories (EFTs) allows us to describe strong interactions in terms of degrees of freedom relevant to the energy regimes of interest, in the most general way consistent with the symmetries of QCD. Observables are expanded systematically in powers of M lo /M hi , where M lo (M hi ) denotes a low-(high-)energy scale. This organizational principle is referred to as 'power counting'. Terms of increasing powers in the expansion parameter are referred to as leading order (LO), next-to-leading order (NLO), etc. Details of the QCD dynamics not included explicitly are encoded in interaction parameters, or 'low-energy constants' (LECs), which can in principle be calculated from an explicit solution of QCD - for example via lattice simulations- but can also be determined directly from experimental data. QCD has an intrinsic scale M QCD ≅ 1 GeV, at which the QCD coupling constant α s (M QCD ) becomes large and the dynamics becomes non-perturbative. As a consequence M QCD sets the scale for the masses of most hadrons, such as the nucleon mass m N ≅ 940 MeV. EFTs can roughly be divided into two categories: those that can be matched onto QCD in perturbation theory, which we call high-energy EFTs, and those that cannot be matched perturbatively, which we call low-energy EFTs. In high-energy EFTs, M QCD typically sets the low-energy scale, and all the dynamics associated with this scale reside in matrix elements of EFT operators. These non-perturbative matrix elements are the LECs and are also referred to as long-distance contributions. Each matrix element is multiplied by a short-distance coefficient, which contains the dynamics from the high scale M hi . Since M hi >> M QCD , α s (M hi ) hi ∼ M Q , the heavy-quark mass, and in addition to M QCD there are low scales associated with the typical relative momentum ∼ M Q v and energy ∼ M Q v 2 of the heavy quarks. Depending on the sizes of M Q and the heavy-quark velocity v these scales can
Chiral spiral induced by a strong magnetic field
Directory of Open Access Journals (Sweden)
Abuki Hiroaki
2016-01-01
Full Text Available We study the modification of the chiral phase structure of QCD due to an external magnetic field. We first demonstrate how the effect of magnetic field can systematically be incorporated into a generalized Ginzburg-Landau framework. We then analyze the phase structure in the vicinity of the chiral critical point. In the chiral limit, the effect is found to be so drastic that it brings a “continent” of chiral spiral in the phase diagram, by which the chiral tricritical point is totally washed out. This is the case no matter how small the intensity of magnetic field is. On the other hand, the current quark mass protects the chiral critical point from a weak magnetic field. However, the critical point will eventually be covered by the chiral spiral phase as the magnetic field grows.
Operating a magnetic nozzle helicon thruster with strong magnetic field
Energy Technology Data Exchange (ETDEWEB)
Takahashi, Kazunori, E-mail: kazunori@ecei.tohoku.ac.jp; Komuro, Atsushi; Ando, Akira [Department of Electrical Engineering, Tohoku University, Sendai 980-8579 (Japan)
2016-03-15
A pulsed axial magnetic field up to ∼2.8 kG is applied to a 26-mm-inner-diameter helicon plasma thruster immersed in a vacuum chamber, and the thrust is measured using a pendulum target. The pendulum is located 30-cm-downstream of the thruster, and the thruster rf power and argon flow rate are fixed at 1 kW and 70 sccm (which gives a chamber pressure of 0.7 mTorr). The imparted thrust increases as the applied magnetic field is increased and saturates at a maximum value of ∼9.5 mN for magnetic field above ∼2 kG. At the maximum magnetic field, it is demonstrated that the normalized plasma density, and the ion flow energy in the magnetic nozzle, agree within ∼50% and of 10%, respectively, with a one-dimensional model that ignores radial losses from the nozzle. This magnetic nozzle model is combined with a simple global model of the thruster source that incorporates an artificially controlled factor α, to account for radial plasma losses to the walls, where α = 0 and 1 correspond to zero losses and no magnetic field, respectively. Comparison between the experiments and the model implies that the radial losses in the thruster source are experimentally reduced by the applied magnetic field to about 10% of that obtained from the no magnetic field model.
Radial oscillations of neutron stars in strong magnetic fields
Indian Academy of Sciences (India)
The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic ﬁeld. At low densities we use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained from the relativistic nuclear mean ﬁeld theory is taken and extended to ...
Certain relativistic effects due to strong electromagnetic fields in plasmas
International Nuclear Information System (INIS)
Tsintsadze, N.L.
1974-01-01
It is shown that the propagation of a strong electromagnetic wave in an electron plasma can lead to a generation of a constant electron current along the direction of propagation and to a large increase in the average electron density. (Auth.)
Inherent resistivity of graphene to strong THz fields
DEFF Research Database (Denmark)
Turchinovich, Dmitry; Mics, Zoltán; Jensen, Søren
2014-01-01
The nonlinear THz conductivity of graphene is characterized using nonlinear ultrafast THz spectroscopy. Efficient carrier heating by the THz field reduces carrier scattering, yet, counter-intuitively, simultaneously suppresses the high-frequency conductivity of graphene. © 2014 OSA....
International Nuclear Information System (INIS)
Koinov, Z.G.; Yanchev, I.Y.
1981-09-01
The density of states in heavily doped strongly compansated semiconductors in a strong magnetic field is calculated by using the path-integral method. The case is considered when correlation exists in the impurity positions owing to the Coulomb interactions between the charged donors and acceptors during the high-temperature preparation of the samples. The semiclassical formula is rederived and corrections to it due to the long-range character of the potential and its short-range fluctuations are obtained. The density of states in the tail is studied and analytical results are given in the classical and quantum cases. (author)
Classical field theory on electrodynamics, non-Abelian gauge theories and gravitation
Scheck, Florian
2012-01-01
The book describes Maxwell's equations first in their integral, directly testable form, then moves on to their local formulation. The first two chapters cover all essential properties of Maxwell's equations, including their symmetries and their covariance in a modern notation. Chapter 3 is devoted to Maxwell theory as a classical field theory and to solutions of the wave equation. Chapter 4 deals with important applications of Maxwell theory. It includes topical subjects such as metamaterials with negative refraction index and solutions of Helmholtz' equation in paraxial approximation relevant for the description of laser beams. Chapter 5 describes non-Abelian gauge theories from a classical, geometric point of view, in analogy to Maxwell theory as a prototype, and culminates in an application to the U(2) theory relevant for electroweak interactions. The last chapter 6 gives a concise summary of semi-Riemannian geometry as the framework for the classical field theory of gravitation. The chapter concludes wit...
Apparent paradoxes in classical electrodynamics: a fluid medium in an electromagnetic field
International Nuclear Information System (INIS)
Kholmetskii, A L; Yarman, T
2008-01-01
In this paper we analyse a number of teaching paradoxes of classical electrodynamics, dealing with the relativistic transformation of energy and momentum for a fluid medium in an external electromagnetic field. In particular, we consider a moving parallel plate charged capacitor, where the electric attraction of its plates is balanced by the pressure of gas convicted between the plates
On the classical origins of yangian symmetry in integrable field theory
International Nuclear Information System (INIS)
MacKay, N.J.
1992-01-01
We show that Drinfeld's yangian algebra, studied recently as the algebra of conserved charges in certain two-dimensional integrable quantum field theories, is also present in the classical theory as a Poisson-Hopf algebra, and exhibit explicitly the Serre relations, coproduct and antipode. (orig.)
Apparent Paradoxes in Classical Electrodynamics: A Fluid Medium in an Electromagnetic Field
Kholmetskii, A. L.; Yarman, T.
2008-01-01
In this paper we analyse a number of teaching paradoxes of classical electrodynamics, dealing with the relativistic transformation of energy and momentum for a fluid medium in an external electromagnetic field. In particular, we consider a moving parallel plate charged capacitor, where the electric attraction of its plates is balanced by the…
Channel-closing effects in strong-field ionization by a bicircular field
Milošević, D. B.; Becker, W.
2018-03-01
Channel-closing effects, such as threshold anomalies and resonantlike intensity-dependent enhancements in strong-field ionization by a bicircular laser field are analyzed. A bicircular field consists of two coplanar corotating or counter-rotating circularly polarized fields having different frequencies. For the total detachment rate of a negative ion by a bicircular field we observe threshold anomalies and explain them using the Wigner threshold law and energy and angular momentum conservation. For the corotating bicircular case, these effects are negligible, while for the counter-rotating case they are pronounced and their position depends on the magnetic quantum number of the initial state. For high-order above-threshold ionization of rare-gas atoms by a counter-rotating bicircular laser field we observe very pronounced intensity-dependent enhancements. We find all four types of threshold anomalies known from collision theory. Contrary to the case of linear polarization, channel-closing effects for a bicircular field are visible also in the cutoff region of the electron energy spectrum, which is explained using quantum-orbit theory.
On tidal phenomena in a strong gravitational field
International Nuclear Information System (INIS)
Mashoon, B.
1975-01-01
A simple framework based on the concept of quadrupole tidal potential is presented for the calculation of tidal deformation of an extended test body in a gravitational field. This method is used to study the behavior of an initially faraway nonrotating spherical body that moves close to a Schwarzschild or an extreme Kerr black hole. In general, an extended body moving in an external gravitational field emits gravitational radiation due to its center of mass motion, internal tidal deformation, and the coupling between the internal and center of mass motions. Estimates are given of the amount of tidal radiation emitted by the body in the gravitational fields considered. The results reported in this paper are expected to be of importance in the dynamical evolution of a dense stellar system with a massive black hole in its center
Quantum processes in a strong electromagnetic field producing pairs. 3
International Nuclear Information System (INIS)
Gitman, D.M.; Gavrilov, S.P.
1977-01-01
The Furry picture in quantum electrodynamics with an external field producing real pairs has been generalized. For the required generalization to be achieved all operators of a spinor field are expressed through functions of production and annihilation operators and formulated are the rules for reduction to a generalized normal form, i.e., to such a form in which all the production operators in each term are on the left from all the annihilation operators. The diagram technique for matrix elements of random processes has been considered
Neutron star in the presence of strong magnetic field
Indian Academy of Sciences (India)
Stars: neutron stars; magnetic fields; equation of state. PACS Nos 26.60.Kp; 52.35.Tc; 97.10.Cv. 1. Introduction. The central density of neutron stars (NS) exceeds the nuclear saturation density (n0 ∼. 0.15 fm. −3. ), thereby giving the idea that compact stars might contain deconfined and chirally restored quark matter in them.
Effective magnetic moment of neutrinos in strong magnetic fields
Pérez, A; Masood, S S; Gaitan, R; Rodríguez, S
2002-01-01
In this paper we compute the effective magnetic moment of neutrinos propagating in dense high magnetized medium. Taking typical values of magnetic field and densities of astrophysical objects (such as the cores of supernovae and neutron stars) we obtain an effective type of dipole magnetic moment in agreement with astrophysical and cosmological bounds. (Author)
Multistage ionization of atoms in a very strong electromagnetic field
International Nuclear Information System (INIS)
Krajnov, V.P.; Manykin, Eh.A.
1980-01-01
Considered is a problem of multiple ionization of middle and heavy atoms as a function of the intensity of an electromagnetic field. The atom is considered in the Thomas -Fermi approximation. Presented are estimates of ionization degree for lead, tungsten and tantalum
Force acting on an atom and a classical oscillator in an electromagnetic field
International Nuclear Information System (INIS)
Makarov, V. P.; Rukhadze, A. A.
2010-01-01
The expression for the force exerted by the field on an atom and averaged over the field period is derived in quantum-mechanical perturbation theory, in which a quasi-monochromatic electromagnetic field plays the role of a perturbation. An approximate solution is obtained to the classical (Newton) equation of motion in the same field for a harmonic isotropic oscillator. In both problems, the expressions for the force acting on a particle are completely identical if they are written in terms of the polarizability (of the atom and the oscillator). These results conform with the data obtained in macroscopic electrodynamics for rarefied media.
Classical open-string field theory: A∞-algebra, renormalization group and boundary states
International Nuclear Information System (INIS)
Nakatsu, Toshio
2002-01-01
We investigate classical bosonic open-string field theory from the perspective of the Wilson renormalization group of world-sheet theory. The microscopic action is identified with Witten's covariant cubic action and the short-distance cut-off scale is introduced by length of open-string strip which appears in the Schwinger representation of open-string propagator. Classical open-string field theory in the title means open-string field theory governed by a classical part of the low energy action. It is obtained by integrating out suitable tree interactions of open-strings and is of non-polynomial type. We study this theory by using the BV formalism. It turns out to be deeply related with deformation theory of A ∞ -algebra. We introduce renormalization group equation of this theory and discuss it from several aspects. It is also discussed that this theory is interpreted as a boundary open-string field theory. Closed-string BRST charge and boundary states of closed-string field theory in the presence of open-string field play important roles
Field-Free Alignment and Strong Field Control of Molecular Rotors
Spanner, Michael
2004-12-01
Methods of controlling molecular rotations using linearly polarized femtosecond and picosecond pulses are considered and analyzed theoretically. These laser pulses, typically in the infrared, are highly non-resonant with respect to the electronic degrees of freedom of the molecules and have intensities of ~ 10^13 to 10^14 W/cm?. It is shown how these laser pulses can force small linear molecules to align with the direction of the electric field vector of the laser both in the presence of the laser field as well as after the application of a short laser pulse. Recent experiments on laser-induced molecular alignment are modeled and excellent agreement between experiment and theory is found. Additional methods of controlling molecular rotational dynamics are outlined. The first method considers the forced rotational acceleration of diatomic molecules, called the optical centrifuge. Here, the direction of polarization of a linearly polarized laser field is made to smoothly rotate faster and faster. The molecules, which tend to align with the polarization vector of the laser field, follow the rotation of the laser polarization and are accelerated to high angular momentum. The second method considers the control of field-free rotational dynamics by applying phase shifts to the molecular wave function at select times called fractional revivals. At these select moments, an initially localized wave function splits into several copies of the initial state. Adding phase shifts to the copies then induces interference effects which can be used to control the subsequent evolution of the rotational wave function. This same control scheme has a close link to quantum information and this connection is outlined. Finally, a recently proposed method of controlling the quantum dynamics of the classically chaotic kicked rotor system [J. Gong and P. Brumer, Phys. Rev. Lett. 86, 1741 (2001)] is analyzed from a phase space perspective. It is shown that the proposed quantum control can be
Cigar-shaped quarkonia under strong magnetic field
Suzuki, Kei; Yoshida, Tetsuya
2016-03-01
Heavy quarkonia in a homogeneous magnetic field are analyzed by using a potential model with constituent quarks. To obtain anisotropic wave functions and corresponding eigenvalues, the cylindrical Gaussian expansion method is applied, where the anisotropic wave functions are expanded by a Gaussian basis in the cylindrical coordinates. Deformation of the wave functions and the mass shifts of the S-wave heavy quarkonia (ηc, J /ψ , ηc(2 S ), ψ (2 S ) and bottomonia) are examined for the wide range of external magnetic field. The spatial structure of the wave functions changes drastically as adjacent energy levels cross each other. Possible observables in heavy-ion collision experiments and future lattice QCD simulations are also discussed.
The realization of strong, stray static magnetic fields
Czech Academy of Sciences Publication Activity Database
Žežulka, Václav; Straka, Pavel
2012-01-01
Roč. 9, č. 1 (2012), s. 71-77 ISSN 1214-9705 Institutional research plan: CEZ:AV0Z30460519 Keywords : magnetic fields * magnetic circuits * permanent NdFeB magnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/materialy/acta_content/2012_01/7_Zezulka.pdf
The classical wormhole solution and wormhole wavefunction with a nonlinear Born-Infeld scalar field
Lu, H. Q.; Shen, L. M.; Ji, P.; Ji, G. F.; Sun, N. J.
2002-01-01
On this paper we consider the classical wormhole solution of the Born-Infeld scalar field. The corresponding classical wormhole solution can be obtained analytically for both very small and large $\\dot{\\phi}$. At the extreme limits of small $\\dot{\\phi}$ the wormhole solution has the same format as one obtained by Giddings and Strominger[10]. At the extreme limits of large $\\dot{\\phi}$ the wormhole solution is a new one. The wormhole wavefunctions can also be obtained for both very small and l...
Strong magnetic field induces superconductivity in a Weyl semimetal
Rosenstein, Baruch; Shapiro, B. Ya.; Li, Dingping; Shapiro, I.
2017-12-01
Microscopic theory of the normal-to-superconductor coexistence line of a multiband Weyl superconductor subjected to magnetic field is constructed. It is shown that the Weyl semimetal that is nonsuperconducting or having a small critical temperature Tc at zero field might become a superconductor at higher temperatures when the magnetic field is tuned to a series of quantized values Hn. The pairing occurs on Landau levels. It is argued that the phenomenon is detectable much easier in Weyl semimetals than in parabolic band metals since the quantum limit already has been approached in several Weyl materials. The effect of Zeeman coupling leading to splitting of the reentrant superconducting regions on the magnetic phase diagram is considered. An experimental signature of the superconductivity on Landau levels is the reduction of magnetoresistivity. This has been observed already in Cd3As2 and several other compounds. The novel kind of quantum oscillations of magnetoresistance detected in ZrTe5 is discussed along these lines.
Electrohydrodynamics of drops in strong electric fields: Simulations and theory
Saintillan, David; Das, Debasish
2016-11-01
Weakly conducting dielectric liquid drops suspended in another dielectric liquid exhibit a wide range of dynamical behaviors when subject to an applied uniform electric field contingent on field strength and material properties. These phenomena are best described by the much celebrated Maylor-Taylor leaky dielectric model that hypothesizes charge accumulation on the drop-fluid interface and prescribes a balance between charge relaxation, the jump in Ohmic currents and charge convection by the interfacial fluid flow. Most previous numerical simulations based on this model have either neglected interfacial charge convection or restricted themselves to axisymmetric drops. In this work, we develop a three-dimensional boundary element method for the complete leaky dielectric model to systematically study the deformation and dynamics of liquid drops in electric fields. The inclusion of charge convection in our simulation permits us to investigate drops in the Quincke regime, in which experiments have demonstrated symmetry-breaking bifurcations leading to steady electrorotation. Our simulation results show excellent agreement with existing experimental data and small deformation theories. ACSPRF Grant 53240-ND9.
Spin and Angular Momentum in Strong-Field Ionization
Trabert, D.; Hartung, A.; Eckart, S.; Trinter, F.; Kalinin, A.; Schöffler, M.; Schmidt, L. Ph. H.; Jahnke, T.; Kunitski, M.; Dörner, R.
2018-01-01
The spin polarization of electrons from multiphoton ionization of Xe by 395 nm circularly polarized laser pulses at 6 ×1013 W /cm2 has been measured. At this photon energy of 3.14 eV the above-threshold ionization peaks connected to Xe+ ions in the ground state (J =3 /2 , ionization potential Ip=12.1 eV ) and the first excited state (J =1 /2 , Ip=13.4 eV ) are clearly separated in the electron energy distribution. These two combs of above-threshold ionization peaks show opposite spin polarizations. The magnitude of the spin polarization is a factor of 2 higher for the J =1 /2 than for the J =3 /2 final ionic state. In turn, the data show that the ionization probability is strongly dependent on the sign of the magnetic quantum number.
Force-Field Functor Theory: Classical Force-Fields which Reproduce Equilibrium Quantum Distributions
Directory of Open Access Journals (Sweden)
Ryan eBabbush
2013-10-01
Full Text Available Feynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exact quantum equilibrium density and partition function. The usefulness of such a mapping rests in its ability to readily improve Born-Oppenheimer potentials for use with classical sampling. We show that such a map is unique and must exist. To explore the feasibility of using this result to improve classical molecular mechanics, we numerically produce a map from a library of randomly generated one-dimensional potential/effective potential pairs then evaluate its performance on independent test problems. We also apply the map to simulate liquid para-hydrogen, finding that the resulting radial pair distribution functions agree well with path integral Monte Carlo simulations. The surprising accessibility and transferability of the technique suggest a quantitative route to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to the powerful ideas and approximations of density functional theory.
Babbush, Ryan; Parkhill, John; Aspuru-Guzik, Alán
2013-01-01
Feynman and Hibbs were the first to variationally determine an effective potential whose associated classical canonical ensemble approximates the exact quantum partition function. We examine the existence of a map between the local potential and an effective classical potential which matches the exact quantum equilibrium density and partition function. The usefulness of such a mapping rests in its ability to readily improve Born-Oppenheimer potentials for use with classical sampling. We show that such a map is unique and must exist. To explore the feasibility of using this result to improve classical molecular mechanics, we numerically produce a map from a library of randomly generated one-dimensional potential/effective potential pairs then evaluate its performance on independent test problems. We also apply the map to simulate liquid para-hydrogen, finding that the resulting radial pair distribution functions agree well with path integral Monte Carlo simulations. The surprising accessibility and transferability of the technique suggest a quantitative route to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to the powerful ideas and approximations of density functional theory.
Study of the interaction of atoms with strong laser fields
International Nuclear Information System (INIS)
Edwards, M.
1984-01-01
Three aspects of the interactions of atoms with high intensity laser fields were treated. All three were motivated by experiment. The first investigation was prompted by a recent experiment (Kruit et al. 1983) involving multiphoton ionization of Xe. In this experiment it was found that the photoelectron energy spectrum contained peaks that corresponded to the absorption of more than the minimum number of photons required to ionize the atom. A model approximation here showed good qualitative agreement with experiment. An experiment (Grove et al. 1977) designed to test a theoretical calculation of the dynamical Stark effect stimulated the second part of this thesis, namely: a study of how an adiabatically and near-adiabatically changing field intensity affects the resonance fluorescence spectrum of a two-level atom. It was found that there is an asymmetry in the spectrum for off-resonance excitation produced because the field turn-on repopulates the dressed state that is depopulated by spontaneous emission. The third part of this thesis was based on an experiment (Granneman and Van der Wiel 1976) that attempted to verify a perturbation calculation of the two-photon ionization cross section of Cs. A discrepancy of four orders of magnitude near a minimum in the cross section was found between theory and experiment. To explain this discrepancy it was suggested (Armstrong and Beers 1977) that the effective order of nonlinearity (k) for this process varied significantly around the minimum. This study involves a perturbation calculation of k. It was found that k varies rapidly around the minimum, and that this variation should be experimentally observable for laser intensities of the order of tens of GW cm -2
Dynamics of Molecular Gyroscopes Created by Strong Optical Fields
Mullin, Amy
2015-03-01
We explore the behavior of molecules in ultra-high angular momentum states prepared in an optical centrifuge and detected with transient IR absorption spectroscopy. In the optical centrifuge, the polarizable electron cloud of molecules interacts with the electric field of linearly polarized light that angularly accelerates over the time of the optical pulse. The centrifuge pulse is generated by combining oppositely chirped pulsed of light. Trapped molecules are driven into high angular momentum states that are spatially oriented with the optical field and have energies far above the average at 300 K. High resolution transient IR spectroscopy reveals the dynamics of collisional energy transfer for the super-rotors. Polarization-dependent studies show that the initial angular momentum orientation persists for many collisions, indicating that molecules in an optical centrifuge behave as quantum gyroscopes. Time-dependent population and energy profiles for individual J- states give information about the dynamics of super-rotors. Research support provided by NSF and the University of Maryland.
Hydrogen atom in a strong uniform electric field
International Nuclear Information System (INIS)
Damburg, R.Ya.
1989-01-01
It has been shown that notwithstanding the separability of the Schroedinger equation for the Lo-Surdo s tark (LS-S) problem for hydrogen, the quasistationary states cannot be always characterized by parabolic quantum numbers of n 1 , n 2 ,m. It is a reason why any numerical procedure of the calculation of the LS-S parameters E 0 and Γ which ignores this circumstance can appear to be invalid for large values of n 1 and F and small ones of n 2 and m. Experimental data on the photoionization of atoms in the presence of an electric field in the vicinity of the Rydberg series limit E=0 are in an accord with theoretical predictions. 32 refs.; 6 figs
Statistical mechanics of the quantum and classical sine-gordon fields
International Nuclear Information System (INIS)
Bullough, R.K.; Pilling, D.J.; Timonen, J.
1985-01-01
A number of results obtained by functional integration for the statistical mechanics of the integrable sine-Gordon and sine-Gordon fields is reported. In some respects these two fields relate one to the other as the attractive (c<0) and repulsive (c<0) cases of the nonlinear Schroedinger equation do. An attempt has been made to bring the functional integral method into line with the Bethe ansatz and quantum inverse methods. Measure for using action-angle variables is chosen. Classical and thermodynamic limits for action-angle variables are established. Partition function for sine-Gordon and sine-Gordon fields is derived in terms of action-angle variables
International Nuclear Information System (INIS)
Remler, E.A.
1977-01-01
A gauge-invariant version of the Wigner representation is used to relate relativistic mechanics, statistical mechanics, and quantum field theory in the context of the electrodynamics of scalar particles. A unified formulation of quantum field theory and statistical mechanics is developed which clarifies the physics interpretation of the single-particle Wigner function. A covariant form of Ehrenfest's theorem is derived. Classical electrodynamics is derived from quantum field theory after making a random-phase approximation. The validity of this approximation is discussed
General treatment of quantum and classical spinning particles in external fields
Obukhov, Yuri N.; Silenko, Alexander J.; Teryaev, Oleg V.
2017-11-01
We develop the general theory of spinning particles with electric and magnetic dipole moments moving in arbitrary electromagnetic, inertial, and gravitational fields. Both the quantum-mechanical and classical dynamics is investigated. We start from the covariant Dirac equation extended to a spin-1/2 fermion with anomalous magnetic and electric dipole moments and then perform the relativistic Foldy-Wouthuysen transformation. This transformation allows us to obtain the quantum-mechanical equations of motion for the physical operators in the Schrödinger form and to establish the classical limit of relativistic quantum mechanics. The results obtained are then compared to the general classical description of the spinning particle interacting with electromagnetic, inertial and gravitational fields. The complete agreement between the quantum mechanics and the classical theory is proven in the general case. As an application of the results obtained, we consider the dynamics of a spinning particle in a gravitational wave and analyze the prospects of using the magnetic resonance setup to find possible manifestations of the gravitational wave on spin.
Classical and quantum chaos in a quantum dot in time-periodic magnetic fields
Badrinarayanan, R.; José, Jorge V.
1996-09-01
We investigate the classical and quantum dynamics of an electron confined to a circular quantum dot in the presence of homogeneous Bdc+Bac magnetic fields. The classical motion shows a transition to chaotic behavior depending on the ratio ɛ=Bac/Bdc of field magnitudes and the cyclotron frequency ω~c in units of the drive frequency. We determine a phase boundary between regular and chaotic classical behavior in the ɛ vs ω~c plane. In the quantum regime we evaluate the quasienergy spectrum of the time-evolution operator. We show that the nearest-neighbor quasienergy eigenvalues show a transition from level clustering to level repulsion as one moves from the regular to chaotic regime in the (ɛ,ω~c) plane. The Δ3 statistic confirms this transition. In the chaotic regime, the eigenfunction statistics coincides with the Porter-Thomas prediction. Finally, we explicitly establish the phase-space correspondence between the classical and quantum solutions via the Husimi phase-space distributions of the model. Possible experimentally feasible conditions to see these effects are discussed.
Radiation effects on relativistic electrons in strong external fields
International Nuclear Information System (INIS)
Iqbal, Khalid
2013-01-01
The effects of radiation of high energy electron beams are a major issue in almost all types of charged particle accelerators. The objective of this thesis is both the analytical and numerical study of radiation effects. Due to its many applications the study of the self force has become a very active and productive field of research. The main part of this thesis is devoted to the study of radiation effects in laser-based plasma accelerators. Analytical models predict the existence of radiation effects. The investigation of radiation reaction show that in laser-based plasma accelerators, the self force effects lower the energy gain and emittance for moderate energies electron beams and increase the relative energy spread. However, for relatively high energy electron beams, the self radiation and retardation (radiation effects of one electron on the other electron of the system) effects increase the transverse emittance of the beam. The energy gain decreases to even lower value and relative energy spread increases to even higher value due to high radiation losses. The second part of this thesis investigates with radiation reaction in focused laser beams. Radiation effects are very weak even for high energy electrons. The radiation-free acceleration and the simple practical setup make direct acceleration in a focused laser beam very attractive. The results presented in this thesis can be helpful for the optimization of future electron acceleration experiments, in particular in the case of laser-plasma accelerators.
Strong-field physics with singular light beams
Zürch, M.; Kern, C.; Hansinger, P.; Dreischuh, A.; Spielmann, Ch.
2012-10-01
Light beams carrying a point singularity with a screw-type phase distribution are associated with an optical vortex. The corresponding momentum flow leads to an orbital angular momentum of the photons. The study of optical vortices has led to applications such as particle micro-manipulation, imaging, interferometry, quantum information and high-resolution microscopy and lithography. Recent analyses showed that transitions forbidden by selection rules seem to be allowed when using optical vortex beams. To exploit these intriguing new applications, it is often necessary to shorten the wavelength by nonlinear frequency conversion. However, during the conversion the optical vortices tend to break up. Here we show that optical vortices can be generated in the extreme ultraviolet (XUV) region using high-harmonic generation. The singularity impressed on the fundamental beam survives the highly nonlinear process. Vortices in the XUV region have the same phase distribution as the driving field, which is in contradiction to previous findings, where multiplication of the momentum by the harmonic order is expected. This approach opens the way for several applications based on vortex beams in the XUV region.
Test of Horizontal Magnetic Field Measurements in the Presence of a Strong Vertical Field
Vasserman, Isaac
2004-01-01
Trajectory straightness is an important parameter defining the performance of free-electron laser (FEL) devices. The first test of horizontal field measurements using Hall probes was done in 1998 as a preparation to the tuning of undulators for the FEL project at the Advanced Photon Source. This work continues the 1998 work, now associated with Linac Coherent Light Source (LCLS) project. Tolerances for the LCLS FEL undulator specify 2 um trajectory excursion in both (horizontal and vertical) planes for a particle energy of 14.1 GeV, which means that measurements of a small horizontal field in presence of strong (up to 1.5 T) vertical field are required. Hall probe measurements under such conditions are complicated due to a planar Hall probe effect. Previous tests done in 1998 showed that a 2- axis Sentron probe is a possible choice. The high sensitivity of horizontal field integrals to the vertical position of the sensor was observed. It was shown that this probe could be used for fast measurements and tuning...
Numerical Hydrodynamics in Strong-Field General Relativity
East, William Edward
In this thesis we develop and test methods for numerically evolving hydrodynamics coupled to the Einstein field equations, and then apply them to several problems in gravitational physics and astrophysics. The hydrodynamics scheme utilizes high-resolution shock-capturing techniques with flux corrections while the Einstein equations are evolved in the generalized harmonic formulation using finite difference methods. We construct initial data by solving the constraint equations using a multigrid algorithm with free data chosen based on superposing isolated compact objects. One application we consider is the merger of black hole-neutron star and neutron star-neutron star binaries that form through dynamical capture, as may occur in globular clusters or galactic nuclei. These systems can merge with non-negligible orbital eccentricity and display significant variability in dynamics and outcome as a function of initial impact parameter. We study the electromagnetic and gravitational-wave transients that these mergers may produce and their prospects for being detected with upcoming observations. We also introduce a numerical technique that allows solutions to the full Einstein equations to be obtained for extreme-mass-ratio systems where the spacetime is dominated by a known background solution. This technique is based on using the knowledge of a background solution to subtract off its contribution to the truncation error. We use this to study the tidal effects and gravitational radiation from a solar-type star falling into a supermassive black hole. Finally, we utilize general-relativistic hydrodynamics to study ultrarelativistic black hole formation. We study the head-on collision of fluid particles well within the kinetic energy dominated regime (Lorentz factors of 8-12). We find that black hole formation does occur at energies a factor of a few below simple hoop conjecture estimates. We also find that near the threshold for black hole formation, the collision leads to
DEFF Research Database (Denmark)
Overgaard, Johannes; Sørensen, Jesper Givskov; A. Hoffmann, Ary
2008-01-01
Physiological and evolutionary responses to thermal variation are often investigated under controlled laboratory conditions. However, this approach may fail to account for the complexity of natural environments. Here we investigated the costs and benefits of developmental or adult cold acclimation...... that the ability to locate a field resource has a genetic basis with a high heritability since only round of selection on parental flies (F0) revealed clear differences in the ability of offspring (F1 and F2) to locate field resources at cold temperatures. Again we found a poor association between field...... and laboratory performance emphasising the importance of testing thermal resistance under relevant/natural conditions....
Perez, Uzziel; Ang, Angeleene S.; Sugon Jr., Quirino M.; McNamara, Daniel J.; Yoshikawa, Akimasa
2015-01-01
We studied the orbit of an electron revolving around an infinitely massive nucleus of a large classical Hydrogen atom subject to an AC electric field oscillating perpendicular to the electron's circular orbit. Using perturbation theory in geometric algebra, we show that the equation of motion of the electron perpendicular to the unperturbed orbital plane satisfies a forced simple harmonic oscillator equation found in Lorentz dispersion law in Optics. We show that even though we did not introd...
Field-induced decay of quantum vacuum: visualizing pair production in a classical photonic system
Longhi, Stefano
2010-01-01
The phenomenon of vacuum decay, i.e. electron-positron pair production due to the instability of the quantum electrodynamics vacuum in an external field, is a remarkable prediction of Dirac theory whose experimental observation is still lacking. Here a classic wave optics analogue of vacuum decay, based on light propagation in curved waveguide superlattices, is proposed. Our photonic analogue enables a simple and experimentally-accessible visualization in space of the process of pair producti...
Phase-space representation of non-classical behaviour of scalar wave-fields
Energy Technology Data Exchange (ETDEWEB)
Canas-Cardona, Gustavo; Castaneda, Roman [Physics School, Universidad Nacional de Colombia Sede Medellin, A.A. 3840 Medellin (Colombia); Vinck-Posada, Herbert, E-mail: gcanas@unal.edu.co [Physics Department, Universidad Nacional de Colombia Sede Bogota, Bogota D.C (Colombia)
2011-01-01
The modelling of optical fields by using radiant and virtual point sources for the spatial coherence wavelets in the phase-space representation evidences some effects, conventionally attributed to non-classical correlations of light, although such type of correlations are not explicitly included in the model. Specifically, a light state is produced that has similar morphology to the Wigner Distribution Function of the well-known quantum Schroedinger cat and squeezed states.
On the existence of classical solutions for stationary extended mean field games
Gomes, Diogo A.
