Non-linear vacuum polarization in strong fields
Energy Technology Data Exchange (ETDEWEB)
Gyulassy, M.
1981-07-01
The Wichmann-Kroll formalism for calculating the vacuum polarization density to first order in ..cap alpha.. but to all orders in Z..cap alpha.. is derived. The most essential quantity is shown to be the electrons Green's function in these calculations. The method of constructing that Green's function in the field of finite radius nuclei is then presented.
Vacuum nonlinear electrodynamic polarization effects in hard emission of pulsars and magnetars
Denisov, V. I.; Sokolov, V. A.; Svertilov, S. I.
2017-09-01
The nonlinear electrodynamics influence of pulsar magnetic field on the electromagnetic pulse polarization is discussed from the point of observation interpretation. The calculations of pulsar magnetic field impact on the electromagnetic pulse polarization are made in such a way to make it easier to interpret these effects in space experiments. The law of hard emission pulse propagation in the pulsar magnetic field according to the vacuum (nonlinear electrodynamics is obtained. It has been shown, that due to the birefringence in the vacuum the front part of any hard emission pulse coming from a pulsar should be linearly polarized and the rest of pulse can have arbitrary polarization. The observational possibilities of vacuum birefringence are discussed. In this paper we give the estimations of detector parameters such as effective area, exposure time and necessity of polarization measurements with high accuracy. The combination of large area and extremely long exposure time gives the good opportunity to search the fine polarization effects like vacuum nonlinear electrodynamics birefringence.
Quantum Electrodynamics vacuum polarization solver
Carneiro, Pedro; Fonseca, Ricardo; Silva, Luís
2016-01-01
The self-consistent modeling of vacuum polarization due to virtual electron-positron fluctuations is of relevance for many near term experiments associated with high intensity radiation sources and represents a milestone in describing scenarios of extreme energy density. We present a generalized finite-difference time-domain solver that can incorporate the modifications to Maxwells equations due to virtual vacuum polarization. Our multidimensional solver reproduced in one dimensional configurations the results for which an analytic treatment is possible, yielding vacuum harmonic generation and birefringence. The solver has also been tested for two-dimensional scenarios where finite laser beam spot sizes must be taken into account. We employ this solver to explore different types of counter-propagating configurations that can be relevant for future planned experiments aiming to detect quantum vacuum dynamics at ultra-high electromagnetic field intensities.
Vacuum polarization and Hawking radiation
Rahmati, Shohreh
Quantum gravity is one of the interesting fields in contemporary physics which is still in progress. The purpose of quantum gravity is to present a quantum description for spacetime at 10-33cm or find the 'quanta' of gravitational interaction.. At present, the most viable theory to describe gravitational interaction is general relativity which is a classical theory. Semi-classical quantum gravity or quantum field theory in curved spacetime is an approximation to a full quantum theory of gravity. This approximation considers gravity as a classical field and matter fields are quantized. One interesting phenomena in semi-classical quantum gravity is Hawking radiation. Hawking radiation was derived by Stephen Hawking as a thermal emission of particles from the black hole horizon. In this thesis we obtain the spectrum of Hawking radiation using a new method. Vacuum is defined as the possible lowest energy state which is filled with pairs of virtual particle-antiparticle. Vacuum polarization is a consequence of pair creation in the presence of an external field such as an electromagnetic or gravitational field. Vacuum polarization in the vicinity of a black hole horizon can be interpreted as the cause of the emission from black holes known as Hawking radiation. In this thesis we try to obtain the Hawking spectrum using this approach. We re-examine vacuum polarization of a scalar field in a quasi-local volume that includes the horizon. We study the interaction of a scalar field with the background gravitational field of the black hole in the desired quasi-local region. The quasi-local volume is a hollow cylinder enclosed by two membranes, one inside the horizon and one outside the horizon. The net rate of particle emission can be obtained as the difference of the vacuum polarization from the outer boundary and inner boundary of the cylinder. Thus we found a new method to derive Hawking emission which is unitary and well defined in quantum field theory.
Gravitational Correction to Vacuum Polarization
Jentschura, U D
2015-01-01
We consider the gravitational correction to (electronic) vacuum polarization in the presence of a gravitational background field. The Dirac propagators for the virtual fermions are modified to include the leading gravitational correction (potential term) which corresponds to a coordinate-dependent fermion mass. The mass term is assumed to be uniform over a length scale commensurate with the virtual electron-positron pair. The on-mass shell renormalization condition ensures that the gravitational correction vanishes on the mass shell of the photon, i.e., the speed of light is unaffected by the quantum field theoretical loop correction, in full agreement with the equivalence principle. Nontrivial corrections are obtained for off-shell, virtual photons. We compare our findings to other works on generalized Lorentz transformations and combined quantum-electrodynamic gravitational corrections to the speed of light which have recently appeared in the literature.
Measuring vacuum polarization with high-power lasers
Institute of Scientific and Technical Information of China (English)
B.King; T.Heinzl
2016-01-01
When exposed to intense electromagnetic fields, the quantum vacuum is expected to exhibit properties of a polarizable medium akin to a weakly nonlinear dielectric material. Various schemes have been proposed to measure such vacuum polarization effects using a combination of high- power lasers. Motivated by several planned experiments, we provide an overview of experimental signatures that have been suggested to confirm this prediction of quantum electrodynamics of real photon–photon scattering.
Renormalization of Dirac's Polarized Vacuum
Lewin, Mathieu
2010-01-01
We review recent results on a mean-field model for relativistic electrons in atoms and molecules, which allows to describe at the same time the self-consistent behavior of the polarized Dirac sea. We quickly derive this model from Quantum Electrodynamics and state the existence of solutions, imposing an ultraviolet cut-off $\\Lambda$. We then discuss the limit $\\Lambda\\to\\infty$ in detail, by resorting to charge renormalization.
Graviton Corrections to Vacuum Polarization during Inflation
Leonard, Katie E
2014-01-01
We use dimensional regularization to compute the one loop quantum gravitational contribution to the vacuum polarization on de Sitter background. Adding the appropriate BPHZ counterterms gives a fully renormalized result which can be used to quantum correct Maxwell's equations. We use the Hartree approximation to argue that the electric field strengths of photons experience a secular suppression during inflation.
Representing the vacuum polarization on de Sitter
Energy Technology Data Exchange (ETDEWEB)
Leonard, Katie E.; Woodard, Richard P. [Department of Physics, University of Florida, Gainesville, Florida 32611 (United States); Prokopec, Tomislav [Institute of Theoretical Physics (ITP) and Spinoza Institute, Utrecht University, Postbus 80195, 3508 TD Utrecht (Netherlands)
2013-03-15
Previous studies of the vacuum polarization on de Sitter have demonstrated that there is a simple, noncovariant representation of it in which the physics is transparent. There is also a cumbersome, covariant representation in which the physics is obscure. Despite being unwieldy, the latter form has a powerful appeal for those who are concerned about de Sitter invariance. We show that nothing is lost by employing the simple, noncovariant representation because there is a closed form procedure for converting its structure functions to those of the covariant representation. We also present a vastly improved technique for reading off the noncovariant structure functions from the primitive diagrams. And we discuss the issue of representing the vacuum polarization for a general metric background.
Vacuum polarization and chiral lattice fermions
Randjbar-Daemi, S.; Strathdee, J.
1996-02-01
The vacuum polarization due to chiral fermions on a 4-dimensional Euclidean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the polarization tensor is given by second order perturbation theory. In this order the overlap constitutes a gauge-invariant regularization of the fermion vacuum amplitude. Its low-energy-long-wavelength behaviour can be computed explicitly and we verify that it coincides with the Feynman graph result obtainable, for example, by dimensional regularization of continuum gauge theory. In particular, the Standard Model Callan-Symanzik RG functions are recovered. Moreover, there are no residual lattice artefacts such as a dependence on Wilson-type mass parameters.
Vacuum polarization and chiral lattice fermions
Strathdee, J A
1995-01-01
The vacuum polarization due to chiral fermions on a 4--dimensional Euclidean lattice is calculated according to the overlap prescription. The fermions are coupled to weak and slowly varying background gauge and Higgs fields, and the polarization tensor is given by second order perturbation theory. In this order the overlap constitutes a gauge invariant regularization of the fermion vacuum amplitude. Its low energy -- long wavelength behaviour can be computed explicitly and we verify that it coincides with the Feynman graph result obtainable, for example, by dimensional regularization of continuum gauge theory. In particular, the Standard Model Callan--Symanzik RG functions are recovered. Moreover, there are no residual lattice artefacts such as a dependence on Wilson--type mass parameters.
Renormalized vacuum polarization of rotating black holes
Ferreira, Hugo R C
2015-01-01
Quantum field theory on rotating black hole spacetimes is plagued with technical difficulties. Here, we describe a general method to renormalize and compute the vacuum polarization of a quantum field in the Hartle-Hawking state on rotating black holes. We exemplify the technique with a massive scalar field on the warped AdS3 black hole solution to topologically massive gravity, a deformation of (2+1)-dimensional Einstein gravity. We use a "quasi-Euclidean" technique, which generalizes the Euclidean techniques used for static spacetimes, and we subtract the divergences by matching to a sum over mode solutions on Minkowski spacetime. This allows us, for the first time, to have a general method to compute the renormalized vacuum polarization (and, more importantly, the renormalized stress-energy tensor), for a given quantum state, on a rotating black hole, such as the physically relevant case of the Kerr black hole in four dimensions.
Vacuum polarization and photon mass in inflation
Prokopec, T; Prokopec, Tomislav; Woodard, Richard P.
2004-01-01
We give a pedagogical review of a mechanism through which long wave length photons can become massive during inflation. Our account begins with a discussion of the period of exponentially rapid expansion known as inflation. We next describe how, when the universe is not expanding, quantum fluctuations in charged particle fields cause even empty space to behave as a polarizable medium. This is the routinely observed phenomenon of vacuum polarization. We show that the quantum fluctuations of low mass, scalar fields are enormously amplified during inflation. If one of these fields is charged, the vacuum polarization effect of flat space is strengthened to the point that long wave length photons acquire mass. Our result for this mass is shown to agree with a simple model in which the massive photon electrodynamics of Proca emerges from applying the Hartree approximation to scalar quantum electrodynamics during inflation. One does not measure a huge photon mass today because the original phase of inflation ended w...
Hadronic Vacuum Polarization in True Muonium
Lamm, Henry
2016-01-01
The leading-order hadronic vacuum polarization contribution to the hyperfine splitting of true muonium is reevaluated in two ways. The first considers a more complex pionic form factor and better estimates of the perturbative QCD contributions. The second, more accurate method directly integrates the Drell ratio $R(s)$ to obtain $C_{1,\\rm hvp}=-0.0489(3)$. This corresponds to an energy shift in the hyperfine splitting of $\\Delta E^\\mu_{hfs,\\rm hvp}=276196(51)$ MHz.
Vacuum polarization in Coulomb field revisited
Energy Technology Data Exchange (ETDEWEB)
Zamastil, J., E-mail: zamastil@karlov.mff.cuni.cz; Šimsa, D.
2017-04-15
Simplified derivation of Wichmann–Kroll term is presented. The derivation uses two formulas for hypergeometric functions, but otherwise is elementary. It is found that Laplace transform of the vacuum charge density diverges at zero momentum transfer. This divergence has nothing to do with known ultraviolet divergence. The latter is related to the large momentum behavior of the pertinent integral, while the former to the small momentum behavior. When these divergences are removed, the energy shift caused by vacuum polarization for an ordinary hydrogen obtained here is in an exact agreement with the result obtained by Wichmann and Kroll. Also, for muonic hydrogen the result obtained here reasonably agrees with that given in literature.