2014-04-01
In this paper we consider extended stationary mean-field games, that is mean-field games which depend on the velocity field of the players. We prove various a-priori estimates which generalize the results for quasi-variational mean-field games in Gomes et al. (2012). In addition we use adjoint method techniques to obtain higher regularity bounds. Then we establish the existence of smooth solutions under fairly general conditions by applying the continuity method. When applied to standard stationary mean-field games as in Lasry and Lions (2006), Gomes and Sanchez-Morgado (2011) or Gomes et al. (2012) this paper yields various new estimates and regularity properties not available previously. We discuss additionally several examples where the existence of classical solutions can be proved. © 2013 Elsevier Ltd. All rights reserved.
Korobkin, Vladlen V.; Romanovsky, Michael Y.
1992-06-01
It is shown that in a strong circularly polarized laser field, classical electron motion around the ions can occur. The non-relativistic scattering by these electrons in plasma has a certain (Thomson) cross-section only in the limit of a very strong field (it is practically the case of relativistic motion of electrons). In a circularly polarized field with an amplitude on the order of the inneratomic one, the cross section of this process is less. In the spectrum that the scattering of this field gives in plasma, there are non-ion satellites along with the basic frequency.
Gonoskov, I A; Tsatrafyllis, N; Kominis, I K; Tzallas, P
2016-09-07
We analytically describe the strong-field light-electron interaction using a quantized coherent laser state with arbitrary photon number. We obtain a light-electron wave function which is a closed-form solution of the time-dependent Schrödinger equation (TDSE). This wave function provides information about the quantum optical features of the interaction not accessible by semi-classical theories. With this approach we can reveal the quantum optical properties of high harmonic generation (HHG) process in gases by measuring the photon statistics of the transmitted infrared (IR) laser radiation. This work can lead to novel experiments in high-resolution spectroscopy in extreme-ultraviolet (XUV) and attosecond science without the need to measure the XUV light, while it can pave the way for the development of intense non-classical light sources.
High-resolution Ultraviolet Radiation Fields of Classical T Tauri Stars
France, Kevin; Schindhelm, Eric; Bergin, Edwin A.; Roueff, Evelyne; Abgrall, Hervé
2014-04-01
The far-ultraviolet (FUV; 912-1700 Å) radiation field from accreting central stars in classical T Tauri systems influences the disk chemistry during the period of giant planet formation. The FUV field may also play a critical role in determining the evolution of the inner disk (r publicly available in machine-readable format. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.
Verger, Yoann
2016-01-01
Martins (2016) recently emphasized the role that classical economics can play in building sustainability economics. In this respect, he uses Sraffa's theory of value and Sen and Nussbaum's capability theory to support his argument. My comment focuses on the part of his article concerning Sraffa's theory, and aims to refine some of Martins claims in order to avoid misunderstandings about the possibilities offered by Sraffa's theory.
Coherence and quasi-stable states in a strong infrared field
Zhong, Changchun; Robicheaux, Francis
2016-05-01
We study the quasi-stability of UV-pulse-train-excited H atoms in a strong infrared (IR) laser as a function of the phase delay of the UV-pulse-train relative to the IR laser. The UV-pulse-train contains two frequency components. When the two components have frequencies separated by two IR photons, the population of surviving electrons is modulated by up to ten percent. When electrons are excited to right above or below the threshold, the survival probabilities have inverted phase delay dependence which can be explained classically. When the two frequencies are one IR-photon apart, the angular symmetry of the quasi-stable electrons is broken, and the asymmetry is also controlled by the phase delay. The asymmetrical distribution can be observed while the IR is on and smoothly evolves to a nonzero asymmetry that only weakly depends on the duration of the IR field. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0012193.
Prokop, Alexandr; Vacek, Jaroslav; Michl, Josef
2012-03-27
Friction in molecular rotors is examined by classical molecular dynamics simulations for grid-mounted azimuthal dipolar molecular rotors, whose rotation is either allowed to decay freely or is driven at GHz frequencies by a flow of rare gas or by a rotating electric field. The rotating parts (rotators) are propeller-shaped. Their two to six blades consist of condensed aromatic rings and are attached to a deltahedral carborane hub, whose antipodal carbons carry [n]staffane axles mounted on a square molecular grid. The dynamic friction constant η has been derived in several independent ways with similar results. Analysis of free rotation decay yields η as a continuous exponentially decreasing function of rotor frequency. The calculated dependence of friction torque on frequency resembles the classical macroscopic Stribeck curve. Its relation to rotational potential energy barriers and the key role of the rate of intramolecular vibrational redistribution (IVR) of energy and angular momentum from rotator rotation to other modes are considered in two limiting regimes. (i) In the strongly overdamped regime, rotation is much slower than IVR, and effective friction can be expressed through potential barriers to rotation. (ii) In the strongly underdamped regime, rotation is much faster than IVR, whose rate then determines friction. © 2012 American Chemical Society
Ionization of highly excited states of a hydrogen atom by a strong low-frequency field
International Nuclear Information System (INIS)
Bersons, I.Y.
1984-01-01
The probability of ionization of highly excited states of a hydrogen atom by a low-frequency field is estimated by using the previously derived quasi-classical wave function of an electron in a Coulomb field and in a radiation field. The expression obtained predicts an ionization threshold at field intensities approximately equal to those observed experimentally, but predicts an increase in ionization probability that is approximately ten times the increase observed experimentally when the field intensity in the threshold region is increased. The approximations underlying the derivation of the equation for the ionization probability are discussed
A New Semi-Symmetric Uniﬁed Field Theory of the Classical Fields of Gravity and Electromagnetism
Directory of Open Access Journals (Sweden)
Suhendro I.
2007-10-01
Full Text Available We attempt to present a classical theoretical framework in which the gravitational and electromagnetic fields are unified as intrinsic geometric objects in the space-time manifold. For this purpose, we first present the preliminary geometric considerations dealing with the metric differential geometry of Cartan connections. The unified field theory is then developed as an extension of the general theory of relativity based on a semi- symmetric Cartan connection which is meant to be as close as possible structurally to the symmetric connection of the Einstein-Riemann space-time.
Restrictions on Possible Forms of Classical Matter Fields Carrying no Energy
International Nuclear Information System (INIS)
Sokolowski, L.M.
2004-01-01
It is postulated in general relativity that the matter energy-momentum tensor vanishes if and only if all the matter fields vanish. In classical Lagrangian field theory the energy and momentum density are described by the variational (symmetric) energy-momentum tensor (named the stress tensor) and a priori it might occur that for some systems the tensor is identically to zero for all field configurations whereas evolution of the system is subject to deterministic Lagrange equations of motion. Such a system would not generate its own gravitational field. To check if these systems can exist in the framework of classical field theory we find a relationship between the stress tensor and the Euler operator (i.e. the Lagrange field equations). We prove that if a system of interacting scalar fields (the number of fields cannot exceed the spacetime dimension d) or a single vector field (in spacetimes with d even) has the stress tensor such that its divergence is identically zero (i.e. ''on and of shell''), then the Lagrange equations of motion hold identically too. These systems have then no propagation equations at all and should be regarded as unphysical. Thus nontrivial field equations require the stress tensor be nontrivial too. This relationship between vanishing (of divergence) of the stress tensor and of the Euler operator breaks down if the number of fields is greater than d. We show on concrete examples that a system of n > d interacting scalars or two interacting vector fields can have the stress tensor equal identically to zero while their propagation equations are nontrivial. This means that non-self-gravitating (and yet detectable) field systems are in principle admissible. Their equations of motion are, however, in some sense degenerate. We also show, that for a system of arbitrary number of interacting scalar fields or for a single vector field (in some specific spacetimes in the latter case), if the stress tensor is not identically zero, then it cannot
The classical centre-of-mass separation for two particles in a homogeneous magnetic field
International Nuclear Information System (INIS)
Dickinson, A.S.; Patterson, J.M.
1986-01-01
The authors investigate classically the problem of the centre-of-mass separation for a two-body system with net charge in a homogeneous magnetic field. Particular attention is paid to the case where one particle is much heavier than the other. Alternative momenta involving a suggested near-constant of the motion are investigated for use with a translation-invariant internal potential. These lead to a 'near separation' in terms of two coupled particles characterised by vectors which possess a simple classical interpretation, even in the presence of an interaction potential. However it is found that the coupling is not small and is not reduced when one of the particles is much heavier than the other, although the frequencies of the two motions then differ widely. (author)
Classical field theory on electrodynamics, non-abelian gauge theories and gravitation
Scheck, Florian
2018-01-01
Scheck’s successful textbook presents a comprehensive treatment, ideally suited for a one-semester course. The textbook describes Maxwell's equations first in their integral, directly testable form, then moves on to their local formulation. The first two chapters cover all essential properties of Maxwell's equations, including their symmetries and their covariance in a modern notation. Chapter 3 is devoted to Maxwell's theory as a classical field theory and to solutions of the wave equation. Chapter 4 deals with important applications of Maxwell's theory. It includes topical subjects such as metamaterials with negative refraction index and solutions of Helmholtz' equation in paraxial approximation relevant for the description of laser beams. Chapter 5 describes non-Abelian gauge theories from a classical, geometric point of view, in analogy to Maxwell's theory as a prototype, and culminates in an application to the U(2) theory relevant for electroweak interactions. The last chapter 6 gives a concise summary...
International Nuclear Information System (INIS)
Galilo, Bogdan V.; Nedelko, Sergei N.
2011-01-01
The one-loop quark contribution to the QCD effective potential for the homogeneous Abelian gluon field in the presence of an external strong electromagnetic field is evaluated. The structure of extrema of the potential as a function of the angles between chromoelectric, chromomagnetic, and electromagnetic fields is analyzed. In this setup, the electromagnetic field is considered as an external one while the gluon field represents domain structured nonperturbative gluon configurations related to the QCD vacuum in the confinement phase. Two particularly interesting gluon configurations, (anti-)self-dual and crossed orthogonal chromomagnetic and chromoelectric fields, are discussed specifically. Within this simplified framework it is shown that the strong electromagnetic fields can play a catalyzing role for a deconfinement transition. At the qualitative level, the present consideration can be seen as a highly simplified study of an impact of the electromagnetic fields generated in relativistic heavy ion collisions on the strongly interacting hadronic matter.
Classical solutions in quantum field theory solitons and instantons in high energy physics
Weinberg, Erick J
2012-01-01
Classical solutions play an important role in quantum field theory, high energy physics and cosmology. Real-time soliton solutions give rise to particles, such as magnetic monopoles, and extended structures, such as domain walls and cosmic strings, that have implications for early universe cosmology. Imaginary-time Euclidean instantons are responsible for important nonperturbative effects, while Euclidean bounce solutions govern transitions between metastable states. Written for advanced graduate students and researchers in elementary particle physics, cosmology and related fields, this book brings the reader up to the level of current research in the field. The first half of the book discusses the most important classes of solitons: kinks, vortices and magnetic monopoles. The cosmological and observational constraints on these are covered, as are more formal aspects, including BPS solitons and their connection with supersymmetry. The second half is devoted to Euclidean solutions, with particular emphasis on ...
A Langevin Approach to a Classical Brownian Oscillator in an Electromagnetic Field
International Nuclear Information System (INIS)
Espinoza Ortiz, J. S.; Bauke, F. C.; Lagos, R. E.
2016-01-01
We consider a charged Brownian particle bounded by an harmonic potential, embedded in a Markovian heat bath and driven from equilibrium by external electric and magnetic fields. We develop a quaternionic-like (or Pauli spinor-like) representation, hitherto exploited in classical Lorentz related dynamics. Within this formalism, in a very straight forward and elegant fashion, we compute the exact solution for the resulting generalized Langevin equation, for the case of a constant magnetic field. For the case the source electromagnetic fields satisfy Maxwell's equations, yielding spinor-like Mathieu equations, we compute the solutions within the JWKB approximation. With the solutions at hand we further compute spatial, velocities and crossed time correlations. In particular we study the (kinetically defined) nonequilbrium temperature. Therefore, we can display the system's time evolution towards equilibrium or towards non equilibrium (steady or not) states. (paper)
A Langevin Approach to a Classical Brownian Oscillator in an Electromagnetic Field
Espinoza Ortiz, J. S.; Bauke, F. C.; Lagos, R. E.
2016-08-01
We consider a charged Brownian particle bounded by an harmonic potential, embedded in a Markovian heat bath and driven from equilibrium by external electric and magnetic fields. We develop a quaternionic-like (or Pauli spinor-like) representation, hitherto exploited in classical Lorentz related dynamics. Within this formalism, in a very straight forward and elegant fashion, we compute the exact solution for the resulting generalized Langevin equation, for the case of a constant magnetic field. For the case the source electromagnetic fields satisfy Maxwell's equations, yielding spinor-like Mathieu equations, we compute the solutions within the JWKB approximation. With the solutions at hand we further compute spatial, velocities and crossed time correlations. In particular we study the (kinetically defined) nonequilbrium temperature. Therefore, we can display the system's time evolution towards equilibrium or towards non equilibrium (steady or not) states.
Classical and quantal Lorentz covariant models of the electromagnetic radiation field
Aaberge, Terje
2000-07-01
We present Lorentz covariant models of the radiation field, i.e., plane wave solutions of the Maxwell equations satisfying the Coulomb gauge condition. The theory is constructed along traditional lines. We apply the interpretation of the field as a collection of photons and starts by constructing the state space of the photon. The novelty of this formulation is the use of a new action of the Lorentz group on the space of circular helicities of spin 1 which permits the construction of an action on the state space of the photon. Moreover, the generators of the action provide objects that can be used to construct the field observables both in the classical and quantum case. The result is a theory with a tight structure. It is a generalization of the standard theory, a covariant generalization, and it contains this as a special case.
On gravity's role in the genesis of rest masses of classical fields
Szabados, László B.
2018-03-01
It is shown that in the Einstein-conformally coupled Higgs-Maxwell system with Friedman-Robertson-Walker symmetries the energy density of the Higgs field has stable local minimum only if the mean curvature of the t=const hypersurfaces is less than a finite critical value χ _c, while for greater mean curvature the energy density is not bounded from below. Therefore, there are extreme gravitational situations in which even quasi-locally defined instantaneous vacuum states of the Higgs sector cannot exist, and hence one cannot at all define the rest mass of all the classical fields. On hypersurfaces with mean curvature less than χ _c the energy density has the `wine bottle' (rather than the familiar `Mexican hat') shape, and the gauge field can get rest mass via the Brout-Englert-Higgs mechanism. The spacelike hypersurface with the critical mean curvature represents the moment of `genesis' of rest masses.
Redshift of A 1(longitudinal optical) mode for GaN crystals under strong electric field
Gu, Hong; Wu, Kaijie; Zheng, Shunan; Shi, Lin; Zhang, Min; Liu, Zhenghui; Liu, Xinke; Wang, Jianfeng; Zhou, Taofei; Xu, Ke
2018-01-01
We investigated the property of GaN crystals under a strong electric field. The Raman spectra of GaN were measured using an ultraviolet laser, and a remarkable redshift of the A 1(LO) mode was observed. The role of the surface depletion layer was discussed, and the interrelation between the electric field and phonons was revealed. First-principles calculations indicated that, in particular, the phonons that vibrate along the [0001] direction are strongly influenced by the electric field. This effect was confirmed by a surface photovoltage experiment. The results revealed the origin of the redshift and presented the phonon property of GaN under a strong electric field.
Field theory reformulated without self-energy parts: Divergence-free classical electrodynamics
International Nuclear Information System (INIS)
Haan, Michel de
2006-01-01
This paper provides a formalism that allows the use of methods of statistical physics [R. Balescu, Equilibrium and Nonequilibrium Statistical Mechanics Wiley-Interscience, New York, 1975] to tackle the problem of the divergence of the self-mass. Our approach leads to expressions that are finite even for point-like charged particles: the limit of an infinite cutoff can be taken in an harmless way on self consistent equations. It combines without difficulties a manifestly gauge-invariant hamiltonian formulation of classical electrodynamics [R. Balescu, M. Poulain, Physica 76 (3) (1974) 421-444] with the reformulation of field theory without self-energy parts [M. de Haan, Ann. Phys. 311 (2004) 314-349]: all processes associated with self-energy are now integrated in a kinetic operator, while keeping the equivalence with the original description. The original formulation in terms of reduced distribution functions for the particles and the fields is applied here to the case of two charges interacting through a classical electrodynamical field
Classic and Quantum Capacitances in Bernal Bilayer and Trilayer Graphene Field Effect Transistor
Directory of Open Access Journals (Sweden)
Hatef Sadeghi
2013-01-01
Full Text Available Our focus in this study is on characterizing the capacitance voltage (C-V behavior of Bernal stacking bilayer graphene (BG and trilayer graphene (TG as the channel of FET devices. The analytical models of quantum capacitance (QC of BG and TG are presented. Although QC is smaller than the classic capacitance in conventional devices, its contribution to the total metal oxide semiconductor capacitor in graphene-based FET devices becomes significant in the nanoscale. Our calculation shows that QC increases with gate voltage in both BG and TG and decreases with temperature with some fluctuations. However, in bilayer graphene the fluctuation is higher due to its tunable band structure with external electric fields. In similar temperature and size, QC in metal oxide BG is higher than metal oxide TG configuration. Moreover, in both BG and TG, total capacitance is more affected by classic capacitance as the distance between gate electrode and channel increases. However, QC is more dominant when the channel becomes thinner into the nanoscale, and therefore we mostly deal with quantum capacitance in top gate in contrast with bottom gate that the classic capacitance is dominant.
Field-testing of the ICHD-3 beta diagnostic criteria for classical trigeminal neuralgia
DEFF Research Database (Denmark)
Maarbjerg, Stine; Sørensen, Morten Togo; Gozalov, Aydin
2015-01-01
INTRODUCTION: We aimed to field-test the beta version of the third edition of the International Classification of Headache Disorders (ICHD-3 beta) diagnostic criteria for classical trigeminal neuralgia (TN). The proposed beta draft of the 11th version of the International Classification of Diseases...... (ICD-11 beta) is almost exclusively based on the ICHD-3 beta classification structure although slightly abbreviated. We compared sensitivity and specificity to ICHD-2 criteria, and evaluated the needs for revision. METHODS: Clinical characteristics were systematically and prospectively collected from...
Shvetsov-Shilovski, N. I.; Lein, M.
2018-01-01
Using the semiclassical two-step model for strong-field ionization we investigate the interference structures emerging in strong-field photoelectron holography, taking into account the Coulomb potential of the atomic core. For every kind of the interference pattern predicted by the three-step model, we calculate the corresponding structure in the presence of the Coulomb field, showing that the Coulomb potential modifies the interference patterns significantly.
One-loop QCD thermodynamics in a strong homogeneous and static magnetic field
Rath, Shubhalaxmi; Patra, Binoy Krishna
2017-12-01
We have studied how the equation of state of thermal QCD with two light flavors is modified in a strong magnetic field. We calculate the thermodynamic observables of hot QCD matter up to one-loop, where the magnetic field affects mainly the quark contribution and the gluon part is largely unaffected except for the softening of the screening mass. We have first calculated the pressure of a thermal QCD medium in a strong magnetic field, where the pressure at fixed temperature increases with the magnetic field faster than the increase with the temperature at constant magnetic field. This can be understood from the dominant scale of thermal medium in the strong magnetic field, being the magnetic field, in the same way that the temperature dominates in a thermal medium in the absence of magnetic field. Thus although the presence of a strong magnetic field makes the pressure of hot QCD medium larger, the dependence of pressure on the temperature becomes less steep. Consistent with the above observations, the entropy density is found to decrease with the temperature in the presence of a strong magnetic field which is again consistent with the fact that the strong magnetic field restricts the dynamics of quarks to two dimensions, hence the phase space becomes squeezed resulting in the reduction of number of microstates. Moreover the energy density is seen to decrease and the speed of sound of thermal QCD medium increases in the presence of a strong magnetic field. These findings could have phenomenological implications in heavy ion collisions because the expansion dynamics of the medium produced in non-central ultra-relativistic heavy ion collisions is effectively controlled by both the energy density and the speed of sound.
Noether symmetries, energy-momentum tensors, and conformal invariance in classical field theory
International Nuclear Information System (INIS)
Pons, Josep M.
2011-01-01
In the framework of classical field theory, we first review the Noether theory of symmetries, with simple rederivations of its essential results, with special emphasis given to the Noether identities for gauge theories. With this baggage on board, we next discuss in detail, for Poincare invariant theories in flat spacetime, the differences between the Belinfante energy-momentum tensor and a family of Hilbert energy-momentum tensors. All these tensors coincide on shell but they split their duties in the following sense: Belinfante's tensor is the one to use in order to obtain the generators of Poincare symmetries and it is a basic ingredient of the generators of other eventual spacetime symmetries which may happen to exist. Instead, Hilbert tensors are the means to test whether a theory contains other spacetime symmetries beyond Poincare. We discuss at length the case of scale and conformal symmetry, of which we give some examples. We show, for Poincare invariant Lagrangians, that the realization of scale invariance selects a unique Hilbert tensor which allows for an easy test as to whether conformal invariance is also realized. Finally we make some basic remarks on metric generally covariant theories and classical field theory in a fixed curved background.
Field transformations and the classical equation of motion in chiral perturbation theory
International Nuclear Information System (INIS)
Scherer, S.; Fearing, H.W.
1995-01-01
The construction of effective Lagrangians commonly involves the application of the ''classical equation of motion'' to eliminate redundant structures and thus generate the minimal number of independent terms. We investigate this procedure in the framework of chiral perturbation theory with particular emphasis on the new features which appear at O(p 6 ). The use of the ''classical equation of motion'' is interpreted in terms of field transformations. Such an interpretation is crucial if one wants to bring a given Lagrangian into a canonical form with a minimal number of terms. We emphasize that the application of field transformations leads to a modification of the coefficients of higher-order terms as well as eliminating structures, or what is equivalent, expressing certain structures in terms of already known different structures. This will become relevant once one considers the problem of expressing in canonical form a model effective interaction containing terms beyond next-to-leading order, i.e., beyond O(p 4 ). In such circumstances the naive application of the clasical equation of motion to simply drop terms, as is commonly done at lowest order, leads to subtle errors, which we discuss
Classical trajectory analysis of Mg in a circularly polarized laser field
Xu, Tong-Tong; Ben, Shuai; Zhang, Jun; Liu, Xue-Shen
2017-05-01
The nonsequential double ionization (NSDI) of Mg atoms is investigated in a circularly polarized laser field using the classical ensemble method. We demonstrate the time evolution of the two-electron energy distribution, the time evolution of the repulsion energy distribution between two electrons in the double ionization process and the time of evolution of the distance distribution between the nucleus and two electrons. The theoretical results indicate that a single recollision leads to the NSDI process. Moreover, we also look into the elliptical trajectories to illustrate the difference in the return process of the first ionized electron. The dependence of the electron momentum distribution on the angle between the momentum and the force of laser field at the time of the first electron is also investigated and the results show that the angle plays a key role in the electron recollision time.
High energy heavy ion collisions from the view point of the 'strong field physics'
International Nuclear Information System (INIS)
Itakura, Kazunori
2012-01-01
In the high energy heavy ion collisions at the facilities like RHIC and LHC, two strongest fields in the present universe are generated. First of all, a very strong electromagnetic field is generated, though its duration is very short due to the very high speed collisions of nuclei and the large electric charges. On the other hand, the nuclei are described as the high density saturation gluon state just before the moment of the collision and the high density gluon is released by the collision. A very strong color electromagnetic field is generated. The color glass condensate (CGC) is a reasonable picture. In this text, dynamics of the GLASMA (Glass + plasma), the new physics brought about by those 'strong fields', are introduced and are explained how the yet unsolved problems of the heavy ion collisions are going to be investigated on the new view point. The mechanism of the apparitions of the strong electromagnetic field and the strong color electromagnetic field are explained at first. The heavy ion collisions can be described as the process CGC to develop into QGP. As the phenomena under the strong electromagnetic field and the heavy ion collisions, their synchrotron radiations, the photon birefringence, the photon decay, the splitting of photons and the chiral phase transitions under high field are picked up. Concerning the strong color electromagnetic field dynamics and the heavy ion collisions, the plasma flux tube dynamics, the color magnetic flux tube, the color electric flux tube and the coexisting case of the color electric field and magnetic field are presented. (S. Funahashi)
Attention operates uniformly throughout the classical receptive field and the surround
Verhoef, Bram-Ernst; Maunsell, John HR
2016-01-01
Shifting attention among visual stimuli at different locations modulates neuronal responses in heterogeneous ways, depending on where those stimuli lie within the receptive fields of neurons. Yet how attention interacts with the receptive-field structure of cortical neurons remains unclear. We measured neuronal responses in area V4 while monkeys shifted their attention among stimuli placed in different locations within and around neuronal receptive fields. We found that attention interacts uniformly with the spatially-varying excitation and suppression associated with the receptive field. This interaction explained the large variability in attention modulation across neurons, and a non-additive relationship among stimulus selectivity, stimulus-induced suppression and attention modulation that has not been previously described. A spatially-tuned normalization model precisely accounted for all observed attention modulations and for the spatial summation properties of neurons. These results provide a unified account of spatial summation and attention-related modulation across both the classical receptive field and the surround. DOI: http://dx.doi.org/10.7554/eLife.17256.001 PMID:27547989
International Nuclear Information System (INIS)
Song, Min Seop; Park, So Hyun; Kim, Eung Soo
2014-01-01
Many researchers conducted experiments and numerical simulations to measure or predict a Nusselt number or a friction factor in a pipe with a twisted tape while some other studies focused on the heat transfer performance enhancement using various twisted tape configurations. However, since the optical access to the inner space of a pipe with a twisted tape was limited, the detailed flow field data were not obtainable so far. Thus, researchers mainly relied on the numerical simulations to obtain the data of the flow field. In this study, a 3D printing technique was used to manufacture a transparent test section for optical access. And also, a noble refractive index matching technique was used to eliminate optical distortion. This two combined techniques enabled to measure the velocity profile with Particle Image Velocimetry (PIV). The measured velocity field data can be used either to understand the fundamental flow characteristics around a twisted tape or to validate turbulence models in Computational Fluid Dynamics (CFD). In this study, the flow field in the test-section was measured for various flow conditions and it was finally compared with numerically calculated data. Velocity fields in a pipe with a classic twisted tape was measured using a particle image velocimetry (PIV) system. To obtain undistorted particle images, a noble optical technique, refractive index matching, was used and it was proved that high-quality image can be obtained from this experimental equipment. The velocity data from the PIV was compared with the CFD simulations
Thermodynamic properties for applications in chemical industry via classical force fields.
Guevara-Carrion, Gabriela; Hasse, Hans; Vrabec, Jadran
2012-01-01
Thermodynamic properties of fluids are of key importance for the chemical industry. Presently, the fluid property models used in process design and optimization are mostly equations of state or G (E) models, which are parameterized using experimental data. Molecular modeling and simulation based on classical force fields is a promising alternative route, which in many cases reasonably complements the well established methods. This chapter gives an introduction to the state-of-the-art in this field regarding molecular models, simulation methods, and tools. Attention is given to the way modeling and simulation on the scale of molecular force fields interact with other scales, which is mainly by parameter inheritance. Parameters for molecular force fields are determined both bottom-up from quantum chemistry and top-down from experimental data. Commonly used functional forms for describing the intra- and intermolecular interactions are presented. Several approaches for ab initio to empirical force field parameterization are discussed. Some transferable force field families, which are frequently used in chemical engineering applications, are described. Furthermore, some examples of force fields that were parameterized for specific molecules are given. Molecular dynamics and Monte Carlo methods for the calculation of transport properties and vapor-liquid equilibria are introduced. Two case studies are presented. First, using liquid ammonia as an example, the capabilities of semi-empirical force fields, parameterized on the basis of quantum chemical information and experimental data, are discussed with respect to thermodynamic properties that are relevant for the chemical industry. Second, the ability of molecular simulation methods to describe accurately vapor-liquid equilibrium properties of binary mixtures containing CO(2) is shown.
High resolution field study of sediment dynamics on a strongly heterogeneous bed
Bailly Du Bois, P.; Blanpain, O.; Lafite, R.; Cugier, P.; Lunven, M.
2010-12-01
Extensive field measurements have been carried out at several stations in a macrotidal inner continental shelf in the English Channel (around 25 m depth) during spring tide period. The strong tidal current measured (up to 1.6 m.s-1) allowed sediment dynamics on a bed characterised by a mixture of size with coarse grains to be dominant. Data acquired in such hydro-sedimentary conditions are scarce. A new instrument, the DYnamic Sediment Profile Imagery (DySPI) system, was specifically conceived and implemented in-situ to observe and measure, with a high temporal resolution, the dynamics of a strongly heterogeneous mixture of particles in a grain-size scale. The data collected covered: 1) grain size range (side scan sonar, video observations, Shipeck grab samples, DySPI images) and vertical sorting (stratigraphic sampling by divers) of sediment cover, 2) hydrodynamic features (acoustic Doppler velocimeter, acoustic Doppler profiler), 3) suspended load nature and dynamics (optical backscatter, chlorophyll fluorometer, particle size analyser, Niskin bottles, scanning electron microscopy), 4) sand and gravel bedload transport estimates (DySPI image processing), 5) transfer dynamics of fine grains within a coarse matrix and their depth of penetration (radionuclides measurements in stratigraphic samples). The four stations present different grain size vertical sorting from a quasi-permanent armouring to a homogenous distribution. The sediment cover condition is directly linked to hydrodynamic capacity and sediment availability. Fine grain ratio within deep sediment layers (up to 10 cm) is higher when the bed armouring is durable. However, fine sediments are not permanently depth trapped: deep layers are composed of few years-old radionuclide tracers fixed on fine grains and a vertical mixing coefficient has been evaluated for each sediment cover. Fine grain dynamics within a coarse matrix is inversely proportional to the robustness of the armour layer. For current
Spectrum of absorption of a weak signal by an atom in a strong field
International Nuclear Information System (INIS)
Bakaev, D.S.; Vdovin, Y.A.; Ermachenko, V.M.; Yakovlenko, S.I.
1985-01-01
An analysis is made of the spectrum of absorption of a weak probe electromagnetic field by two-level atoms in a strong resonant laser field, undergoing collision with buffer gas atoms. The analysis is made using an approach that allows for the direct influence of a strong electromagnetic field on the dynamics of an elastic collision between an active atom and a buffer gas atom. Rate equations are analyzed for a combined ''atom--strong electromagnetic field'' system (an atom ''dressed'' by the field) allowing for spontaneous and optical collisional transitions, and also for the interaction with the probe field. In the steady-state case, an expression is derived for the electric susceptibility of the medium at the small-signal frequency. This expression contains the rates of the optical collisional transitions that depend nontrivially on the parameters of the strong electromagnetic field. The phenomenological characteristics of optical collisional transitions generally used are only valid at low intensities and for small frequency detunings of the strong electromagnetic field, i.e., in the impact limit
Regularity and Chaos in the Hydrogen Atom Highly Excited with a Strong Magnetic Field
Directory of Open Access Journals (Sweden)
M. Amdouni
2014-01-01
Full Text Available The effects of the relativistic corrections on the energy spectra are analyzed. Effective simulations based on manipulations of operators in the Sturmian basis are developed. Discrete and continuous energy spectra of a hydrogen atom with realistic nucleus mass in a strong magnetic field are computed. The transition from regularity to chaos in diamagnetic problem with the effect of the nucleus recoil energy is explored. Anticrossing of energy levels is observed for strong magnetic field.
Computational strong-field quantum dynamics intense light-matter interactions
2017-01-01
This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time-dependent Schrödinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi-configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.
Computational strong-field quantum dynamics. Intense light-matter interactions
Energy Technology Data Exchange (ETDEWEB)
Bauer, Dieter (ed.) [Rostock Univ. (Germany). Inst. fuer Physik
2017-09-01
This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time dependent Schroedinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.
Lin, Fang-Yu; MacKerell, Alexander D
2018-02-13
The quality of the force field is crucial to ensure the accuracy of simulations used in molecular modeling, including computer-aided drug design (CADD). To perform more accurate modeling and simulations of halogenated molecules, in this study the polarizable force field based on the classical Drude oscillator model was extended to both aliphatic and aromatic systems using halogenated ethane and benzene model compounds for the halogens F, Cl, Br, and I. The force field parameters were optimized targeting quantum mechanical dipole moments, water interactions, and molecular polarizabilities as well as experimental observables, including enthalpies of vaporization, molecular volumes, hydration free energies, and dielectric constants. The developed halogenated polarizable force field is capable of reproducing QM relative energies and geometries of both halogen bonds and halogen-hydrogen bond donor interactions at an unprecedented level due to the inclusion of a virtual particle and anisotropic atomic polarizability on the halogen and, notably, the inclusion of Lennard-Jones parameters on the halogen Drude particle. The model was validated on the basis of its ability to accurately reproduce pure solvent properties for halogenated naphthalenes and alkanes, including species analogous to those used as refrigerants. Accordingly, it is anticipated that the model will be applicable for the study of halogenated derivatives in CADD as well as in other chemical and biophysical studies.
MgB2 superconducting particles in a strong electric field
International Nuclear Information System (INIS)
Tao, R.; Xu, X.; Amr, E.
2003-01-01
The electric-field induced ball formation has been observed with MgB 2 powder in a strong static or quasi-static electric field. The effect of temperature and magnetic field on the ball formation shows surprising features. For quite a wide range of temperature from T c =39 K and below, the ball size is proportional to (1-T/T c ). As the temperature further goes below 20 K, the ball size becomes almost a constant. If MgB 2 particles are in a strong electric field and a moderate magnetic field, the electric-field induced balls align in the magnetic-field direction to form ball chains
Hole dynamics and spin currents after ionization in strong circularly polarized laser fields
International Nuclear Information System (INIS)
Barth, Ingo; Smirnova, Olga
2014-01-01
We apply the time-dependent analytical R-matrix theory to develop a movie of hole motion in a Kr atom upon ionization by strong circularly polarized field. We find rich hole dynamics, ranging from rotation to swinging motion. The motion of the hole depends on the final energy and the spin of the photoelectron and can be controlled by the laser frequency and intensity. Crucially, hole rotation is a purely non-adiabatic effect, completely missing in the framework of quasistatic (adiabatic) tunneling theories. We explore the possibility to use hole rotation as a clock for measuring ionization time. Analyzing the relationship between the relative phases in different ionization channels we show that in the case of short-range electron-core interaction the hole is always initially aligned along the instantaneous direction of the laser field, signifying zero delays in ionization. Finally, we show that strong-field ionization in circular fields creates spin currents (i.e. different flow of spin-up and spin-down density in space) in the ions. This phenomenon is intimately related to the production of spin-polarized electrons in strong laser fields Barth and Smirnova (2013 Phys. Rev. A 88 013401). We demonstrate that rich spin dynamics of electrons and holes produced during strong field ionization can occur in typical experimental conditions and does not require relativistic intensities or strong magnetic fields. (paper)
Sun, Xiao; Chai, Guobei; Liu, Wei; Bao, Wenzhuo; Zhao, Xiaoning; Ming, Delie
2018-02-01
Simple cells in primary visual cortex are believed to extract local edge information from a visual scene. In this paper, inspired by different receptive field properties and visual information flow paths of neurons, an improved Combination of Receptive Fields (CORF) model combined with non-classical receptive fields was proposed to simulate the responses of simple cell's receptive fields. Compared to the classical model, the proposed model is able to better imitate simple cell's physiologic structure with consideration of facilitation and suppression of non-classical receptive fields. And on this base, an edge detection algorithm as an application of the improved CORF model was proposed. Experimental results validate the robustness of the proposed algorithm to noise and background interference.
Gauge bridges in classical field theory; Eichbruecken in der klassischen Feldtheorie
Energy Technology Data Exchange (ETDEWEB)
Jakobs, S.
2009-03-15
In this thesis Poisson structures of two classical gauge field theories (Maxwell-Klein-Gordon- and Maxwell-Dirac-system) are constructed using the parametrix construction of Green's functions. Parametrices for the Maxwell-Klein-Gordon- and Maxwell-Dirac-system are constructed in Minkowski space and this construction is later generalized to curved space times for the Maxwell-Klein-Gordon-system. With these Green's functions Poisson brackets will be defined as Peierls brackets. Finally non-local, gauge invariant observables, the so-called 'gauge bridges'are constructed. Gauge bridges are the matrix elements of holonomy operators. It is shown, that these emerge from Poisson brackets of local, gauge invariant observables. (orig.)
Electron cyclotron maser instability (ECMI in strong magnetic guide field reconnection
Directory of Open Access Journals (Sweden)
R. A. Treumann
2017-08-01
Full Text Available The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is
Electron cyclotron maser instability (ECMI) in strong magnetic guide field reconnection
Treumann, Rudolf A.; Baumjohann, Wolfgang
2017-08-01
The ECMI model of electromagnetic radiation from electron holes is shown to be applicable to spontaneous magnetic reconnection. We apply it to reconnection in strong current-aligned magnetic guide fields. Such guide fields participate only passively in reconnection, which occurs in the antiparallel components to both sides of the guide-field-aligned current sheets with current carried by kinetic Alfvén waves. Reconnection generates long (the order of hundreds of electron inertial scales) electron exhaust regions at the reconnection site X point, which are extended perpendicular to the current and the guide fields. Exhausts contain a strongly density-depleted hot electron component and have properties similar to electron holes. Exhaust electron momentum space distributions are highly deformed, exhibiting steep gradients transverse to both the reconnecting and guide fields. Such properties suggest application of the ECMI mechanism with the fundamental ECMI X-mode emission beneath the nonrelativistic guide field cyclotron frequency in localized source regions. An outline of the mechanism and its prospects is given. Potential applications are the kilometric radiation (AKR) in auroral physics, solar radio emissions during flares, planetary emissions and astrophysical scenarios (radiation from stars and compact objects) involving the presence of strong magnetic fields and field-aligned currents. Drift of the exhausts along the guide field maps the local field and plasma properties. Escape of radiation from the exhaust and radiation source region still poses a problem. The mechanism can be studied in 2-D particle simulations of strong guide field reconnection which favours 2-D, mapping the deformation of the electron distribution perpendicular to the guide field, and using it in the numerical calculation of the ECMI growth rate. The mechanism suggests also that reconnection in general may become a source of the ECMI with or without guide fields. This is of particular
Schaap, K.
2015-01-01
Magnetic resonance imaging (MRI) makes use of electromagnetic fields in the non-ionizing radiation frequency ranges. One of them is a continuously present strong static magnetic field (SMF), which extends up to several meters around the scanner. Each time an MRI worker performs tasks near the
Sensitivity Analysis and Simulation of Theoretical Response of Ceramics to Strong Magnetic Fields
2016-09-01
448. 23. Song Q, Zhang ZJ. Shape control and associated magnetic properties of spinel cobalt ferrite nanocrystals. Journal of the American Chemical...Strong Magnetic Fields by Carli A Moorehead, Michael M Kornecki, Victoria L Blair, Raymond E Brennan Approved for... Magnetic Fields by Carli A Moorehead Drexel University, Philadelphia, Pennsylvannia Michael M Kornecki, Victoria L Blair, and Raymond E Brennan
Schlegel, Theodor; Tikhonchuk, Vladimir T.
2012-07-01
The propagation of a relativistic electron with initial energy ≳100 MeV in a number of simple one-dimensional laser field configurations with circular polarization is studied by solving the relativistic equation of motion in the Landau-Lifschitz approach to account for the radiation friction force. The radiation back-reaction on the electron dynamics becomes visible at dimensionless field amplitudes a ≳ 10 at these high particle energies. Analytical expressions are derived for the energy and the longitudinal momentum of the electron, the frequency shift of the light scattered by the electron and the particle trajectories. These findings are compared with the numerical solutions of the basic equations. A strong radiation damping effect results in reduced light scattering, forming at the same time a broad quasi-continuous spectrum. In addition, the electron dynamics in the strong field of a quasistationary laser piston is investigated. Analytical solutions for the electron trajectories in this complex field pattern are obtained and compared with the numerical solutions. The radiation friction force may stop a relativistic electron after propagation over several laser wavelengths at high laser field strengths, which supports the formation of a stable piston.
ON MULTIPLE RECONNECTION X-LINES AND TRIPOLAR PERTURBATIONS OF STRONG GUIDE MAGNETIC FIELDS
International Nuclear Information System (INIS)
Eriksson, S.; Gosling, J. T.; Lapenta, G.; Newman, D. L.; Goldman, M. V.; Phan, T. D.; Lavraud, B.; Khotyaintsev, Yu. V.; Carr, C. M.; Markidis, S.
2015-01-01
We report new multi-spacecraft Cluster observations of tripolar guide magnetic field perturbations at a solar wind reconnection exhaust in the presence of a guide field B M which is almost four times as strong as the reversing field B L . The novel tripolar field consists of two narrow regions of depressed B M , with an observed 7%–14% ΔB M magnitude relative to the external field, which are found adjacent to a wide region of enhanced B M within the exhaust. A stronger reversing field is associated with each B M depression. A kinetic reconnection simulation for realistic solar wind conditions and the observed strong guide field reveals that tripolar magnetic fields preferentially form across current sheets in the presence of multiple X-lines as magnetic islands approach one another and merge into fewer and larger islands. The simulated ΔB M /ΔX N over the normal width ΔX N between a B M minimum and the edge of the external region agree with the normalized values observed by Cluster. We propose that a tripolar guide field perturbation may be used to identify candidate regions containing multiple X-lines and interacting magnetic islands at individual solar wind current sheets with a strong guide field
Khine, Y. Y.; Walker, J. S.
1995-02-01
This paper treats the buoyant convection during the Czochralski growth of silicon crystals with a steady, strong, non-uniform, axisymmetric magnetic field. We consider a family of magnetic fields which includes a uniform axial magnetic field and a "cusp" field which is produced by identical solenoids placed symmetrically above and below the plane of the crystal-melt interface and free surface. We investigate the evolution of the buoyant convection as the magnetic field is changed continuously from a uniform axial field to a cusp field, with a constant value of the root-mean-squared magnetic flux density in the melt. We also investigate changes as the magnetic flux density is increased. While the cusp field appears very promising, perfect alignment between the local magnetic field vector and the crystal-melt interface or free surface is not possible, so the effects of a slight misalignment are also investigated.
Strong field approximation within a Faddeev-like formalism for laser-matter interactions
International Nuclear Information System (INIS)
Popov, Y.; Galstyan, A.; Piraux, B.; Mota-Furtado, F.; O'Mahony, P.F.
2017-01-01
We consider the interaction of atomic hydrogen with an intense laser field within the strong-field approximation (SFA). By using a Faddeev-like formalism, we introduce a new perturbative series in the binding potential of the atom. As a first test of this new approach, we calculate the electron energy spectrum in the very simple case of a photon energy higher than the ionisation potential. We show that by contrast to the standard perturbative series in the binding potential obtained within the strong field approximation, the first terms of the new series converge rapidly towards the results we get by solving the corresponding time-dependent Schroedinger equation. (authors)
Charge states of high Z atoms in a strong laser field
International Nuclear Information System (INIS)
Susskind, S.M.; Valeo, E.J.; Oberman, C.R.; Bernstein, I.B.
1989-11-01
We present a numerical solution of the Thomas-Fermi atom in the presence of a static electric field as a model of the adiabatic response of a heavy atom in the presence of a strong laser field. In this semiclassical approach, we calculate the resulting charge state of the atom and its induced dipole moment after the field is turned on. Due to the scaling properties of the Thomas-Fermi approach, the resulting total atomic charge and dipole moment can be expressed as a universal function of the field. We compare our results with recent ionization experiments performed on noble gases using laser fields. 7 refs., 5 figs
Imaginary potential in strongly coupled N = 4 SYM plasma in a magnetic field
Zhang, Zi-qiang; Hou, De-fu
2018-03-01
We study the effect of a constant magnetic field on the imaginary part of a quarkonia potential in a strongly-coupled N = 4 SYM plasma. We consider the pair axis to be aligned perpendicularly and parallel to the magnetic field, respectively. For both cases, we find that the presence of the magnetic field tends to enhance the imaginary potential thus decreasing the thermal width. In addition, the magnetic field has a stronger effect on the imaginary potential when the pair axis is perpendicular to the magnetic field rather than parallel.
Sharp-front wave of strong magnetic field diffusion in solid metal
Energy Technology Data Exchange (ETDEWEB)
Xiao, Bo; Gu, Zhuo-wei; Kan, Ming-xian; Wang, Gang-hua; Zhao, Jian-heng [Institute of Fluid Physics, CAEP, P.O. Box 919-105, Mianyang 621900 (China)
2016-08-15
When a strong magnetic field diffuses into a solid metal, if the metal's resistance possesses an abrupt rise at some critical temperature and the magnetic field strength is above some critical value, the magnetic field will diffuse into the metal in the form of a sharp-front wave. Formulas for the critical conditions under which a sharp-front magnetic diffusion wave emerges and a formula for the wave-front velocity are derived in this work.
Strongly coupled chameleon fields: Possible test with a neutron Lloyd's mirror interferometer
Energy Technology Data Exchange (ETDEWEB)
Pokotilovski, Yu.N., E-mail: pokot@nf.jinr.ru [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation)
2013-02-26
The consideration of possible neutron Lloyd's mirror interferometer experiment to search for strongly coupled chameleon fields is presented. The chameleon scalar fields were proposed to explain the acceleration of expansion of the Universe. The presence of a chameleon field results in a change of a particle's potential energy in vicinity of a massive body. This interaction causes a phase shift of neutron waves in the interferometer. The sensitivity of the method is estimated.
On the Classical String Solutions and String/Field Theory Duality
Aleksandrova, D.; Bozhilov, P.
2003-01-01
We classify almost all classical string configurations, considered in the framework of the semi-classical limit of the string/gauge theory duality. Then, we describe a procedure for obtaining the conserved quantities and the exact classical string solutions in general string theory backgrounds, when the string embedding coordinates depend non-linearly on the worldsheet time parameter.
THE EXTRAORDINARY COMPLEX MAGNETIC FIELD OF THE HELIUM-STRONG STAR HD 37776
International Nuclear Information System (INIS)
Kochukhov, Oleg; Lundin, Andreas; Romanyuk, Iosif; Kudryavtsev, Dmitry
2011-01-01
The early-type chemically peculiar stars often show strong magnetic fields on their surfaces. These magnetic topologies are organized on large scales and are believed to be close to an oblique dipole for most of the stars. In a striking exception to this general trend, the helium-strong star HD 37776 shows an extraordinary double-wave rotational modulation of the longitudinal magnetic field measurements, indicating a topologically complex and, possibly, record-strong magnetic field. Here we present a new investigation of the magnetic field structure of HD 37776, using both simple geometrical interpretation of the longitudinal field curve and detailed modeling of the time-resolved circular polarization line profiles with the help of a magnetic Doppler imaging technique. We derive a model of the magnetic field structure of HD 37776, which reconciles for the first time all magnetic observations available for this star. We find that the local surface field strength does not exceed ∼30 kG, while the overall field topology of HD 37776 is dominated by a non-axisymmetric component and represents by far the most complex magnetic field configuration found among early-type stars.
Jorna, P.
2005-01-01
Electromagnetic field theory plays a very important role in present-day technology; examples of technologies based on electromagnetism that are inextricably bound up with every day life are: radar, remote sensing, geoelectromagnetics, bioelectromagnetics, antennas, wireless communication, optics,
Khine, Y. Y.; Walker, J. S.
1996-08-01
Centrifugal pumping flows are produced in the melt by the rotations of crystal and crucible during the Czochralski growth of silicon crystals. This paper treats the centrifugal pumping effects with a steady, strong, non-uniform axisymmetric magnetic field. We consider a family of magnetic fields ranging from a uniform axial field to a "cusp" field, which has a purely radial field at the crystal-melt interface and free surface. We present the numerical solutions for the centrifugal pumping flows as the magnetic field is changed continuously from a uniform axial field to a cusp one, and for arbitrary Hartmann number. Since the perfect alignment between the local magnetic field vector and the crystal-melt interface or free surface is not likely, we also investigate the effects of a slight misalignment.
Non-Gaussian statistics, classical field theory, and realizable Langevin models
International Nuclear Information System (INIS)
Krommes, J.A.
1995-11-01
The direct-interaction approximation (DIA) to the fourth-order statistic Z ∼ left-angle λψ 2 ) 2 right-angle, where λ is a specified operator and ψ is a random field, is discussed from several points of view distinct from that of Chen et al. [Phys. Fluids A 1, 1844 (1989)]. It is shown that the formula for Z DIA already appeared in the seminal work of Martin, Siggia, and Rose (Phys. Rev. A 8, 423 (1973)] on the functional approach to classical statistical dynamics. It does not follow from the original generalized Langevin equation (GLE) of Leith [J. Atmos. Sd. 28, 145 (1971)] and Kraichnan [J. Fluid Mech. 41, 189 (1970)] (frequently described as an amplitude representation for the DIA), in which the random forcing is realized by a particular superposition of products of random variables. The relationship of that GLE to renormalized field theories with non-Gaussian corrections (''spurious vertices'') is described. It is shown how to derive an improved representation, that realizes cumulants through O(ψ 4 ), by adding to the GLE a particular non-Gaussian correction. A Markovian approximation Z DIA M to Z DIA is derived. Both Z DIA and Z DIA M incorrectly predict a Gaussian kurtosis for the steady state of a solvable three-mode example
Gomes, Diogo A.
2016-01-06
We present recent developments in the theory of first-order mean-field games (MFGs). A standard assumption in MFGs is that the cost function of the agents is monotone in the density of the distribution. This assumption leads to a comprehensive existence theory and to the uniqueness of smooth solutions. Here, our goals are to understand the role of local monotonicity in the small perturbation regime and the properties of solutions for problems without monotonicity. Under a local monotonicity assumption, we show that small perturbations of MFGs have unique smooth solutions. In addition, we explore the connection between first-order MFGs and classical mechanics and KAM theory. Next, for non-monotone problems, we construct non-unique explicit solutions for a broad class of first-order mean-field games. We provide an alternative formulation of MFGs in terms of a new current variable. These examples illustrate two new phenomena: the non-uniqueness of solutions and the breakdown of regularity.
Jirsák, Jan; Moučka, Filip; Škvor, Jiří; Nezbeda, Ivo
2015-04-01
Exposing aqueous surfaces to a strong electric field gives rise to interesting phenomena, such as formation of a floating water bridge or an eruption of a jet in electrospinning. In an effort to account for the phenomena at the molecular level, we performed molecular dynamics simulations using several protocols on both pure water and aqueous solutions of sodium chloride subjected to an electrostatic field. All simulations consistently point to the same mechanisms which govern the rearrangement of the originally planar surface. The results show that the phenomena are primarily governed by an orientational reordering of the water molecules driven by the applied field. It is demonstrated that, for pure water, a sufficiently strong field yields a columnar structure parallel to the field with an anisotropic arrangement of the water molecules with their dipole moments aligned along the applied field not only in the surface layer but over the entire cross section of the column. Nonetheless, the number of hydrogen bonds per molecule does not seem to be affected by the field regardless of its strength and molecule's orientation. In the electrolyte solutions, the ionic charge is able to overcome the effect of the external field tending to arrange the water molecules radially in the first coordination shell of an ion. The ion-water interaction interferes thus with the water-electric field interaction, and the competition between these two forces (i.e., strength of the field versus concentration) provides the key mechanism determining the stability of the observed structures.
Liao, Qing-Hong; Zhang, Qi; Xu, Juan; Yan, Qiu-Rong; Liu, Ye; Chen, An
2016-06-01
We have studied the dynamics and transfer of the entanglement of the two identical atoms simultaneously interacting with vacuum field by employing the dressed-state representation. The two atoms are driven by classical fields. The influence of the initial entanglement degree of two atoms, the coupling strength between the atom and the classical field and the detuning between the atomic transition frequency and the frequency of classical field on the entanglement and atomic linear entropy is discussed. The initial entanglement of the two atoms can be transferred into the entanglement between the atom and cavity field when the dissipation is neglected. The maximally entangled state between the atoms and cavity field can be obtained under some certain conditions. The time of disentanglement of two atoms can be controlled and manipulated by adjusting the detuning and classical driving fields. Moreover, the larger the cavity decay rate is, the more quickly the entanglement of the two atoms decays. Supported by National Natural Science Foundation of China under Grant Nos. 11247213, 61368002, 11304010, 11264030, 61168001, China Postdoctoral Science Foundation under Grant No. 2013M531558, Jiangxi Postdoctoral Research Project under Grant No. 2013KY33, the Natural Science Foundation of Jiangxi Province under Grant No. 20142BAB217001, the Foundation for Young Scientists of Jiangxi Province (Jinggang Star) under Grant No. 20122BCB23002, the Research Foundation of the Education Department of Jiangxi Province under Grant Nos. GJJ13051, GJJ13057, and the Graduate Innovation Special Fund of Nanchang University under Grant No. cx2015137
Axion production from Landau quantization in the strong magnetic field of magnetars
Maruyama, Tomoyuki; Balantekin, A. Baha; Cheoun, Myung-Ki; Kajino, Toshitaka; Mathews, Grant J.
2018-04-01
We utilize an exact quantum calculation to explore axion emission from electrons and protons in the presence of the strong magnetic field of magnetars. The axion is emitted via transitions between the Landau levels generated by the strong magnetic field. The luminosity of axions emitted by protons is shown to be much larger than that of electrons and becomes stronger with increasing matter density. Cooling by axion emission is shown to be much larger than neutrino cooling by the Urca processes. Consequently, axion emission in the crust may significantly contribute to the cooling of magnetars. In the high-density core, however, it may cause heating of the magnetar.
Plane Couette flow in the presence of a strong centrifugal field
International Nuclear Information System (INIS)
Johnson, E.A.
1982-05-01
The Pomraning problem of plane Couette flow in a strong centrifugal field is studied by several methods: a half-range polynomial expansion of the linearized BGK equation; the Liu-Lees method; and a new matching approximation constructed to give the correct solution in the free-molecule limit. The matching approximation, which appears valid for strong enough centrifugal field, predicts major differences from hydrodynamic behaviour, and suggests ways in which the lack of convergence of one method studied may be corrected. (author)
Dynamics of valence-shell electrons and nuclei probed by strong-field holography and rescattering
Walt, Samuel G.; Bhargava Ram, Niraghatam; Atala, Marcos; Shvetsov-Shilovski, Nikolay I; von Conta, Aaron; Baykusheva, Denitsa; Lein, Manfred; Wörner, Hans Jakob
2017-01-01
Strong-field photoelectron holography and laser-induced electron diffraction (LIED) are two powerful emerging methods for probing the ultrafast dynamics of molecules. However, both of them have remained restricted to static systems and to nuclear dynamics induced by strong-field ionization. Here we extend these promising methods to image purely electronic valence-shell dynamics in molecules using photoelectron holography. In the same experiment, we use LIED and photoelectron holography simultaneously, to observe coupled electronic-rotational dynamics taking place on similar timescales. These results offer perspectives for imaging ultrafast dynamics of molecules on femtosecond to attosecond timescales. PMID:28643771
Directory of Open Access Journals (Sweden)
Emmanuel Frenod
2002-01-01
Full Text Available We study the qualitative behavior of solutions to the Vlasov equation with strong external magnetic field and oscillating electric field. This model is relevant to the understanding of isotop resonant separation. We show that the effective equation is a kinetic equation with a memory term. This memory term involves a pseudo-differential operator whose kernel is characterized by an integral equation involving Bessel functions. The kernel is explicitly given in some particular cases.
Equation of state of strange quark matter in a strong magnetic field
International Nuclear Information System (INIS)
Isayev, A.A.; Yang, J.
2012-01-01
Thermodynamic properties of strange quark matter (SQM) in strong magnetic fields H up to 10 20 G are considered at zero temperature within the MIT bag model. The effects of the pressure anisotropy, exhibiting in the difference between the pressures along and perpendicular to the field direction, become essential at H>H t h , with the estimate 10 17 t h 18 G. The longitudinal pressure vanishes in the critical field H c , which can be somewhat less or larger than 10 18 G, depending on the total baryon number density and bag pressure. As a result, the longitudinal instability occurs in strongly magnetized SQM. The appearance of such instability sets the upper bound on the magnetic field strength which can be reached in the interior of a neutron star with the quark core. The longitudinal and transverse pressures as well as the anisotropic equation of state of SQM are determined under the conditions relevant for the cores of magnetars
One-electron atomic-molecular ions containing lithium in a strong magnetic field
International Nuclear Information System (INIS)
Olivares-Pilon, H; Turbiner, A V; Vieyra, J C Lopez; Baye, D
2010-01-01
The one-electron lithium-containing Coulomb systems of atomic type Li 2+ and molecular type Li 5+ 2 , LiHe 4+ and LiH 3+ are studied in the presence of a strong magnetic field B ≤ 10 7 au in a non-relativistic framework. They are considered at the Born-Oppenheimer approximation of zero order (infinitely massive centres) within the parallel configuration (molecular axis parallel to the magnetic field). The variational and Lagrange-mesh methods are employed, complementing each other. It is demonstrated that the molecular systems LiH 3+ , LiHe 4+ and Li 5+ 2 can exist for sufficiently strong magnetic fields B ∼> 10 4 au and that Li 5+ 2 can even be stable at magnetic fields typical of magnetars.
Interference effects at photoionization of Rydberg atoms by a strong electromagnetic field
International Nuclear Information System (INIS)
Movsesyan, A.M.; Fedorov, M.V.
1989-01-01
The photoionization of Rydberg atoms in a strong electromagnetic field is considered. Degeneration of the levels with respect to the orbital moment, their Stark splitting and the possibility of resonant interaction with levels of lower energy are taken into account. The complex quasi-energies of the system, photoelectron spectrum in the limit of an infinite duration of interaction and the time dependence of the total ionization probability are found. It is shown that a narrowing of the quasi-energy levels occurs in a strong field. Against a background of the quasi- continuum the quasi-energy spectrum consists of more or less narrow levels. In this case the photoelectron spectrum acquires a multi-peak form. With increasing field strength the height of the peaks increases, whereas their width decreases. The ionization rate decreases with increasing field strength. The presence of a quasi-continuum is the cause of the partially non-exponential nature of the atomic disintegration
Feng, Yan; Lin, Wei; Murillo, M S
2017-11-01
Transport properties of two-dimensional (2D) strongly coupled dusty plasmas have been investigated in detail, but never for viscosity with a strong perpendicular magnetic field; here, we examine this scenario using Langevin dynamics simulations of 2D liquids with a binary Yukawa interparticle interaction. The shear viscosity η of 2D liquid dusty plasma is estimated from the simulation data using the Green-Kubo relation, which is the integration of the shear stress autocorrelation function. It is found that, when a perpendicular magnetic field is applied, the shear viscosity of 2D liquid dusty plasma is modified substantially. When the magnetic field is increased, its viscosity increases at low temperatures, while at high temperatures its viscosity diminishes. It is determined that these different variational trends of η arise from the different behaviors of the kinetic and potential parts of the shear stress under external magnetic fields.
Energy Technology Data Exchange (ETDEWEB)
Ristow, T.
2007-12-17
Electron-ion-collisions in plasmas in the presence of an ultra-short intensive laser pulse can cause high energy transfers to the electrons. During the collision the oscillation energy of the electron in the laser field is changed into drift energy. In this regime, multi-photon processes, known from the ionization of neutral atoms (Above-Threshold Ionization), and successive, so called correlated collisions, are important. The subject of the thesis is a study of binary Coulomb collisions in strong laser fields. The collisions are treated both in the context of classical Newtonian mechanics and in the quantum-mechanical framework by the Schroedinger equation. In the classical case a simplified instantaneous collision model and a complete dynamical treatment are discussed. Collisions can be treated instantaneously, if the ratio of the impact parameter to the quiver amplitude is small. The energy distributions calculated in this approximation show an elastic peak and a broad plateau due to rescattered electrons. At incident velocities smaller than the quiver velocity, correlated collisions are observed in the electron trajectories of the dynamical model. This effect leads to characteristic momentum distributions of the electrons, that are explicitly calculated and compared with the results of the instantaneous model. In addition, the time-dependence of the collisions is discussed in the framework of a singular perturbation theory. The complete description of the Coulomb scattering requires a quantum-mechanical description. A time-dependent method of wave-packet scattering is used and the corresponding time-dependent three-dimensional Schroedinger equation is solved by an implicit ADImethod on a spatial grid. The momentum and the energy distributions of the scattered electrons are calculated by the Fourier transformation of the wavefunction. A comparison of the scattering from a repulsive and an attractive potential is used to distinguish between simple collisions and
Khrennikov, Andrei
2017-02-01
The scientific methodology based on two descriptive levels, ontic (reality as it is) and epistemic (observational), is briefly presented. Following Schrödinger, we point to the possible gap between these two descriptions. Our main aim is to show that, although ontic entities may be unaccessible for observations, they can be useful for clarification of the physical nature of operational epistemic entities. We illustrate this thesis by the concrete example: starting with the concrete ontic model preceding quantum mechanics (the latter is treated as an epistemic model), namely, prequantum classical statistical field theory (PCSFT), we propose the natural physical interpretation for the basic quantum mechanical entity-the quantum state ("wave function"). The correspondence PCSFT ↦ QM is not straightforward, it couples the covariance operators of classical (prequantum) random fields with the quantum density operators. We use this correspondence to clarify the physical meaning of the pure quantum state and the superposition principle-by using the formalism of classical field correlations. In classical mechanics the phase space description can be considered as the ontic description, here states are given by points λ =(x , p) of phase space. The dynamics of the ontic state is given by the system of Hamiltonian equations.We can also consider probability distributions on the phase space (or equivalently random variables valued in it). We call them probabilistic ontic states. Dynamics of probabilistic ontic states is given by the Liouville equation.In classical physics we can (at least in principle) measure both the coordinate and momentum and hence ontic states can be treated as epistemic states as well (or it is better to say that here epistemic states can be treated as ontic states). Probabilistic ontic states represent probabilities for outcomes of joint measurement of position and momentum.However, this was a very special, although very important, example of
International Nuclear Information System (INIS)
Oeien, A.H.
1977-06-01
Sets of lower order and higher order kinetic and macroscopic equations are developed for a plasma where collisions are important but electrons and ions are allowed to have different temperatures when transports, due to gradients and fields, set in. Solving the lower order kinetic equations and taking appropriate velocity moments we show that usual classical transports emerge. From the higher order kinetic equations special notice is taken of some new correction terms to the classical transports. These corrections are linear in gradients and fields, some of which are found in a two-temperature state only. (Auth.)
Direct URCA-processes in neutron star quark core with strong magnetic field.
Directory of Open Access Journals (Sweden)
Belyaev Vasily
2017-01-01
In evaluations, the strength of magnetic field corresponds to the case, where the quarks of medium occupy a lot of Landau levels, while the electrons are in ground Landau level. The analytical dependence of neutrino emissivity on chemical potentials of quarks and electrons, temperature and magnetic field strength is obtained and briefly discussed. The result could be important in application to a massive strongly magnetized neutron star with quark core.
Heavy quark potential in a static and strong homogeneous magnetic field
Energy Technology Data Exchange (ETDEWEB)
Hasan, Mujeeb; Chatterjee, Bhaswar; Patra, Binoy Krishna [Indian Institute of Technology Roorkee, Department of Physics, Roorkee (India)
2017-11-15
We have investigated the properties of quarkonia in a thermal QCD medium in the background of strong magnetic field. For that purpose, we employ the Schwinger proper-time quark propagator in the lowest Landau level to calculate the one-loop gluon self-energy, which in the sequel gives the effective gluon propagator. As an artifact of strong magnetic field approximation (eB >> T{sup 2} and eB >> m{sup 2}), the Debye mass for massless flavors is found to depend only on the magnetic field which is the dominant scale in comparison to the scales prevalent in the thermal medium. However, for physical quark masses, it depends on both magnetic field and temperature in a low temperature and high magnetic field but the temperature dependence is very meager and becomes independent of the temperature beyond a certain temperature and magnetic field. With the above mentioned ingredients, the potential between heavy quark (Q) and anti-quark (anti Q) is obtained in a hot QCD medium in the presence of a strong magnetic field by correcting both short- and long-range components of the potential in the real-time formalism. It is found that the long-range part of the quarkonium potential is affected much more by magnetic field as compared to the short-range part. This observation facilitates us to estimate the magnetic field beyond which the potential will be too weak to bind Q anti Q together. For example, the J/ψ is dissociated at eB ∝ 10 m{sub π}{sup 2} and Υ is dissociated at eB ∝ 100 m{sub π}{sup 2} whereas its excited states, ψ{sup '} and Υ{sup '} are dissociated at smaller magnetic field eB = m{sub π}{sup 2}, 13 m{sub π}{sup 2}, respectively. (orig.)
Classical gluon fields and collective dynamics of color-charge systems
International Nuclear Information System (INIS)
Voronyuk, V.; Goloviznin, V. V.; Zinovjev, G. M.; Cassing, W.; Molodtsov, S. V.; Snigirev, A. M.; Toneev, V. D.
2015-01-01
An investigation of color fields that arise in collisions of relativistic heavy ions reveals that, in the non-Abelian case, a change in the color charge leads to the appearance of an extra term that generates a sizable contribution of color-charge glow in chromoelectric and chromomagnetic fields. The possibility of the appearance of a color echo in the scattering of composite color particles belonging to the dipole type is discussed. Arguments are adduced in support of the statement that such effects are of importance in simulating the first stage of ultrarelativistic heavy-ion collisions,where the initial parton state is determined by a high nonequilibrium parton density and by strong local color fluctuations
Gor'kov, L P; Teitel'baum, G B
2014-01-29
We address recent experiments shedding light on the energy spectrum of under and optimally doped cuprates at temperatures above the superconducting transition. Angle resolved photoemission reveals coherent excitation only near nodal points on parts of the 'bare' Fermi surface known as the Fermi arcs. The question debated in the literature is whether the small normal pocket, seen via quantum oscillations, exists at higher temperatures or forms below a charge order transition in strong magnetic fields. Assuming the former case as a possibility, expressions are derived for the resistivity and the Hall coefficient (in weak and strong magnetic fields) with both types of carriers participating in the transport. There are two regimes. At higher temperatures (at a fixed field) electrons are dragged by the Fermi arcs' holes. The pocket being small, its contribution to conductivity and the Hall coefficient is negligible. At lower temperatures electrons decouple from holes behaving as a Fermi gas in the magnetic field. As the mobility of holes on the arcs decreases in strong fields with a decrease of temperature, below a crossover point the pocket electrons prevail, changing the sign of the Hall coefficient in the low temperature limit. Such behavior finds its confirmation in recent high-field experiments.
Bound-state β decay of a neutron in a strong magnetic field
International Nuclear Information System (INIS)
Kouzakov, Konstantin A.; Studenikin, Alexander I.
2005-01-01
The β decay of a neutron into a bound (pe - ) state and an antineutrino in the presence of a strong uniform magnetic field (B > or approx. 10 13 G) is considered. The β decay process is treated within the framework of the standard model of weak interactions. A Bethe-Salpeter formalism is employed for description of the bound (pe - ) system in a strong magnetic field. For the field strengths 10 13 18 G the estimate for the ratio of the bound-state decay rate w b and the usual (continuum-state) decay rate w c is derived. It is found that in such strong magnetic fields w b /w c ∼0.1-0.4. This is in contrast to the field-free case, where w b /w c ≅4.2x10 -6 [J. N. Bahcall, Phys. Rev. 124, 495 (1961); L. L. Nemenov, Sov. J. Nucl. Phys. 15, 582 (1972); X. Song, J. Phys. G: Nucl. Phys. 13, 1023 (1987)]. The dependence of the ratio w b /w c on the magnetic field strength B exhibits a logarithmiclike behavior. The obtained results can be important for applications in astrophysics and cosmology
Do strong, static magnetic fields act on living beings and chemical reactions
International Nuclear Information System (INIS)
Demmer, W.
1986-01-01
In general, magnetic fields are said to have no direct influence on living beings or simple chemical reactions. There is, however, evidence to confirm that changes in the earth's magnetic field or of artificially produced magnetic fields can alter the activity of different neuronal enzyme systems. An effect on the synthesis of β-galactosidase in the bacterium Escherichia coli by a feeble magnetic field (0.2 to 0.8 mT) and disturbances of the embryogenesis of frogs by a strong magnetic field (1.0 T) have been described. These and similar investigations with whole cells raise the question as to what the effect of magnetic fields on isolated and purified enzymes will be. (orig./SHA) [de
Monte Carlo solutions of Schroedinger's equation for H2+ ion in strong magnetic fields
International Nuclear Information System (INIS)
Ozaki, Jiro; Tomishima, Yasuo
1980-01-01
The analytical expressions suitable for the Monte Carlo calculation to obtain the solution of Schroedinger's equation of hydrogen molecular ion in a strong magnetic field are derived. The wave functions, the energy values and the equilibrium internuclear distances of 1σsub(g) state of H 2 + are obtained numerically through the Monte Carlo simulation and compared with other results based on the variational method. The agreement between them is fairly good over a wide range of magnetic field. The calculation of the energy values of 1πsub(g) state of H 2 + for various internuclear distances taking a constant magnetic field as a parameter, shows that the antibonding 1πsub(g) state in the absence of the external magnetic field changes to a bonding state with an increasing magnetic field. The lowest energy values and the equilibrium internuclear distances of 1πsub(g) state are also calculated for various magnetic field. (author)
Hagen Kleinert
2018-01-01
This is an introductory book dealing with collective phenomena in many-body systems. A gas of bosons or fermions can show oscillations of various types of density. These are described by different combinations of field variables. Especially delicate is the competition of these variables. In superfluid 3He, for example, the atoms can be attracted to each other by molecular forces, whereas they are repelled from each other at short distance due to a hardcore repulsion. The attraction gives rise to Cooper pairs, and the repulsion is overcome by paramagnon oscillations. The combination is what finally led to the discovery of superfluidity in 3He. In general, the competition between various channels can most efficiently be studied by means of a classical version of the Hubbard-Stratonovich transformation. A gas of electrons is controlled by the interplay of plasma oscillations and pair formation. In a system of rod- or disc-like molecules, liquid crystals are observed with directional orientations that behave in ...