Renormalization and asymptotic expansion of Dirac's polarized vacuum
Gravejat, Philippe; Séré, Eric
2010-01-01
We perform rigorously the charge renormalization of the so-called reduced Bogoliubov-Dirac-Fock (rBDF) model. This nonlinear theory, based on the Dirac operator, describes atoms and molecules while taking into account vacuum polarization effects. We consider the total physical density including both the external density of a nucleus and the self-consistent polarization of the Dirac sea, but no `real' electron. We show that it admits an asymptotic expansion to any order in powers of the physical coupling constant $\\alphaph$, provided that the ultraviolet cut-off behaves as $\\Lambda\\sim e^{3\\pi(1-Z_3)/2\\alphaph}\\gg1$. The renormalization parameter $0
QED multi-dimensional vacuum polarization finite-difference solver
Carneiro, Pedro; Grismayer, Thomas; Silva, Luís; Fonseca, Ricardo
2015-11-01
The Extreme Light Infrastructure (ELI) is expected to deliver peak intensities of 1023 - 1024 W/cm2 allowing to probe nonlinear Quantum Electrodynamics (QED) phenomena in an unprecedented regime. Within the framework of QED, the second order process of photon-photon scattering leads to a set of extended Maxwell's equations [W. Heisenberg and H. Euler, Z. Physik 98, 714] effectively creating nonlinear polarization and magnetization terms that account for the nonlinear response of the vacuum. To model this in a self-consistent way, we present a multi dimensional generalized Maxwell equation finite difference solver with significantly enhanced dispersive properties, which was implemented in the OSIRIS particle-in-cell code [R.A. Fonseca et al. LNCS 2331, pp. 342-351, 2002]. We present a detailed numerical analysis of this electromagnetic solver. As an illustration of the properties of the solver, we explore several examples in extreme conditions. We confirm the theoretical prediction of vacuum birefringence of a pulse propagating in the presence of an intense static background field [arXiv:1301.4918 [quant-ph
Hadronic vacuum polarization in true muonium
Lamm, Henry
2017-01-01
In order to reduce the theoretical uncertainty in the prediction, the leading-order hadronic vacuum polarization contribution to the hyperfine splitting of true muonium is reevaluated in two ways. A more complex pionic form factor and better estimates of the perturbative QCD contributions are used to study the model dependence of the previous calculation. The second, more accurate method directly integrates the Drell ratio R (s ) to obtain C1 ,HVP=-0.04874 (9 ) . This corresponds to an energy shift in the hyperfine splitting (HFS) of Δ EHFS,HVP μ=-8202 (16 ) MHz and represents a factor-of-50 reduction in the theoretical uncertainty from hadronic sources. We also compute the contribution in positronium, which is too small at present to detect.
Pulsar radiation in post-Maxwellian vacuum nonlinear electrodynamics
Denisov, V. I.; Shvilkin, B. N.; Sokolov, V. A.; Vasili'ev, M. I.
2016-08-01
The effects of nonlinear vacuum electrodynamics are most clearly pronounced in a strong electromagnetic field close to Schwinger limit. Electromagnetic fields of such intensity can be obtained in laboratory conditions only on very few extreme laser facilities and during a short time interval. At the same time, the astrophysical compact objects with a strong electromagnetic field such as pulsars and magnetars are the best suited to study the effects of nonlinear vacuum electrodynamics. We present analytical calculations for pulsar proper radiation in parametrized post-Maxwellian nonlinear vacuum electrodynamics. Based on the obtained solutions, the effect of nonlinear vacuum corrections to pulsar spin down is being investigated. The analysis of torque functions show that the nonlinear vacuum electrodynamics corrections to the electromagnetic radiation for some pulsars may be comparable to the energy loss by gravitational radiation.
Rapidly rotating pulsar radiation in vacuum nonlinear electrodynamics
Denisov, V I; Pimenov, A B; Sokolov, V A
2016-01-01
In this paper we investigate vacuum nonlinear electrodynamics corrections on rapidly rotating pulsar radiation and spin-down in the perturbative QED approach (post-Maxwellian approximation). An analytical expression for the pulsar's radiation intensity has been obtained and analyzed.
Black hole quantum vacuum polarization in higher dimensions
Flachi, Antonino; Quinta, Gonçalo M.; Lemos, José P. S.
2016-11-01
The goal of this paper is to extend to higher dimensionality the methods and computations of vacuum polarization effects in black hole spacetimes. We focus our attention on the case of five dimensional Schwarzschild-Tangherlini black holes, for which we adapt the general method initially developed by Candelas and later refined by Anderson and others. We make use of point splitting regularization and of the WKB approximation to extract the divergences occurring in the coincidence limit of the Green function and, after calculating the counterterms using the Schwinger-De Witt expansion, we explicitly prove the cancellation of the divergences and the regularity of the vacuum polarization once counterterms are added up. We finally handle numerically the renormalized expression of the vacuum polarization. As a check on the method we also prove the regularity of the vacuum polarization in the six dimensional case in the large mass limit.
Black Hole Quantum Vacuum Polarization in Higher Dimensions
Flachi, Antonino; Lemos, José P S
2016-01-01
The goal of this paper is to extend to higher dimensionality the methods and computations of vacuum polarization effects in black hole spacetimes. We focus our attention on the case of five dimensional Schwarzschild-Tangherlini black holes, for which we adapt the general method initially developed by Candelas and later refined by Anderson and others. We make use of point splitting regularization and of the WKB approximation to extract the divergences occuring in the coincidence limit of the Green function and, after calculating the counter-terms using the Schwinger - De Witt expansion, we explicitly prove the cancellation of the divergences and the regularity of the vacuum polarization once counter-terms are added up. We finally handle numerically the renormalized expression of the vacuum polarization. As a check on the method we also prove the regularity of the vacuum polarization in the six dimensional case in the large mass limit.
Determining the QCD coupling from lattice vacuum polarization
Hudspith, Renwick J; Maltman, Kim; Shintani, Eigo
2015-01-01
The QCD coupling appears in the perturbative expansion of the current-current two-point (vacuum polarization) function. Any lattice calculation of vacuum polarization is plagued by several competing non-perturbative effects at small momenta and by discretization errors at large momenta. We work in an intermediate region, computing the vacuum polarization for many off-axis momentum directions on the lattice. Having many momentum directions provides a way to monitor and account for lattice artifacts. Our results are competitive with, and have certain systematic advantages over, the alternate phenomenological determination of the strong coupling from the same light quark vacuum polarization produced by sum rule analyses of hadronic tau decay data.
Gravitational vacuum polarization; 2, energy conditions in the Boulware vacuum
Visser, M
1996-01-01
I show that in the Boulware vacuum (1) all standard (point-wise and averaged) energy conditions are violated throughout the exterior region---all the way from spatial infinity down to the event horizon, and (2) outside the event horizon the standard point-wise energy conditions are violated in a maximal manner: they are violated at all points and for all null/timelike vectors. (The region inside the event horizon is considerably messier, and of dubious physical relevance. Nevertheless the standard point-wise energy conditions also seem to be violated even inside the event horizon.) This is rather different from the case of the Hartle--Hawking vacuum, wherein violations of the energy conditions were confined to the region inside the unstable photon orbit. These calculations are for the quantum stress-energy tensor corresponding to a conformally-coupled massless scalar field in the Boulware vacuum. I work in the test-field limit, restrict attention to the Schwarzschild geometry, and invoke a mixture of analytic...
Gravitational vacuum polarization; 4, Energy conditions in the Unruh vacuum
Visser, M
1997-01-01
Building on a series of earlier papers [gr-qc/9604007, gr-qc/9604008, gr-qc/9604009], I investigate the various point-wise and averaged energy conditions in the Unruh vacuum. I consider the quantum stress-energy tensor corresponding to a conformally coupled massless scalar field, work in the test-field limit, restrict attention to the Schwarzschild geometry, and invoke a mixture of analytical and numerical techniques. I construct a semi-analytic model for the stress-energy tensor that globally reproduces all known numerical results to within 0.8%, and satisfies all known analytic features of the stress-energy tensor. I show that in the Unruh vacuum (1) all standard point-wise energy conditions are violated throughout the exterior region--all the way from spatial infinity down to the event horizon, and (2) the averaged null energy condition is violated on all outgoing radial null geodesics. In a pair of appendices I indicate general strategy for constructing semi-analytic models for the stress-energy tensor in...
Femtosecond nonlinear polarization evolution based on cascade quadratic nonlinearities.
Liu, X; Ilday, F O; Beckwitt, K; Wise, F W
2000-09-15
We experimentally demonstrate that one can exploit nonlinear phase shifts produced in type I phase-mismatched second-harmonic generation to produce intensity-dependent polarization evolution with 100-fs pulses. An amplitude modulator based on nonlinear polarization rotation provides passive amplitude-modulation depth of up to ~50%. Applications of the amplitude and phase modulations to mode locking of femtosecond bulk and fiber lasers are promising and are discussed.
Isospin Invariance and the Vacuum Polarization Energy of Cosmic Strings
Weigel, H; Graham, N
2016-01-01
We corroborate the previously applied spectral approach to compute the vacuum polarization energy of string configurations in models similar to the standard model of particle physics. The central observation underlying this corroboration is the existence of a particular global isospin transformation of the string configuration. Under this transformation the single particle energies of the quantum fluctuations are invariant, while the inevitable implementation of regularization and renormalization requires operations that are not invariant. We verify numerically that all such variances eventually cancel, and that the vacuum polarization energy obtained in the spectral approach is indeed gauge invariant.
Vacuum polarization energy for general backgrounds in one space dimension
Weigel, H.
2017-03-01
For field theories in one time and one space dimensions we propose an efficient method to compute the vacuum polarization energy of static field configurations that do not allow a decomposition into symmetric and anti-symmetric channels. The method also applies to scenarios in which the masses of the quantum fluctuations at positive and negative spatial infinity are different. As an example we compute the vacuum polarization energy of the kink soliton in the ϕ6 model. We link the dependence of this energy on the position of the soliton to the different masses.
Polarization shaping for control of nonlinear propagation
Bouchard, Frédéric; Yao, Alison M; Travis, Christopher; De Leon, Israel; Rubano, Andrea; Karimi, Ebrahim; Oppo, Gian-Luca; Boyd, Robert W
2016-01-01
We study the nonlinear optical propagation of two different classes of space-varying polarized light beams -- radially symmetric vector beams and Poincar\\'e beams with lemon and star topologies -- in a rubidium vapour cell. Unlike Laguerre-Gauss and other types of beams that experience modulational instabilities, we observe that their propagation is not marked by beam breakup while still exhibiting traits such as nonlinear confinement and self-focusing. Our results suggest that by tailoring the spatial structure of the polarization, the effects of nonlinear propagation can be effectively controlled. These findings provide a novel approach to transport high-power light beams in nonlinear media with controllable distortions to their spatial structure and polarization properties.
Polarization Shaping for Control of Nonlinear Propagation.
Bouchard, Frédéric; Larocque, Hugo; Yao, Alison M; Travis, Christopher; De Leon, Israel; Rubano, Andrea; Karimi, Ebrahim; Oppo, Gian-Luca; Boyd, Robert W
2016-12-02
We study the nonlinear optical propagation of two different classes of light beams with space-varying polarization-radially symmetric vector beams and Poincaré beams with lemon and star topologies-in a rubidium vapor cell. Unlike Laguerre-Gauss and other types of beams that quickly experience instabilities, we observe that their propagation is not marked by beam breakup while still exhibiting traits such as nonlinear confinement and self-focusing. Our results suggest that, by tailoring the spatial structure of the polarization, the effects of nonlinear propagation can be effectively controlled. These findings provide a novel approach to transport high-power light beams in nonlinear media with controllable distortions to their spatial structure and polarization properties.