Testing nonclassicality in multimode fields: A unified derivation of classical inequalities
International Nuclear Information System (INIS)
Miranowicz, Adam; Bartkowiak, Monika; Wang Xiaoguang; Liu Yuxi; Nori, Franco
2010-01-01
We consider a way to generate operational inequalities to test nonclassicality (or quantumness) of multimode bosonic fields (or multiparty bosonic systems) that unifies the derivation of many known inequalities and allows to propose new ones. The nonclassicality criteria are based on Vogel's criterion corresponding to analyzing the positivity of multimode P functions or, equivalently, the positivity of matrices of expectation values of, e.g., creation and annihilation operators. We analyze not only monomials but also polynomial functions of such moments, which can sometimes enable simpler derivations of physically relevant inequalities. As an example, we derive various classical inequalities which can be violated only by nonclassical fields. In particular, we show how the criteria introduced here easily reduce to the well-known inequalities describing (a) multimode quadrature squeezing and its generalizations, including sum, difference, and principal squeezing; (b) two-mode one-time photon-number correlations, including sub-Poisson photon-number correlations and effects corresponding to violations of the Cauchy-Schwarz and Muirhead inequalities; (c) two-time single-mode photon-number correlations, including photon antibunching and hyperbunching; and (d) two- and three-mode quantum entanglement. Other simple inequalities for testing nonclassicality are also proposed. We have found some general relations between the nonclassicality and entanglement criteria, in particular those resulting from the Cauchy-Schwarz inequality. It is shown that some known entanglement inequalities can be derived as nonclassicality inequalities within our formalism, while some other known entanglement inequalities can be seen as sums of more than one inequality derived from the nonclassicality criterion. This approach enables a deeper analysis of the entanglement for a given nonclassicality.
Ehrenfest's theorem and the validity of the two-step model for strong-field ionization
DEFF Research Database (Denmark)
Shvetsov-Shilovskiy, Nikolay; Dimitrovski, Darko; Madsen, Lars Bojer
By comparison with the solution of the time-dependent Schrodinger equation we explore the validity of the two-step semiclassical model for strong-field ionization in elliptically polarized laser pulses. We find that the discrepancy between the two-step model and the quantum theory correlates...
Parity violation effects in the hydrogen atom in the field of a strong electromagnetic wave
International Nuclear Information System (INIS)
Labzovsky, L.N.; Mitrushchenkov, A.O.
1989-01-01
The parity violation effects in the hydrogen atom in a strong electromagnetic laser field are considered. It is shown that there is the possibility of hyperrate measurements of different constants of the weak interaction in the hydrogen magnetic resonance experiments. (orig.)
Interaction of a neutral composite particle with a strong Coulomb field
International Nuclear Information System (INIS)
Wong, Cheuk-Yin.
1988-01-01
The author discusses the interaction of the quasi-composite (e/sup /plus//e/sup /minus//) system with an external electromagnetic field. This problem addresses the question of the origin of strong positron lines in quasi-elastic heavy-ion reactions. 3 refs
Kenjeres, S.
2008-01-01
The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier–Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell’s equations
The permanent magnet systems generating strong stray fields with large localization region
International Nuclear Information System (INIS)
Samofalov, V.N.; Belozorov, D.P.; Ravlik, A.G.
2008-01-01
Three systems of permanent magnets, which produce strong magnetic stray fields (SFs) with H>B r =4πM r were studied in this work. Remarkable feature of the developed systems is localization of the strong fields in large region with linear dimension Δr comparable to characteristic magnet dimension a. The first system composed of uniformly magnetized magnets generates sufficiently homogeneous strong SFs, which amounts up to 1.5 of magnets induction B r . The second system with nonuniform magnetization is represented by cylindrical and hemispheric magnets their magnetization vector directed at every point along the radius. Such distribution of magnetization is assumed to be the consequence of magnet radial crystal texture resulting in a high uniaxial anisotropy field H K . It is shown that maximal SFs can exist on the flat surface of cylindrical magnet at the distance r from its axis and their limiting value equals to 4πM r ln(2a/r). Here, the localization region of the fields is comparable to diameter of cylindrical magnet Δr∼2R. As for the hemisphere its SFs are less than corresponding SFs for the cylinder. The third so-called quasi-nonuniform system consists of uniformly magnetized cylindrical sectors their magnetization vector is directed along the sector bisectrix. The strong SFs and their localization region are calculated in details for this case. The passage to radial magnetized cylinder is considered
The Bekenstein bound in strongly coupled O(N) scalar field theory
International Nuclear Information System (INIS)
Magalhaes, T. Santos; Svaiter, N.F.; Menezes, G.
2009-09-01
We discuss the O(N) self-interacting scalar field theory, in the strong-coupling regime and also in the limit of large N. Considering that the system is in thermal equilibrium with a reservoir at temperature β -1 , we assume the presence of macroscopic boundaries conning the field in a hypercube of side L. Using the strong-coupling perturbative expansion, we generalize previous results, i.e., we obtain the renormalized mean energy E and entropy S for the system in rst order of the strong-coupling perturbative expansion, presenting an analytical proof that the specific entropy also satisfies in some situations a quantum bound. When considering the low temperature behavior of the specific entropy, the sign of the renormalized zero-point energy can invalidate this quantum bound. If the renormalized zero point-energy is a positive quantity, at intermediate temperatures and in the low temperature limit, there is a quantum bound. (author)
Light bending by nonlinear electrodynamics under strong electric and magnetic field
Energy Technology Data Exchange (ETDEWEB)
Kim, Jin Young; Lee, Taekoon, E-mail: jykim@kunsan.ac.kr, E-mail: tlee@kunsan.ac.kr [Department of Physics, Kunsan National University, Daihakro 558, Kunsan 573-701 (Korea, Republic of)
2011-11-01
We calculate the bending angles of light under the strong electric and magnetic fields by a charged black hole and a magnetized neutron star according to the nonlinear electrodynamics of Euler-Heisenberg interaction. The bending angle of light by the electric field of charged black hole is computed from geometric optics and a general formula is derived for light bending valid for any orientation of the magnetic dipole. The astronomical significance of the light bending by magnetic field of a neutron star is discussed.
arXiv Plasmon mass scale and quantum fluctuations of classical fields on a real time lattice
Lappi, Tuomas; Peuron, Jarkko
2018-01-01
Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Above the Debye scale the classical Yang-Mills (CYM) theory can be matched smoothly to kinetic theory. First we study the limits of the quasiparticle picture of the CYM fields by determining the plasmon mass of the system using 3 different methods. Then we argue that one needs a numerical calculation of a system of classical gauge fields and small linearized fluctuations, which correspond to quantum fluctuations, in a way that keeps the separation between the two manifest. We demonstrate and test an implementation of an algorithm with the linearized fluctuation showing that the linearization indeed works and that the Gauss’s law is conserved.
Particle Production in Strong Electromagnetic Fields in Relativistic Heavy-Ion Collisions
Directory of Open Access Journals (Sweden)
Kirill Tuchin
2013-01-01
Full Text Available I review the origin and properties of electromagnetic fields produced in heavy-ion collisions. The field strength immediately after a collision is proportional to the collision energy and reaches ~mπ2 at RHIC and ~10mπ2 at LHC. I demonstrate by explicit analytical calculation that after dropping by about one-two orders of magnitude during the first fm/c of plasma expansion, it freezes out and lasts for as long as quark-gluon plasma lives as a consequence of finite electrical conductivity of the plasma. Magnetic field breaks spherical symmetry in the direction perpendicular to the reaction plane, and therefore all kinetic coefficients are anisotropic. I examine viscosity of QGP and show that magnetic field induces azimuthal anisotropy on plasma flow even in spherically symmetric geometry. Very strong electromagnetic field has an important impact on particle production. I discuss the problem of energy loss and polarization of fast fermions due to synchrotron radiation, consider photon decay induced by magnetic field, elucidate J/ψ dissociation via Lorentz ionization mechanism, and examine electromagnetic radiation by plasma. I conclude that all processes in QGP are affected by strong electromagnetic field and call for experimental investigation.
High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED.
Ullmann, Johannes; Andelkovic, Zoran; Brandau, Carsten; Dax, Andreas; Geithner, Wolfgang; Geppert, Christopher; Gorges, Christian; Hammen, Michael; Hannen, Volker; Kaufmann, Simon; König, Kristian; Litvinov, Yuri A; Lochmann, Matthias; Maaß, Bernhard; Meisner, Johann; Murböck, Tobias; Sánchez, Rodolfo; Schmidt, Matthias; Schmidt, Stefan; Steck, Markus; Stöhlker, Thomas; Thompson, Richard C; Trageser, Christian; Vollbrecht, Jonas; Weinheimer, Christian; Nörtershäuser, Wilfried
2017-05-16
Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209 Bi 82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron-nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209 Bi 82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction.
Spin dynamics in relativistic ionization with highly charged ions in super-strong laser fields
International Nuclear Information System (INIS)
Klaiber, Michael; Yakaboylu, Enderalp; Bauke, Heiko; Hatsagortsyan, Karen Z; Müller, Carsten; Paulus, Gerhard G
2014-01-01
Spin dynamics and induced spin effects in above-threshold ionization of hydrogenlike highly charged ions in super-strong laser fields are investigated. Spin-resolved ionization rates in the tunnelling regime are calculated by employing two versions of a relativistic Coulomb-corrected strong-field approximation (SFA). An intuitive simpleman model is developed which explains the derived scaling laws for spin flip and spin asymmetry effects. The intuitive model as well as our ab initio numerical simulations support the analytical results for the spin effects obtained in the dressed SFA where the impact of the laser field on the electron spin evolution in the bound state is taken into account. In contrast, the standard SFA is shown to fail in reproducing spin effects in ionization even at a qualitative level. The anticipated spin-effects are expected to be measurable with modern laser techniques combined with an ion storage facility. (paper)
Probing strong-field electron-nuclear dynamics of polyatomic molecules using proton motion
International Nuclear Information System (INIS)
Markevitch, Alexei N.; Smith, Stanley M.; Levis, Robert J.; Romanov, Dmitri A.
2007-01-01
Proton ejection during Coulomb explosion is studied for several structure-related organic molecules (anthracene, anthraquinone, and octahydroanthracene) subjected to 800 nm, 60 fs laser pulses at intensities from 0.50 to 4.0x10 14 W cm -2 . The proton kinetic energy distributions are found to be markedly structure specific. The distributions are bimodal for anthracene and octahydroanthracene and trimodal for anthraquinone. Maximum (cutoff) energies of the distributions range from 50 eV for anthracene to 83 eV for anthraquinone. The low-energy mode (∼10 eV) is most pronounced in octahydroanthracene. The dependence of the characteristic features of the distributions on the laser intensity provides insights into molecular specificity of such strong-field phenomena as (i) nonadiabatic charge localization and (ii) field-mediated restructuring of polyatomic molecules polarized by a strong laser field
International Nuclear Information System (INIS)
Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Xie, Yanqiong; Xu, Xiaojun
2015-01-01
In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector
Dynamics of a two-level system in a classical field. A description in different observation levels
International Nuclear Information System (INIS)
Heiner, E.; Steinbeck, L.
1992-01-01
Effects of contraction in the description of a two-level quantum system coupled to a classical electromagnetic field are studied. Different observation levels are introduced and the corresponding nonlinear equations of motion are obtained. The solutions are discussed with respect to stability, constants of motion and evolution of relevant entropies. (orig.)
International Nuclear Information System (INIS)
Clauer, C.R.; Friis-Christensen, E.
1988-01-01
On July 23, 1983, the Interplanetary Magnetic Field turned strongly northward, becoming about 22 nT for several hours. Using a combined data set of ionospheric convection measurements made by the Sondre Stromfjord incoherent scatter radar and convection inferred from Greenland magnetometer measurements, we observe the onset of the reconfiguration of the high-latitude ionospheric currents to occur about 3 min following the northward IMF encountering the magnetopause. The large-scale reconfiguration of currents, however, appears to evolve over a period of about 22 min. Using a computer model in which the distribution of field-aligned current in the polar cleft is directly determined by the strength and orientation of the interplanetary electric field, we are able to simulate the time-varying pattern of ionospheric convection, including the onset of high-latitude ''reversed convection'' cells observed to form during the interval of strong northward IMF. These observations and the simulation results indicate that the dayside polar cap electric field observed during strong northward IMF is produced by a direct electrical current coupling with the solar wind. copyright American Geophysical Union 1988
Critical point in the QCD phase diagram for extremely strong background magnetic fields
International Nuclear Information System (INIS)
Endrödi, Gergely
2015-01-01
Lattice simulations have demonstrated that a background (electro)magnetic field reduces the chiral/deconfinement transition temperature of quantum chromodynamics for eB<1 GeV 2 . On the level of observables, this reduction manifests itself in an enhancement of the Polyakov loop and in a suppression of the light quark condensates (inverse magnetic catalysis) in the transition region. In this paper, we report on lattice simulations of 1+1+1-flavor QCD at an unprecedentedly high value of the magnetic field eB=3.25 GeV 2 . Based on the behavior of various observables, it is shown that even at this extremely strong field, inverse magnetic catalysis prevails and the transition, albeit becoming sharper, remains an analytic crossover. In addition, we develop an algorithm to directly simulate the asymptotically strong magnetic field limit of QCD. We find strong evidence for a first-order deconfinement phase transition in this limiting theory, implying the presence of a critical point in the QCD phase diagram. Based on the available lattice data, we estimate the location of the critical point.
DEFF Research Database (Denmark)
Hansen, Jonas Lerche; Stapelfeldt, Henrik; Dimitrovski, Darko
2011-01-01
A nanosecond laser pulse confines the spatial orientation of naphthalene in 1D or 3D while a femtosecond kick pulse initiates rotation of the molecular plane around the fixed long axis. Time-dependent photoelectron angular distributions (PADs), resulting from ionization by an intense femtosecond...... probe pulse, exhibit pronounced changes as the molecular plane rotates. Enhanced 3D alignment, occurring shortly after the kick pulse, provides strongly improved contrast in molecular-frame PADs. Calculations in the strong-field approximation show that the striking structures observed in the PADs...
Drag force in strongly coupled { N }=4 supersymmetric Yang–Mills plasma in a magnetic field
Zhang, Zi-qiang; Ma, Ke; Hou, De-fu
2018-02-01
Applying AdS/CFT correspondence, we study the effect of a constant magnetic field { B } on the drag force associated with a heavy quark moving through a strongly-coupled { N }=4 supersymmetric Yang–Mills plasma. The quark is considered moving transverse and parallel to { B }. It is shown that for transverse case, the drag force is linearly dependent on { B } in all regions, while for parallel case, the drag force increases monotonously with increasing { B } and also reveals a linear behavior in the regions of strong { B }. In addition, we find that { B } has a more important effect in the transverse case than for the parallel.
A Simple Model of Fields Including the Strong or Nuclear Force and a Cosmological Speculation
Directory of Open Access Journals (Sweden)
David L. Spencer
2016-10-01
Full Text Available Reexamining the assumptions underlying the General Theory of Relativity and calling an object's gravitational field its inertia, and acceleration simply resistance to that inertia, yields a simple field model where the potential (kinetic energy of a particle at rest is its capacity to move itself when its inertial field becomes imbalanced. The model then attributes electromagnetic and strong forces to the effects of changes in basic particle shape. Following up on the model's assumption that the relative intensity of a particle's gravitational field is always inversely related to its perceived volume and assuming that all black holes spin, may create the possibility of a cosmic rebound where a final spinning black hole ends with a new Big Bang.
Electric conductivity of TlInTe2 monocrystal in strong electric fields
International Nuclear Information System (INIS)
Zarbaliev, M.M.; Godzhaev, Eh.M.; Gadzhiev, V.A.
1980-01-01
Electric condUctivity of the TlInTe 2 single crystal in strong electric fields has been studied in the range of 77-300 K. The electron part of the TlInTe 2 dielectric constant has been found to be 4. The dependence of the activation energy of current carriers on the electric field strength is constructed and the value of the activation energy of current carriers in the absence of an electric field is determined by the extrapolation method. The results of the experiments are in good agreement with the Frenkel-Pool theory, and this affords grounds for asserting that the obtained dependences of electric conductivity on temperature and the electric field strength are defined by variation in the current carrier concentration due to action of the thermal-electron ionization mechanism
Strong-field effects in Rabi oscillations between a single state and a superposition of states
International Nuclear Information System (INIS)
Zhdanovich, S.; Milner, V.; Hepburn, J. W.
2011-01-01
Rabi oscillations of quantum population are known to occur in two-level systems driven by spectrally narrow laser fields. In this work we study Rabi oscillations induced by shaped broadband femtosecond laser pulses. Due to the broad spectral width of the driving field, the oscillations are initiated between a ground state and a coherent superposition of excited states, or a ''wave packet,'' rather than a single excited state. Our experiments reveal an intricate dependence of the wave-packet phase on the intensity of the laser field. We confirm numerically that the effect is associated with the strong-field nature of the interaction and provide a qualitative picture by invoking a simple theoretical model.
Resonance enhancement of two photon absorption by magnetically trapped atoms in strong rf-fields
Chakraborty, A.; Mishra, S. R.
2018-01-01
Applying a many mode Floquet formalism for magnetically trapped atoms interacting with a polychromatic rf-field, we predict a large two photon transition probability in the atomic system of cold 87Rb atoms. The physical origin of this enormous increase in the two photon transition probability is due to the formation of avoided crossings between eigen-energy levels originating from different Floquet sub-manifolds and redistribution of population in the resonant intermediate levels to give rise to the resonance enhancement effect. Other exquisite features of the studied atom-field composite system include the splitting of the generated avoided crossings at the strong field strength limit and a periodic variation of the single and two photon transition probabilities with the mode separation frequency of the polychromatic rf-field. This work can find applications to characterize properties of cold atom clouds in the magnetic traps using rf-spectroscopy techniques.
First Detection of a Strong Magnetic Field on a Bursty Brown Dwarf: Puzzle Solved
Berdyugina, S. V.; Harrington, D. M.; Kuzmychov, O.; Kuhn, J. R.; Hallinan, G.; Kowalski, A. F.; Hawley, S. L.
2017-09-01
We report the first direct detection of a strong, 5 kG magnetic field on the surface of an active brown dwarf. LSR J1835+3259 is an M8.5 dwarf exhibiting transient radio and optical emission bursts modulated by fast rotation. We have detected the surface magnetic field as circularly polarized signatures in the 819 nm sodium lines when an active emission region faced the Earth. Modeling Stokes profiles of these lines reveals the effective temperature of 2800 K and log gravity acceleration of 4.5. These parameters place LSR J1835+3259 on evolutionary tracks as a young brown dwarf with the mass of 55+/- 4{M}{{J}} and age of 22 ± 4 Myr. Its magnetic field is at least 5.1 kG and covers at least 11% of the visible hemisphere. The active region topology recovered using line profile inversions comprises hot plasma loops with a vertical stratification of optical and radio emission sources. These loops rotate with the dwarf in and out of view causing periodic emission bursts. The magnetic field is detected at the base of the loops. This is the first time that we can quantitatively associate brown dwarf non-thermal bursts with a strong, 5 kG surface magnetic field and solve the puzzle of their driving mechanism. This is also the coolest known dwarf with such a strong surface magnetic field. The young age of LSR J1835+3259 implies that it may still maintain a disk, which may facilitate bursts via magnetospheric accretion, like in higher-mass T Tau-type stars. Our results pave a path toward magnetic studies of brown dwarfs and hot Jupiters.
Quantum-orbit theory of high-order atomic processes in strong fields
International Nuclear Information System (INIS)
Milosevic, D.B.
2005-01-01
Full text: Atoms submitted to strong laser fields can emit electrons and photons of very high energies. These processes find a highly intuitive and also quantitative explanation in terms of Feynman's path integral and the concept of quantum orbits. The quantum-orbit formalism is particularly useful for high-order atomic processes in strong laser fields. For such multi-step processes there is an intermediate step during which the electron is approximately under the influence of the laser field only and can absorb energy from the field. This leads to the appearance of the plateau structures in the emitted electron or photon spectra. Usual examples of such processes are high-order harmonic generation (HHG) and high-order above threshold ionization (HATI). These structures were also observed in high-order above-threshold detachment, laser-assisted x-ray-atom scattering, laser-assisted electron-ion recombination, and electron-atom scattering. We will present high-order strong-field approximation (SFA) and show how the quantum-orbit formalism follows from it. This will be done for various above-mentioned processes. For HHG a classification of quantum orbits will be given [10) and generalized to the presence of a static field. The low-energy part of the HHG spectra and the enhancement of HHG near the channel closings can be explained taking into account a large number of quantum orbits. For HATI we will concentrate on the case of few-cycle laser pulse. The influence of the carrier-envelope relative phase on the HATI spectrum can easily be explained in terms of quantum orbits. The SFA and the quantum-orbit results will be compared with the results obtained by Dieter Bauer using ab initio solutions of the time-dependent Schroedinger equation. It will be shown that the Coulomb effects are important for low-energy electron spectra. Refs. 11 (author)
Acceleration of neutral atoms in strong short-pulse laser fields.
Eichmann, U; Nubbemeyer, T; Rottke, H; Sandner, W
2009-10-29
A charged particle exposed to an oscillating electric field experiences a force proportional to the cycle-averaged intensity gradient. This so-called ponderomotive force plays a major part in a variety of physical situations such as Paul traps for charged particles, electron diffraction in strong (standing) laser fields (the Kapitza-Dirac effect) and laser-based particle acceleration. Comparably weak forces on neutral atoms in inhomogeneous light fields may arise from the dynamical polarization of an atom; these are physically similar to the cycle-averaged forces. Here we observe previously unconsidered extremely strong kinematic forces on neutral atoms in short-pulse laser fields. We identify the ponderomotive force on electrons as the driving mechanism, leading to ultrastrong acceleration of neutral atoms with a magnitude as high as approximately 10(14) times the Earth's gravitational acceleration, g. To our knowledge, this is by far the highest observed acceleration on neutral atoms in external fields and may lead to new applications in both fundamental and applied physics.
Study of Strong Magnetic Fields Using Parametric Instability in a Magnetised Plasma
Ivanov, V. V.; Maximov, A. V.; Anderson, A. A.; Bauer, B. S.; Yates, K.
2014-10-01
Generation of strong magnetic fields with a strength of 10--50 MG plays a key role in some recent conceptions for controlled fusion. We suggest a laser method for measuring the local magnetic field, B > 10 MG, based on the parametric decay of the laser radiation to ω/2 and 3/2 ω harmonics which are generated in the area with the electron density of a quarter of the critical plasma density. Spectral components of parametric harmonics carry a signature of both the plasma temperature and strong magnetic field. A two-plasmon decay of laser radiation was studied in a magnetized plasma at the 1 MA pulsed power Zebra facility at the University of Nevada, Reno. Dense magnetized plasma with a magnetic field of 1--3 MG was created by the 1MA current flowing in the metal rod 0.7--2 mm in diameter. Radiation from the narrowband laser with intensity >1014 W/cm2 was focused on the surface plasma. Spectrum of the backscattering 3/2 ω harmonic included ``red'' and ``blue'' shifted components. Large 2-3 nm shifts of spectral components was identified with laser heating of plasma. Components with a small 0.1 nm spectral shift of may be linked to the magnetic field. Work was supported by the DOE Grant DE-SC0008824 and DOE/NNSA UNR Grant DE-FC52-06NA27616.
Probes and Tests of Strong-Field Gravity with Observations in the Electromagnetic Spectrum
Directory of Open Access Journals (Sweden)
Psaltis Dimitrios
2008-11-01
Full Text Available Neutron stars and black holes are the astrophysical systems with the strongest gravitational fields in the universe. In this article, I review the prospect of using observations of such compact objects to probe some of the most intriguing general relativistic predictions in the strong-field regime: the absence of stable circular orbits near a compact object and the presence of event horizons around black-hole singularities. I discuss the need for a theoretical framework, within which future experiments will provide detailed, quantitative tests of gravity theories. Finally, I summarize the constraints imposed by current observations of neutron stars on potential deviations from general relativity.
Chiral soliton lattice and charged pion condensation in strong magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Brauner, Tomáš [Faculty of Science and Technology, University of Stavanger,N-4036 Stavanger (Norway); Yamamoto, Naoki [Department of Physics, Keio University,Yokohama 223-8522 (Japan)
2017-04-21
The Chiral Soliton Lattice (CSL) is a state with a periodic array of topological solitons that spontaneously breaks parity and translational symmetries. Such a state is known to appear in chiral magnets. We show that CSL also appears as a ground state of quantum chromodynamics at nonzero chemical potential in a magnetic field. By analyzing the fluctuations of the CSL, we furthermore demonstrate that in strong but achievable magnetic fields, charged pions undergo Bose-Einstein condensation. Our results, based on a systematic low-energy effective theory, are model-independent and fully analytic.
Attosecond counter-rotating-wave effect in xenon driven by strong fields
Anand, M.; Pabst, Stefan; Kwon, Ojoon; Kim, Dong Eon
2017-05-01
We investigate the subfemtosecond dynamics of a highly excited xenon atom coherently driven by a strong control field at which the Rabi frequency of the system is comparable to the frequency of a driving laser. The widely used rotating-wave approximation breaks down at such fields, resulting in features such as the counter-rotating-wave (CRW) effect. We present a time-resolved observation of the CRW effect in the highly excited 4 d-1n p xenon using attosecond transient absorption spectroscopy. Time-dependent many-body theory confirms the observation and explains the various features of the absorption spectrum seen in experiment.
Samkharadze, N; Kumar, A; Manfra, M J; Pfeiffer, L N; West, K W; Csáthy, G A
2011-05-01
We fabricated a He-3 immersion cell for transport measurements of semiconductor nanostructures at ultra low temperatures and in strong magnetic fields. We have a new scheme of field-independent thermometry based on quartz tuning fork Helium-3 viscometry which monitors the local temperature of the sample's environment in real time. The operation and measurement circuitry of the quartz viscometer is described in detail. We provide evidence that the temperature of two-dimensional electron gas confined to a GaAs quantum well follows the temperature of the quartz viscometer down to 4 mK.
Fritz, Sean; Hernandez-Castillo, Alicia O.; Abeysekera, Chamara; Zwier, Timothy S.
2017-06-01
The 8-18 GHz conformer specific rotational spectrum of gauche- and anti-3-phenylpropionitrile (C6H5-CH2-CH2-CN) conformers has been recorded using the strong field coherence breaking (SFCB) technique [1] with a modified line picking scheme for multiple selective excitations (MSE). As the recombination product of benzyl and cyanomethyl resonance-stabilized radicals, 3-phenylpropionitrile is a likely component of the complex organics in Titan's atmosphere, motivating its structural characterization. Details of the modified line picking scheme, hyperfine constants and relative population ratios of the two conformers will be presented. [1] A.O Hernandez-Castillo, Chamara Abeysekera, Brian M. Hays, Timothy S. Zwier, "Broadband Multi-Resonant Strong Field Coherence Breaking as a Tool for Single Isomer Microwave Spectroscopy." J. Chem. Phys. 145, 114203 (2016).
Null Geodesics and Strong Field Gravitational Lensing of Black Hole with Global Monopole
International Nuclear Information System (INIS)
Iftikhar, Sehrish; Sharif, M.
2015-01-01
We study two interesting features of a black hole with an ordinary as well as phantom global monopole. Firstly, we investigate null geodesics which imply unstable orbital motion of particles for both cases. Secondly, we evaluate deflection angle in strong field regime. We then find Einstein rings, magnifications, and observables of the relativistic images for supermassive black hole at the center of galaxy NGC4486B. We also examine time delays for different galaxies and present our results numerically. It is found that the deflection angle for ordinary/phantom global monopole is greater/smaller than that of Schwarzschild black hole. In strong field limit, the remaining properties of these black holes are quite different from the Schwarzschild black hole
Spin polarization in high density quark matter under a strong external magnetic field
DEFF Research Database (Denmark)
Tsue, Yasuhiko; Da Providência, João; Providência, Constança
2016-01-01
In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor-type interact......In high density quark matter under a strong external magnetic field, possible phases are investigated by using the two-flavor Nambu-Jona-Lasinio (NJL) model with tensor-type four-point interaction between quarks, as well as the axial-vector-type four-point interaction. In the tensor...... phase appears in the wide range of the quark chemical potential. In both the interactions, the quark mass in zero and small chemical potential regions increases which indicates that the chiral symmetry breaking is enhanced, namely the magnetic catalysis occurs....
Higher Order QED Contributions to the Atomic Structure at Strong Central Fields
International Nuclear Information System (INIS)
Mokler, P H
2007-01-01
An accurate determination of the precise structure of highly charged, very heavy ions is crucial for understanding QED at strong fields. The experimental advances in the spectroscopy of very heavy, highly charged ions-in particular H-, He- and Li-like species-are reviewed: Presently the ground state Lamb shift for H-like U ions is measured on a 1% level of accuracy; the screening terms in two-electron QED have just been touched by experiments for He-like U; and two-loop QED terms have been determined with ultimate accuracy for Li-like heavy species. The different approaches on QED measurements in strong fields will be discussed and the results compared to theory
Rotzien, J. R.; Mayhew, B.; Yospin, S.; Beiki, A.; Tewksbury, C.; Hardman, D.; Bank, C.; Noblett, J.; Semken, S.; Kroeger, G.
2007-12-01
The Navajo Volcanic Field (NVF) is an area of late-Tertiary volcanism along the New Mexico-Arizona border near the Four Corners region of the American Southwest. Among the roughly 80 exhumed diatremes that comprise the NVF, Ship Rock and The Thumb are two diatremes that present an interesting problem concerning magma ascent and emplacement within the NVF. Are the diatremes remnants of classical volcanoes with underlying magma chambers, or are the diatremes formed from buds off of upward propagating dike swarms? The 2006 Keck Consortium Geophysics Project collected non-invasive gravity and magnetic data to image the subsurface of Ship Rock and The Thumb to suggest constraints concerning the formation of these diatremes within the Navajo Volcanic Field. At Ship Rock, we collected over 120 gravity points spaced 500 m apart along 10 lines. We also collected about 65,000 magnetic points that cover an area of 1,570,000 square meters surrounding Ship Rock. The gravity data reveal gravity lows several kilometers away from Ship Rock, probably as a result of thick sedimentary units close to the surface. A steep gradient of 5 mGal/km separates the gravity lows from a strong gravity high immediately to the southwest of Ship Rock. We interpret this gravity high to be uneven basement topography or a magma chamber at depth; further studies are required to determine which of the interpretations is more likely. The Ship Rock magnetic data show the prominent west and northeast dikes extend well beyond their surface outcrops while the southern dike extends only to its visible termination. The magnetic data we collected at The Thumb along ~18 km of lines reveal a linear northeast-southwest trending magnetic anomaly about 105 to 360 nT in amplitude that crosses the diatreme. We interpret the anomaly to be a dike beneath The Thumb. Models of the total field magnetic data suggest a dike at shallow depths of about 0.1 to 4.8 m and widths of about 0.25 to 1.5 m with a steep dip to the
Time profile of harmonics generated by a single atom in a strong electromagnetic field
International Nuclear Information System (INIS)
Antoine, P.; Piraux, B.; Maquet, A.
1995-01-01
We show that the time profile of the harmonics emitted by a single atom exposed to a strong electromagnetic field may be obtained through a wavelet or a Gabor analysis of the acceleration of the atomic dipole. This analysis is extremely sensitive to the details of the dynamics and sheds some light on the competition between the atomic excitation or ionization processes and photon emission. For illustration we study the interaction of atomic hydrogen with an intense laser pulse
Role of high-order dispersion on strong-field laser-molecule interactions
Dantus, Marcos; Nairat, Muath
2016-05-01
Strong-field (1012- 1016 W/ cm2) laser-matter interactions are characterized by the extent of fragmentation and charge of the resulting ions as a function of peak intensity and pulse duration. Interactions are influenced by high-order dispersion, which is difficult to characterize and compress. Fourth-order dispersion (FOD) causes a time-symmetric pedestal, while third-order dispersion (TOD) causes a leading (negative) or following (positive) pedestal. Here, we report on strong-field interactions with pentane and toluene molecules, tracking the molecular ion and the doubly charged carbon ion C2+ yields as a function of TOD and FOD for otherwise transform-limited (TL) 35fs pulses. We find TL pulses enhance molecular ion yield and suppress C2+ yield, while FOD reverses this trend. Interestingly, the leading pedestal in negative TOD enhances C2+ yield compared to positive TOD. Pulse pedestals are of particular importance in strong-field science because target ionization or alignment can be induced well before the main pulse arrives. A pedestal following an intense laser pulse can cause sequential ionization or accelerate electrons causing cascaded ionization. Control of high-order dispersion allows us to provide strong-field measurements that can help address the mechanisms responsible for different product ions in the presence and absence of pedestals. Financial support of this work comes from the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, DOE SISGR (DE-SC0002325)
Sundar, Vikram; Gelbwaser-Klimovsky, David; Aspuru-Guzik, Alán
2018-04-05
Modeling nuclear quantum effects is required for accurate molecular dynamics (MD) simulations of molecules. The community has paid special attention to water and other biomolecules that show hydrogen bonding. Standard methods of modeling nuclear quantum effects like Ring Polymer Molecular Dynamics (RPMD) are computationally costlier than running classical trajectories. A force-field functor (FFF) is an alternative method that computes an effective force field that replicates quantum properties of the original force field. In this work, we propose an efficient method of computing FFF using the Wigner-Kirkwood expansion. As a test case, we calculate a range of thermodynamic properties of Neon, obtaining the same level of accuracy as RPMD, but with the shorter runtime of classical simulations. By modifying existing MD programs, the proposed method could be used in the future to increase the efficiency and accuracy of MD simulations involving water and proteins.
Angular-momentum-assisted dissociation of CO in strong optical fields
Mullin, Amy; Ogden, Hannah; Murray, Matthew; Liu, Qingnan; Toro, Carlos
2017-04-01
Filaments are produced in CO gas by intense, chirped laser pulses. Visible emission from C2 is observed as a result of chemical reactions of highly excited CO. At laser intensities greater than 1014 W cm-2, the C2 emission shows a strong dependence on laser polarization. Oppositely chirped pulses of light with ω0 = 800 nm are recombined spatially and temporally to generate angularly accelerating electric fields (up to 30 THz) that either have an instantaneous linear polarization or act as a dynamic polarization grating that oscillates among linear and circular polarizations. The angularly accelerating linear polarization corresponds to an optical centrifuge that concurrently drives molecules into high rotational states (with J 50) and induces strong-field dissociation. Higher order excitation is observed for the time-varying laser polarization configuration that does not induce rotational excitation. The results indicate that the presence of rotational angular momentum lowers the threshold for CO dissociation in strong optical fields by coupling nuclear and electronic degrees of freedom. Support from NSF CHE-1058721 and the University of Maryland.
International Nuclear Information System (INIS)
Jalilian-Marian, Jamal; Jeon, Sangyong; Venugopalan, Raju; Wirstam, Jens
2000-01-01
The one loop effective action in quantum field theory can be expressed as a quantum mechanical path integral over world lines, with internal symmetries represented by Grassmanian variables. In this paper, we develop a real time, many body, world line formalism for the one loop effective action. In particular, we study hot QCD and obtain the classical transport equations which, as Litim and Manuel have shown, reduce in the appropriate limit to the non-Abelian Boltzmann-Langevin equation first obtained by Boedeker. In the Vlasov limit, the classical kinetic equations are those that correspond to the hard thermal loop effective action. We also discuss the imaginary time world line formalism for a hot φ 4 theory, and elucidate its relation to classical transport theory. (c) 2000 The American Physical Society
Benacquista, Matthew J
2018-01-01
This textbook provides an introduction to classical mechanics at a level intermediate between the typical undergraduate and advanced graduate level. This text describes the background and tools for use in the fields of modern physics, such as quantum mechanics, astrophysics, particle physics, and relativity. Students who have had basic undergraduate classical mechanics or who have a good understanding of the mathematical methods of physics will benefit from this book.
Strong-field QED processes in short laser pulses. One- and two-photon Compton scattering
Energy Technology Data Exchange (ETDEWEB)
Seipt, Daniel
2012-12-20
The purpose of this thesis is to advance the understanding of strong-field QED processes in short laser pulses. The processes of non-linear one-photon and two-photon Compton scattering are studied, that is the scattering of photons in the interaction of relativistic electrons with ultra-short high-intensity laser pulses. These investigations are done in view of the present and next generation of ultra-high intensity optical lasers which are supposed to achieve unprecedented intensities of the order of 10{sup 24} W/cm{sup 2} and beyond, with pulse lengths in the order of some femtoseconds. The ultra-high laser intensity requires a non-perturbative description of the interaction of charged particles with the laser field to allow for multi-photon interactions, which is beyond the usual perturbative expansion of QED organized in powers of the fine structure constant. This is achieved in strong-field QED by employing the Furry picture and non-perturbative solutions of the Dirac equation in the presence of a background laser field as initial and final state wave functions, as well as the laser dressed Dirac-Volkov propagator. The primary objective is a realistic description of scattering processes with regard to the finite laser pulse duration beyond the common approximation of infinite plane waves, which is made necessary by the ultra-short pulse length of modern high-intensity lasers. Non-linear finite size effects are identified, which are a result of the interplay between the ultra-high intensity and the ultra-short pulse length. In particular, the frequency spectra and azimuthal photon emission spectra are studied emphasizing the differences between pulsed and infinite laser fields. The proper description of the finite temporal duration of the laser pulse leads to a regularization of unphysical infinities (due to the infinite plane-wave description) of the laser-dressed Dirac-Volkov propagator and in the second-order strong-field process of two-photon Compton
Strong-field QED processes in short laser pulses. One- and two-photon Compton scattering
International Nuclear Information System (INIS)
Seipt, Daniel
2012-01-01
The purpose of this thesis is to advance the understanding of strong-field QED processes in short laser pulses. The processes of non-linear one-photon and two-photon Compton scattering are studied, that is the scattering of photons in the interaction of relativistic electrons with ultra-short high-intensity laser pulses. These investigations are done in view of the present and next generation of ultra-high intensity optical lasers which are supposed to achieve unprecedented intensities of the order of 10 24 W/cm 2 and beyond, with pulse lengths in the order of some femtoseconds. The ultra-high laser intensity requires a non-perturbative description of the interaction of charged particles with the laser field to allow for multi-photon interactions, which is beyond the usual perturbative expansion of QED organized in powers of the fine structure constant. This is achieved in strong-field QED by employing the Furry picture and non-perturbative solutions of the Dirac equation in the presence of a background laser field as initial and final state wave functions, as well as the laser dressed Dirac-Volkov propagator. The primary objective is a realistic description of scattering processes with regard to the finite laser pulse duration beyond the common approximation of infinite plane waves, which is made necessary by the ultra-short pulse length of modern high-intensity lasers. Non-linear finite size effects are identified, which are a result of the interplay between the ultra-high intensity and the ultra-short pulse length. In particular, the frequency spectra and azimuthal photon emission spectra are studied emphasizing the differences between pulsed and infinite laser fields. The proper description of the finite temporal duration of the laser pulse leads to a regularization of unphysical infinities (due to the infinite plane-wave description) of the laser-dressed Dirac-Volkov propagator and in the second-order strong-field process of two-photon Compton scattering. An
Experimental study of transport of relativistic electron beams in strong magnetic mirror field
Sakata, Shohei; Kondo, Kotaro; Bailly-Grandvaux, Mathiu; Bellei, Claudio; Santos, Joao; Firex Project Team
2015-11-01
Relativistic electron beams REB produced by ultra high intense laser pulses have generally a large divergence angle that results in degradation of energy coupling between the REB and a fuel core in the fast ignition scheme. Guiding and focusing of the REB by a strong external magnetic field was proposed to achieve high efficiency. We investigated REB transport through 50 μm or 250 μm thick plastic foils CuI doped under external magnetic fields, in magnetic mirror configurations of 1.2 or 4 mirror ratio. The experiment was carried out at the GEKKO XII and LFEX laser facility. Spatial pattern of the REB was measured by coherent transition radiation and/or Cu Ka x ray emission from the rear surface of the foil targets. Strong collimation of the REB by the external magnetic field was observed with 50 μm thick plastic targets, while the REB scattered in 250 μm thick targets. The experimental results are compared with computer simulations to understand the physical mechanisms of the REB transport in the external magnetic field. This work is supported by NIFS (Japan), MEXT/JSPS KAKENHI (Japan), JSPS Fellowship (Japan), ANR (France) and COST (Europe).
International Nuclear Information System (INIS)
Kenjeres, Sasa
2008-01-01
The paper reports on a comprehensive mathematical model for simulations of blood flow under the presence of strong non-uniform magnetic fields. The model consists of a set of Navier-Stokes equations accounting for the Lorentz and magnetisation forces, and a simplified set of Maxwell's equations (Biot-Savart/Ampere's law) for treating the imposed magnetic fields. The relevant hydrodynamic and electromagnetic properties of human blood were taken from the literature. The model is then validated for different test cases ranging from a simple cylindrical geometry to real-life right-coronary arteries in humans. The time-dependency of the wall-shear-stress for different stenosis growth rates and the effects of the imposed strong non-uniform magnetic fields on the blood flow pattern are presented and analysed. It is concluded that an imposed non-uniform magnetic field can create significant changes in the secondary flow patterns, thus making it possible to use this technique for optimisations of targeted drug delivery
Process γγ → νν-bar in a strong magnetic field
International Nuclear Information System (INIS)
Kuznetsov, A.V.; Mikheev, N.V.; Rumyantsev, D.A.
2003-01-01
The three-vertex loop amplitude in a strong magnetic field are analyzed in a general form by using the asymptotic behavior of the electron propagator in an external field. The process γγ → νν-bar is studied in terms of the scalar-vector-vector (SVV), pseudoscalar-vector-vector (PVV), vector-vector-vector (VVV), and axial-vector-vector-vector (AVV) combinations of couplings. It is shown that only in the case of the SVV combination does the amplitude grow linearly with increasing magnetic-field strength, the amplitudes evaluated with the other combinations of couplings (PVV, VVV, and AVV) featuring no linearly increasing terms. The process γγ → νν-bar is also studied within the left-right model, which is an extension of the Standard Model of electroweak interactions and which may involve an effective scalar ννee coupling. Possible astrophysical manifestations of this process are discussed
Characteristics of electron emission from PZT ferroelectric cathode under strong accelerating field
Energy Technology Data Exchange (ETDEWEB)
Hayashi, Yasushi [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan)]. E-mail: hayashi@es.titech.ac.jp; Hotta, Eiki [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan); Flechtner, Donald [High Voltage Laboratory, Cornell University, Ithaca, NY (United States)
2002-02-07
We have studied emission characteristics of a PZT ferroelectric cathode under the influence of a strong accelerating field by varying the triggering conditions. The beam current pulse reveals a rising and a steady phase. In the rising phase, the time variation of the beam current is found to be linearly dependent on both the trigger voltage and the diode voltage at the time when the current starts. In the steady phase, field emission characteristics are observed. The results show that the diode voltage is not only accelerating the emitted electrons but also assisting the electron emission from the ferroelectric cathode. An empirical model is proposed and is found to yield a reasonable beam current pulse when the electric field on the surface of the cathode is uniformly distributed. It also provides us with a new possibility to diagnose the emission process of a ferroelectric electron gun. (author)
Metal-insulator crossover in superconducting cuprates in strong magnetic fields
International Nuclear Information System (INIS)
Marchetti, P.A.; Su Zhaobin; Yu Lu
2001-02-01
The metal-insulator crossover of the in-plane resistivity upon temperature decrease, recently observed in several classes of cuprate superconductors, when a strong magnetic field suppresses the superconductivity, is explained using the U(1)xSU(2) Chern-Simons gauge field theory. The origin of this crossover is the same as that for a similar phenomenon observed in heavily underdoped cuprates without magnetic field. It is due to the interplay between the diffusive motion of the charge carriers and the 'peculiar' localization effect due to short-range antiferromagnetic order. We also calculate the in-plane transverse magnetoresistance which is in a fairly good agreement with available experimental data. (author)
The process γγ → νν-bar in a strong magnetic field
International Nuclear Information System (INIS)
Kuznetsov, A.V.; Mikheev, N.V.; Rumyantsev, D.A.
2003-01-01
A general analysis of the three-vertex loop amplitude in a strong magnetic field, based on the asymptotic form of the electron propagator in the field, is performed. In order to investigate the photon-neutrino process γγ → νν-bar, the vertex combinations of the scalar-vector-vector (SVV), pseudoscalar- vector-vector (PVV), 3-vector (VVV), and axial-vector-vector (AVV) types are considered. It is shown that only the SVV amplitude grows linearly with the magnetic-field strength, while in the other amplitudes, PVV, VVV, and AVV, the linearly growing terms are cancelled. The process γγ → νν-bar is investigated in the left-right-symmetric extension of the standard model of electroweak interaction, where the effective scalar ννee coupling could exist. Possible astrophysical manifestations of the considered process are discussed [ru
Control and dynamics of attosecond electron wave packets in strong laser fields
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Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier; Lopez-Martens, R.; Valentin, C.; Balcou, P.; Kazamias, S.; Mauritsson, J.; Gaarde, M.B.; Schafer, K.J.; Mairess, Y.; Wabnitz, H.; Boutu, W.; Salieres, P.
2005-01-01
Full text: Trains of attosecond pulses, emerging from the phase-locking of high-order harmonics generated in a strong laser field are now being routinely produced and characterized in a few laser laboratories. Attosecond pulse trains (APTs) are flexible attosecond sources, since the amplitude and relative phase of the spectral components (the harmonics) can be tailored, allowing us to vary both the duration and the carrier frequency of the pulses. Attosecond pulses interacting with a gas of atoms generate electron wave packets (EWPs), which are temporally localized with approximately the same duration as the attosecond pulses. In contrast to the tunneling electron wave packets giving rise to processes such as high-order harmonic generation and above-threshold-ionization (ATI), the properties of these EWPs are inherited from the attosecond pulses through the single-photon ionization step. Thus the energy and temporal characteristics of the EWPs can be varied independently of the process under investigation, by controlling the properties of the attosecond pulses. This talk will describe two recent experiments done in Lund. First we report on the generation, compression and delivery on target of ultrashort extreme-ultraviolet light pulses using external amplitude and phase control. The APT is synthesized from the 13 th to 35 th harmonics of a 35 fs Ti:sapphire laser. The harmonics are generated by focusing the laser beam into a window-less gas cell, filled with argon. To achieve the required on-target attosecond pulses, the harmonics are filtered spatially, using a fixed aperture, and spectrally using aluminum filters. The aluminum filters also serve the purpose of compressing the attosecond pulses, using the negative group-delay dispersion of aluminum to compensate for the intrinsic positive chirp of the attosecond pulses. This experiment demonstrates a practical method for the synthesis and control of attosecond waveforms, and in this case the production of pulses
Horwitz, L. P.; Land, Martin C.; Gill, Tepper; Lusanna, Luca; Salucci, Paolo
2013-04-01
Although the subject of relativistic dynamics has been explored, from both classical and quantum mechanical points of view, since the work of Einstein and Dirac, its most striking development has been in the framework of quantum field theory. The very accurate calculations of spectral and scattering properties, for example, of the anomalous magnetic moment of the electron and the Lamb shift in quantum electrodynamics, and many qualitative features of the strong and electroweak interactions, demonstrate the very great power of description achieved in this framework. Yet, many fundamental questions remain to be clarified, such as the structure of classical relativistic dynamical theories on the level of Hamilton and Lagrange in Minkowski space as well as on the curved manifolds of general relativity. There moreover remains the important question of the covariant classical description of systems at high energy for which particle production effects are not large, such as discussed in Synge's book, The Relativistic Gas, and in Balescu's book on relativistic statistical mechanics. In recent years, the study of high energy plasmas and heavy ion collisions has emphasized the importance of developing the techniques of relativistic mechanics. The results of Lindner et al [Physical Review Letters 95 0040401 (2005)] as well as the more recent proposal of Palacios et al [Phys. Rev. Lett. 103 253001 (2009)] and others, have shown that there must be a quantum theory with coherence in time. Such a theory, manifestly covariant under the transformations of special relativity with an invariant evolution parameter, such as that of Stueckelberg [Helv. Phys. Acta 14 322, 588 (1941); 15 23 (1942); see also R P Feynman Phys. Rev. 80 4401 and J S Schwinger Phys. Rev. 82 664 (1951)] could provide a suitable basis for the study of such questions, as well as many others for which the application of the standard methods of quantum field theory are difficult to manage, involving, in particular
Lectures on classical electrodynamics
Englert, Berthold-Georg
2014-01-01
These lecture notes cover classical electrodynamics at the level of advanced undergraduates or postgraduates. There is a strong emphasis on the general features of the electromagnetic field and, in particular, on the properties of electromagnetic radiation. It offers a comprehensive and detailed, as well as self-contained, account of material that can be covered in a one-semester course for students with a solid undergraduate knowledge of basic electricity and magnetism.
Hach, Edwin Ellison, III
We examine the dynamics of a gas of three level atoms. Each atom is taken to exhibit the so-called lambda configuration. This system has been considered previously by G. S. Agarwal. In the present work we refine and extend these earlier considerations. We assume the atomic system to be driven by two co-propagating, resonant classical fields. We assume the classical fields to be undepleted by the interaction. We further assume that the interaction takes place within an optical cavity which has two modes available to interact with the medium. All atom-field interactions are assumed to occur by way of the electric dipole coupling. Our principal focus is the quantized field which develops within the cavity. We develop a Master equation for the time evolution of this field. We then use this equation to study certain properties of the optical field. In particular, we study the system as it operates near the Rabi side bands for the semi-classical system. We find some evidence for the nonclassical nature of the field in this regime. In the course of developing the general equation of motion for the system we derive results for the resonant semi-classical system. Our approach to this treatment is novel and does reproduce results familiar to those working in Coherent Population Trapping, Lasing Without Inversion and Electromagnetically Induced Transparency . We also present numerical results concerning a system in which a single atom interacts within the cavity. These results are generated by a numerical integration of the Master equation for the system. The integration implements a fourth order Runge-Kutta algorithm. In the single atom system we see clear evidence for such nonclassical effects as quadrature squeezing and photon antibunching. We see throughout this work that inter-mode correlations exist between the cavity photons. It is clearly possible for information to shared between the modes. As such, this system may be worthwhile for study by those interested in
International Nuclear Information System (INIS)
Fogel, M.B.; Trullinger, S.E.; Bishop, A.R.; Krumhansl, J.A.
1976-02-01
We show that classical Sine-Gordon solitons maintain their integrity to a high degree in the presence of external perturbations. Two examples, of particular importance in condensed matter, are described in detail: (i) a model impurity is found to bind low-velocity solitons but merely phase-shift those with high-velocities, (ii) external static driving terms with damping accelerate the soliton to a terminal velocity. The importance of a translation mode is emphasized and it is concluded that the soliton behaves as a classical particle in all essential respects
Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum
Fujiwara, Yoshihisa; Tomishige, Masahiko; Itoh, Yasuhiro; Fujiwara, Masao; Shibata, Naho; Kosaka, Toshikazu; Hosoya, Hiroshi; Tanimoto, Yoshifumi
2006-05-01
Effect of horizontal strong static magnetic field on swimming behaviour of Paramecium caudatum was studied by using a superconducting magnet. Around a centre of a round vessel, random swimming at 0 T and aligned swimming parallel to the magnetic field (MF) of 8 T were observed. Near a wall of the vessel, however, swimming round and round along the wall at 0 T and aligned swimming of turning at right angles upon collision with the wall, which was remarkable around 1-4 T, were detected. It was experimentally revealed that the former MF-induced parallel swimming at the vessel centre was caused physicochemically by the parallel magnetic orientation of the cell itself. From magnetic field dependence of the extent of the orientation, the magnetic susceptibility anisotropy (χ ∥-χ ⊥) was first obtained to be 3.4× 10-23 emu cell-1 at 298 K for Paramecium caudatum. The orientation of the cell was considered to result from the magnetic orientation of the cell membrane. On the other hand, although mechanisms of the latter swimming near the vessel wall regardless of the absence and presence of the magnetic field are unclear at present, these experimental results indicate that whether the cell exists near the wall alters the magnetic field effect on the swimming in the horizontal magnetic field.
Zhu, Wuming; Trickey, S. B.
2017-12-01
In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li+, Be+, and B+, in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B field.
Zhu, Wuming; Trickey, S B
2017-12-28
In high magnetic field calculations, anisotropic Gaussian type orbital (AGTO) basis functions are capable of reconciling the competing demands of the spherically symmetric Coulombic interaction and cylindrical magnetic (B field) confinement. However, the best available a priori procedure for composing highly accurate AGTO sets for atoms in a strong B field [W. Zhu et al., Phys. Rev. A 90, 022504 (2014)] yields very large basis sets. Their size is problematical for use in any calculation with unfavorable computational cost scaling. Here we provide an alternative constructive procedure. It is based upon analysis of the underlying physics of atoms in B fields that allow identification of several principles for the construction of AGTO basis sets. Aided by numerical optimization and parameter fitting, followed by fine tuning of fitting parameters, we devise formulae for generating accurate AGTO basis sets in an arbitrary B field. For the hydrogen iso-electronic sequence, a set depends on B field strength, nuclear charge, and orbital quantum numbers. For multi-electron systems, the basis set formulae also include adjustment to account for orbital occupations. Tests of the new basis sets for atoms H through C (1 ≤ Z ≤ 6) and ions Li + , Be + , and B + , in a wide B field range (0 ≤ B ≤ 2000 a.u.), show an accuracy better than a few μhartree for single-electron systems and a few hundredths to a few mHs for multi-electron atoms. The relative errors are similar for different atoms and ions in a large B field range, from a few to a couple of tens of millionths, thereby confirming rather uniform accuracy across the nuclear charge Z and B field strength values. Residual basis set errors are two to three orders of magnitude smaller than the electronic correlation energies in multi-electron atoms, a signal of the usefulness of the new AGTO basis sets in correlated wavefunction or density functional calculations for atomic and molecular systems in an external strong B
International Nuclear Information System (INIS)
Scully, M O
2008-01-01
The time dependent Schrodinger equation is frequently 'derived' by postulating the energy E → i h-bar (∂/∂t) and momentum p-vector → ( h-bar /i)∇ operator relations. In the present paper we review the quantum field theoretic route to the Schrodinger wave equation which treats time and space as parameters, not operators. Furthermore, we recall that a classical (nonlinear) wave equation can be derived from the classical action via Hamiltonian-Jacobi theory. By requiring the wave equation to be linear we again arrive at the Schrodinger equation, without postulating operator relations. The underlying philosophy is operational: namely 'a particle is what a particle detector detects.' This leads us to a useful physical picture combining the wave (field) and particle paradigms which points the way to the time-dependent Schrodinger equation
Monthus, Cécile; Garel, Thomas
2012-09-01
To avoid the complicated topology of surviving clusters induced by standard strong disorder RG in dimension d > 1, we introduce a modified procedure called ‘boundary strong disorder RG’ where the order of decimations is chosen a priori. We apply this modified procedure numerically to the random transverse field Ising model in dimension d = 2. We find that the location of the critical point, the activated exponent ψ ≃ 0.5 of the infinite-disorder scaling, and the finite-size correlation exponent νFS ≃ 1.3 are compatible with the values obtained previously using standard strong disorder RG. Our conclusion is thus that strong disorder RG is very robust with respect to changes in the order of decimations. In addition, we analyze the RG flows within the two phases in more detail, to show explicitly the presence of various correlation length exponents: we measure the typical correlation exponent νtyp ≃ 0.64 for the disordered phase (this value is very close to the correlation exponent {\
Sequential nonadiabatic excitation of large molecules and ions driven by strong laser fields
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Markevitch, Alexei N.; Levis, Robert J.; Romanov, Dmitri A.; Smith, Stanley M.; Schlegel, H. Bernhard; Ivanov, Misha Yu.
2004-01-01
Electronic processes leading to dissociative ionization of polyatomic molecules in strong laser fields are investigated experimentally, theoretically, and numerically. Using time-of-flight ion mass spectroscopy, we study the dependence of fragmentation on laser intensity for a series of related molecules and report regular trends in this dependence on the size, symmetry, and electronic structure of a molecule. Based on these data, we develop a model of dissociative ionization of polyatomic molecules in intense laser fields. The model is built on three elements: (i) nonadiabatic population transfer from the ground electronic state to the excited-state manifold via a doorway (charge-transfer) transition; (ii) exponential enhancement of this transition by collective dynamic polarization of all electrons, and (iii) sequential energy deposition in both neutral molecules and resulting molecular ions. The sequential nonadiabatic excitation is accelerated by a counterintuitive increase of a large molecule's polarizability following its ionization. The generic theory of sequential nonadiabatic excitation forms a basis for quantitative description of various nonlinear processes in polyatomic molecules and ions in strong laser fields
Electric-field-induced strong enhancement of electroluminescence in multilayer molybdenum disulfide
Li, Dehui; Cheng, Rui; Zhou, Hailong; Wang, Chen; Yin, Anxiang; Chen, Yu; Weiss, Nathan O.; Huang, Yu; Duan, Xiangfeng
2015-07-01
The layered transition metal dichalcogenides have attracted considerable interest for their unique electronic and optical properties. While the monolayer MoS2 exhibits a direct bandgap, the multilayer MoS2 is an indirect bandgap semiconductor and generally optically inactive. Here we report electric-field-induced strong electroluminescence in multilayer MoS2. We show that GaN-Al2O3-MoS2 and GaN-Al2O3-MoS2-Al2O3-graphene vertical heterojunctions can be created with excellent rectification behaviour. Electroluminescence studies demonstrate prominent direct bandgap excitonic emission in multilayer MoS2 over the entire vertical junction area. Importantly, the electroluminescence efficiency observed in multilayer MoS2 is comparable to or higher than that in monolayers. This strong electroluminescence can be attributed to electric-field-induced carrier redistribution from the lowest energy points (indirect bandgap) to higher energy points (direct bandgap) in k-space. The electric-field-induced electroluminescence is general for other layered materials including WSe2 and can open up a new pathway towards transition metal dichalcogenide-based optoelectronic devices.
Photoluminescence spectrum changes of GaN quantum wells caused by the strong piezoelectric fields
International Nuclear Information System (INIS)
Herrera, H.; Calderon, A.; Gonzalez de la Cruz, G.
2007-01-01
Full text: Spontaneous and piezoelectric fields are known to be the key to understanding the optical properties of nitride heterostructures. This effect modifies the electronic states in the quantum well (QW) and the emission energy in the photoluminescence (PL) spectrum. These fields induce a reduction of the oscillator strength on the transition energy between the confined electron and hole states in GaN/Al x Ga 1-x N QW's and dramatically increase the carrier life time as the QW thickness increases. In this work we solve analytically the Schrodinger equation for moderate electric fields when the electron-hole transition energy in the QW is larger than the energy gap of the GaN. Furthermore, the large redshifts of the PL energy position and the spatial separation of the electron and hole by several times of the Bohr radius caused by the strong piezoelectric fields are explained using a triangular potential in the Schrodinger equation. The transition energy calculations between the electron-hole pair as a function of the well width with the electric field as a fitting parameter are in agreement with the measured photoluminescence energy peaks. (Author)
Photoluminescence spectrum changes of GaN quantum wells caused by the strong piezoelectric fields
Energy Technology Data Exchange (ETDEWEB)
Herrera, H.; Calderon, A. [CICATA-IPN, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D.F. (Mexico); Gonzalez de la Cruz, G. [CINVESTAV-IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico)
2006-07-01
Spontaneous and piezoelectric fields are known to be the key to understanding the optical properties of nitride heterostructures. This effect modifies the electronic states in the quantum well (QW) and the emission energy in the photoluminescence (PL) spectrum. These fields induce a reduction of the oscillator strength on the transition energy between the confined electron and hole states in GaN/Al{sub x}Ga{sub 1-x}N QW's and dramatically increase the carrier life time as the QW thickness increases. In this work, we solve analytically the Schroedinger equation for moderate electric fields when the electron-hole transition energy in the QW is larger than the energy gap of the GaN. Furthermore, the large redshifts of the PL energy position and the spatial separation of the electron and hole by several times of the Bohr radius caused by the strong piezoelectric fields are explained using a triangular potential in the Schrodinger equation. The transition energy calculations between the electron-hole pair as a function of the well width with the electric field as a fitting parameter are in agreement with the measured photoluminescence energy peaks. (Author)
Two-photon annihilation of thermal pairs in strong magnetic fields
Baring, Matthew G.; Harding, Alice K.
1992-01-01
The annihilation spectrum of pairs with 1-D thermal distributions in the presence of a strong magnetic field is calculated. Numerical analysis of the spectrum are performed for mildly relativistic temperatures and for different angles of emission with respect to field lines. Teragauss magnetic fields are assumed so that conditions are typical of gamma ray burst and pulsar environments. The spectra at each viewing angle reveal asymmetric line profiles that are signatures of the magnetic broadening and red shifting of the line: these asymmetries are more prominent for small viewing angles. Thermal Doppler broadening tends to dominate in the right wing of the line and obscures the magnetic broadening more at high temperatures and smaller viewing angles. This angular dependence of the line asymmetry may prove a valuable diagnostic tool. For low temperatures and magnetic field strengths, useful analytic expressions are presented for the line width, and also for the annihilation spectrum at zero viewing angle. The results presented find application in gamma ray burst and pulsar models, and may prove very helpful in deducing field strengths and temperatures of the emission regions of these objects from line observations made by Compton GRO and future missions.
Semi-classical noise investigation for sub-40nm metal-oxide-semiconductor field-effect transistors
C. Spathis; A. Birbas; K. Georgakopoulou
2015-01-01
Device white noise levels in short channel Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) dictate the performance and reliability of high-frequency circuits ranging from high-speed microprocessors to Low-Noise Amplifiers (LNAs) and microwave circuits. Recent experimental noise measurements with very short devices demonstrate the existence of suppressed shot noise, contrary to the predictions of classical channel thermal noise models. In this work we show that, as the dimensions ...
Schweiner, Frank; Main, Jörg; Cartarius, Holger; Wunner, Günter
2015-01-01
When superimposing the potentials of external fields on the Coulomb potential of the hydrogen atom, a saddle point (called the Stark saddle point) appears. For energies slightly above the saddle point energy, one can find classical orbits that are located in the vicinity of this point. We follow those so-called quasi-Penning orbits to high energies and field strengths, observing structural changes and uncovering their bifurcation behavior. By plotting the stability behavior of those orbits against energy and field strength, the appearance of a stability apex is reported. A cusp bifurcation, located in the vicinity of the apex, will be investigated in detail. In this cusp bifurcation, another orbit of similar shape is found. This orbit becomes completely stable in the observed region of positive energy, i.e., in a region of parameter space, where the Kepler-like orbits located around the nucleus are already unstable. By quantum mechanically exact calculations, we prove the existence of signatures in quantum spectra belonging to those orbits. Husimi distributions are used to compare quantum-Poincaré sections with the extension of the classical torus structure around the orbits. Since periodic orbit theory predicts that each classical periodic orbit contributes an oscillating term to photoabsorption spectra, we finally give an estimation for future experiments, which could verify the existence of the stable orbits.
Relativistic quantum dynamics in strong fields: Photon emission from heavy, few-electron ions
International Nuclear Information System (INIS)
Fritzsche, S.; Stoehlker, T.
2005-03-01
Recent progress in the study of the photon emission from highly-charged heavy ions is reviewed. These investigations show that high-Z ions provide a unique tool for improving the understanding of the electron-electron and electron-photon interaction in the presence of strong fields. Apart from the bound-state transitions, which are accurately described in the framework of quantum electrodynamics, much information has been obtained also from the radiative capture of (quasi-) free electrons by high-Z ions. Many features in the observed spectra hereby confirm the inherently relativistic behavior of even the simplest compound quantum systems in nature. (orig.)
ac Stark shift and dephasing of a superconducting qubit strongly coupled to a cavity field.
Schuster, D I; Wallraff, A; Blais, A; Frunzio, L; Huang, R-S; Majer, J; Girvin, S M; Schoelkopf, R J
2005-04-01
We have performed spectroscopy of a superconducting charge qubit coupled nonresonantly to a single mode of an on-chip resonator. The strong coupling induces a large ac Stark shift in the energy levels of both the qubit and the resonator. The dispersive shift of the resonator frequency is used to nondestructively determine the qubit state. Photon shot noise in the measurement field induces qubit level fluctuations leading to dephasing which is characteristic for the measurement backaction. A crossover in line shape with measurement power is observed and theoretically explained. For weak measurement a long intrinsic dephasing time of T2>200 ns of the qubit is found.
Peculiarities of two-electron atom ionization in strong electromagnetic field
International Nuclear Information System (INIS)
Ovodova, O.V.; Popov, A.M.; Tikhonova, O.V.
1997-01-01
One-dimensional model of helium atom in strong field of electromagnetic wave of femtosecond activity is plotted within the Hartree method frames. Comparison of 'exact' calculations with the calculations conducted within the frames of the 'frozen' and 'passive' electrons is made. The nonmonotonous dependence of one-dimensional ionization probability on the radiation intensity is found. It is shown that the ionization minima are connected with multiphoton resonances between various atomic states, originating due to the Stark effect. It is supposed that the effect of ionization suppression in this case is related to interference stabilization
International Nuclear Information System (INIS)
Zakharov, V.U.
1993-01-01
An analytical method for the investigation of special types of dispersion relations is presented. In particular, analysis of the propagation of small-amplitude hydromagnetic waves in a collisionless plasma in a strong magnetic field leads to such dispersion relations. The fifth-degree dispersion relation corresponding to a particular case is considered. The necessary stability condition for a steady state and conditions for the degeneration of small-amplitude waves are derived. A comparison with other methods for the analysis of similar dispersion relations is also presented. (author)
Strong Field-Induced Frequency Conversion of Laser Radiation in Plasma Plumes: Recent Achievements
Directory of Open Access Journals (Sweden)
R. A. Ganeev
2013-01-01
Full Text Available New findings in plasma harmonics studies using strong laser fields are reviewed. We discuss recent achievements in the growth of the efficiency of coherent extreme ultraviolet (XUV radiation sources based on frequency conversion of the ultrashort pulses in the laser-produced plasmas, which allowed for the spectral and structural studies of matter through the high-order harmonic generation (HHG spectroscopy. These studies showed that plasma HHG can open new opportunities in many unexpected areas of laser-matter interaction. Besides being considered as an alternative method for generation of coherent XUV radiation, it can be used as a powerful tool for various spectroscopic and analytical applications.
Vibrational Excitation of Diatomic Molecular Ions in Strong Field Ionization of Diatomic Molecules
International Nuclear Information System (INIS)
Kjeldsen, Thomas K.; Madsen, Lars Bojer
2005-01-01
A model based on the strong-field and Born-Oppenheimer approximations qualitatively describes the distribution over vibrational states formed in a diatomic molecular ion following ionization of the neutral molecule by intense laser pulses. Good agreement is found with a recent experiment [X. Urbain et al., Phys. Rev. Lett. 92, 163004 (2004)]. In particular, the observed deviation from a Franck-Condon-like distribution is reproduced. Additionally, we demonstrate control of the vibrational distribution by a variation of the peak intensity or a change of frequency of the laser pulse
Tian, Justin; Wang, Xu; Eberly, J. H.
2017-05-01
The lack of analytical solutions for the exit momentum in the laser-driven tunneling theory is a well-recognized problem in strong field physics. Theoretical studies of electron momentum distributions in the neighborhood of the tunneling exit depend heavily on ad hoc assumptions. In this Letter, we apply a new numerical method to study the exiting electron's longitudinal momentum distribution under intense short-pulse laser excitation. We present the first realizations of the dynamic behavior of an electron near the so-called tunneling exit region without adopting a tunneling approximation.