Half polarized U(1) symmetric vacuum spacetimes with AVTD behavior
Choquet-Bruhat, Y; Choquet-Bruhat, Yvonne; Isenberg, James
2006-01-01
In a previous work, we used a polarization condition to show that there is a family of U(1) symmetric solutions of the vacuum Einstein equations such that each exhibits AVTD (Asymptotic Velocity Term Dominated) behavior in the neighborhood of its singularity. Here we consider the general case of U(1) bundles and determine a condition, called the half polarization condition, necessary and sufficient in our context, for AVTD behavior near the singularity.
Rapidly rotating pulsar radiation in vacuum nonlinear electrodynamics
Energy Technology Data Exchange (ETDEWEB)
Denisov, V.I.; Pimenov, A.B.; Sokolov, V.A. [Moscow State University, Physics Department, Moscow (Russian Federation); Denisova, I.P. [Moscow Aviation Institute (National Research University), Moscow (Russian Federation)
2016-11-15
In this paper we investigate the corrections of vacuum nonlinear electrodynamics on rapidly rotating pulsar radiation and spin-down in the perturbative QED approach (post-Maxwellian approximation). An analytical expression for the pulsar's radiation intensity has been obtained and analyzed. (orig.)
Rapidly rotating pulsar radiation in vacuum nonlinear electrodynamics
Denisov, V. I.; Denisova, I. P.; Pimenov, A. B.; Sokolov, V. A.
2016-11-01
In this paper we investigate the corrections of vacuum nonlinear electrodynamics on rapidly rotating pulsar radiation and spin-down in the perturbative QED approach (post-Maxwellian approximation). An analytical expression for the pulsar's radiation intensity has been obtained and analyzed.
Vacuum Polarization in QED with World-Line Methods
Dittrich, W; Shaisultanov, R.
2000-01-01
Motivated by several recent papers on string-inspired calculations in QED, we here present our own use of world-line techniques in order to calculate the vacuum polarization and effective action in scalar and spinor QED with external arbitrary constant electromagnetic field configuration.
Using analytic continuation for the hadronic vacuum polarization computation
Energy Technology Data Exchange (ETDEWEB)
Feng, Xu; Hashimoto, Shoji; Hotzel, Grit; Jansen, Karl; Petschlies, Marcus; B, Renner Dru
2014-11-01
We present two examples of applications of the analytic continuation method for computing the hadronic vacuum polarization function in space- and time-like momentum regions. These examples are the Adler function and the leading order hadronic contribution to the muon anomalous magnetic moment. We comment on the feasibility of the analytic continuation method and provide an outlook for possible further applications.
On the polarization of nonlinear gravitational waves
Poplawski, Nikodem J.
2011-01-01
We derive a relation between the two polarization modes of a plane, linear gravitational wave in the second-order approximation. Since these two polarizations are not independent, an initially monochromatic gravitational wave loses its periodic character due to the nonlinearity of the Einstein field equations. Accordingly, real gravitational waves may differ from solutions of the linearized field equations, which are being assumed in gravitational-wave detectors.
Vacuum polarization in asymptotically Lifshitz black holes
Quinta, Gonçalo M; Lemos, José P S
2016-01-01
There has been considerable interest in applying the gauge/gravity duality to condensed matter theories with particular attention being devoted to gravity duals (Lifshitz spacetimes) of theories that exhibit anisotropic scaling. In this context, black hole solutions with Lifshitz asymptotics have also been constructed aiming at incorporating finite temperature effects. The goal here is to look at quantum polarization effects in these spacetimes, and to this aim, we develop a way to compute the coincidence limit of the Green's function for massive, non-minimally coupled scalar fields, adapting to the present situation the analysis developed for the case of asymptotically anti de Sitter black holes. The basics are similar to previous calculations, however in the Lifshitz case one needs to extend previous results to include a more general form for the metric and dependence on the dynamical exponent. All formulae are shown to reduce to the AdS case studied before once the value of the dynamical exponent is set to...
Vacuum polarization in asymptotically Lifshitz black holes
Quinta, Gonçalo M.; Flachi, Antonino; Lemos, José P. S.
2016-06-01
There has been considerable interest in applying the gauge-gravity duality to condensed matter theories with particular attention being devoted to gravity duals (Lifshitz spacetimes) of theories that exhibit anisotropic scaling. In this context, black hole solutions with Lifshitz asymptotics have also been constructed, focused on incorporating finite temperature effects. The goal here is to look at quantum polarization effects in these spacetimes and, to this aim, we develop a way to compute the coincidence limit of the Green's function for massive, nonminimally coupled scalar fields, adapting to the present situation the analysis developed for the case of asymptotically anti-de Sitter black holes. The basics are similar to previous calculations; however, in the Lifshitz case, one needs to extend the previous results to include a more general form for the metric and dependence on the dynamical exponent. All formulas are shown to reduce to the anti-de Sitter (AdS) case studied before once the value of the dynamical exponent is set to unity and the metric functions are accordingly chosen. The analytical results we present are general and can be applied to a variety of cases, in fact, to all spherically symmetric Lifshitz black hole solutions. We also implement the numerical analysis choosing some known Lifshitz black hole solutions as illustration.
New nonlinear polarization effects for frequency selection
Karagodova, Tamara Y.; Karagodov, Alexander I.
1998-05-01
The method of computer simulations on nonlinear resonant magnetooptical effects developed for real multi-level atoms in the two laser fields of arbitrary intensity and external magnetic field is applied for the polarization effects of different types calculations and investigations of the dependence of the characteristics of these effects on magnetic field strength, intensities, polarization and detunings of laser fields for alkaline atoms. The essence of the method consists in simulations and analysis of the plots of dependence of quasi energies on parameters, which are obtained with the help of sorting subprogram, and selection of suitable algorithms for calculations of characteristics of nonlinear resonant magnetooptical effects. One photon and two photon resonant effects are investigated for wide range of magnetic field strength from Zeeman to Paschen Back effects. Some new features in the spectra of rotation of plane of polarization and circular dichroism of different types are predicted. The results show the agreement with known experiments. Such calculations of nonlinear resonant magnetooptical effects in the intense laser fields resonant to adjacent transitions and magnetic field show the opportunity of investigation the modifications of electronic structure due to intense radiation fields and strong external magnetic field in atomic gases and also may be used for the treatment of new methods of phase-polarization selection of modes of tunable lasers.
The Stability of the Vacuum Polarization Surrounding a Charged Particle
Himpsel, F J
2015-01-01
The internal stability of the electron has been debated for a century at both the classical and the quantum level. Recently, a local force density balance was established for the 1s electron in the H atom, based on the energy-momentum tensor of the classical Dirac field. This methodology is now extended to quantum fields by considering the force densities acting on the vacuum polarization induced by a point charge. Such a model is applicable to any charged particle at large distances, since the only vestige of its internal structure is the electric Coulomb field together with the vacuum polarization induced by it. While the polarization charge density is attracted to the point charge, it is kept from collapsing by repulsive forces due to confinement and degeneracy. It is shown analytically that the corresponding force densities are balanced for every filled shell of mj states at a given angular momentum j. The force densities are then summed over all single-electron states in the Dirac sea and renormalized by...
Effective action and vacuum expectations in nonlinear $\\sigma$ model
Fayzullaev, B A
2015-01-01
The equations for effective action for nonlinear $\\sigma$ model are derived using DeWitt method in two forms - for generator of vertex parts $\\Gamma$ and for generator of weakly connected parts $W$. Loop-expansion solutions to these equations are found. It is shown that vacuum expectation values for various quantities including divergence of a N\\"{o}ther current, trace of the energy-momentum tensor and so on, can be calculated by this method. Also it is shown that vacuum expectation to the sigma-field is determined by an explicit combination of tree Green function and classical solution. It is shown that the limit when coupling constant tends to zero is singular one.
Transient evolution of a photon gas in the nonlinear QED vacuum
Energy Technology Data Exchange (ETDEWEB)
Wu, S Q; Hartemann, F V
2011-10-04
Thermally induced vacuum polarization stemming from QED radiative corrections to the electromagnetic field equations is studied. The physical behavior of thermal radiation, in the nonlinear QED vacuum first described by Heisenberg and Euler, is a problem of some theoretical importance in view of its relation to the cosmic microwave background (CMB), early universe evolution, and Hawking-Unruh radiation. The questions of evolution toward equilibrium, stability, and invariance of thermal radiation under such conditions are of great interest. Our analysis presents novel aspects associated with photon-photon scattering in a photon gas in the framework of quantum kinetic theory. Within the context of the Euler-Heisenberg theory, we show that a homogeneous, isotropic photon gas with arbitrary spectral distribution function evolves toward an equilibrium state with a Bose-Einstein distribution. The transient evolution toward equilibrium of a gas of photons undergoing photon-photon scattering is studied in detail via the Boltzmann transport equation.
Vacuum polarization of planar Dirac fermions by a superstrong Coulomb potential
Khalilov, V R
2016-01-01
We study the vacuum polarization of planar charged Dirac fermions by a strong Coulomb potential. Induced vacuum charge density is calculated and analyzed at the subcritical and supercritical Coulomb potentials for massless and massive fermions. For the massless case the induced vacuum charge density is localized at the origin when the Coulomb center charge is subcritical while it has a power-law tail when the Coulomb center charge is supercritical. The finite mass contribution into the induced charge due to the vacuum polarization is small and insignificantly distorts the Coulomb potential only at distances of order of the Compton length. The induced vacuum charge has a screening sign. As is known the quantum electrodynamics vacuum becomes unstable when the Coulomb center charge is increased from subcritical to supercritical values. In the supercritical Coulomb potential the quantum electrodynamics vacuum acquires the charge due to the so-called real vacuum polarization. We calculate the real vacuum polarizat...
Testing non-linear vacuum electrodynamics with Michelson interferometry
Schellstede, Gerold O; Lämmerzahl, Claus
2015-01-01
We discuss the theoretical foundations for testing non-linear vacuum electrodynamics with Michelson interferometry. Apart from some non-degeneracy conditions to be imposed, our discussion applies to all non-linear electrodynamical theories of the Pleba\\'nski class, i.e., to all Lagrangians that depend only on the two Lorentz-invariant scalars quadratic in the field strength. The main idea of the experiment proposed here is to use the fact that, according to non-linear electrodynamics, the phase velocity of light should depend on the strength and on the direction of an electromagnetic background field. There are two possible experimental set-ups for testing this prediction with Michelson interferometry. The first possibility is to apply a strong electromagnetic field to the beam in one arm of the interferometer and to compare the situation where the field is switched on with the situation where it is switched off. The second possibility is to place the whole interferometer in a strong electromagnetic field and...
Vacuum polarization in $d+{1/2}$ dimensions
Fosco, C D; Roditi, I
2004-01-01
We study the main properties of the one-loop vacuum polarization function ($\\Pi_{\\alpha \\beta}$) for spinor $QED$ in `$d + {1/2}$ dimensions', i.e., with fields defined on ${\\mathcal M} \\subset {\\mathbb R}^{d+1}$ such that ${\\mathcal M} = \\{(x_0,...,x_d) | x_{d}\\geq 0 \\}$, with bag-like boundary conditions on the boundary $\\partial{\\mathcal M} = \\{(x_0,...,x_d) | x_{d}= 0 \\}$. We obtain an exact expression for the induced current due to an external constant electric field normal to the boundary. We show that, for the particular case of 2+1 dimensions, there is a transverse component for the induced current, which is localized on a region close to $\\partial{\\mathcal M}$. This current is a parity breaking effect purely due to the boundary.