Laser-driven platform for generation and characterization of strong quasi-static magnetic fields
Czech Academy of Sciences Publication Activity Database
Santos, J.J.; Bailly-Grandvaux, M.; Giuffrida, Lorenzo; Forestier-Colleoni, P.; Fujioka, H.; Zhang, Z.; Korneev, P.; Bouillaud, R.; Dorard, S.; Batani, D.; Chevrot, M.; Cross, J. E.; Crowston, R.; Dubois, J.L.; Gazave, J.; Gregori, G.; d'Humieres, E.; Hulin, S.; Ishihara, K.; Kojima, S.; Loyez, E.; Marqués, J.-R.; Morace, A.; Nicolaï, P.; Peyrusse, O.; Poyé, A.; Raffestin, D.; Ribolzi, J.; Roth, M.; Schaumann, G.; Serres, F.; Tikhonchuk, V.T.; Vacar, P.; Woolsey, N.
2015-01-01
Roč. 17, Aug (2015), s. 1-10, č. článku 083051. ISSN 1367-2630 R&D Projects: GA MŠk ED1.1.00/02.0061 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061 Institutional support: RVO:68378271 Keywords : strong magnetic field * laser-driven coil targets * laser-plasma interaction Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.570, year: 2015
Viscosity in strongly interacting quantum field theories from black hole physics.
Kovtun, P K; Son, D T; Starinets, A O
2005-03-25
The ratio of shear viscosity to volume density of entropy can be used to characterize how close a given fluid is to being perfect. Using string theory methods, we show that this ratio is equal to a universal value of variant Planck's over 2pi/4pik(B) for a large class of strongly interacting quantum field theories whose dual description involves black holes in anti-de Sitter space. We provide evidence that this value may serve as a lower bound for a wide class of systems, thus suggesting that black hole horizons are dual to the most ideal fluids.
Transport coefficients of InSb in a strong magnetic field
International Nuclear Information System (INIS)
Nakamura, Hiroaki; Ikeda, Kazuaki; Yamaguchi, Satarou
1998-02-01
Improvement of a superconducting magnet system makes induction of a strong magnetic field easier. This fact gives us a possibility of energy conversion by the Nernst effect. As the first step to study the Nernst element, we measured the conductivity, the Hall coefficient, the thermoelectric power and the Nernst coefficient of the InSb, which is one of candidates of the Nernst elements. From this experiment, it is concluded that the Nernst coefficient is smaller than the theoretical values. On the other hand, the conductivity, the Hall coefficient and the thermoelectric power has the values expected by the theory. (author)
Ehrenfest's theorem and the validity of the two-step model for strong-field ionization
DEFF Research Database (Denmark)
Shvetsov-Shilovskiy, Nikolay; Dimitrovski, Darko; Madsen, Lars Bojer
2013-01-01
with situations where the ensemble average of the force deviates considerably from the force calculated at the average position of the trajectories of the ensemble. We identify the general trends for the applicability of the semiclassical model in terms of intensity, ellipticity, and wavelength of the laser pulse......By comparison with the solution of the time-dependent Schrödinger equation we explore the validity of the two-step semiclassical model for strong-field ionization in elliptically polarized laser pulses. We find that the discrepancy between the two-step model and the quantum theory correlates...
Mathematical methods of classical physics
Cortés, Vicente
2017-01-01
This short primer, geared towards students with a strong interest in mathematically rigorous approaches, introduces the essentials of classical physics, briefly points out its place in the history of physics and its relation to modern physics, and explains what benefits can be gained from a mathematical perspective. As a starting point, Newtonian mechanics is introduced and its limitations are discussed. This leads to and motivates the study of different formulations of classical mechanics, such as Lagrangian and Hamiltonian mechanics, which are the subjects of later chapters. In the second part, a chapter on classical field theories introduces more advanced material. Numerous exercises are collected in the appendix.
Observation of the Avalanche of Runaway Electrons in Air in a Strong Electric Field
Gurevich, A. V.; Mesyats, G. A.; Zybin, K. P.; Yalandin, M. I.; Reutova, A. G.; Shpak, V. G.; Shunailov, S. A.
2012-08-01
The generation of an avalanche of runaway electrons is demonstrated for the first time in a laboratory experiment. Two flows of runaway electrons are formed sequentially in an extended air discharge gap at the stage of delay of a pulsed breakdown. The first, picosecond, runaway electron flow is emitted in the cathode region where the field is enhanced. Being accelerated in the gap, this beam generates electrons due to impact ionization. These secondary electrons form a delayed avalanche of runaway electrons if the field is strong enough. The properties of the avalanche correspond to the existing notions about the runaway breakdown in air. The measured current of the avalanche exceeds up to an order the current of the initiating electron beam.
Strong-field photoelectron holography of atoms by bicircular two-color laser pulses
Li, Min; Jiang, Wei-Chao; Xie, Hui; Luo, Siqiang; Zhou, Yueming; Lu, Peixiang
2018-02-01
We study photoelectron holography in strong bicircular two-color laser fields by solving the time-dependent Schrödinger equation (TDSE) and a semiclassical rescattering model with implementing interference effect. The holographic patterns observed in the TDSE are well recaptured by the semiclassical rescattering model. Four types of photoelectron holographic interferences between the forward scattered and nonscattered trajectories are predicted by the semiclassical rescattering model in the bicircular two-color laser field. We find that those holographic patterns are spatially separated from each other in the electron momentum distribution. We further show that the dependence of the initial transverse momentum at the tunnel exit on the ionization time for the rescattering electron is recorded by the holographic patterns.
Influence of the initial angular distribution on strong-field molecular dissociation
Yu, Youliang; Zeng, Shuo; Hernández, J. V.; Wang, Yujun; Esry, B. D.
2016-08-01
We study few-cycle, strong-field dissociation of aligned H2+ by solving the time-dependent Schrödinger equation including rotation. We examine the dependence of the final angular distribution, the kinetic energy release spectrum, and the total dissociation yield on the initial nuclear angular distribution. In particular, we look at the dependence on the relative angle θ0 between the laser polarization and the symmetry axis of a well-aligned initial distribution, as well as the dependence on the delay between the "pump" pulse that prepares the alignment and the few-cycle probe pulse. Surprisingly, we find the dissociation probability for θ0=90∘ can be appreciable even though the transitions involved are purely parallel. We therefore address the limits of the commonly held "ball-and-stick" picture for molecules in intense fields as well as the validity of the axial recoil approximation.
Horwitz, Lawrence; Hu, Bei-Lok; Lee, Da-Shin; Gill, Tepper; Land, Martin
2011-12-01
Although the subject of relativistic dynamics has been explored from both classical and quantum mechanical points of view since the work of Einstein and Dirac, its most striking development has been in the framework of quantum field theory. The very accurate calculations of spectral and scattering properties, for example, of the anamolous magnetic moment of the electron and the Lamb shift in quantum electrodynamics, and many qualitative features of the strong and electroweak interactions, demonstrate the very great power of description achieved in this framework. Yet, many fundamental questions remain to be clarified, such as the structure of classical realtivistic dynamical theories on the level of Hamilton and Lagrange in Minkowski space as well as on the curved manifolds of general relativity. There moreover remains the important question of the covariant classical description of systems at high energy for which particle production effects are not large, such as discussed in Synge's book, The Relativistic Gas, and in Balescu's book on relativistic statistical mechanics. In recent years, the study of high energy plasmas and heavy ion collisions has emphasized the importance of developing the techniques of relativistic mechanics. The results of Linder et al (Phys. Rev. Lett. 95 0040401 (2005)) as well as the more recent work of Palacios et al (Phys. Rev. Lett. 103 253001 (2009)) and others, have shown that there must be a quantum theory with coherence in time. Such a theory, manifestly covariant under the transformations of special relativity with an invariant evolution parameter, such as that of Stueckelberg (Helv. Phys. Acta 14 322, 588 (1941); 15 23 (1942); see also R P Feynman Phys. Rev. 80 4401 and J S Schwinger Phys. Rev. 82 664 (1951)) could provide a suitable basis for the study of such questions, as well as many others for which the application of the standard methods of quantum field theory are difficult to manage, involving, in particular, local
Múnera, Héctor A.
2016-07-01
It is postulated that there exists a fundamental energy-like fluid, which occupies the flat three-dimensional Euclidean space that contains our universe, and obeys the two basic laws of classical physics: conservation of linear momentum, and conservation of total energy; the fluid is described by the classical wave equation (CWE), which was Schrödinger's first candidate to develop his quantum theory. Novel solutions for the CWE discovered twenty years ago are nonharmonic, inherently quantized, and universal in the sense of scale invariance, thus leading to quantization at all scales of the universe, from galactic clusters to the sub-quark world, and yielding a unified Lorentz-invariant quantum theory ab initio. Quingal solutions are isomorphic under both neo-Galilean and Lorentz transformations, and exhibit nother remarkable property: intrinsic unstability for large values of ℓ (a quantum number), thus limiting the size of each system at a given scale. Unstability and scale-invariance together lead to nested structures observed in our solar system; unstability may explain the small number of rows in the chemical periodic table, and nuclear unstability of nuclides beyond lead and bismuth. Quingal functions lend mathematical basis for Boscovich's unified force (which is compatible with many pieces of evidence collected over the past century), and also yield a simple geometrical solution for the classical three-body problem, which is a useful model for electronic orbits in simple diatomic molecules. A testable prediction for the helicoidal-type force is suggested.
A strong magnetic field around the supermassive black hole at the centre of the Galaxy.
Eatough, R P; Falcke, H; Karuppusamy, R; Lee, K J; Champion, D J; Keane, E F; Desvignes, G; Schnitzeler, D H F M; Spitler, L G; Kramer, M; Klein, B; Bassa, C; Bower, G C; Brunthaler, A; Cognard, I; Deller, A T; Demorest, P B; Freire, P C C; Kraus, A; Lyne, A G; Noutsos, A; Stappers, B; Wex, N
2013-09-19
Earth's nearest candidate supermassive black hole lies at the centre of the Milky Way. Its electromagnetic emission is thought to be powered by radiatively inefficient accretion of gas from its environment, which is a standard mode of energy supply for most galactic nuclei. X-ray measurements have already resolved a tenuous hot gas component from which the black hole can be fed. The magnetization of the gas, however, which is a crucial parameter determining the structure of the accretion flow, remains unknown. Strong magnetic fields can influence the dynamics of accretion, remove angular momentum from the infalling gas, expel matter through relativistic jets and lead to synchrotron emission such as that previously observed. Here we report multi-frequency radio measurements of a newly discovered pulsar close to the Galactic Centre and show that the pulsar's unusually large Faraday rotation (the rotation of the plane of polarization of the emission in the presence of an external magnetic field) indicates that there is a dynamically important magnetic field near the black hole. If this field is accreted down to the event horizon it provides enough magnetic flux to explain the observed emission--from radio to X-ray wavelengths--from the black hole.
Active galaxies. A strong magnetic field in the jet base of a supermassive black hole.
Martí-Vidal, Ivan; Muller, Sébastien; Vlemmings, Wouter; Horellou, Cathy; Aalto, Susanne
2015-04-17
Active galactic nuclei (AGN) host some of the most energetic phenomena in the universe. AGN are thought to be powered by accretion of matter onto a rotating disk that surrounds a supermassive black hole. Jet streams can be boosted in energy near the event horizon of the black hole and then flow outward along the rotation axis of the disk. The mechanism that forms such a jet and guides it over scales from a few light-days up to millions of light-years remains uncertain, but magnetic fields are thought to play a critical role. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we have detected a polarization signal (Faraday rotation) related to the strong magnetic field at the jet base of a distant AGN, PKS 1830-211. The amount of Faraday rotation (rotation measure) is proportional to the integral of the magnetic field strength along the line of sight times the density of electrons. The high rotation measures derived suggest magnetic fields of at least tens of Gauss (and possibly considerably higher) on scales of the order of light-days (0.01 parsec) from the black hole. Copyright © 2015, American Association for the Advancement of Science.
Dynamics of liquid metal droplets and jets influenced by a strong axial magnetic field
Hernández, D.; Karcher, Ch
2017-07-01
Non-contact electromagnetic control and shaping of liquid metal free surfaces is crucial in a number of high-temperature metallurgical processes like levitation melting and electromagnetic sealing, among others. Other examples are the electromagnetic bending or stabilization of liquid metal jets that frequently occur in casting or fusion applications. Within this context, we experimentally study the influence of strong axial magnetic fields on the dynamics of falling metal droplets and liquid metal jets. GaInSn in eutectic composition is used as test melt being liquid at room temperature. In the experiments, we use a cryogen-free superconducting magnet (CFM) providing steady homogeneous fields of up to 5 T and allowing a tilt angle between the falling melt and the magnet axis. We vary the magnetic flux density, the tilt angle, the liquid metal flow rate, and the diameter and material of the nozzle (electrically conducting/insulating). Hence, the experiments cover a parameter range of Hartmann numbers Ha, Reynolds numbers Re, and Weber numbers We within 0 rotation ceases and the droplets are stretched in the field direction. Moreover, we observe that the jet breakup into droplets (spheroidization) is suppressed, and in the case of electrically conducting nozzles and tilt, the jets are bent towards the field axis.
Nonlinear propagation of strong-field THz pulses in doped semiconductors
DEFF Research Database (Denmark)
Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.
2012-01-01
We report on nonlinear propagation of single-cycle THz pulses with peak electric fields reaching 300 kV/cm in n-type semiconductors at room temperature. Dramatic THz saturable absorption effects are observed in GaAs, GaP, and Ge, which are caused by the nonlinear electron transport in THz fields......-effective-mass states in the energy-momentum space of the conduction band. Further, we observe the typical accompanying effects of saturable absorption on the THz pulses, such as an increase of the group delay, as the peak electric field of the pulse increases. In this paper we present the results of nonlinear THz time....... The semiconductor conductivity, and hence the THz absorption, is modulated due to the acceleration of carriers in strong THz fields, leading to an increase of the effective mass of the electron population, as the electrons are redistributed from the low-momentum, low-effective-mass states to the high-momentum, high...
Breakdown of the Chiral Anomaly in Weyl Semimetals in a Strong Magnetic Field
Kim, Pilkwang; Ryoo, Ji Hoon; Park, Cheol-Hwan
2017-12-01
The low-energy quasiparticles of Weyl semimetals are a condensed-matter realization of the Weyl fermions introduced in relativistic field theory. Chiral anomaly, the nonconservation of the chiral charge under parallel electric and magnetic fields, is arguably the most important phenomenon of Weyl semimetals and has been explained as an imbalance between the occupancies of the gapless, zeroth Landau levels with opposite chiralities. This widely accepted picture has served as the basis for subsequent studies. Here we report the breakdown of the chiral anomaly in Weyl semimetals in a strong magnetic field based on ab initio calculations. A sizable energy gap that depends sensitively on the direction of the magnetic field may open up due to the mixing of the zeroth Landau levels associated with the opposite-chirality Weyl points that are away from each other in the Brillouin zone. Our study provides a theoretical framework for understanding a wide range of phenomena closely related to the chiral anomaly in topological semimetals, such as magnetotransport, thermoelectric responses, and plasmons, to name a few.
Radiative Processes in Graphene and Similar Nanostructures in Strong Electric Fields
Gavrilov, S. P.; Gitman, D. M.
2017-03-01
Low-energy single-electron dynamics in graphene monolayers and similar nanostructures is described by the Dirac model, being a 2+1 dimensional version of massless QED with the speed of light replaced by the Fermi velocity vF ≃ c/300. Methods of strong-field QFT are relevant for the Dirac model, since any low-frequency electric field requires a nonperturbative treatment of massless carriers in the case it remains unchanged for a sufficiently long time interval. In this case, the effects of creation and annihilation of electron-hole pairs produced from vacuum by a slowly varying and small-gradient electric field are relevant, thereby substantially affecting the radiation pattern. For this reason, the standard QED text-book theory of photon emission cannot be of help. We construct the Fock-space representation of the Dirac model, which takes exact accounts of the effects of vacuum instability caused by external electric fields, and in which the interaction between electrons and photons is taken into account perturbatively, following the general theory (the generalized Furry representation). We consider the effective theory of photon emission in the first-order approximation and construct the corresponding total probabilities, taking into account the unitarity relation.
He2+ molecular ion and the He- atomic ion in strong magnetic fields
Vieyra, J. C. Lopez; Turbiner, A. V.
2017-08-01
We study the question of existence, i.e., stability with respect to dissociation of the spin-quartet permutation- and reflection-symmetric 4(-3) +g (Sz=-3 /2 ,M =-3 ) state of the (α α e e e ) Coulomb system: the He2 + molecular ion, placed in a magnetic field 0 ≤B ≤10 000 a.u. We assume that the α particles are infinitely massive (Born-Oppenheimer approximation of zero order) and adopt the parallel configuration, when the molecular axis and the magnetic field direction coincide, as the optimal configuration. The study of the stability is performed variationally with a physically adequate trial function. To achieve this goal, we explore several helium-containing compounds in strong magnetic fields, in particular; we study the spin-quartet ground state of the He- ion and the ground (spin-triplet) state of the helium atom, both for a magnetic field in 100 ≤B ≤10 000 a.u. The main result is that the He2 + molecular ion in the state 4(-3) +g is stable towards all possible decay modes for magnetic fields B ≳120 a .u . and with the magnetic field increase the ion becomes more tightly bound and compact with a cigar-type form of electronic cloud. At B =1000 a .u . , the dissociation energy of He2 + into He-+α is ˜702 eV and the dissociation energy for the decay channel to He +α +e is ˜729 eV , and both energies are in the energy window for one of the observed absorption features of the isolated neutron star 1E1207.4-5209.
Pair production in a strong electric field with back-reaction
International Nuclear Information System (INIS)
Eisenberg, J.M.; Kluger, Y.; Svetitsky, B.
1992-01-01
We present a summary of the present status of efforts to solve the problem in which pairs are produced in a strong electric field, are accelerated by it, and then react back on it through the counter-field produced by their current. This picture has been used by Bialas and Czyz and others as a model for effects that may possibly arise in the study of the quark-gluon plasma. We here give a didactic review of recent developments in this back-reaction problem. We first present a simple version of the theory of pair tunneling from a fixed electric field, and then sketch how this has been applied to the quark-gluon plasma. Then we turn to a field formulation of the problem for charged bosons, which leads to the need to carry out a renormalization program, outlined again in simple terms. Numerical results for this program are presented for one spatial dimension, the corresponding physical behaviour of the system is discussed, and the implications for three spatial dimensions are considered. We exhibit a phenomenological transport equation embodying physics that is essentially identical to that of the field formulation, thus helping to tie the model of Bialas and Czyz for the quark-gluon plasma to a field-theory formulation. Last, we note the status of extensions to the problem with three space dimensions; the fermion case; the formulation in terms of boost-invariant variables (as desirable for the quark-gluon plasma); and transport equations derived in a fundamental and consistent fashion. 5 figs., 13 refs. (author)
Classical and quantum mechanical behaviour in the low-field magneto-resistance in open quantum dots
International Nuclear Information System (INIS)
Brunner, R.
2005-09-01
Electronic transport through open dots has received much attention in recent years. An interesting aspect of this research focuses on the use of such low-dimensional systems to probe the connection between semi-classical physics and quantum mechanics. The purpose of this thesis is to understand the transport properties in a ballistic open quantum dot and dot arrays and to find clear evidence that, although the system is open, still discrete energy states are present. This is achieved by using a classical model calculation and performing DC and microwave experiments in the single open quantum dot and 3-dot array. By comparing the magneto-resistance obtained from the experiment with the calculated magneto-resistance the confining potential of the open quantum dot is found to be a soft parabolic potential. Peaks in the low-field magneto-resistance are attributed to backscattering events in the open dot. At certain magnetic fields classically calculated trajectories are obtained which are backscattered. As a consequence the magneto-resistance is raised. As a consequence of a stability analysis by calculating the Poincare section and estimating the Lyapunov exponent, the single open quantum dot is identified as an integrable system. In the case of an open quantum dot array the symmetry of the single dot is broken. Depending on the magnetic field, the open quantum dot array is characterized as an integrable system or a nonintegrable system with mixed phase space. The mixed phase space exists of chaotic and quasi-periodic trajectories. The quasi-periodic trajectories are attributed to Kolmogorov-Arnol'd-Moser (KAM) islands. These islands are completely decoupled from the surrounding and therefore classically inaccessible. We argue that the closed orbits which generate a series of delta functions in the density of states might be associated with discrete energy states in the open quantum dot. To search for discrete energy states in the open quantum dot microwave
Charge transfer of He2 + with H in a strong magnetic field
Liu, Chun-Lei; Zou, Shi-Yang; He, Bin; Wang, Jian-Guo
2015-09-01
By solving a time-dependent Schrödinger equation (TDSE), we studied the electron capture process in the He2 + +H collision system under a strong magnetic field in a wide projectile energy range. The strong enhancement of the total charge transfer cross section is observed for the projectile energy below 2.0 keV/u. With the projectile energy increasing, the cross sections will reduce a little and then increase again, compared with those in the field-free case. The cross sections to the states with different magnetic quantum numbers are presented and analyzed where the influence due to Zeeman splitting is obviously found, especially in the low projectile energy region. The comparison with other models is made and the tendency of the cross section varying with the projectile energy is found closer to that from other close coupling models. Project supported by the National Natural Science Foundation of China (Grants Nos. 11104017, 11025417, 11275029, and 11474032), the National Basic Research Programm of China (Grant No. 2013CB922200), and the Foundation for the Development of Science and Technology of the Chinese Academy of Engineering Physics (Grant Nos. 2014B09036 and 2013A0102005).
Attosecond transient-absorption dynamics of xenon core-excited states in a strong driving field
Kobayashi, Yuki; Timmers, Henry; Sabbar, Mazyar; Leone, Stephen R.; Neumark, Daniel M.
2017-03-01
We present attosecond transient-absorption experiments on xenon 4 d-16 p core-level states resonantly driven by intense (1.6 ×1014W/cm 2 ) few-cycle near-infrared laser pulses. In this strongly driven regime, broad induced absorption features with half-cycle (1.3-fs) delay-dependent modulation are observed over the range of 58-65 eV, predicted as a signature of the breakdown of the rotating-wave approximation in strong-field driving of Autler-Townes splitting [A. N. Pfeiffer and S. R. Leone, Phys. Rev. A 85, 053422 (2012), 10.1103/PhysRevA.85.053422]. Relevant atomic states are identified by a numerical model involving three electronic states, and the mechanism behind the broad induced absorption is discussed in the Floquet formalism. These results demonstrate that a near-infrared field well into the tunneling regime can still control the optical properties of an atomic system over a several-electron-volt spectral range and with attosecond precision.
Behavior of Particle Depots in Molten Silicon During Float-Zone Growth in Strong Magnetic Fields
Jauss, T.; Croell, A.; SorgenFrei, T.; Azizi, M.; Reimann, C.; Friedrich, J.; Volz, M. P.
2014-01-01
Solar cells made from directionally solidified silicon cover 57% of the photovoltaic industry's market [1]. One major issue during directional solidification of silicon is the precipitation of foreign phase particles. These particles, mainly SiC and Si3N4, are precipitated from the dissolved crucible coating, which is made of silicon nitride, and the dissolution of carbon monoxide from the furnace atmosphere. Due to their hardness and size of several hundred micrometers, those particles can lead to severe problems during the wire sawing process for wafering the ingots. Additionally, SiC particles can act as a shunt, short circuiting the solar cell. Even if the particles are too small to disturb the wafering process, they can lead to a grit structure of silicon micro grains and serve as sources for dislocations. All of this lowers the yield of solar cells and reduces the performance of cells and modules. We studied the behaviour of SiC particle depots during float-zone growth under an oxide skin, and strong static magnetic fields. For high field strengths of 3T and above and an oxide layer on the sample surface, convection is sufficiently suppressed to create a diffusive like regime, with strongly dampened convection [2, 3]. To investigate the difference between atomically rough phase boundaries and facetted growth, samples with [100] and [111] orientation were processed.
Morishita, Toru; Tolstikhin, Oleg I.
2017-11-01
We present a comprehensive treatise on the derivation of the factorization formula describing strong-field photoelectron momentum distributions near the outermost backward rescattering caustic within the adiabatic theory and its validation by calculations. The formula derived holds for ionization by linearly polarized laser pulses of sufficiently low frequency and becomes exact as the frequency tends to zero for a fixed pulse amplitude. The convergence of the results obtained from the formula to accurate photoelectron momentum distributions obtained by solving the time-dependent Schrödinger equation is demonstrated. The formula is shown to work quantitatively in both tunneling and over-the-barrier regimes of ionization for finite-range potentials as well as potentials with a Coulomb tail. This paves the way for future applications of the present theory in strong-field physics. In particular, the explicit analytical form of the returning photoelectron wave packet given here enables one to extract differential cross sections for elastic scattering of a photoelectron on the parent ion from experimental photoelectron momentum distributions.
Describing nonequilibrium behavior in strongly correlated materials via dynamical mean-field theory
Freericks, James
2010-03-01
Dynamical mean-field theory was introduced in 1989 and has become one of the most successful methods for solving models of strongly correlated electrons in equilibrium (it becomes exact in the infinite-dimensional limit). In this talk, I show how to generalize dynamical mean-field theory to nonequilibrium situations. For transient response, one discretizes the Kadanoff-Baym-Keldysh contour then solves the discrete problem directly. For steady-state response, one can formulate a theory directly in the long-time limit for the retarded Green's functions. These techniques are applied to the problem of the quenching of Bloch oscillations due to electron-electron interactions and to the problem of time-resolved pump/probe photoemission spectroscopy of strongly correlated electrons when a system is driven to a nonequilibrium steady state and cannot be described by the quasiequilibrium approximation with an effective temperature. This work was completed in collaboration with Tom Devereaux, Sasha Joura, Hulikal Krishnamurthy, Brian Moritz, Thomas Pruschke, Volodomyr Turkowski, and Velko Zlati'c. Recent references include: J. K. Freericks, V. M. Turkowski, and V. Zlati'c, Phys. Rev. Lett. 97, 266408 (2006); J. K. Freericks, Phys. Rev. B 77, 075109 (2008); A. V.Joura, J. K. Freericks, and Th. Pruschke, Phys. Rev. Lett. 101, 196401 (2008); J. K. Freericks, H. R. Krishnamurthy and Th. Pruschke, Phys. Rev. Lett. 102, 136401 (2009); and B. Moritz, T. P. Devereaux, and J. K. Freericks, arXiv:0908.1807.
Patel, Anita; Pulugundla, Gautam; Smolentsev, Sergey; Abdou, Mohamed; Bhattacharyay, Rajendraprasad
2018-04-01
Following the magnetohydrodynamic (MHD) code validation and verification proposal by Smolentsev et al. (Fusion Eng Des 100:65-72, 2015), we perform code to code and code to experiment comparisons between two computational solvers, FLUIDYN and HIMAG, which are presently considered as two of the prospective CFD tools for fusion blanket applications. In such applications, an electrically conducting breeder/coolant circulates in the blanket ducts in the presence of a strong plasma-confining magnetic field at high Hartmann numbers, it{Ha} (it{Ha}^2 is the ratio between electromagnetic and viscous forces) and high interaction parameters, it{N} (it{N} is the ratio of electromagnetic to inertial forces). The main objective of this paper is to provide the scientific and engineering community with common references to assist fusion researchers in the selection of adequate computational means to be used for blanket design and analysis. As an initial validation case, the two codes are applied to the classic problem of a laminar fully developed MHD flows in a rectangular duct. Both codes demonstrate a very good agreement with the analytical solution for it{Ha} up to 15, 000. To address the capabilities of the two codes to properly resolve complex geometry flows, we consider a case of three-dimensional developing MHD flow in a geometry comprising of a series of interconnected electrically conducting rectangular ducts. The computed electric potential distributions for two flows (Case A) it{Ha}=515, it{N}=3.2 and (Case B) it{Ha}=2059, it{N}=63.8 are in very good agreement with the experimental data, while the comparisons for the MHD pressure drop are still unsatisfactory. To better interpret the observed differences, the obtained numerical data are analyzed against earlier theoretical and experimental studies for flows that involve changes in the relative orientation between the flow and the magnetic field.
International Nuclear Information System (INIS)
Monthus, Cécile; Garel, Thomas
2012-01-01
To avoid the complicated topology of surviving clusters induced by standard strong disorder RG in dimension d > 1, we introduce a modified procedure called ‘boundary strong disorder RG’ where the order of decimations is chosen a priori. We apply this modified procedure numerically to the random transverse field Ising model in dimension d = 2. We find that the location of the critical point, the activated exponent ψ ≃ 0.5 of the infinite-disorder scaling, and the finite-size correlation exponent ν FS ≃ 1.3 are compatible with the values obtained previously using standard strong disorder RG. Our conclusion is thus that strong disorder RG is very robust with respect to changes in the order of decimations. In addition, we analyze the RG flows within the two phases in more detail, to show explicitly the presence of various correlation length exponents: we measure the typical correlation exponent ν typ ≃ 0.64 for the disordered phase (this value is very close to the correlation exponent ν pure Q (d=2)≅0.6 3 of the pure two-dimensional quantum Ising model), and the typical exponent ν h ≃ 1 for the ordered phase. These values satisfy the relations between critical exponents imposed by the expected finite-size scaling properties at infinite-disorder critical points. We also measure, within the disordered phase, the fluctuation exponent ω ≃ 0.35 which is compatible with the directed polymer exponent ω DP (1+1)= 1/3 in (1 + 1) dimensions. (paper)
Study of Fluid Flow Control in Protein Crystallization using Strong Magnetic Fields
Ramachandran, Narayanan; Leslie, Fred; Ciszak, Ewa
2002-01-01
An important component in biotechnology, particularly in the area of protein engineering and rational drug design is the knowledge of the precise three-dimensional molecular structure of proteins. The quality of structural information obtained from X-ray diffraction methods is directly dependent on the degree of perfection of the protein crystals. As a consequence, the growth of high quality macromolecular crystals for diffraction analyses has been the central focus for biochemists, biologists, and bioengineers. Macromolecular crystals are obtained from solutions that contain the crystallizing species in equilibrium with higher aggregates, ions, precipitants, other possible phases of the protein, foreign particles, the walls of the container, and a likely host of other impurities. By changing transport modes in general, i.e., reduction of convection and sedimentation, as is achieved in "microgravity", researchers have been able to dramatically affect the movement and distribution of macromolecules in the fluid, and thus their transport, formation of crystal nuclei, and adsorption to the crystal surface. While a limited number of high quality crystals from space flights have been obtained, as the recent National Research Council (NRC) review of the NASA microgravity crystallization program pointed out, the scientific approach and research in crystallization of proteins has been mainly empirical yielding inconclusive results. We postulate that we can reduce convection in ground-based experiments and we can understand the different aspects of convection control through the use of strong magnetic fields and field gradients. Whether this limited convection in a magnetic field will provide the environment for the growth of high quality crystals is still a matter of conjecture that our research will address. The approach exploits the variation of fluid magnetic susceptibility with concentration for this purpose and the convective damping is realized by appropriately
Molecules in strong laser fields. In depth study of H2 molecule
International Nuclear Information System (INIS)
Awasthi, Manohar
2009-01-01
-threshold-ionization peaks is also demonstrated. The CI-TDSE results for H 2 are used for testing the validity of SAE approximation. In strong field physics, there are models based on the SAE approximation. Most popular are the Ammosov-Delone-Krainov (ADK) model, a molecular version of the ADK model called MO-ADK (MO stands for molecular orbital) and the strong field approximation (SFA). The validity of the second method for the solution of TDSE in SAE approximation is investigated by applying it to H 2 molecule where the exact two-electron results were already calculated using CI-TDSE. The SAE method uses density-functional-theory (DFT) for the description of field-free eigenstates and is thus abbreviated as DFT-SAE-TDSE. Since DFT is used for the calculation of field-free states, different functionals were also tested. The validity of MO-ADK model is also investigated. After establishing the DFT-SAE-TDSE method, the first excited state B 1 Σ u + of H 2 is studied over a large range of laser parameters. The effect of the closely lying excited states on ionization and excitation is studied. After successful testing of DFT-SAE-TDSE method on H 2 molecule, the results for larger molecules like N 2 , O 2 and C 2 H 2 in the DFT-SAE framework are presented. (orig.)
Molecules in strong laser fields. In depth study of H{sub 2} molecule
Energy Technology Data Exchange (ETDEWEB)
Awasthi, Manohar
2009-10-29
above-threshold-ionization peaks is also demonstrated. The CI-TDSE results for H{sub 2} are used for testing the validity of SAE approximation. In strong field physics, there are models based on the SAE approximation. Most popular are the Ammosov-Delone-Krainov (ADK) model, a molecular version of the ADK model called MO-ADK (MO stands for molecular orbital) and the strong field approximation (SFA). The validity of the second method for the solution of TDSE in SAE approximation is investigated by applying it to H{sub 2} molecule where the exact two-electron results were already calculated using CI-TDSE. The SAE method uses density-functional-theory (DFT) for the description of field-free eigenstates and is thus abbreviated as DFT-SAE-TDSE. Since DFT is used for the calculation of field-free states, different functionals were also tested. The validity of MO-ADK model is also investigated. After establishing the DFT-SAE-TDSE method, the first excited state B{sup 1}{sigma}{sub u}{sup +} of H{sub 2} is studied over a large range of laser parameters. The effect of the closely lying excited states on ionization and excitation is studied. After successful testing of DFT-SAE-TDSE method on H{sub 2} molecule, the results for larger molecules like N{sub 2}, O{sub 2} and C{sub 2}H{sub 2} in the DFT-SAE framework are presented. (orig.)
Reinhardt, W.; Farrelly, D.
1982-01-01
Semi-classical quantization of multidimensional systems is discussed both in terms of the Einstein-Brillouin-Keller quantization on invariant tori, and in terms of infinite families of periodic orbits. The notions of separability, integrability, and non-integrability of classical systems are introduced. An approximate integrability is used to quantize the quadratic Zeeman problem, via analytic calculation of the Birkhoff-Gustavson normal form.
Open and Closed String field theory interpreted in classical Algebraic Topology
Sullivan, Dennis
2003-01-01
There is an interpretation of open string field theory in algebraic topology. An interpretation of closed string field theory can be deduced from this open string theory to obtain as well the interpretation of open and closed string field theory combined.
The superluminal velocities as the consequence of non-classical states of electromagnetic field
Veklenko, B. A.
2017-06-01
It was shown within the framework of conventional quantum electrodynamics, and without using perturbation theory, the presence of superluminal signals, transferring the information, while investigating the scattering of quantum electromagnetic field by excited atom. The superluminal signals are impossible in the theory of free fields, but their existence is predicted by the theory of interacting fields.
Semi-classical noise investigation for sub-40nm metal-oxide-semiconductor field-effect transistors
Directory of Open Access Journals (Sweden)
C. Spathis
2015-08-01
Full Text Available Device white noise levels in short channel Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs dictate the performance and reliability of high-frequency circuits ranging from high-speed microprocessors to Low-Noise Amplifiers (LNAs and microwave circuits. Recent experimental noise measurements with very short devices demonstrate the existence of suppressed shot noise, contrary to the predictions of classical channel thermal noise models. In this work we show that, as the dimensions continue to shrink, shot noise has to be considered when the channel resistance becomes comparable to the barrier resistance at the source-channel junction. By adopting a semi-classical approach and taking retrospectively into account transport, short-channel and quantum effects, we investigate the partitioning between shot and thermal noise, and formulate a predictive model that describes the noise characteristics of modern devices.
Semi-classical noise investigation for sub-40nm metal-oxide-semiconductor field-effect transistors
Spathis, C.; Birbas, A.; Georgakopoulou, K.
2015-08-01
Device white noise levels in short channel Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) dictate the performance and reliability of high-frequency circuits ranging from high-speed microprocessors to Low-Noise Amplifiers (LNAs) and microwave circuits. Recent experimental noise measurements with very short devices demonstrate the existence of suppressed shot noise, contrary to the predictions of classical channel thermal noise models. In this work we show that, as the dimensions continue to shrink, shot noise has to be considered when the channel resistance becomes comparable to the barrier resistance at the source-channel junction. By adopting a semi-classical approach and taking retrospectively into account transport, short-channel and quantum effects, we investigate the partitioning between shot and thermal noise, and formulate a predictive model that describes the noise characteristics of modern devices.
Energy Technology Data Exchange (ETDEWEB)
Rosnitskiy, P., E-mail: pavrosni@yandex.ru; Yuldashev, P., E-mail: petr@acs366.phys.msu.ru; Khokhlova, V., E-mail: vera@acs366.phys.msu.ru [Physics Faculty, Moscow State University, Leninskie Gory, 119991 Moscow (Russian Federation)
2015-10-28
An equivalent source model was proposed as a boundary condition to the nonlinear parabolic Khokhlov-Zabolotskaya (KZ) equation to simulate high intensity focused ultrasound (HIFU) fields generated by medical ultrasound transducers with the shape of a spherical shell. The boundary condition was set in the initial plane; the aperture, the focal distance, and the initial pressure of the source were chosen based on the best match of the axial pressure amplitude and phase distributions in the Rayleigh integral analytic solution for a spherical transducer and the linear parabolic approximation solution for the equivalent source. Analytic expressions for the equivalent source parameters were derived. It was shown that the proposed approach allowed us to transfer the boundary condition from the spherical surface to the plane and to achieve a very good match between the linear field solutions of the parabolic and full diffraction models even for highly focused sources with F-number less than unity. The proposed method can be further used to expand the capabilities of the KZ nonlinear parabolic equation for efficient modeling of HIFU fields generated by strongly focused sources.
The mass limit of white dwarfs with strong magnetic fields in general relativity
International Nuclear Information System (INIS)
Wen De-Hua; Liu He-Lei; Zhang Xiang-Dong
2014-01-01
Recently, U. Das and B. Mukhopadhyay proposed that the Chandrasekhar limit of a white dwarf could reach a new high level (2.58M⊙) if a superstrong magnetic field were considered (Das U and Mukhopadhyay B 2013 Phys. Rev. Lett. 110 071102), where the structure of the strongly magnetized white dwarf (SMWD) is calculated in the framework of Newtonian theory (NT). As the SMWD has a far smaller size, in contrast with the usual expectation, we found that there is an obvious general relativistic effect (GRE) in the SMWD. For example, for the SMWD with a one Landau level system, the super-Chandrasekhar mass limit in general relativity (GR) is approximately 16.5% lower than that in NT. More interestingly, the maximal mass of the white dwarf will be first increased when the magnetic field strength keeps on increasing and reaches the maximal value M = 2.48M⊙ with B D = 391.5. Then if we further increase the magnetic fields, surprisingly, the maximal mass of the white dwarf will decrease when one takes the GRE into account. (geophysics, astronomy, and astrophysics)
Photogeneration of neutrino and axions under stimulating effect of strong magnetic field
Skobelev, V V
2001-01-01
The processes of the neutrino and axions photoproduction on the gamma(Ze) -> gamma(nu nu-bar), gamma alpha nuclei, as well as the photon inelastic scattering on the gamma gamma -> gamma(nu nu-bar), gamma alpha photon are considered within the frames of the developed two-dimensional co-variant theory for calculating the matrix of the Feynman diagrams in the strong magnetic field. The contribution of the neutrino radiative photoproduction on the nuclei to the luminosity of the magnetic neutron stars on the early stages of their evolution may compete with the URCA-processes, because the matrix elements in the four-pole diagram depend linearly on the induction of B magnetic field by the B values approx 10 sup 3 -10 sup 4 B sub 0 (B sub 0 = m sub e sup 2 /|e| = 4.41 x 10 sup 1 sup 3 Gs). The evaluation of the axion mass upper boundary, compatible with other independent results, is obtained from the condition of the neutrino luminosity prevailing over the axion one at supposed temperature and magnetic field inducti...
Calculation of low-frequency sound fields in irregular waveguides with strong backscattering
Gulin, O. E.
2008-07-01
An approach is developed for calculating the sound fields in a non-stratified sea medium with irregularities that are not weak. The method of cross sections for horizontal parts of acoustic modes is used to obtain first-order causal equations that are equivalent to the boundary-value problem. A matrix equation describing the backscattered field of modes is analyzed, and the conditions that determine the weakness of the irregularities of the medium and the validity of the known approximate methods of sound field calculations are considered. The approximation of unidirectional propagation is represented in the form of quadratures. The example of a 2D shallow-water waveguide with a strongly irregular profile of a perfectly rigid bottom is considered to illustrate the advantages of the proposed approach in comparison with the approximate methods for specific low frequencies. The qualitative and quantitative differences that arise because of taking into account the backscattering between the curves of propagation losses corresponding to the exact solution and the conventional approximate methods are discussed.
International Nuclear Information System (INIS)
Oka, T.; Tanaka, K.; Kimura, T.; Mimura, D.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Yokoyama, K.; Yamaguchi, M.
2010-01-01
The magnetic separation technique in combination with high temperature superconducting bulk magnets has been investigated to purify the ground water which has been used in the coolant system for the incinerator furnace to cool the burning gas. The experiment has been operated by means of the newly-built alternating channel type magnetic separating device. The separation ratios of ferromagnetic flocks including fine magnetite powder have been estimated by means of the high gradient magnetic separation method with small iron balls filled in the water channels. As the magnetic force acting on the magnetic particle is given by the product of a magnetization of the material and a gradient of magnetic field, and as the ferromagnetic stainless steel balls yield the steep gradient of magnetic field around them in a strong magnetic field, the system has exhibited a quite excellent performance with respect to the separation ratios. The separation ratios of the flocks which contain the magnetite powder with the values more than 50 ppm have remained over 80% for under the flow rates less than 5 L/min.
Oka, T.; Tanaka, K.; Kimura, T.; Mimura, D.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M.; Yokoyama, K.; Yamaguchi, M.
2010-11-01
The magnetic separation technique in combination with high temperature superconducting bulk magnets has been investigated to purify the ground water which has been used in the coolant system for the incinerator furnace to cool the burning gas. The experiment has been operated by means of the newly-built alternating channel type magnetic separating device. The separation ratios of ferromagnetic flocks including fine magnetite powder have been estimated by means of the high gradient magnetic separation method with small iron balls filled in the water channels. As the magnetic force acting on the magnetic particle is given by the product of a magnetization of the material and a gradient of magnetic field, and as the ferromagnetic stainless steel balls yield the steep gradient of magnetic field around them in a strong magnetic field, the system has exhibited a quite excellent performance with respect to the separation ratios. The separation ratios of the flocks which contain the magnetite powder with the values more than 50 ppm have remained over 80% for under the flow rates less than 5 L/min.
Probabilistic Path Planning of Montgolfier Balloons in Strong, Uncertain Wind Fields
Wolf, Michael; Blackmore, James C.; Kuwata, Yoshiaki
2011-01-01
Lighter-than-air vehicles such as hot-air balloons have been proposed for exploring Saturn s moon Titan, as well as other bodies with significant atmospheres. For these vehicles to navigate effectively, it is critical to incorporate the effects of surrounding wind fields, especially as these winds will likely be strong relative to the control authority of the vehicle. Predictive models of these wind fields are available, and previous research has considered problems of planning paths subject to these predicted forces. However, such previous work has considered the wind fields as known a priori, whereas in practical applications, the actual wind vector field is not known exactly and may deviate significantly from the wind velocities estimated by the model. A probabilistic 3D path-planning algorithm was developed for balloons to use uncertain wind models to generate time-efficient paths. The nominal goal of the algorithm is to determine what altitude and what horizontal actuation, if any is available on the vehicle, to use to reach a particular goal location in the least expected time, utilizing advantageous winds. The solution also enables one to quickly evaluate the expected time-to-goal from any other location and to avoid regions of large uncertainty. This method is designed for balloons in wind fields but may be generalized for any buoyant vehicle operating in a vector field. To prepare the planning problem, the uncertainty in the wind field is modeled. Then, the problem of reaching a particular goal location is formulated as a Markov decision process (MDP) using a discretized space approach. Solving the MDP provides a policy of what actuation option (how much buoyancy change and, if applicable, horizontal actuation) should be selected at any given location to minimize the expected time-to-goal. The results provide expected time-to-goal values from any given location on the globe in addition to the action policy. This stochastic approach can also provide
Strong Static Magnetic Fields Increase the Gel Signal in Partially Hydrated DPPC/DMPC Membranes
Directory of Open Access Journals (Sweden)
Jennifer Tang
2015-09-01
Full Text Available NIt was recently reported that static magnetic fields increase lipid order in the hydrophobic membrane core of dehydrated native plant plasma membranes [Poinapen, Soft Matter 9:6804-6813, 2013]. As plasma membranes are multicomponent, highly complex structures, in order to elucidate the origin of this effect, we prepared model membranes consisting of a lipid species with low and high melting temperature. By controlling the temperature, bilayers coexisting of small gel and fluid domains were prepared as a basic model for the plasma membrane core. We studied molecular order in mixed lipid membranes made of dimyristoyl-sn-glycero-3-phosphocholine (DMPC and dipalmitoyl-sn-glycero-3-phosphocholine (DPPC using neutron diffraction in the presence of strong static magnetic fields up to 3.5 T. The contribution of the hydrophobic membrane core was highlighted through deuterium labeling the lipid acyl chains. There was no observable effect on lipid organization in fluid or gel domains at high hydration of the membranes. However, lipid order was found to be enhanced at a reduced relative humidity of 43%: a magnetic field of 3.5 T led to an increase of the gel signal in the diffraction patterns of 5%. While all biological materials have weak diamagnetic properties, the corresponding energy is too small to compete against thermal disorder or viscous effects in the case of lipid molecules. We tentatively propose that the interaction between the fatty acid chains’ electric moment and the external magnetic field is driving the lipid tails in the hydrophobic membrane core into a better ordered state.
Strong Static Magnetic Fields Increase the Gel Signal in Partially Hydrated DPPC/DMPC Membranes.
Tang, Jennifer; Alsop, Richard J; Schmalzl, Karin; Epand, Richard M; Rheinstädter, Maikel C
2015-09-29
NIt was recently reported that static magnetic fields increase lipid order in the hydrophobic membrane core of dehydrated native plant plasma membranes [Poinapen, Soft Matter 9:6804-6813, 2013]. As plasma membranes are multicomponent, highly complex structures, in order to elucidate the origin of this effect, we prepared model membranes consisting of a lipid species with low and high melting temperature. By controlling the temperature, bilayers coexisting of small gel and fluid domains were prepared as a basic model for the plasma membrane core. We studied molecular order in mixed lipid membranes made of dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) using neutron diffraction in the presence of strong static magnetic fields up to 3.5 T. The contribution of the hydrophobic membrane core was highlighted through deuterium labeling the lipid acyl chains. There was no observable effect on lipid organization in fluid or gel domains at high hydration of the membranes. However, lipid order was found to be enhanced at a reduced relative humidity of 43%: a magnetic field of 3.5 T led to an increase of the gel signal in the diffraction patterns of 5%. While all biological materials have weak diamagnetic properties, the corresponding energy is too small to compete against thermal disorder or viscous effects in the case of lipid molecules. We tentatively propose that the interaction between the fatty acid chains' electric moment and the external magnetic field is driving the lipid tails in the hydrophobic membrane core into a better ordered state.
Willingham, D; Brenes, D A; Winograd, N; Wucher, A
2011-01-01
Molecular depth profiles of model organic thin films were performed using a 40 keV C 60 + cluster ion source in concert with TOF-SIMS. Strong-field photoionization of intact neutral molecules sputtered by 40 keV C 60 + primary ions was used to analyze changes in the chemical environment of the guanine thin films as a function of ion fluence. Direct comparison of the secondary ion and neutral components of the molecular depth profiles yields valuable information about chemical damage accumulation as well as changes in the molecular ionization probability. An analytical protocol based on the erosion dynamics model is developed and evaluated using guanine and trehalose molecular secondary ion signals with and without comparable laser photoionization data.
Spatial characterization of Bessel-like beams for strong-field physics.
Summers, Adam M; Yu, Xiaoming; Wang, Xinya; Raoul, Maxime; Nelson, Josh; Todd, Daniel; Zigo, Stefan; Lei, Shuting; Trallero-Herrero, Carlos A
2017-02-06
We present a compact, simple design for the generation and tuning of both the spot size and effective focal length of Bessel-like beams. In particular, this setup provides an important tool for the use of Bessel-like beams with high-power, femtosecond laser systems. Using a shallow angle axicon in conjunction with a spherical lens, we show that it is possible to focus Bessel-like modes to comparable focal spot sizes to sharp axicons while maintaining a long effective focal length. The resulting focal profiles are characterized in detail using an accurate high dynamic range imaging technique. Quantitatively, we introduce a metric (R0.8) which defines the spot-size containing 80% of the total energy. Our setup overcomes the typical compromise between long working distances and small spot sizes. This is particularly relevant for strong-field physics where most experiments must operate in vacuum.
Field-theoretic Methods in Strongly-Coupled Models of General Gauge Mediation
Fortin, Jean-Francois
2013-01-01
An often-exploited feature of the operator product expansion (OPE) is that it incorporates a splitting of ultraviolet and infrared physics. In this paper we use this feature of the OPE to perform simple, approximate computations of soft masses in gauge-mediated supersymmetry breaking. The approximation amounts to truncating the OPEs for hidden-sector current-current operator products. Our method yields visible-sector superpartner spectra in terms of vacuum expectation values of a few hidden-sector IR elementary fields. We manage to obtain reasonable approximations to soft masses, even when the hidden sector is strongly coupled. We demonstrate our techniques in several examples, including a new framework where supersymmetry-breaking arises both from a hidden sector and dynamically.
Auxiliary-Field Quantum Monte Carlo Simulations of Strongly-Correlated Systems, the Final Report
Energy Technology Data Exchange (ETDEWEB)
Chang, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2017-11-07
In this final report, we present preliminary results of ground state phases of interacting spinless Dirac fermions. The name "Dirac fermion" originates from the fact that low-energy excitations of electrons hopping on the honeycomb lattice are described by a relativistic Dirac equation. Dirac fermions have received much attention particularly after the seminal work of Haldale1 which shows that the quantum Hall physics can be realized on the honeycomb lattice without magnetic fields. Haldane's work later becomes the foundation of topological insulators (TIs). While the physics of TIs is based largely on spin-orbit coupled non-interacting electrons, it was conjectured that topological insulators can be induced by strong correlations alone.
Combined visible and near-infrared OPA for wavelength scaling experiments in strong-field physics
Lloyd, David T.; O'Keeffe, Kevin; Wyatt, Adam S.; Anderson, Patrick N.; Treacher, Daniel; Hooker, Simon M.
2017-02-01
We report the operation of an optical parametric amplifier (OPA) capable of producing gigawatt peak-power laser pulses with tunable wavelength in either the visible or near-infrared spectrum. The OPA has two distinct operation modes (i) generation of > 350 μJ, sub 100 fs pulses, tunable between 1250 - 1550 nm; (ii) generation of > 170 μJ, sub 150 fs pulses tunable between 490 - 530 nm. We have recorded high-order harmonic spectra over a wide range of driving wavelengths. This flexible source of femtosecond pulses presents a useful tool for exploring the wavelength-dependence of strong-field phenomena, in both the multi-photon and tunnel ionization regimes.
Resonance fluorescence spectrum of two atoms, coherently driven by a strong resonant laser field
International Nuclear Information System (INIS)
Ficek, Z.; Tanas, R.; Kielich, S.
1981-01-01
In Lehmberg's approach, we consider the resonance fluorescence spectrum of two radiatively interacting atoms. In the strong field limit we have obtained analytical solutions for the spectrum of the symmetric and antisymmetric modes without decoupling approximation. Our solutions are valid for all values of the distance r 12 separating the atoms. The spectrum of the symmetric modes contains additional sidebands in 2Ω (Ω is the Rabi frequency) with amplitude dependent on (a/Ω) 2 , where a is a parameter dependent on r 12 . The antisymmetric part of the spectrum has no additional sidebands in 2Ω. For small distances r 12 (a = 1) our results for the symmetric modes are identical with those of Agarwal et al. apart from the so-called scaling factor. For large distance r 12 (a = 0) the spectra of the symmetric and antisymmetric modes are identical with the well-known one-atom spectrum. (orig.)
Influence of strong magnetic fields on laser pulse propagation in underdense plasma
Wilson, T. C.; Li, F. Y.; Weikum, M.; Sheng, Z. M.
2017-06-01
We examine the interaction between intense laser pulses and strongly magnetised plasmas in the weakly relativistic regime. An expression for the electron Lorentz factor coupling both relativistic and cyclotron motion nonlinearities is derived for static magnetic fields along the laser propagation axis. This is applied to predict modifications to the refractive index, critical density, group velocity dispersion and power threshold for relativistic self-focusing. It is found that electron quiver response is enhanced under right circularly-polarised light, decreasing the power threshold for various instabilities, while a dampening effect occurs under left circularly-polarised light, increasing the power thresholds. Derived theoretical predictions are tested by one- and three-dimensional particle-in-cell simulations.
Direct Visualization of Valence Electron Motion Using Strong-Field Photoelectron Holography
He, Mingrui; Li, Yang; Zhou, Yueming; Li, Min; Cao, Wei; Lu, Peixiang
2018-03-01
Watching the valence electron move in molecules on its intrinsic timescale has been one of the central goals of attosecond science and it requires measurements with subatomic spatial and attosecond temporal resolutions. The time-resolved photoelectron holography in strong-field tunneling ionization holds the promise to access this realm. However, it remains to be a challenging task hitherto. Here we reveal how the information of valence electron motion is encoded in the hologram of the photoelectron momentum distribution (PEMD) and develop a novel approach of retrieval. As a demonstration, applying it to the PEMDs obtained by solving the time-dependent Schrödinger equation for the prototypical molecule H2+ , the attosecond charge migration is directly visualized with picometer spatial and attosecond temporal resolutions. Our method represents a general approach for monitoring attosecond charge migration in more complex polyatomic and biological molecules, which is one of the central tasks in the newly emerging attosecond chemistry.
Numerical simulations of a cylinder wake under a strong axial magnetic field
Dousset, Vincent; Pothérat, Alban
2008-01-01
We study the flow of a liquid metal in a square duct past a circular cylinder in a strong externally imposed magnetic field. In these conditions, the flow is quasi-two-dimensional, which allows us to model it using a two-dimensional (2D) model. We perform a parametric study by varying the two control parameters Re and Ha (Ha2 is the ratio of Lorentz to viscous forces) in the ranges [0…6000] and [0…2160], respectively. The flow is found to exhibit a sequence of four regimes. The first three regimes are similar to those of the non-magnetohydrodynamic (non-MHD) 2D circular wake, with transitions controlled by the friction parameter Re /Ha. The fourth one is characterized by vortices raising from boundary layer separations at the duct side walls, which strongly disturbs the Kármán vortex street. This provides the first explanation for the breakup of the 2D Kármán vortex street first observed experimentally by Frank, Barleon, and Müller [Phys. Fluids 13, 2287 (2001)]. We also show that, for high values of Ha (Ha⩾1120), the transition to the fourth regime occurs for Re ∝0.56Ha, and that it is accompanied by a sudden drop in the Strouhal number. In the first three regimes, we show that the drag coefficient and the length of the steady recirculation regions located behind the cylinder are controlled by the parameter Re /Ha4/5. Also, the free shear layer that separates the recirculation region from the free stream is similar to a free MHD parallel layer, with a thickness of the order of Ha-1/2 that is quite different to that of the non-MHD case, and therefore strongly influences the dynamics of this region. We also present one case at Re =3×104 and Ha =1120, where this layer undergoes an instability of the Kelvin-Helmholtz-type.
Contribution to the study of molecular multi-ionisation and multifragmentation in strong laser field
International Nuclear Information System (INIS)
Hering, P.
1999-12-01
Molecular multi-ionization in strong laser field is studied using different experimental and theoretical techniques. In the 10 13 -10 16 W/cm 2 laser intensity range, the strong non-linear laser-molecule coupling allows the absorption of energies necessary to the ejection of valence electrons. The double ionization is characterized by the production of doubly charged molecular ions and by charge separation channels such as A + + B + . For molecular charge states greater than two, the multi-ionization dynamics study is based on the observables due to the multifragmentation, which are the fragments charge states and initial momenta. For strong intensities in the 1015-1016 w/cm 2 range, the multicharged atomic ions production efficiency depends on the initial electronic density localization of the molecule. For intensities less than 5 x 10 14 w/cm 2 , double ionization leads to the simultaneous emission of two electrons from the molecule. The two-missing electrons fragmentation channels appear at internuclear equilibrium distance following the Franck-Condon principle. For more than two-missing electrons channels, the internuclear distance of excitation is more difficult to determine. However the reported different experiments show that the multifragmentation dynamics is independent of the electronic emission dynamics. The theoretical approach is based on the Thomas-Fermi equations and allows a non-perturbative description of the laser-molecule coupling. The calculated fragmentation kinetic energies are smaller than the coulombic repulsion energies calculated at the internuclear equilibrium distance because of an electronic screening effect. This model reproduce the experimental fragmentation 'energy releases obtained experimentally for molecules such as N 2 , CO 2 or N 2 O. (author)
STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS
International Nuclear Information System (INIS)
Wang Yan; Li Xiangdong
2012-01-01
If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.
Strong-lensing analysis of A2744 with MUSE and Hubble Frontier Fields images
Mahler, G.; Richard, J.; Clément, B.; Lagattuta, D.; Schmidt, K.; Patrício, V.; Soucail, G.; Bacon, R.; Pello, R.; Bouwens, R.; Maseda, M.; Martinez, J.; Carollo, M.; Inami, H.; Leclercq, F.; Wisotzki, L.
2018-01-01
We present an analysis of Multi Unit Spectroscopic Explorer (MUSE) observations obtained on the massive Frontier Fields (FFs) cluster A2744. This new data set covers the entire multiply imaged region around the cluster core. The combined catalogue consists of 514 spectroscopic redshifts (with 414 new identifications). We use this redshift information to perform a strong-lensing analysis revising multiple images previously found in the deep FF images, and add three new MUSE-detected multiply imaged systems with no obvious Hubble Space Telescope counterpart. The combined strong-lensing constraints include a total of 60 systems producing 188 images altogether, out of which 29 systems and 83 images are spectroscopically confirmed, making A2744 one of the most well-constrained clusters to date. Thanks to the large amount of spectroscopic redshifts, we model the influence of substructures at larger radii, using a parametrization including two cluster-scale components in the cluster core and several group scale in the outskirts. The resulting model accurately reproduces all the spectroscopic multiple systems, reaching an rms of 0.67 arcsec in the image plane. The large number of MUSE spectroscopic redshifts gives us a robust model, which we estimate reduces the systematic uncertainty on the 2D mass distribution by up to ∼2.5 times the statistical uncertainty in the cluster core. In addition, from a combination of the parametrization and the set of constraints, we estimate the relative systematic uncertainty to be up to 9 per cent at 200 kpc.
State-resolved attosecond reversible and irreversible dynamics in strong optical fields
Sabbar, Mazyar; Timmers, Henry; Chen, Yi-Jen; Pymer, Allison K.; Loh, Zhi-Heng; Sayres, Scott G.; Pabst, Stefan; Santra, Robin; Leone, Stephen R.
2017-02-01
Strong-field ionization (SFI) is a key process for accessing real-time quantum dynamics of electrons on the attosecond timescale. The theoretical foundation of SFI was pioneered in the 1960s, and later refined by various analytical models. While asymptotic ionization rates predicted by these models have been tested to be in reasonable agreement for a wide range of laser parameters, predictions for SFI on the sub-laser-cycle timescale are either beyond the scope of the models or show strong qualitative deviations from full quantum-mechanical simulations. Here, using the unprecedented state specificity of attosecond transient absorption spectroscopy, we follow the real-time SFI process of the two valence spin-orbit states of xenon. The results reveal that the irreversible tunnelling contribution is accompanied by a reversible electronic population that exhibits an observable spin-orbit-dependent phase delay. A detailed theoretical analysis attributes this observation to transient ground-state polarization, an unexpected facet of SFI that cannot be captured by existing analytical models that focus exclusively on the production of asymptotic electron/ion yields.
ForceFit: a code to fit classical force fields to ab-initio potential energy surfaces
Energy Technology Data Exchange (ETDEWEB)
Henson, Neil Jon [Los Alamos National Laboratory; Waldher, Benjamin [WSU; Kuta, Jadwiga [WSU; Clark, Aurora [WSU; Clark, Aurora E [NON LANL
2009-01-01
The ForceFit program package has been developed for fitting classical force field parameters based upon a force matching algorithm to quantum mechanical gradients of configurations that span the potential energy surface of the system. The program, which runs under Unix and is written in C++, is an easy to use, nonproprietary platform that enables gradient fitting of a wide variety of functional force field forms to quantum mechanical information obtained from an array of common electronic structure codes. All aspects of the fitting process are run from a graphical user interface, from the parsing of quantum mechanical data, assembling of a potential energy surface database, setting the force field and variables to be optimized, choosing a molecular mechanics code for comparison to the reference data, and finally, the initiation of a least squares minimization algorithm. Furthermore, the code is based on a modular templated code design that enables the facile addition of new functionality to the program.
Study of Fluid Flow Control in Protein Crystallization using Strong Magnetic Fields
Ramachandran, Narayanan; Leslie, Fred; Ciszak, Ewa
2002-11-01
An important component in biotechnology, particularly in the area of protein engineering and rational drug design is the knowledge of the precise three-dimensional molecular structure of proteins. The quality of structural information obtained from X-ray diffraction methods is directly dependent on the degree of perfection of the protein crystals. As a consequence, the growth of high quality macromolecular crystals for diffraction analyses has been the central focus for biochemists, biologists, and bioengineers. Macromolecular crystals are obtained from solutions that contain the crystallizing species in equilibrium with higher aggregates, ions, precipitants, other possible phases of the protein, foreign particles, the walls of the container, and a likely host of other impurities. By changing transport modes in general, i.e., reduction of convection and sedimentation, as is achieved in "microgravity", researchers have been able to dramatically affect the movement and distribution of macromolecules in the fluid, and thus their transport, formation of crystal nuclei, and adsorption to the crystal surface. While a limited number of high quality crystals from space flights have been obtained, as the recent National Research Council (NRC) review of the NASA microgravity crystallization program pointed out, the scientific approach and research in crystallization of proteins has been mainly empirical yielding inconclusive results. We postulate that we can reduce convection in ground-based experiments and we can understand the different aspects of convection control through the use of strong magnetic fields and field gradients. Whether this limited convection in a magnetic field will provide the environment for the growth of high quality crystals is still a matter of conjecture that our research will address. The approach exploits the variation of fluid magnetic susceptibility with concentration for this purpose and the convective damping is realized by appropriately
Currents and the energy-momentum tensor in classical field theory: a fresh look at an old problem
International Nuclear Information System (INIS)
Forger, Michael; Roemer, Hartmann
2004-01-01
We give a comprehensive review of various methods to define currents and the energy-momentum tensor in classical field theory, with emphasis on a geometric point of view. The necessity of 'improving' the expressions provided by the canonical Noether procedure is addressed and given an adequate geometric framework. The main new ingredient is the explicit formulation of a principle of 'ultralocality' with respect to the symmetry generators, which is shown to fix the ambiguity inherent in the procedure of improvement and guide it towards a unique answer: when combined with the appropriate splitting of the fields into sectors, it leads to the well-known expressions for the current as the variational derivative of the matter field Lagrangian with respect to the gauge field and for the energy-momentum tensor as the variational derivative of the matter field Lagrangian with respect to the metric tensor. In the second case, the procedure is shown to work even when the matter field Lagrangian depends explicitly on the curvature, thus establishing the correct relation between scale invariance, in the form of local Weyl invariance 'on shell', and tracelessness of the energy-momentum tensor, required for a consistent definition of the concept of a conformal field theory
International Nuclear Information System (INIS)
Kapuria, S; Yaqoob Yasin, M
2013-01-01
In this work, we present an electromechanically coupled efficient layerwise finite element model for the static response of piezoelectric laminated composite and sandwich plates, considering the nonlinear behavior of piezoelectric materials under strong electric field. The nonlinear model is developed consistently using a variational principle, considering a rotationally invariant second order nonlinear constitutive relationship, and full electromechanical coupling. In the piezoelectric layer, the electric potential is approximated to have a quadratic variation across the thickness, as observed from exact three dimensional solutions, and the equipotential condition of electroded piezoelectric surfaces is modeled using the novel concept of an electric node. The results predicted by the nonlinear model compare very well with the experimental data available in the literature. The effect of the piezoelectric nonlinearity on the static response and deflection/stress control is studied for piezoelectric bimorph as well as hybrid laminated plates with isotropic, angle-ply composite and sandwich substrates. For high electric fields, the difference between the nonlinear and linear predictions is large, and cannot be neglected. The error in the prediction of the smeared counterpart of the present theory with the same number of primary displacement unknowns is also examined. (paper)
Mass evaporation rate of globular clusters in a strong tidal field
Madrid, Juan P.; Leigh, Nathan W. C.; Hurley, Jarrod R.; Giersz, Mirek
2017-09-01
The mass evaporation rate of globular clusters evolving in a strong Galactic tidal field is derived through the analysis of large, multimass N-body simulations. For comparison, we also study the same evaporation rates using mocca Monte Carlo models for globular cluster evolution. Our results show that the mass evaporation rate is a dynamical value, that is, far from a constant single number found in earlier analytical work and commonly used in the literature. Moreover, the evaporation rate derived with these simulations is higher than values previously published. These models also show that the value of the mass evaporation rate depends on the strength of the tidal field. We give an analytical estimate of the mass evaporation rate as a function of time and galactocentric distance ξ(RGC, t). Upon extrapolating this formula to smaller RGC values, our results provide tentative evidence for a very high ξ value at small RGC. Our results suggest that the corresponding mass-loss in the inner Galactic potential could be high and it should be accounted for when star clusters pass within it. This has direct relevance to nuclear cluster formation/growth via the infall of globular clusters through dynamical friction. As an illustrative example, we estimate how the evaporation rate increases for an ˜105 M⊙ globular cluster that decays through dynamical friction into the Galactic Centre. We discuss the findings of this work in relation to the formation of nuclear star clusters by inspiralling globular clusters.
International Nuclear Information System (INIS)
Varma, R.K.; Punithavelu, A.M.; Banerjee, S.B.
1994-01-01
The properties of the motion of charged particles injected almost parallel to the magnetic field are studied by measuring the electron current as a function of the cathode voltage (electron energy), as electrons from the gun traverse a distance L to the detector. The plate current is found to exhibit oscillatory behaviour in contradistinction with the behaviour expected according to the standard classical mechanical paradigm, with the peaks fitting a relation obtained from a quantum like theory predicting such a behaviour. (author). 4 refs, 1 fig, 1 tab
Anomaly disturbances of the magnetic fields before the strong earthquake in Japan on March 11, 2011
Directory of Open Access Journals (Sweden)
Masashi Hayakawa
2012-04-01
Full Text Available
One of the strongest earthquakes, with magnitude M 8.9, occurred at the sea bottom near to the east coast of Japan on March 11, 2011. This study is devoted to the investigation of anomaly disturbances in the main magnetic field of the Earth and in ultra-low frequency magnetic variations (F <10 Hz observed before this earthquake. Secular variations of the main geomagnetic field were investigated using three-component 1-h data from three magnetic observatories over the 11-year period of January 1, 2000, to January 31, 2011. The Esashi and Mizusawa magnetic stations are situated northwest of the earthquake epicenter, at distances of around 170 km to 200 km, and the Kakioka observatory is situated southwest of the earthquake epicenter, at a distance of about 300 km. During this period, there were four local anomalies in the secular variations. The last anomaly was the biggest, which began around 3 years prior to the earthquake moment. All of the anomalies can be most distinctly recognized, in the form of differences in the corresponding magnetic components at these remote magnetic stations. For investigations of the ultra-low frequency magnetic field disturbances, three-component 1-s data at two magnetic stations (Kakioka and Uchiura were used. The Uchiura station is situated 119 km south of Kakioka, at a distance of about 420 km from the earthquake epicenter. Data from the time interval of February 18, 2011 to March 10, 2011 (only at night-time: 01:00 to 04:00 local time were investigated in a wide frequency range. In the frequency range of 0.033 Hz to 0.01 Hz, there was the clearest anomaly, seen as a decrease in the correlation coefficients of the corresponding magnetic components at these two stations, from February 22, 2011. Differences in the Z components showed an increase, and became positive after this date. This might suggest that the ultra-low frequency lithospheric source appeared north of the Kakioka station. Outside this specified
A SPECTROSCOPIC SURVEY OF THE FIELDS OF 28 STRONG GRAVITATIONAL LENSES: THE GROUP CATALOG
Energy Technology Data Exchange (ETDEWEB)
Wilson, Michelle L.; Zabludoff, Ann I. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Ammons, S. Mark [Lawrence Livermore National Laboratory, Physics Division L-210, 7000 East Avenue, Livermore, CA 94550 (United States); Momcheva, Ivelina G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Williams, Kurtis A. [Department of Physics and Astronomy, Texas A and M University-Commerce, Commerce, TX, 75428 (United States); Keeton, Charles R. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)
2016-12-20
With a large, unique spectroscopic survey in the fields of 28 galaxy-scale strong gravitational lenses, we identify groups of galaxies in the 26 adequately sampled fields. Using a group-finding algorithm, we find 210 groups with at least 5 member galaxies; the median number of members is 8. Our sample spans redshifts of 0.04 ≤ z {sub grp} ≤ 0.76 with a median of 0.31, including 174 groups with 0.1 < z {sub grp} < 0.6. The groups have radial velocity dispersions of 60 ≤ σ {sub grp} ≤ 1200 km s{sup −1} with a median of 350 km s{sup −1}. We also discover a supergroup in field B0712+472 at z = 0.29 that consists of three main groups. We recover groups similar to ∼85% of those previously reported in these fields within our redshift range of sensitivity and find 187 new groups with at least five members. The properties of our group catalog, specifically, (1) the distribution of σ {sub grp}, (2) the fraction of all sample galaxies that are group members, and (3) the fraction of groups with significant substructure, are consistent with those for other catalogs. The distribution of group virial masses agrees well with theoretical expectations. Of the lens galaxies, 12 of 26 (46%) (B1422+231, B1600+434, B2114+022, FBQS J0951+2635, HE0435-1223, HST J14113+5211, MG0751+2716, MGJ1654+1346, PG 1115+080, Q ER 0047-2808, RXJ1131-1231, and WFI J2033-4723) are members of groups with at least five galaxies, and one more (B0712+472) belongs to an additional, visually identified group candidate. There are groups not associated with the lens that still are likely to affect the lens model; in six of 25 (24%) fields (excluding the supergroup), there is at least one massive ( σ {sub grp} ≥ 500 km s{sup −1}) group or group candidate projected within 2′ of the lens.