Vacuum polarization of scalar electrodynamics in flat space-time with nontrivial topology
Institute of Scientific and Technical Information of China (English)
吴普训; 余洪伟
2002-01-01
The one-loop vacuum polarization is calculated for scalar electrodynamics in a flat space-time with the topologyS1 ×R3. The effect of vacuum polarization upon photon propagation is considered. It is found that photon propagationbecomes anisotropic with some photon modes acquiring a positive topological mass and thus travelling at a subluminalspeed.
Gravitational vacuum polarization; 1, energy conditions in the Hartle-Hawking vacuum
Visser, M
1996-01-01
It is well-known that gravitationally induced vacuum polarization often violates the point-wise energy conditions and sometimes violates the averaged energy conditions. In this paper I begin a systematic attack on the question of where and by how much the various energy conditions are violated. I work in the test-field limit, and focus on conformally coupled massless scalar fields in Schwarzschild spacetime, using the Hartle--Hawking vacuum. I invoke a mixture of analytical and numerical techniques, and critically compare the qualitative behaviour to be expected from the Page approximation with that adduced from the numerical calculations of Anderson, Hiscock, and Samuel. I show that the various point-wise energy conditions are violated in a series of onion-like layers located between the unstable photon orbit and the event horizon, the sequence of violations being DEC, WEC, and (NEC+SEC). Furthermore the ANEC is violated for *some* of the null geodesics trapped in this region. Having established the basic ma...
Atmospheres and Spectra of Strongly Magnetized Neutron Stars II Effect of Vacuum Polarization
Ho, W C G; Ho, Wynn C. G.; Lai, Dong
2003-01-01
We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B=10^14-10^15 G, as appropriate for magnetars. Vacuum polarization modifies the dielectric property of the medium and gives rise to a resonance feature in the opacity; this feature is narrow and occurs at a photon energy that depends on the plasma density. Vacuum polarization can also induce resonant conversion of photon modes via a mechanism analogous to the MSW mechanism for neutrino oscillation. We construct atmosphere models in radiative equilibrium with an effective temperature of a few \\times 10^6 K by solving the full radiative transport equations for both polarization modes in a fully ionized hydrogen plasma. We discuss the subtleties in treating the vacuum polarization effects in the atmosphere models and present approximate solutions to the radiative transfer problem which bracket the true answer. We show from both analytic considerations and numerical calculatio...
Vacuum polarization screening corrections to the ground state energy of two-electron ions
Artemiev, A N; Yerokhin, V A
1997-01-01
Vacuum polarization screening corrections to the ground state energy of two-electron ions are calculated in the range $Z=20-100$. The calculations are carried out for a finite nucleus charge distribution.
Nonlinear self-flipping of polarization states in asymmetric waveguides
Zhang, Wen Qi; Monro, Tanya M; Afshar, V Shahraam
2012-01-01
Waveguides of subwavelength dimensions with asymmetric geometries, such as rib waveguides, can display nonlinear polarization effects in which the nonlinear phase difference dominates the linear contribution, provided the birefringence is sufficiently small. We demonstrate that self-flipping polarization states can appear in such rib waveguides at low (mW) power levels. We describe an optical power limiting device with optimized rib waveguide parameters that can operate at low powers with switching properties.
Nonlinear Gyrokinetic Theory With Polarization Drift
Energy Technology Data Exchange (ETDEWEB)
L. Wang and T.S. Hahm
2010-03-25
A set of the electrostatic toroidal gyrokinetic Vlasov equation and the Poisson equation, which explicitly includes the polarization drift, is derived systematically by using Lie-transform method. The polarization drift is introduced in the gyrocenter equations of motion, and the corresponding polarization density is derived. Contrary to the wide-spread expectation, the inclusion of the polarization drift in the gyrocenter equations of motion does not affect the expression for the polarization density significantly. This is due to modification of the gyrocenter phase-space volume caused by the electrostatic potential [T. S. Hahm, Phys. Plasmas 3, 4658 (1996)] .
Kong, Lingjie; Xiao, Xiaosheng; Yang, Changxi
2011-09-12
We numerically studied the polarization dynamics in dissipative soliton lasers mode-locked by nonlinear polarization rotation (NPR). It was found that the polarization states of the intracavity dissipative soliton vary with time across the pulse. Depending on output coupling ratios, the polarization states of the pulse peak before the polarizer can be either nearly circular or nearly linear polarizations. The polarization dependent component in NPR is found to play a role of spectral filter under high and medium output coupling. However, NPR may work as a weak optical limiter under low output coupling, when additional spectral filtering is necessary to maintain steady mode-locking state.
Fernández, Rodrigo; Davis, Shane W.
2011-04-01
In the magnetar model, the quiescent non-thermal soft X-ray emission from anomalous X-ray pulsars and soft gamma repeaters is thought to arise from resonant Comptonization of thermal photons by charges moving in a twisted magnetosphere. Robust inference of physical quantities from observations is difficult, because the process depends strongly on geometry, and current understanding of the magnetosphere is not very deep. The polarization of soft X-ray photons is an independent source of information, and its magnetospheric imprint remains only partially explored. In this paper, we calculate how resonant cyclotron scattering would modify the observed polarization signal relative to the surface emission, using a multidimensional Monte Carlo radiative transfer code that accounts for the gradual coupling of polarization eigenmodes as photons leave the magnetosphere. We employ a globally twisted, self-similar, force-free magnetosphere with a power-law momentum distribution, assume a blackbody spectrum for the seed photons, account for general relativistic light deflection close to the star, and assume that vacuum polarization dominates the dielectric properties of the magnetosphere. The latter is a good approximation if the pair multiplicity is not much larger than unity. Phase-averaged polarimetry is able to provide a clear signature of the magnetospheric reprocessing of thermal photons and to constrain mechanisms generating the thermal emission. Phase-resolved polarimetry, in addition, can characterize the spatial extent and magnitude of the magnetospheric twist angle at ~100 stellar radii, and discern between uni- or bidirectional particle energy distributions, almost independently of every other parameter in the system. We discuss prospects for detectability with the Gravity and Extreme Magnetism (GEMS) mission.
Equilateral pentagon polarization maintaining photonic crystal fibre with low nonlinearity
Institute of Scientific and Technical Information of China (English)
Yang Han-Rui; Li Xu-You; Hong Wei; Hao Jin-Hui
2012-01-01
A new pentagon polarization maintaining photonic crystal fibre with low nonlinearity is introduced. The full vector finite element method was used to investigate the distribution and the effective area of modal field,the nonlinear properties,the effective indices of two orthogonal polarization modes and the birefringence of the new PM-PCF effectively.It is found that the birefringence of the new polarization maintaining photonic crystal fibre can easily achieve the order of 10-4,and it can obtain higher birefringence,larger effectively mode-field area and lower nonlinearity than traditional hexagonal polarization maintaining photonic crystal fibre with the same hole pitch,same hole diameter,and same ring number.It is important for sensing and communication applications,especially has potential application for fibre optical gyroscope.
Analysis on the effect of nonlinear polarization evolution in nonlinear amplifying loop mirror
Institute of Scientific and Technical Information of China (English)
Feng Qu; Xiaoming Liu; Pu Zhang; Xubiao Jiang; Hongming Zhang; Minyu Yao
2005-01-01
By considering the cross phase modulation (XPM) between the two orthogonal poparization components,the nonlinear birefringence and nonlinear polarization evolution (NPE) in highly-nonlinear fiber (HNLF),as well as the unequal evolutions of the state of polarization (SOP) between the clockwise (CW) and counter-clockwise (CCW) waves in a nonlinear amplifying loop mirror (NALM) are analyzed. It is pointed out that the traditional cosine expression is no longer valid for the power transmission of NALM due to uncompleted interference under the high power condition. The analytical expression considering NPE effect is derived, and the experimental result is presented.
Nonlinear Magnetic Phenomena in Highly Polarized Target Materials
Kiselev, Yu F
2007-01-01
The report introduces and surveys nonlinear magnetic phenomena which have been observed at high nuclear polarizations in polarized targets of the SMC and of the COMPASS collaborations at CERN. Some of these phenomena, namely the frequency modulation eect and the distortion of the NMR line shape, promote the development of the polarized target technique. Others, as the spin-spin cross-relaxation between spin subsystems can be used for the development of quantum statistical physics. New findings bear on an electromagnetic noise and the spectrally resolved radiation from LiD with negatively polarized nuclei detected by low temperature bolometers. These nonlinear phenomena need to be taken into account for achieving the ultimate polarizations.
Institute of Scientific and Technical Information of China (English)
ZHAO Shuang; WU Chong-Qing; WANG Yong-Jun
2009-01-01
Linewidth enhancement factors (LEFs) of the transverse electric mode and the transverse magnetic mode in bulk semiconductor optical amplifiers are measured using the nonlinear optical loop mirror method and the principal state of polarization vector method.The polarization dependence of LEFs plays an important role in the nonlinear polarization rotation.The relationship between the polarization-dependence of LEFs and nonlinear polarization rotation in the Stokes space is demonstrated.
Vacuum polarization of a scalar field in wormhole spacetimes
Popov, A A; Popov, Arkadii A.; Sushkov, Sergey V.
2001-01-01
An analitical approximation of $$ for a scalar field in a static spherically symmetric wormhole spacetime is obtained. The scalar field is assumed to be both massive and massless, with an arbitrary coupling $\\xi$ to the scalar curvature, and in a zero temperature vacuum state.
Modeling of nonlinear responses for reciprocal transducers involving polarization switching
DEFF Research Database (Denmark)
Willatzen, Morten; Wang, Linxiang
2007-01-01
Nonlinearities and hysteresis effects in a reciprocal PZT transducer are examined by use of a dynamical mathematical model on the basis of phase-transition theory. In particular, we consider the perovskite piezoelectric ceramic in which the polarization process in the material can be modeled....... We present numerical results for the reciprocal-transducer system and identify the influence of nonlinearities on the system dynamics at high and low frequency as well as electrical impedance effects due to tuning by a series inductance. It is found that nonlinear effects are not important at high...... by Landau theory for the first-order phase transformation, in which each polarization state is associated with a minimum of the Landau free-energy function. Nonlinear constitutive laws are obtained by using thermodynamical equilibrium conditions, and hysteretic behavior of the material can be modeled...
Vacuum Characterization and Improvement for the Jefferson Lab Polarized Electron Source
Energy Technology Data Exchange (ETDEWEB)
Stutzman, Marcy L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Poelker, Matthew [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Adderley, Philip A. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Mamun, Md Abdullah [Old Dominion Univ., Norfolk, VA (United States)
2015-09-01
Operating the JLab polarized electron source with high reliability and long lifetime requires vacuum near the XHV level, defined as pressure below 7.5×10^{-13} Torr. This paper describes ongoing vacuum research at Jefferson Lab including characterization of outgassing rates for surface coatings and heat treatments, ultimate pressure measurements, investigation of pumping including an XHV cryopump, and characterization of ionization gauges in this pressure regime.
A Mode-Sum Prescription for Vacuum Polarization in Odd Dimensions
Taylor, Peter
2016-01-01
We present a new mode-sum regularization prescription for computing the vacuum polarization of a scalar field in static spherically-symmetric black hole spacetimes in odd dimensions. This is the first general and systematic approach to regularized vacuum polarization in higher dimensions. Remarkably, the regularization parameters can be computed in closed form in arbitrary dimensions and for arbitrary metric function $f(r)$. In fact, we show that in spite of the increasing severity and number of the divergences to be regularized, the method presented is mostly agnostic to the number of dimensions. Finally, as an explicit example of our method, we show plots for vacuum polarization in Schwarzschild-Tangherlini spacetime for odd $d=5,...,11$.
Axion-induced birefringence effects in laser driven nonlinear vacuum interaction
Villalba-Chávez, Selym
2013-01-01
The propagation of a probe electromagnetic field through a counterpropagating strong plane wave is investigated. The effects of the electromagnetic field-(pseudo)scalar axion field interaction and of the self-interaction of the electromagnetic field mediated by virtual electron-positron pairs in the effective Lagrangian approach are included. First, we show that if the strong field is circularly polarized, contrary to the leading-order nonlinear QED effects, the axion-photon interaction induces a chiral-like birefringence and a dichroism in the vacuum. The latter effect is explained by evoking the conservation of the total angular momentum along the common propagation direction of probe and the strong wave, which allows for real axion production only for probe and strong fields with the same helicity. Moreover, in the case of ultra-short strong pulses, it is shown that the absorption coefficients of probe photons depend on the form of the pulse and, in particular, on the carrier-envelope phase of the strong b...
Muonic vacuum polarization correction to the bound-electron $g$-factor
Belov, N A; Weis, R; Yerokhin, V A; Sturm, S; Blaum, K; Keitel, C H; Harman, Z
2016-01-01
The muonic vacuum polarization contribution to the $g$-factor of the electron bound in a nuclear potential is investigated theoretically. The electric as well as the magnetic loop contributions are evaluated. We found these muonic effects to be observable in planned trapped-ion experiments with light and medium-heavy highly charged ions. The enhancement due to the strong Coulomb field boosts these contributions much above the corresponding terms in the free-electron $g$-factor. Due to their magnitude, muonic vacuum polarization terms are also significant in planned determinations of the fine-structure constant from the bound-electron $g$-factor.
Automated control of optical polarization for nonlinear microscopy
Brideau, Craig; Stys, Peter K.
2012-03-01
Laser-scanning non-linear optical techniques such as multi-photon fluorescence excitation microscopy (MPM), Second/ Third Harmonic Generation (SHG/THG), and Coherent Anti-Stokes Raman Scattering (CARS) are being utilized in research laboratories worldwide. The efficiencies of these non-linear effects are dependent on the polarization state of the excitation light relative to the orientation of the sample being imaged. In highly ordered anisotropic biological samples this effect can become pronounced and the excitation polarization can have a dramatic impact on imaging experiments. Therefore, controlling the polarization state of the exciting light is important; however this is challenging when the excitation light passes through a complex optical system. In a typical laser-scanning microscope, components such as the dichroic filters, lenses, and even mirrors can alter the polarization state of a laser beam before it reaches the sample. We present an opto-mechanical solution to compensate for the polarization effects of an optical path, and to precisely program the polarization state of the exciting laser light. The device and accompanying procedures allow the delivery of precise laser polarization states at constant average power levels to a sample during an imaging experiment.
Nonlinear interferometer for tailoring the frequency spectrum of bright squeezed vacuum
Iskhakov, T Sh; Perez, A; Boyd, R W; Leuchs, G; Chekhova, M
2015-01-01
We propose a method for tailoring the frequency spectrum of bright squeezed vacuum by generating it in a nonlinear interferometer, consisting of two down-converting nonlinear crystals separated by a dispersive medium. Due to a faster dispersive spreading of higher-order Schmidt modes, the spectral width of the radiation at the output is reduced as the length of the dispersive medium is increased. Preliminary results show 30\\% spectral narrowing.
Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide
Cui, Yudong; Lu, Feifei; Liu, Xueming
2017-01-01
Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of μJ/cm2 and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system.
Nonlinear Saturable and Polarization-induced Absorption of Rhenium Disulfide
Cui, Yudong; Lu, Feifei; Liu, Xueming
2017-01-01
Monolayer of transition metal dichalcogenides (TMDs), with lamellar structure as that of graphene, has attracted significant attentions in optoelectronics and photonics. Here, we focus on the optical absorption response of a new member TMDs, rhenium disulphide (ReS2) whose monolayer and bulk forms have the nearly identical band structures. The nonlinear saturable and polarization-induced absorption of ReS2 are investigated at near-infrared communication band beyond its bandgap. It is found that the ReS2-covered D-shaped fiber (RDF) displays the remarkable polarization-induced absorption, which indicates the different responses for transverse electric (TE) and transverse magnetic (TM) polarizations relative to ReS2 plane. Nonlinear saturable absorption of RDF exhibits the similar saturable fluence of several tens of μJ/cm2 and modulation depth of about 1% for ultrafast pulses with two orthogonal polarizations. RDF is utilized as a saturable absorber to achieve self-started mode-locking operation in an Er-doped fiber laser. The results broaden the operation wavelength of ReS2 from visible light to around 1550 nm, and numerous applications may benefit from the anisotropic and nonlinear absorption characteristics of ReS2, such as in-line optical polarizers, high-power pulsed lasers, and optical communication system. PMID:28053313
The light filament as a new nonlinear polarization state
Kovachev, Lubomir M
2015-01-01
We present an analytical approach to the theory of nonlinear propagation in gases of femtosecond optical pulses with broad-band spectrum . The vector character of the nonlinear third-order polarization of the electrical field in air is investigated in details. A new polarization state is presented by using left-hand and right-hand circular components of the electrical field . The corresponding system of vector amplitude equations is derived in the rotating basis. We found that this system of nonlinear equations has $3D+1$ vector soliton solutions with Lorentz shape. The solution presents a relatively stable propagation and rotation with GHz frequency of the vector of the electrical field in a plane orthogonal to the direction of propagation. The evolution of the intensity profile demonstrates a weak self-compression and a week spherical wave in the first milliseconds of propagation.
Graviton loop corrections to vacuum polarization in de Sitter in a general covariant gauge
Glavan, D.; Miao, S. P.; Prokopec, Tom; Woodard, R. P.
2015-01-01
We evaluate the one-graviton loop contribution to the vacuum polarization on de Sitter background in a 1-parameter family of exact, de Sitter invariant gauges. Our result is computed using dimensional regularization and fully renormalized with Bogoliubov, Parasiuk, Hepp and Zimmerman counterterms,
The hadronic vacuum polarization and automatic O(a) improvement for twisted mass fermions
Energy Technology Data Exchange (ETDEWEB)
Burger, Florian; Hotzel, Grit [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC; Petschlies, Marcus [The Cyprus Institute, Nicosia (Cyprus)
2014-12-15
The vacuum polarization tensor and the corresponding vacuum polarization function are the basis for calculations of numerous observables in lattice QCD. Examples are the hadronic contributions to lepton anomalous magnetic moments, the running of the electroweak and strong couplings and quark masses. Quantities which are derived from the vacuum polarization tensor often involve a summation of current correlators over all distances in position space leading thus to the appearance of short-distance terms. The mechanism of O(a) improvement in the presence of such short-distance terms is not directly covered by the usual arguments of on-shell improvement of the action and the operators for a given quantity. If such short-distance contributions appear, the property of O(a) improvement needs to be reconsidered. We discuss the effects of these short-distance terms on the vacuum polarization function for twisted mass lattice QCD and find that even in the presence of such terms automatic O(a) improvement is retained if the theory is tuned to maximal twist.
Waveguide transition with vacuum window for multiband dynamic nuclear polarization systems
DEFF Research Database (Denmark)
Rybalko, Oleksandr; Bowen, Sean; Zhurbenko, Vitaliy
2016-01-01
A low loss waveguide transition section and oversized microwave vacuum window covering several frequency bands (94 GHz, 140 GHz, 188 GHz) is presented. The transition is compact and was optimized for multiband Dynamic Nuclear Polarization (DNP) systems in a full-wave simulator. The window is more...
Chaotic behavior in nonlinear polarization dynamics
Energy Technology Data Exchange (ETDEWEB)
David, D.; Holm, D.D.; Tratnik, M.V. (Los Alamos National Lab., NM (USA))
1989-01-01
We analyze the problem of two counterpropagating optical laser beams in a slightly nonlinear medium from the point of view of Hamiltonian systems; the one-beam subproblem is also investigated as a special case. We are interested in these systems as integrable dynamical systems which undergo chaotic behavior under various types of perturbations. The phase space for the two-beam problem is C{sup 2} {times} C{sup 2} when we restricted the the regime of travelling-wave solutions. We use the method of reduction for Hamiltonian systems invariant under one-parameter symmetry groups to demonstrate that the phase space reduces to the two-sphere S{sup 2} and is therefore completely integrable. The phase portraits of the system are classified and we also determine the bifurcations that modify these portraits; some new degenerate bifurcations are presented in this context. Finally, we introduce various physically relevant perturbations and use the Melnikov method to prove that horseshoe chaos and Arnold diffusion occur as consequences of these perturbations. 10 refs., 7 figs., 1 tab.
Modified light cone condition via vacuum polarization in a time dependent field
Hu, Huayu
2014-01-01
The appearance of unconventional vacuum properties in intense fields has long been an active field of research. In this paper the vacuum polarization effect is investigated via a pump probe scheme of a probe light propagating in the vacuum excited by two counter-propagating laser beams. The modified light cone condition of the probe light is derived analytically for the situation that it passes through the electric/magnetic antinode plane of the pump field. The derivation does not follow the commonly adopted assumption of treating the pump field as a constant field. Differences from the conventional light cone conditions are identified. The implications of the result are discussed with a consideration of the vacuum birefringence measurement.
Chiral Huygens metasurfaces for nonlinear structuring of linearly polarized light
Lesina, A Calà; Ramunno, L
2016-01-01
We report on a chiral nanostructure, which we term a "butterfly nanoantenna," that, when used in a metasurface, allows the direct conversion of a linearly polarized beam into a nonlinear optical far-field of arbitrary complexity. The butterfly nanoantenna exhibits field enhancement in its gap for every incident linear polarization, which can be exploited to drive nonlinear optical emitters within the gap, for the structuring of light within a frequency range not accessible by linear plasmonics. As the polarization, phase and amplitude of the field in the gap are highly controlled, nonlinear emitters within the gap behave as an idealized Huygens source. A general framework is thereby proposed wherein the butterfly nanoantennas can be arranged on a surface to produce a highly structured far-field nonlinear optical beam with high purity. A third harmonic Laguerre-Gauss beam carrying an optical orbital angular momentum of 41 is demonstrated as an example, through large-scale simulations on a high-performance comp...
Fast and Chaotic Fiber-Based Nonlinear Polarization Scrambler
Guasoni, M; Gilles, M; Picozzi, A; Fatome, J
2015-01-01
We report a simple and efficient all-optical polarization scrambler based on the nonlinear interaction in an optical fiber between a signal beam and its backward replica which is generated and amplified by a reflective loop. When the amplification factor exceeds a certain threshold, the system exhibits a chaotic regime in which the evolution of the output polarization state of the signal becomes temporally chaotic and scrambled all over the surface of the Poincar\\'e sphere. We derive some analytical estimations for the scrambling performances of our device which are well confirmed by the experimental results. The polarization scrambler has been successfully tested on a single channel 10-Gbit/s On/Off Keying Telecom signal, reaching scrambling speeds up to 250-krad/s, as well as in a wavelength division multiplexing configuration. A different configuration based on a sequent cascade of polarization scramblers is also discussed numerically, which leads to an increase of the scrambling performances.