Tiny Stars, Strong Fields: Exploring the Origin of Intense Magnetism in M Stars
Toomre, Juri
. We bring to this our prior experience with studying dynamo processes in the outer convective envelopes of G- (the Sun) and Ftype stars, briefly of M dwarfs, and in full convective cores within more massive A- and B-type stars. Our previous work suggests that M dwarfs could display a broad range of dynamo behavior, from cyclic reversals to more chaotic variations, and further to both weak and strong dynamo states. We will focus on the latter, exploring how superequipartition magnetic fields could be achieved by dynamo action in M dwarfs, as are likely needed to energize super-flares and huge active regions, and what limits the peak field strengths. M-type stars are distinctive in becoming fully convective with decreasing mass at about M3.5 in spectral type (or about 0.35 solar masses). At this transition, a steep rise in the fraction of magnetically active stars is observed that is accompanied by an increasing rotational velocity. Clearly how mass-loss and spin-down can lead to this is of interest in itself. However, here we propose to study the manner in which dynamos operating in fully convective M dwarf interiors beyond the transition may be able to achieve very strong magnetic fields, and how field strengths and apparent magnetic activity increases with rotation rate as suggested by observations. We believe that global connectivity of flows and fields across the core center will admit new classes of strong behavior, as revealed by our B star core dynamos, not realized when a convective envelope is bounded below by a tachocline. These ideas need to be tested in a self-consistent manner with global ASH simulations to gain theoretical insights into what is the origin of the fierce magnetic activity in some of M dwarfs that may be potential hosts to Earth-like planets. Such 3-D MHD simulations, though challenging, are now feasible and would complement the intensive observational searches under way.
Some remarks about the classical Wilson loop for a class of gauge field copies
International Nuclear Information System (INIS)
Bezerra, V.B.
1984-01-01
Ordered integrals along circles for a class of potentials that given the same field strength are computed. The asymptotic behaviour of the Wilson Loop associated to these potentials is discussed. (Author) [pt
International Nuclear Information System (INIS)
Drechsler, W.; Havas, P.; Rosenblum, A.
1984-01-01
In two recent papers, the general form of the laws of motion for point particles which are multipole sources of the classical coupled Yang-Mills-Higgs fields was determined by Havas, and for the special case of monopole singularities of a Yang-Mills field an iteration procedure was developed by Drechsler and Rosenblum to obtain the equations of motion of mass points, i.e., the laws of motion including the explicit form of the fields of all interacting particles. In this paper we give a detailed derivation of the laws of motion of monopole-dipole singularities of the coupled Yang-Mills-Higgs fields for point particles with mass and spin, following a procedure first applied by Mathisson and developed by Havas. To obtain the equations of motion, a systematic approximation method is developed in the following paper for the solution of the nonlinear field equations and determination of the fields entering the laws of motion found here to any given order in the coupling constant g
Quantum corrections to the classical model of the atom-field system.
Ugulava, A; McHedlishvili, G; Chkhaidze, S; Chotorlishvili, L
2011-10-01
The nonlinear-oscillating system in action-angle variables is characterized by the dependence of frequency of oscillation ω(I) on action I. Periodic perturbation is capable of realizing in the system a stable nonlinear resonance at which the action I adapts to the resonance condition ω(I(0))≃ω, that is, "sticking" in the resonance frequency. For a particular physical problem there may be a case when I≫ℏ is the classical quantity, whereas its correction ΔI≃ℏ is the quantum quantity. Naturally, dynamics of ΔI is described by the quantum equation of motion. In particular, in the moderate nonlinearity approximation ɛ≪(dω/dI)(I/ω)≪1/ɛ, where ɛ is the small parameter, the description of quantum state is reduced to the solution of the Mathieu-Schrödinger equation. The state formed as a result of sticking in resonance is an eigenstate of the operator ΔI that does not commute with the Hamiltonian H. Expanding the eigenstate wave functions in Hamiltonian eigenfunctions, one can obtain a probability distribution of energy level population. Thus, an inverse level population for times lower than the relaxation time can be obtained.
Ly{alpha} DOMINANCE OF THE CLASSICAL T TAURI FAR-ULTRAVIOLET RADIATION FIELD
Energy Technology Data Exchange (ETDEWEB)
Schindhelm, Eric [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80303 (United States); France, Kevin; Brown, Alexander [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Herczeg, Gregory J. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Bergin, Edwin [Department of Astronomy, University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109 (United States); Yang Hao [Institute of Astrophysics, Central China Normal University, Wuhan, Hubei 430079 (China); Brown, Joanna M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS-78, Cambridge, MA 02138 (United States); Linsky, Jeffrey L. [JILA, University of Colorado and NIST, 440 UCB, Boulder, CO 80309 (United States); Valenti, Jeff, E-mail: eric@boulder.swri.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
2012-09-01
Far-ultraviolet (FUV) radiation plays an important role in determining chemical abundances in protoplanetary disks. H I Lyman {alpha} (Ly{alpha}) is suspected to be the dominant component of the FUV emission from Classical T Tauri Stars (CTTSs), but is difficult to measure directly due to circumstellar and interstellar H I absorption. To better characterize the intrinsic Ly{alpha} radiation, we present FUV spectra of 14 CTTSs taken with the Hubble Space Telescope Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph instruments. H{sub 2} fluorescence, commonly seen in the spectra of CTTSs, is excited by Ly{alpha} photons, providing an indirect measure of the Ly{alpha} flux incident upon the warm disk surface. We use observed H{sub 2} progression fluxes to reconstruct the CTTS Ly{alpha} profiles. The Ly{alpha} flux correlates with total measured FUV flux, in agreement with an accretion-related source of FUV emission. With a geometry-independent analysis, we confirm that in accreting T Tauri systems Ly{alpha} radiation dominates the FUV flux ({approx}1150 A -1700 A). In the systems surveyed this one line comprises 70%-90% of the total FUV flux.
International Nuclear Information System (INIS)
Boreham, B. W.; Hora, H.
1997-01-01
We have recently developed a correspondence principle for electromagnetic interaction. When applied to laser interactions with electrons this correspondence principle identifies a critical laser intensity I*. This critical intensity is a transition intensity separating classical mechanical and quantum mechanical interaction regimes. In this paper we discuss the further application of I* to the interaction of bound electrons in atoms. By comparing I* with the ionisation threshold intensities as calculated from a cycle-averaged simple-atom model we conclude that I* can be usefully interpreted as a lower bound to the classical regime in studies of ionisation of gas atoms by intense laser beams
Classical relativistic equations for particles with spin moving in external fields
Dam, H. van; Ruijgrok, Th.W.
1980-01-01
We derive equations of motion for a point particle with spin in an external electromagnetic and in an external scalar field. The derivation is based on the ten conservation laws of linear and angular momentum and on a general expression for the current by which the particle interacts with the
Classical electromagnetic non-minimal coupling for spin 3/2 fields
International Nuclear Information System (INIS)
Villanueva, V. M.; Obregon, O.; Nieto, J. A.
1996-01-01
We obtain a non-minimal electromagnetic coupling for spin 3/2 particles from linearized N=2 Supergravity. This coupling coincides with the one found by Ferrara et al. by demanding g=2 at the tree level. Linearized Einstein field equations plus interaction terms are obtained by squaring the Rarita-Schwinger with this non-minimal coupling by using generalized Poisson brackets
Energy Technology Data Exchange (ETDEWEB)
Ali, Ahmed; Blaschke, David; Issadykov, Aidos; Ivanov, Mikhail (eds.)
2017-04-15
The Helmholtz International Summer School (HISS) entitled ''Quantum Field Theory at the Limits: from Strong Fields to Heavy Quarks (SF→HQ)'', was held in the period July 18-30, 2016 at the Bogolyubov Laboratory of Theoretical Physics (BLTP) of the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, as part of the activities of the Dubna International Advanced School of Theoretical Physics (DIAS-TH). It was co-organized by Ahmed Ali (DESY Hamburg), David Blaschke (JINR Dubna, MEPhI and Univ. Wroclaw), Holger Gies (HI Jena), and Mikhail Ivanov (JINR Dubna), and was attended by 82 participants (faculty+students), not counting the JINR physicists who attended some lectures as non-registered participants. The school (SF→HQ) continued the workshops and schools of the HISS series held earlier in Dubna (1993, 1996, 2000, 2005, 2008, 2013), Bad Honnef (1994) and Rostock (1997). The scientific program of the school consisted of five regular (one-hour long) lectures in the morning and afternoon sessions, with typically two contributed talks given by younger participants (students and postdocs), each half-hour long, in the late afternoons. Altogether, we had sixty lectures by the faculty and participants. In addition, black-board exercises were held in the post-lunch periods on selected aspects of strong fields and field theory. The HISS series of schools has played an important role in bringing together an international faculty and young physicists (Ph.D. and postdocs), mostly from Russia and Germany, but increasingly also from other countries, including those affiliated to JINR Dubna. They participate in two-week long intense scientific discourse, mainly dedicated lectures on selected topics covering the foundation and the frontiers of high energy physics and cosmology. The novelty of this year's school was its bifocal interest, which brought together two different physical science communities - particle and laser physicists. There were
International Nuclear Information System (INIS)
Ali, Ahmed; Blaschke, David; Issadykov, Aidos; Ivanov, Mikhail
2017-04-01
The Helmholtz International Summer School (HISS) entitled ''Quantum Field Theory at the Limits: from Strong Fields to Heavy Quarks (SF→HQ)'', was held in the period July 18-30, 2016 at the Bogolyubov Laboratory of Theoretical Physics (BLTP) of the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, as part of the activities of the Dubna International Advanced School of Theoretical Physics (DIAS-TH). It was co-organized by Ahmed Ali (DESY Hamburg), David Blaschke (JINR Dubna, MEPhI and Univ. Wroclaw), Holger Gies (HI Jena), and Mikhail Ivanov (JINR Dubna), and was attended by 82 participants (faculty+students), not counting the JINR physicists who attended some lectures as non-registered participants. The school (SF→HQ) continued the workshops and schools of the HISS series held earlier in Dubna (1993, 1996, 2000, 2005, 2008, 2013), Bad Honnef (1994) and Rostock (1997). The scientific program of the school consisted of five regular (one-hour long) lectures in the morning and afternoon sessions, with typically two contributed talks given by younger participants (students and postdocs), each half-hour long, in the late afternoons. Altogether, we had sixty lectures by the faculty and participants. In addition, black-board exercises were held in the post-lunch periods on selected aspects of strong fields and field theory. The HISS series of schools has played an important role in bringing together an international faculty and young physicists (Ph.D. and postdocs), mostly from Russia and Germany, but increasingly also from other countries, including those affiliated to JINR Dubna. They participate in two-week long intense scientific discourse, mainly dedicated lectures on selected topics covering the foundation and the frontiers of high energy physics and cosmology. The novelty of this year's school was its bifocal interest, which brought together two different physical science communities - particle and laser physicists. There were
Application of discrete variable representation to planar H2+ in strong xuv laser fields.
Ning, Qi-Cheng; Peng, Liang-You; Hou, Xue-Feng; Xu, Zhen; Gong, Qihuang
2012-09-07
We present an efficient and accurate grid method to study the strong field dynamics of planar H(2)(+) under Born-Oppenheimer approximation. After introducing the elliptical coordinates to the planar H(2)(+), we show that the Coulomb singularities at the nuclei can be successfully overcome so that both bound and continuum states can be accurately calculated by the method of separation of variables. The time-dependent Schrödinger equation (TDSE) can be accurately solved by a two-dimensional discrete variable representation (DVR) method, where the radial coordinate is discretized with the finite-element discrete variable representation for easy parallel computation and the angular coordinate with the trigonometric DVR which can describe the periodicity in this direction. The bound states energies can be accurately calculated by the imaginary time propagation of TDSE, which agree very well with those computed by the separation of variables. We apply the TDSE to study the ionization dynamics of the planar H(2)(+) by short extreme ultra-violet (xuv) pulses, in which case the differential momentum distributions from both the length and the velocity gauge agree very well with those calculated by the lowest order perturbation theory.
Using vibrational Cooper minima to determine strong-field molecular-dissociation pathways
Severt, T.; Zohrabi, M.; Armstrong, G. S. J.; McKenna, J.; Gaire, B.; Kling, Nora G.; Ablikim, U.; Carnes, K. D.; Esry, B. D.; Ben-Itzhak, I.
2015-05-01
We explore the possibility of using vibrational ``Cooper minima'' (VCM) locations as a method to determine dissociation pathways of molecules in a strong laser field. As a test case, we study the laser-induced dissociation of an O2+ion beam by several wavelengths (λ = 800 , 400, and 266 nm) using a coincidence three-dimensional momentum imaging technique. Vibrational structure is observed in the kinetic energy release spectra, revealing a suppression of the dissociation of certain vibrational levels, which is a manifestation of the VCM effect. Previously, it has been shown in H2+that first-order time-dependent perturbation theory can be used to predict the locations of the VCM. We explore if the VCM locations predicted by perturbation theory can help uniquely identify dissociation pathways in O2+and consider its utility for other systems. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy. TS was partially supported by NSF-REU under Grant No. PHY-0851599.
Disorder effects on helical edge transport in graphene under a strong tilted magnetic field
Huang, Chunli; Cazalilla, Miguel A.
2015-10-01
In a recent experiment, Young et al. [Nature (London) 505, 528 (2014), 10.1038/nature12800] observed a metal to insulator transition as well as transport through helical edge states in monolayer graphene under a strong, tilted magnetic field. Under such conditions, the bulk is a magnetic insulator which can exhibit metallic conduction through helical edges. It was found that the two-terminal conductance of the helical channels deviates from the expected quantized value (=e2/h per edge, at zero temperature). Motivated by this observation, we study the effect of disorder on the conduction through the edge channels. We show that, unlike for helical edges of topological insulators in semiconducting quantum wells, a disorder Rashba spin-orbit coupling does not lead to backscattering, at least to leading order. Instead, we find that the lack of perfect antialignment of the electron spins in the helical channels to be the most likely cause for backscattering arising from scalar (i.e., spin-independent) impurities. The intrinsic spin-orbit coupling and other time-reversal symmetry-breaking and/or sublattice parity-breaking potentials also lead to (subleading) corrections to the channel conductance.
Resonant excitation and the decay of autoionization states in a strong electromagnetic field
International Nuclear Information System (INIS)
Andryushin, A.I.; Kazakov, A.E.; Fedorov, M.V.
1985-01-01
Photoionization of atoms involving resonant excitation of the auto-ionization state is studied. The evolution of the total ionization probability, its dependence on the frequency of the resonance radiation and also the photoelectron energy spectrum are investigated. It is shown that the energy of the final state of the system may be localized either in the vicinity of E approximately Esub(α), where Esub(α) is the auto-ionization energy, or in the vicinity of E approximately Esub(α)+h/2πω where h/2πω is the quantum energy of the resonance radiation. The photoelectron specturum in the region E approximately Esub(α)+h/2πω as a whole is similar to the electron spectrum on photoionization of atoms involving resonance excitation of the bound state. A strong effect on the photoelectron spectrum in the region E approximately Esub(α) is exerted by interference of various decay channels of the ground state in the resonance field which leads to the appearance in the spectrum of a characteristic structure of the Fano type. Interence also affects the widths of the two spectral curves, the relatve amount of electrons in the two energy ranges and also other characteristics of the ionization process. It is shown that the presence of a noninterfering photoionization channel of the autoionization state ensures the finiteness of the swidths and heights of the spectral curves and the absence of complete ''coherency merging''
Control and identification of strong field dissociative channels in CO2+ via molecular alignment
International Nuclear Information System (INIS)
Oppermann, M; Weber, S J; Marangos, J P; Morales, F; Richter, M; Patchkovskii, S; Ivanov, M; Smirnova, O; Csehi, A; Vibók, Á
2014-01-01
The dissociative excitation of CO 2 + was studied in the molecular frame as a function of probe laser intensity, ellipticity and polarization with respect to the molecular bond at laser wavelengths of 800 nm and 1350 nm. This allowed the identification of the main excitation pathway consisting of tunnel ionization from HOMO-2 followed by a parallel dipole transition from the second excited state B to the predissociating, third excited state C. Recollision excitation was shown to play a negligible role. Using laser induced impulsive alignment, the strong field induced coupling at 800 nm and 1350 nm of the ionic states B and C could thus be controlled by the laser polarization. This leads to a suppression of the fragmentation yield of up to 70% when the laser polarization was perpendicular to the molecular axis compared to parallel polarization. We have performed simulations of various ionization channels of CO 2 . Our simulations reflect the experimental findings and show that dissociation of CO 2 + is induced by tunnelling from deeper molecular orbitals HOMO-1, HOMO-2, HOMO-3, followed by laser driven hole dynamics in the ion. (paper)
International Nuclear Information System (INIS)
Vassout, P.; Franke, R.; Parmentier, G.; Evrard, G.; Dancer, A.
1987-01-01
A theoretical study on the propagation of a pressure wave in a diphasic medium, when compared to the onset mechanism of pulmonary lesions in subjects exposed to strong shock waves, shows an increase in the incident overpressure at the interface level. Using hydrophones, intracorporal pressure was measured in pigs. The authors recorded the costal wall acceleration on the side directly exposed to the shock wave and calculated the displacement of the costal wall after a shock wave passed by. These experiments were conducted for shock waves in a free field, at an overpressure peak level ranging from 26 kFPa to 380 kPa and for a first positive phase lasting 2 ms. Sensors placed in an intracorporal position detected no increase of the overpressure level for any value of the incident pressure. A comparison of the costal wall displacement, measured experimentally, relative to the theoretical displacement of the entire animal mass indicates that the largest relative displacement of the costal wall could be the origin of the pulmonary lesions found. 5 refs., 13 figs
Nonadiabaticity of electron-tunneling-ionization processes in elliptical strong laser fields
Cai, Jun; Chen, Yan-jun; Xia, Qin-zhi; Ye, Di-fa; Liu, Jie; Fu, Li-bin
2017-09-01
We theoretically investigate the electron-tunneling process for a helium atom irradiated by an elliptical strong laser field. The momentum distribution for an electron ionized during the cycle when the laser intensity reaches its maximum is captured, such that we can ignore the interference between the wave packets ionized in different laser cycles and precisely determine the center of the momentum distribution. The quantum mechanical prediction of the center position is further compared to the semiclassical single-trajectory simulation as well as the experimental data. We find that the electron momentums along the minor axis of the laser polarization show good agreement with the nonadiabatic semiclassical calculation for a wide range of laser intensities, indicating the existence of a nonzero lateral momentum when the electron exits the barrier. On the other hand, the offset angles obtained by our quantum mechanical approach for different laser intensities are larger than the nonadiabatic semiclassical results, indicating the importance of the quantum effects during the electron's under-the-barrier dynamics.
International Nuclear Information System (INIS)
Backes, Steffen
2017-04-01
The study of the electronic properties of correlated systems is a very diverse field and has lead to valuable insight into the physics of real materials. In these systems, the decisive factor that governs the physical properties is the ratio between the electronic kinetic energy, which promotes delocalization over the lattice, and the Coulomb interaction, which instead favours localized electronic states. Due to this competition, correlated electronic systems can show unique and interesting properties like the Metal-Insulator transition, diverse phase diagrams, strong temperature dependence and in general a high sensitivity to the environmental conditions. A theoretical description of these systems is not an easy task, since perturbative approaches that do not preserve the competition between the kinetic and interaction terms can only be applied in special limiting cases. One of the most famous approaches to obtain the electronic properties of a real material is the ab initio density functional theory (DFT) method. It allows one to obtain the ground state density of the system under investigation by mapping onto an effective non-interacting system that has to be found self-consistently. While being an exact theory, in practical implementations certain approximations have to be made to the exchange-correlation potential. The local density approximation (LDA), which approximates the exchange-correlation contribution to the total energy by that of a homogeneous electron gas with the corresponding density, has proven quite successful in many cases. Though, this approximation in general leads to an underestimation of electronic correlations and is not able to describe a metal-insulator transition due to electronic localization in the presence of strong Coulomb interaction. A different approach to the interacting electronic problem is the dynamical mean-field theory (DMFT), which is non-perturbative in the kinetic and interaction term but neglects all non
Energy Technology Data Exchange (ETDEWEB)
Backes, Steffen
2017-04-15
The study of the electronic properties of correlated systems is a very diverse field and has lead to valuable insight into the physics of real materials. In these systems, the decisive factor that governs the physical properties is the ratio between the electronic kinetic energy, which promotes delocalization over the lattice, and the Coulomb interaction, which instead favours localized electronic states. Due to this competition, correlated electronic systems can show unique and interesting properties like the Metal-Insulator transition, diverse phase diagrams, strong temperature dependence and in general a high sensitivity to the environmental conditions. A theoretical description of these systems is not an easy task, since perturbative approaches that do not preserve the competition between the kinetic and interaction terms can only be applied in special limiting cases. One of the most famous approaches to obtain the electronic properties of a real material is the ab initio density functional theory (DFT) method. It allows one to obtain the ground state density of the system under investigation by mapping onto an effective non-interacting system that has to be found self-consistently. While being an exact theory, in practical implementations certain approximations have to be made to the exchange-correlation potential. The local density approximation (LDA), which approximates the exchange-correlation contribution to the total energy by that of a homogeneous electron gas with the corresponding density, has proven quite successful in many cases. Though, this approximation in general leads to an underestimation of electronic correlations and is not able to describe a metal-insulator transition due to electronic localization in the presence of strong Coulomb interaction. A different approach to the interacting electronic problem is the dynamical mean-field theory (DMFT), which is non-perturbative in the kinetic and interaction term but neglects all non
Subfemtosecond electron dynamics of H{sub 2} in strong fields or the quest for the molecular clock
Energy Technology Data Exchange (ETDEWEB)
Staudte, A.
2005-07-01
In this work we have studied experimentally and theoretically hydrogen and deuterium molecules in strong laser fields. We wanted to demonstrate that control of dynamical processes on the time scale below a single laser cycle (2.7 fs) can be achieved even without using attosecond pulses just by employing the advanced experimental technique COLTRIMS. In order to do this, we have pursued two goals: 1. To examine, whether laser steered electron wavepackets can be used for laser induced electron diffraction (LIED) on molecules. 2. To demonstrate, that the double ionization of H{sub 2} can be followed with sub laser cycle temporal resolution (the molecular clock). Laser induced electron diffraction needs linearly polarized light since its mechanism relies on rescattering of the ionized electron in the molecular potential. With rescattering occurring within a few hundred attoseconds, LIED is really a process of attosecond physics. In principle, two extreme scattering geometries are possible for a homonuclear diatomic molecule like H{sub 2}: the perpendicular geometry, which corresponds to the classical double slit experiment where the electron microbunch is steered transversely to the molecular axis, and the tangential geometry with the electron moving parallel to the molecular axis. Experimental restrictions prevented us to investigate the perpendicular geometry. The molecular clock, on the other hand, employs circularly polarized light to map the absolute phase of the laser electric field onto the spatial direction of the electron momentum. Thereby, a full laser cycle is mapped onto 360 in momentum space. Thus, different electron ejection angles in the laboratory frame correspond to different ejection times. Together with the correlated kinetic energy release of the Coulomb exploding molecules an unambiguous clock running from 0-8 fs with a few 100 as resolution can be envisioned. In direct relation to this experiment, we studied the influence of the long range
Jurčišinová, E.; Jurčišin, M.
2017-11-01
We investigate the influence of the multisite interaction among sites within elementary triangles of the kagome-like recursive lattice on the properties of the classical spin- 1 / 2 ferromagnetic Ising model in the external magnetic field. The exact solution of the model is found and it is shown that the model exhibits a nontrivial structure of the first order as well as second order phase transitions in nonzero external magnetic fields related to the multisite interaction. The equation for the exact determination of the positions of the critical points of the second order phase transitions is derived. The thermodynamic properties of the model are investigated in detail and it is shown that the competition between the ferromagnetic interaction and the multisite interaction leads to the appearance of strong ferromagnetic frustration effects represented by the formation of a nontrivial system of macroscopically degenerated plateau-like and single-point-like ground states. The residual entropies of all ground states are found and the kagome spin-ice-like highly macroscopically degenerated plateau state with nonzero magnetization is identified with the exact residual entropy per site s /kB = ln(4 / 3) / 3 ≈ 0 . 095894. The properties of the specific heat are investigated, its Schottky-type behavior near the single-point ground state values of the magnetic field is identified, the existence of large magnetocaloric effect is discussed, and the existence of the first order phase transitions without the specific heat capacity change is demonstrated.
Tkachenko, Sergey V
2008-01-01
The evaluation of the electromagnetic field coupling to transmission lines is an important problem in electromagnetic compatibility. The unabated increase in the operating frequency of electronic products and the emergence of sources of disturbances with higher frequency content (such as High Power Microwave and Ultra-Wide Band systems) have led to a breakdown of the TL approximation's basic assumptions for a number of applications. In the last decade or so, the generalization of the TL theory to take into account high frequency effects has emerged as an important topic of study in electromagn
Directory of Open Access Journals (Sweden)
Sergey V. Antipov
2017-11-01
Full Text Available Several strategies for simulating the ultrafast dynamics of molecules induced by interactions with electromagnetic fields are presented. After a brief overview of the theory of molecule-field interaction, we present several representative examples of quantum, semiclassical, and classical approaches to describe the ultrafast molecular dynamics, including the multiconfiguration time-dependent Hartree method, Bohmian dynamics, local control theory, semiclassical thawed Gaussian approximation, phase averaging, dephasing representation, molecular mechanics with proton transfer, and multipolar force fields. In addition to the general overview, some focus is given to the description of nuclear quantum effects and to the direct dynamics, in which the ab initio energies and forces acting on the nuclei are evaluated on the fly. Several practical applications, performed within the framework of the Swiss National Center of Competence in Research “Molecular Ultrafast Science and Technology,” are presented: These include Bohmian dynamics description of the collision of H with H2, local control theory applied to the photoinduced ultrafast intramolecular proton transfer, semiclassical evaluation of vibrationally resolved electronic absorption, emission, photoelectron, and time-resolved stimulated emission spectra, infrared spectroscopy of H-bonding systems, and multipolar force fields applications in the condensed phase.
Antipov, Sergey V; Bhattacharyya, Swarnendu; El Hage, Krystel; Xu, Zhen-Hao; Meuwly, Markus; Rothlisberger, Ursula; Vaníček, Jiří
2017-11-01
Several strategies for simulating the ultrafast dynamics of molecules induced by interactions with electromagnetic fields are presented. After a brief overview of the theory of molecule-field interaction, we present several representative examples of quantum, semiclassical, and classical approaches to describe the ultrafast molecular dynamics, including the multiconfiguration time-dependent Hartree method, Bohmian dynamics, local control theory, semiclassical thawed Gaussian approximation, phase averaging, dephasing representation, molecular mechanics with proton transfer, and multipolar force fields. In addition to the general overview, some focus is given to the description of nuclear quantum effects and to the direct dynamics, in which the ab initio energies and forces acting on the nuclei are evaluated on the fly. Several practical applications, performed within the framework of the Swiss National Center of Competence in Research "Molecular Ultrafast Science and Technology," are presented: These include Bohmian dynamics description of the collision of H with H 2 , local control theory applied to the photoinduced ultrafast intramolecular proton transfer, semiclassical evaluation of vibrationally resolved electronic absorption, emission, photoelectron, and time-resolved stimulated emission spectra, infrared spectroscopy of H-bonding systems, and multipolar force fields applications in the condensed phase.
Energy Technology Data Exchange (ETDEWEB)
Benguria, Rafael [Pontificia Universidad Catolica de Chile, Departamento de Fisica, Casilla 306, Santiago 22, Chile (Chile); Brummelhuis, Raymond [School of Economics, Mathematics and Statistics, 7-15 Gresse Street, University of London (United Kingdom); Duclos, Pierre [Centre de Physique Theorique UMR 6207-Unite Mixte de Recherche du CNRS et des Universites Aix-Marseille I, Aix-Marseille II et de l' Universite du Sud Toulon-Var-Laboratoire affilie a la FRUMAM, Luminy Case 907, F-13288 Marseille Cedex 9 (France); Perez-Oyarzun, Santiago [Instituto de Ciencias Basicas, Facultad de Ingenieria, Universidad Diego Portales, Av. Ejercito 441, Casilla 298-v, Santiago (Chile); Vytras, Petr [Katedra Matematiky, FJFI, CVUT, Trojanova 13, CZ-Prague 12000 (Czech Republic)
2006-06-30
We consider the hydrogen molecular ion H{sup +}{sub 2} in the fixed nuclear approximation, in the presence of a strong homogeneous magnetic field. We determine the leading asymptotic behaviour for the equilibrium distance between the nuclei of this molecule in the limit when the strength of the magnetic field goes to infinity.
Albaugh, Alex; Demerdash, Omar; Head-Gordon, Teresa
2015-11-01
We have adapted a hybrid extended Lagrangian self-consistent field (EL/SCF) approach, developed for time reversible Born Oppenheimer molecular dynamics for quantum electronic degrees of freedom, to the problem of classical polarization. In this context, the initial guess for the mutual induction calculation is treated by auxiliary induced dipole variables evolved via a time-reversible velocity Verlet scheme. However, we find numerical instability, which is manifested as an accumulation in the auxiliary velocity variables, that in turn results in an unacceptable increase in the number of SCF cycles to meet even loose convergence tolerances for the real induced dipoles over the course of a 1 ns trajectory of the AMOEBA14 water model. By diagnosing the numerical instability as a problem of resonances that corrupt the dynamics, we introduce a simple thermostating scheme, illustrated using Berendsen weak coupling and Nose-Hoover chain thermostats, applied to the auxiliary dipole velocities. We find that the inertial EL/SCF (iEL/SCF) method provides superior energy conservation with less stringent convergence thresholds and a correspondingly small number of SCF cycles, to reproduce all properties of the polarization model in the NVT and NVE ensembles accurately. Our iEL/SCF approach is a clear improvement over standard SCF approaches to classical mutual induction calculations and would be worth investigating for application to ab initio molecular dynamics as well.
Energy Technology Data Exchange (ETDEWEB)
Amusia, M.Ya.; Kornyushin, Y. [Racah Institute of Physics, Hebrew University, Jerusalem (Israel)]. E-mail: yurik@vms.huji.ac.il
2000-09-01
The nuclear liquid drop model is applied to describe some basic properties of a negative hydrogen ion in the strong electric field of a laser. The equilibrium ionic size, energy and polarizability of the ion are calculated. Collective modes of the dipole oscillations are considered. A barrier which arises in a strong electric field is studied. The barrier vanishes at some large value of the electric field, which is defined as a critical value. The dependence of the critical field on frequency is studied. At frequencies {omega}{>=}({omega}{sub d}/2{sup 1/2}) ({omega}{sub d} is the frequency of the dipole oscillations of the electronic cloud relative to the nucleus) the barrier remains for any field. At high frequencies a 'stripping' mechanism for instability arises. At the resonant frequency a rather low amplitude of the electric field causes the 'stripping' instability. (author)
Ding, Aihua; Jin, Shouwen; Jin, Shide; Guo, Ming; Liu, Hui; Guo, Jianzhong; Wang, Daqi
2017-12-01
This article demonstrates 5,7-dimethyl-1,8-naphthyridine-2-amine based organic salt formation in nine crystalline solids 1-9, in which the carboxylates have been integrated. Addition of equivalents of the COOH to the solution of 5,7-dimethyl-1,8-naphthyridine-2-amine generates the singly protonated cationic species which direct the carboxylates. The nine compounds crystallize as their organic salts with the COOH proton transferred to the aromatic N of the 5,7-dimethyl-1,8-naphthyridine-2-amine. All salts have been characterized by IR, mp, EA and XRD technique. The major driving force in 1-9 is the classical H-bonds from 5,7-dimethyl-1,8-naphthyridine-2-amine and the acids, here the Nsbnd H⋯O H-bonds were found in all salts. Other extensive non-covalent interactions also exhibit great functions in space association of the molecular counterparts in relevant crystals. Except 4, all salts had the CHsbnd O, or CH3sbnd O interactions or both. Except 9, the common R22 (8) graph set has been observed in all salts due to the H-bonds and the non-covalent associations. For the synergistic interactions of the classical H-bonds and the various non-covalent associations, the salts displayed 1D-3D structures.
International Nuclear Information System (INIS)
Jain, Piyush; Weinfurtner, Silke; Visser, Matt; Gardiner, C. W.
2007-01-01
Analog models of gravity have been motivated by the possibility of investigating phenomena not readily accessible in their cosmological counterparts. In this paper, we investigate the analog of cosmological particle creation in a Friedmann-Robertson-Walker universe by numerically simulating a Bose-Einstein condensate with a time-dependent scattering length. In particular, we focus on a two-dimensional homogeneous condensate using the classical field method via the truncated Wigner approximation. We show that for various forms of the scaling function the particle production is consistent with the underlying theory in the long wavelength limit. In this context, we further discuss the implications of modified dispersion relations that arise from the microscopic theory of a weakly interacting Bose gas