Minicharged particles search by strong laser pulse-induced vacuum polarization effects
Villalba-Chávez, Selym; Müller, Carsten
2016-01-01
Laser-based searches of the yet unobserved vacuum birefringence might be sensitive for very light hypothetical particles carrying a tiny fraction of the electron charge. We show that, with the help of contemporary techniques, polarimetric investigations driven by an optical laser pulse of moderate intensity might allow for excluding regions on the parameter space of these particle candidates which have not been discarded so far by laboratory measurement data. Particular attention is paid to the role of a Gaussian wave profile. It is argued that, at energy regimes in which the vacuum becomes dichroic due to these minicharges, the probability that a photon flips its polarization to an orthogonal state will depend on both the induced ellipticity as well as the rotation of the initial polarization plane. The weak and strong field regimes, relative to the attributes of these degrees of freedom, and the relevance of the polarization of the strong field are investigated.
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...
Polarization-selective optical nonlinearities in cold Rydberg atoms
Wu, Jin-Hui; Artoni, M.; La Rocca, G. C.
2015-12-01
We study the interaction between a probe and a trigger weak fields in a sample of cold rubidium atoms in the presence of a coupling and a dressing strong fields. Dipole Rydberg blockade may occur and can be set to depend on the probe and trigger polarizations giving rise to diverse regimes of electromagnetically induced transparency (EIT) with a concomitant small probe and trigger absorption and dispersion. This is shown to be relevant to the implementation of polarization conditional probe and trigger cross nonlinearities in cold Rydberg atoms.
Proposal for detection of QED vacuum nonlinearities in Maxwell's equations by the use of waveguides.
Brodin, G; Marklund, M; Stenflo, L
2001-10-22
We present a novel method for detecting nonlinearities, due to quantum electrodynamics through photon-photon scattering, in Maxwell's equation. The photon-photon scattering gives rise to self-interaction terms which are similar to the nonlinearities due to the polarization in nonlinear optics. These self-interaction terms vanish in the limit of parallel propagating waves, but if, instead of parallel propagating waves, the modes generated in waveguides are used, there will be a nonzero total effect. Based on this idea, we calculate the nonlinear excitation of new modes and estimate the strength of this effect. Furthermore, we suggest a principal experimental setup.
Non-stationary resonance dynamics of a nonlinear sonic vacuum with grounding supports
Koroleva (Kikot), I. P.; Manevitch, L. I.; Vakakis, Alexander F.
2015-11-01
In a recent work [L.I. Manevitch, A.F.Vakakis, Nonlinear oscillatory acoustic vacuum, SIAM Journal of Applied Mathematics 74(6) (2014), 1742-1762] it was shown that a periodic chain of linearly coupled particles performing low-energy in-plane transverse oscillations behaves as a strongly nonlinear sonic vacuum (with corresponding speed of sound equal to zero). In this work we consider the grounded version of this system by coupling each particle to the ground through lateral springs in order to study the effect of the grounding stiffness on the strongly nonlinear dynamics. In that context we consider the simplest possible such system consisting of two coupled particles and present analytical and numerical studies of the non-stationary planar dynamics. The most significant limiting case corresponding to predominant low energy transversal excitations is considered by taking into account leading order geometric nonlinearities. Then we show that the grounded system behaves as a nonlinear sonic vacuum due to the purely cubic stiffness nonlinearities in the governing equations of motion and the complete absence of any linear stiffness terms. Under certain assumptions the nonlinear normal modes (i.e., the time-periodic nonlinear oscillations) in the configuration space of this system coincide with those of the corresponding linear one, so they obey the same orthogonality relations. Moreover, we analytically find that there are two transitions in the dynamics of this system, with the parameter governing these transitions being the relation between the lateral (grounding) and the interchain stiffnesses. The first transition concerns a bifurcation of one of the nonlinear normal modes (NNMs), whereas the second provides conditions for intense energy transfers and mixing between the NNMs. The drastic effects of these bifurcations on the non-stationary resonant dynamics are discussed. Specifically, the second transition relates to strongly non-stationary dynamics, and signifies
Dispersion and polarization dependence of mobile carrier optical nonlinearities
Rustagi, K. C.
1984-06-01
Based on the author's earlier work, it is shown that the proper inclusion of carrier scattering should strongly modify the frequency and polarization dependence of optical nonlinearities due to mobile carriers in semiconductors. When the momentum relaxation is much faster than the energy relaxation, the intensity dependent refractive index is enhanced, the induced birefringence becomes a sharp function of the difference frequency ωa-ωb, and a collision induced stimulated Raman effect becomes important.
Olivier, Michel; Gagnon, Marc-Daniel; Habel, Joé
2016-02-28
When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.
Evolution and Regularisation of Vacuum Brill Gravitational Waves in Spherical Polar Coordinates
Masterson, Andrew
2014-01-01
In this thesis the universal collapse of vacuum Brill waves is demonstrated numerically and analytically. This thesis presents the mathematical and numerical methods necessary to regularise and evolve Brill Gravitational Waves in spherical polar coordinates. A Cauchy ADM formulation is used for the time evolution. We find strong evidence that all IVP formulations of pure vacuum Brill gravitational waves collapse to form singularities/black holes, and we do not observe critical black hole mass scaling phenomena in the IVP parameter phase space that has been characterised in non-vacuum systems. A theoretical framework to prove this result analytically is presented. We discuss the meaning of Brill metric variables, the topology of trapped surfaces for various scenarios, and verify other results in the field related to critical values of initial value parameters and black hole formation approaching spatial infinity. The instability of Minkowski (flat) space under Brill wave and more general perturbations is demon...
Hardcastle, T. P.; Brydson, R. M. D.; Livi, K. J. T.; Seabourne, C. R.; Scott, A. J.
2012-07-01
All terminations of the (1x1) rutile (110), (101), (001), (100) and (111) surfaces are classified according to their electrostatic polarity. Six are found to be non-polar. The plane-wave density functional theory code CASTEP is used with a GGA-PBE exchange-correlation functional and a vacuum/material slab supercell method to calculate the surface energy density of symmetric thin rutile films with the six non-polar terminations in vacuum. The ratio of the surface energy densities of a rutile crystal with {111} and {110} facets in water is deduced using Lagrange multipliers and found to be consistent with the DFT vacuum results.
Study of weak vacuum polarization in $Z \\to 2l \\gamma$
Zhabin, Viktor
2017-01-01
The goal of the work was to perform a search of weak vacuum polarization in the channel $Z \\to 2l \\gamma$ using $20 \\text{ fb}^{-1}$ of $pp$ collision data collected by the ATLAS experiment in 2012 at 8 TeV. The ratio of the distribution of an invariant mass of $l\\gamma$ obtained from experimental data to the MC distribution from the experimental data was used for the search of the effect. Total significance of weak vacuum polarization signal in the invariant mass distribution of $l \\gamma$ in only one of four channels has some significance. First studies indicate that an evidence of about $3.5 \\sigma$ can be reached. The parameters, amplitude and phase, determined from the fit are different in each channel and thus inconclusive.
Classical electrodynamics with vacuum polarization: electron self-energy and radiation reaction
Blinder, S. M.
2001-04-01
The region very close to an electron ( r ⪅ r0 = e2/ mc2 ≈ 2.8 × 10 -13 cm) is, according to quantum electrodynamics, a seething maelstrom of virtual electron-positron pairs flashing in and out of existence. To take account of this well-established physical reality, a phenomenological representation for vacuum polarization is introduced into the framework of classical electrodynamics. Such a model enables a consistent picture of classical point charges with finite electromagnetic self-energy. It is further conjectured that the reaction of a point charge to its own electromagnetic field is tantamount to interaction with its vacuum polarization charge or "aura." This leads to a modification of the Lorentz-Dirac equation for the force on an accelerating electron, a new differential-difference equation which avoids the pathologies of preacceleration and runaway solutions.
Vacuum polarization in sub-coulomb 12C- 12C scattering (II)
Trautmann, D.; Baur, G.; Vetterli, D.; Egelhof, P.; Henneck, R.; Jaskòla, M.; Mühry, H.; Sick, I.
In order to extract the effect of vacuum polarization from 12C- 12C elastic scattering data, a detailed theoretical study of the low-energy Mott cross section is performed. It is shown that the contributions of nuclear interaction, Coulomb excitation, bremsstrahlung can be neglected, while radiative corrections and nuclear polarizability can be described by a small additional potential. Screening by atomic electrons is corrected by a screening function, which acts on all potentials. Relativistic effects are accounted for using the "Todorov equation". In order to overcome numerical difficulties for very long range potentials a WKB approximation and a semiquantal approach are discussed and compared. The study shows that the first-order vacuum-polarization potential contributes most to the correction of the cross section. All other contributions are at least one order of magnitude smaller.
Gnedin, Y N; Larionov, V M; Naidenov, I D; Natsvlishvili, T M; Piotrovich, M Y; Gnedin, Yu. N.
2004-01-01
We present brief review of two probable physical mechanisms that can explain the results of photometric and spectropolarimetric observations of magnetic white dwarfs: vacuum polarization effect into a strong magnetic field and, so-called, magnetic collision induced absorption (magnetic CIA). Both mechanisms provide observed rotation of polarization ellipse and suppression of spectral energy distributions. The results of spectropolarimetric observations of magnetic white dwarfs made at Russian BTA-6m and the results of the near infrared photometric observations with Russian-Italian AZT-24 telescope located at Campo Imperatore are also presented.
Sixth-Order Vacuum-Polarization Contribution to the Lamb Shift of the Muonic Hydrogen
Kinoshita, T
1999-01-01
The sixth-order electron-loop vacuum-polarization contribution to the $2P_{1/2} - 2S_{1/2}$ Lamb shift of the muonic hydrogen ($\\mu^{-} p^+$ bound state) has been evaluated numerically. Our result is 0.005295(1) meV. This eliminates the largest uncertainty in the theoretical calculation. Combined with the proposed precision measurement of the Lamb shift it will lead to a very precise determination of the proton charge radius.
Martynenko, A P
2016-01-01
On the basis of quasipotential approach in quantum electrodynamics we calculate vacuum polarization and quadrupole corrections in first and second orders of perturbation theory in hyperfine structure of P-states in muonic deuterium. All corrections are presented in integral form and evaluated analytically and numerically. The obtained results can be used for the improvement of the transition frequencies between levels 2P and 2S.
Vacuum laser acceleration using a radially polarized CO sub 2 laser beam
Liu, Y; He, P
1999-01-01
Utilizing the high-power, radially polarized CO sub 2 laser and high-quality electron beam at the Brookhaven Accelerator Test Facility, a vacuum laser acceleration scheme is proposed. In this scheme, optics configuration is simple, a small focused beam spot size can be easily maintained, and optical damage becomes less important. At least 0.5 GeV/m acceleration gradient is achievable by 1 TW laser power.
Yagi-Watanabe, Kazutoshi; Tanaka, Masahito; Kaneko, Fusae; Nakagawa, Kazumichi
2007-12-01
Polarization modulation spectroscopy using an Onuki-type undulator is a useful technique for circular dichroism study in the vacuum-ultraviolet region. We have been developing the vacuum-ultraviolet circular dichroism (vuv-CD) spectroscopy in TERAS BL5 beamline at AIST. This paper describes recent improvements in our instrumentation and methods of analysis to achieve precise and absolute measurements. The CD signal is usually accompanied by experimental artifacts, and elimination of all possible artifacts is the key issue for making reliable measurements. After improving beamline optical system, light flux monitor, and undulator operation method, the base line shift of the CD spectrum is suppressed less than 3x10(-4). Sample manipulation and data processing procedures are also described and absolute CD spectrum can be obtained even for linear anisotropic sample. These progresses lead to more quantitative comparison of experimental with calculation on vuv-CD spectrum.
Nonlinear optical polarization analysis in chemistry and biology
Simpson, Garth J
2017-01-01
This rigorous yet accessible guide presents a molecular-based description of nonlinear optical polarization analysis of chemical and biological assemblies. It includes discussion of the most common nonlinear optical microscopy and interfacial measurements used for quantitative analysis, specifically second harmonic generation (SHG), two-photon excited fluorescence (2PEF), vibrational sum frequency generation (SFG), and coherent anti-Stokes Raman spectroscopy/stimulated Raman spectroscopy (CARS/SRS). A linear algebra mathematical framework is developed, allowing step-wise systematic connections to be made between the observable measurements and the molecular response. Effects considered include local field corrections, the molecular orientation distribution, rotations between the molecular frame, the local frame and the laboratory frame, and simplifications from molecular and macromolecular symmetry. Specific examples are provided throughout the book, working from the common and relatively simple case studies ...
Tests of hadronic vacuum polarization fits for the muon anomalous magnetic moment
Golterman, Maarten; Peris, Santiago
2013-01-01
Using experimental spectral data for hadronic tau decays from the OPAL experiment, supplemented by a phenomenologically successful parameterization for the high-s region not covered by the data, we construct a physically constrained model of the isospin-one vector-channel polarization function. Having such a model as a function of Euclidean momentum Q^2 allows us to explore the systematic error associated with fits to the Q^2 dependence of lattice data for the hadronic electromagnetic current polarization function which have been used in attempts to compute the leading order hadronic contribution, a_\\mu^HLO, to the muon anomalous magnetic moment. In contrast to recent claims made in the literature, we find that a final error in this quantity of the order of a few percent does not appear possible with current lattice data, given the present lack of precision in the determination of the vacuum polarization at low Q^2. We also find that fits to the vacuum polarization using fit functions based on Vector Meson Do...
Alsaadi, Ahmad Salem
2014-08-13
This paper discusses the effect of temperature polarization in Vacuum Membrane Distillation (VMD). The main motivation for using VMD in this work is that this module configuration is much simpler and more suitable for this kind of investigation than the other MD configurations such as Direct Contact Membrane Distillation (DCMD). The coupling between heat and mass transfer mechanisms at the feed-membrane interface is presented from a theoretical point of view. In addition, a new simple graphical method and a mathematical model for determining VMD flux are presented. The two methods used in evaluating the extent of temperature polarization effect on water vapor flux (flux sensitivity factors and temperature polarization coefficient (TPC)) are also analyzed and compared. The effect of integrating a heat recovery system in a large scale module on the TPC coefficient has also been studied and presented in this paper. © 2014 Elsevier B.V.
Fernández, Rodrigo
2011-01-01
In the magnetar model, the quiescent non-thermal soft X-ray emission from Anomalous X-ray Pulsars and Soft-Gamma Repeaters is thought to arise from resonant comptonization of thermal photons by charges moving in a twisted magnetosphere. Robust inference of physical quantities from observations is difficult, because the process depends strongly on geometry and current understanding of the magnetosphere is not very deep. The polarization of soft X-ray photons is an independent source of information, and its magnetospheric imprint remains only partially explored. In this paper we calculate how resonant cyclotron scattering would modify the observed polarization signal relative to the surface emission, using a multidimensional Monte Carlo radiative transfer code that accounts for the gradual coupling of polarization eigenmodes as photons leave the magnetosphere. We employ a globally-twisted, self-similar, force-free magnetosphere with a power-law momentum distribution, assume a blackbody spectrum for the seed pho...
Chang, Chin-Chun; Chan, Che-Kai; Wu, Ling-Hui; Shueh, Chin; Shen, I.-Ching; Cheng, Chia-Mu; Yang, I.-Chen
2017-05-01
Three sets of a vacuum system were developed and fabricated for elliptically polarized undulators (EPU) of a 3-GeV synchrotron facility. These chambers were shaped with low roughness extrusion and oil-free machining; the design combines aluminium and stainless steel. The use of a bimetallic material to connect the EPU to the vacuum system achieves the vacuum sealing and to resolve the leakage issue due to bake process induced thermal expansion difference. The interior of the EPU chamber consists of a non-evaporable-getter strip pump in a narrow space to absorb photon-stimulated desorption and to provide a RF bridge design to decrease impedance effect in the two ends of EPU chamber. To fabricate these chambers and to evaluate the related performance, we performed a computer simulation to optimize the structure. During the machining and welding, the least deformation was achieved, less than 0.1 mm near 4 m. In the installation, the linear slider can provide a stable and precision moved along parallel the electron beam direction smoothly for the EPU chamber to decrease the twist issue during baking process. The pressure of the EPU chamber attained less than 2×10-8 Pa through baking. These vacuum systems of the EPU magnet have been installed in the electron storage ring of Taiwan Photon Source in 2015 May and have normally operated at 300 mA continuously since, and to keep beam life time achieved over than 12 h.
Wang, Charles H -T; Bingham, Robert; Mendonca, J Tito
2008-01-01
We investigate the problem of metric fluctuations in the presence of the vacuum fluctuations of matter fields and critically assess the usual assertion that vacuum energy implies a Planckian cosmological constant. A new stochastic classical approach to the quantum fluctuations of spacetime is developed. The work extends conceptually Boyer's random electrodynamics to a theory of random gravity but has a considerably richer structure for inheriting nonlinearity from general relativity. Attention is drawn to subtleties in choosing boundary conditions for metric fluctuations in relation to their dynamical consequences. Those compatible with the observed Lorentz invariance must allow for spontaneous conformal fluctuations, in addition to stochastic gravitational waves due to zero point gravitons. This is implemented through an effective metric defined in terms of the random spacetime metric modulo a fluctuating conformal factor. It satisfies an effective Einstein equation coupled to an effective stress-energy tens...
The hadronic vacuum polarization function with O(a)-improved Wilson fermions - an update
Della Morte, Michele; Horch, Hanno; Jäger, Benjamin; Meyer, Harvey; Wittig, Hartmut
2016-01-01
We present an update of our lattice QCD study of the vacuum polarization function using O$(a)$-improved $N_ {\\rm f} =2$ Wilson fermions with increased statistics and a large set of momenta. The resulting points are highly correlated and thus require a correlated fitting procedure. We employ an extended frequentist method to estimate the systematic uncertainties due to the momentum dependence and to the continuum and chiral extrapolations. We present preliminary results of the leading order hadronic contribution of the anomalous magnetic moment of the muon $\\left(a_\\mu^{\\mathrm{HLO}}\\right)$ at the physical point for $u,d,s$ and $c$ valence quarks.
Vacuum polarization in the ground states of bi-muonic helium atoms
Frolov, Alexei M.
2004-11-01
The energies and bound-state properties of the bi-muonic helium-3 and helium-4 atoms in their ground 11(S = 0)-states are determined to very high accuracy. It is shown that the lowest order QED (and relativistic) effects play a significantly larger role in the case of bi-muonic 3Heμ2 and 4Heμ2 atoms than in the two-electron He-atoms. In particular, the effect of vacuum polarization and corresponding energy shifts for the ground 11(S = 0)-states in the bi-muonic helium-3 and helium-4 atoms have been evaluated.
Physical Properties of Graphene-like Samples with Kekul\\'e and Vacuum Polarization Corrections
Martins, Ricardo S; Belich, Humberto; Helayël-Neto, José A
2016-01-01
Magnetic and thermodynamical properties of graphene-like materials, such as magnetization, magnetic susceptibility and specific heat, in a low-temperature regime are investigated by considering the effects of a Kekul\\'e scalar exchange and QED vacuum polarization corrections to the interparticle potential. The spin lattice calculations are carried out by means of Monte Carlo simulations. We present a number of comparative plots of all the physical quantities we have considered and a detailed analysis is presented to illustrate the main features and the variation profiles of the properties with the applied external magnetic field and temperature.
Graviton Loop Corrections to Vacuum Polarization in de Sitter in a General Covariant Gauge
Glavan, D; Prokopec, Tomislav; Woodard, R P
2015-01-01
We evaluate the one-graviton loop contribution to the vacuum polarization on de Sitter background in a 1-parameter family of exact, de Sitter invariant gauges. Our result is computed using dimensional regularization and fully renormalized with BPHZ counterterms, which must include a noninvariant owing to the time-ordered interactions. Because the graviton propagator engenders a physical breaking of de Sitter invariance two structure functions are needed to express the result. In addition to its relevance for the gauge issue this is the first time a covariant gauge graviton propagator has been used to compute a noncoincident loop. A number of identities are derived which should facilitate further graviton loop computations.
Nonlinear interaction of impulsive gravitational waves for the vacuum Einstein equations
Luk, Jonathan
2013-01-01
In this paper, we study the problem of the nonlinear interaction of impulsive gravitational waves for the Einstein vacuum equations. The problem is studied in the context of a characteristic initial value problem with data given on two null hypersurfaces and containing curvature delta singularities. We establish an existence and uniqueness result for the spacetime arising from such data and show that the resulting spacetime represents the interaction of two impulsive gravitational waves germinating from the initial singularities. In the spacetime, the curvature delta singularities propagate along 3-dimensional null hypersurfaces intersecting to the future of the data. To the past of the intersection, the spacetime can be thought of as containing two independent, non-interacting impulsive gravitational waves and the intersection represents the first instance of their nonlinear interaction. Our analysis extends to the region past their first interaction and shows that the spacetime still remains smooth away fro...
Indian Academy of Sciences (India)
Hari Prakash; Devendra K Singh
2010-03-01
It is shown that all optical polarization states of light except plane and circular polarization states undergo an intensity-dependent change in normal incidence of light in an isotropic nonlinear Kerr medium. This effect should be detectable and we propose an experiment for detecting nonlinear susceptibility involved in that part of nonlinear polarization, which depends on the polarization state of light also.
Tanaka, Masahito; Yagi-Watanabe, Kazutoshi; Yamada, Toru; Kaneko, Fusae; Nakagawa, Kazumichi
2006-02-01
We have developed an improved circular dichroism (CD) and linear dichroism (LD) simultaneous measurement system for the vacuum ultraviolet (VUV) region by polarization modulation techniques using a four-period Onuki-type crossed undulator as a polarized light source. The system has been constructed at the VUV beamline BL-5 in the electron storage ring TERAS, at AIST. Our improvements, in particular the adoption of an optical chopper as the detection method of incident light, have resulted in a flat baseline and a consequent simplification of the Mueller matrix calculation for our optical system. Based on the Mueller matrix calculation, we have successfully measured real VUV-CD and LD spectra of leucine films for wavelengths down to 160 nm with absolute optical constants. The obtained spectra show good consistency with spectra measured by conventional methods. Copyright 2006 Wiley-Liss, Inc.
Tests of hadronic vacuum polarization fits for the muon anomalous magnetic moment
Golterman, Maarten; Peris, Santiago
2013-01-01
We construct a physically motivated model for the isospin-one non-strange vacuum polarization function Pi(Q^2) based on a spectral function given by vector-channel OPAL data from hadronic tau decays for energies below the tau mass and a successful parametrization, employing perturbation theory and a model for quark-hadron duality violations, for higher energies. Using a covariance matrix and Q^2 values from a recent lattice simulation, we then generate fake data for Pi(Q^2) and use it to test fitting methods currently employed on the lattice for extracting the hadronic vacuum polarization contribution to the muon anomalous magnetic moment. This comparison reveals a systematic error much larger than the few-percent total error sometimes claimed for such extractions in the literature. In particular, we find that errors deduced from fits using a Vector Meson Dominance ansatz are misleading, typically turning out to be much smaller than the actual discrepancy between the fit and exact model results. The use of a ...
Quarkonium spectroscopy in a potential model with vacuum-polarization corrections
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Jena, S.N.
1980-05-01
We consider a potential model taking long-distance vacuum-polarization corrections as suggested by Poggio and Schnitzer, which enables one to interpolate between cc-bar, bb-bar, and tt-bar systems. Taking special care for the accuracy of the numerical integration near the origin, we have developed a numerical method to obtain the heavy-quark--antiquark bound states along with their leptonic widths. We obtain the above flavor-independent potential giving good agreement with the so-called experimental mass splitting of the 1S-2S states of the psi and UPSILON family with reasonable values of the quark-gluon coupling constant ..cap alpha../sub s/, which do not deviate very much from the quantum-chromodynamics value. We obtain some of the bound states of the hypothetical tt-bar family and observe that the effect of screening of the potential due to the vacuum-polarization cloud decreases with increase of the mass of the heavy quark forming the quarkonium.
Trapping polarization of light in nonlinear optical fibers: An ideal Raman polarizer
Kozlov, Victor V; Ania-Castanon, Juan Diego; Wabnitz, Stefan
2012-01-01
The main subject of this contribution is the all-optical control over the state of polarization (SOP) of light, understood as the control over the SOP of a signal beam by the SOP of a pump beam. We will show how the possibility of such control arises naturally from a vectorial study of pump-probe Raman interactions in optical fibers. Most studies on the Raman effect in optical fibers assume a scalar model, which is only valid for high-PMD fibers (here, PMD stands for the polarization-mode dispersion). Modern technology enables manufacturing of low-PMD fibers, the description of which requires a full vectorial model. Within this model we gain full control over the SOP of the signal beam. In particular we show how the signal SOP is pulled towards and trapped by the pump SOP. The isotropic symmetry of the fiber is broken by the presence of the polarized pump. This trapping effect is used in experiments for the design of new nonlinear optical devices named Raman polarizers. Along with the property of improved sig...
Optical polarization based logic functions (XOR or XNOR) with nonlinear Gallium nitride nanoslab.
Bovino, F A; Larciprete, M C; Giardina, M; Belardini, A; Centini, M; Sibilia, C; Bertolotti, M; Passaseo, A; Tasco, V
2009-10-26
We present a scheme of XOR/XNOR logic gate, based on non phase-matched noncollinear second harmonic generation from a medium of suitable crystalline symmetry, Gallium nitride. The polarization of the noncollinear generated beam is a function of the polarization of both pump beams, thus we experimentally investigated all possible polarization combinations, evidencing that only some of them are allowed and that the nonlinear interaction of optical signals behaves as a polarization based XOR. The experimental results show the peculiarity of the nonlinear optical response associated with noncollinear excitation, and are explained using the expression for the effective second order optical nonlinearity in noncollinear scheme.
Kinoshita, T
1999-01-01
The contribution of the $\\alpha^3$ single electron-loop vacuum-polarization diagrams to the Lamb shift of the muonic hydrogen has been evaluated recently by two methods. One uses the exact parametric representation of the vacuum-polarization function while the other relies on the Padé approximation method. High numerical precision of these calculations enables us to examine the accuracy of the Monte-Carlo integration as well as that of the Padé method applied to the Lamb shift problem.
Vacuum polarization and classical self-action near higher-dimensional defects
Energy Technology Data Exchange (ETDEWEB)
Grats, Yuri V.; Spirin, Pavel [Moscow State University, Department of Theoretical Physics, Faculty of Physics, Moscow (Russian Federation)
2017-02-15
We analyze the gravity-induced effects associated with a massless scalar field in a higher-dimensional spacetime being the tensor product of (d - n)-dimensional Minkowski space and n-dimensional spherically/cylindrically symmetric space with a solid/planar angle deficit. These spacetimes are considered as simple models for a multidimensional global monopole (if n ≥ 3) or cosmic string (if n = 2) with (d - n - 1) flat extra dimensions. Thus, we refer to them as conical backgrounds. In terms of the angular-deficit value, we derive the perturbative expression for the scalar Green function, valid for any d ≥ 3 and 2 ≤ n ≤ d - 1, and compute it to the leading order. With the use of this Green function we compute the renormalized vacuum expectation value of the field square left angle φ{sup 2}(x) right angle {sub ren} and the renormalized vacuum averaged of the scalar-field energy-momentum tensor left angle T{sub MN}(x) right angle {sub ren} for arbitrary d and n from the interval mentioned above and arbitrary coupling constant to the curvature ξ. In particular, we revisit the computation of the vacuum polarization effects for a non-minimally coupled massless scalar field in the spacetime of a straight cosmic string. The same Green function enables to consider the old purely classical problem of the gravity-induced self-action of a classical point-like scalar or electric charge, placed at rest at some fixed point of the space under consideration. To deal with divergences, which appear in consideration of the two problems, we apply the dimensional-regularization technique, widely used in quantum field theory. The explicit dependence of the results upon the dimensionalities of both the bulk and conical submanifold is discussed. (orig.)
Vacuum polarization in muonic atoms: the Lamb shift at low and medium Z
Energy Technology Data Exchange (ETDEWEB)
Karshenboim, S.G.; Ivanov, V.G.; Korzinin, E.Y. [D.I. Mendeleev Institute for Metrology (VNIIM), Saint Petersburg (Russian Federation); Karshenboim, S.G. [Max-Planck-Institut fur Quantenoptik, Garching (Germany); Ivanov, V.G. [Pulkovo Observatory, Saint Petersburg (Russian Federation)
2006-09-15
In muonic atoms the Uehling potential (an effect of a free electronic vacuum polarization loop) is responsible for the leading contribution to the Lamb shift causing the splitting of states with {delta}n = 0 and {delta}l {ne} 0. Here we consider the Lamb shift in the leading non-relativistic approximation, i.e., within an approach based on a certain Schroedinger equation. That is valid for low and medium Z as long as (Z{alpha}){sup 2} << 1. The results is a function of a few parameters, including {kappa} Z{alpha}m{sub {mu}}/m{sub e}, n and l. We present various asymptotics and in particular we study a region of validity of asymptotics with large and small {kappa}. Special attention is paid to circular states, which are considered in a limit of n >> 1. (authors)
The hadronic vacuum polarization contribution to $a_{\\mu}$ from full lattice QCD
Chakraborty, Bipasha; de Oliviera, P G; Koponen, J; Lepage, G P
2016-01-01
We determine the contribution to the anomalous magnetic moment of the muon from the $\\alpha^2_{\\mathrm{QED}}$ hadronic vacuum polarization diagram using full lattice QCD and including $u/d$ quarks with physical masses for the first time. We use gluon field configurations that include $u$, $d$, $s$ and $c$ quarks in the sea at multiple values of the lattice spacing, multiple $u/d$ masses and multiple volumes that allow us to include an analysis of finite-volume effects. We obtain a result for $a_{\\mu}^{\\mathrm{HVP,LO}}$ of $666(6)(12)$, where the first error is from the lattice calculation and the second includes systematic errors from missing QED and isospin-breaking effects and from quark-line disconnected diagrams. Our result implies a discrepancy between the experimental determination of $a_{\\mu}$ and the Standard Model of 3$\\sigma$.
Adler-Bell-Jackiw anomaly, the Nieh-Yan form, and vacuum polarization
Soo, C P
1999-01-01
We show from first principles, using explicitly invariant Pauli-Villars regularization of chiral fermions, that the Nieh-Yan form does contribute to the Adler-Bell-Jackiw (ABJ) anomaly for spacetimes with generic torsion, and comment on some of the implications. There are a number of interesting and important differences with the usual ABJ contributions in the absence of torsion. For dimensional reasons, the Nieh-Yan contribution is proportional to the square of the regulator mass. In spacetimes with flat vierbein but non-trivial torsion, the associated diagrams are actually vacuum polarization rather than triangle diagrams, and the Nieh-Yan contribution to the ABJ anomaly arises from the fact that axial torsion "photon" is not transverse.
Renormalized vacuum polarization on rotating warped AdS3 black holes
Ferreira, Hugo R C
2014-01-01
We compute the renormalized vacuum polarization of a massive scalar field in the Hartle-Hawking state on (2+1)-dimensional rotating, spacelike stretched black hole solutions to Topologically Massive Gravity, surrounded by a Dirichlet mirror that makes the state well defined. The Feynman propagator is written as a mode sum on the complex Riemannian section of the spacetime, and a Hadamard renormalization procedure is implemented by matching to a mode sum on the complex Riemannian section of a rotating Minkowski spacetime. No analytic continuation in the angular momentum parameter is invoked. Selected numerical results are given, demonstrating the numerical efficacy of the method. We anticipate that this method can be extended to wider classes of rotating black hole spacetimes, in particular to the Kerr spacetime in four dimensions.
Renormalized vacuum polarization on rotating warped AdS3 black holes
Ferreira, Hugo R. C.; Louko, Jorma
2015-01-01
We compute the renormalized vacuum polarization of a massive scalar field in the Hartle-Hawking state on (2 +1 )-dimensional rotating, spacelike stretched black hole solutions to topologically massive gravity, surrounded by a Dirichlet mirror that makes the state well defined. The Feynman propagator is written as a mode sum on the complex Riemannian section of the spacetime, and a Hadamard renormalization procedure is implemented by matching to a mode sum on the complex Riemannian section of a rotating Minkowski spacetime. No analytic continuation in the angular momentum parameter is invoked. Selected numerical results are given, demonstrating the numerical efficacy of the method. We anticipate that this method can be extended to wider classes of rotating black hole spacetimes, in particular to the Kerr spacetime in four dimensions.
Three-loop QED vacuum polarization and the four-loop muon anomalous magnetic moment
Baikov, P A
1995-01-01
Three--loop contributions to massive QED vacuum polarization are evaluated by a combination of analytical and numerical techniques. The first three Taylor coefficients, at small q^2, are obtained analytically, using d\\/--dimensional recurrence relations. Combining these with analytical input at threshold, and at large q^2, an accurate Pad\\'e approximation is obtained, for all q^2. Inserting this in the one--loop diagram for the muon anomalous magnetic moment, we find reasonable agreement with four--loop, single--electron--loop, muon--anomaly contributions, recently re--evaluated by Kinoshita, using 8--dimensional Monte--Carlo integration. We believe that our new method is at least two orders of magnitude more accurate than the Monte--Carlo approach, whose uncertainties appear to have been underestimated, by a factor of 6.
Vacuum polarization in the ground states of bi-muonic helium atoms
Energy Technology Data Exchange (ETDEWEB)
Frolov, Alexei M [Department of Chemistry, Queen' s University, Kingston, ON K7L 3N6 (Canada)
2004-11-28
The energies and bound-state properties of the bi-muonic helium-3 and helium-4 atoms in their ground 1{sup 1}(S = 0)-states are determined to very high accuracy. It is shown that the lowest order QED (and relativistic) effects play a significantly larger role in the case of bi-muonic {sup 3}He{mu}{sub 2} and {sup 4}He{mu}{sub 2} atoms than in the two-electron He-atoms. In particular, the effect of vacuum polarization and corresponding energy shifts for the ground 1{sup 1}(S 0)-states in the bi-muonic helium-3 and helium-4 atoms have been evaluated.
The hadronic vacuum polarization contribution to $a_{\\mu}$ from full lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Chakraborty, Bipasha [Glasgow U.; Davies, C. T.H. [Glasgow U.; de Oliviera, P. G. [Glasgow U.; Koponen, J. [Glasgow U.; Lepage, G. P. [Cornell U., LEPP; Van de Water, R. S. [Fermilab
2016-01-12
We determine the contribution to the anomalous magnetic moment of the muon from the $\\alpha^2_{\\mathrm{QED}}$ hadronic vacuum polarization diagram using full lattice QCD and including $u/d$ quarks with physical masses for the first time. We use gluon field configurations that include $u$, $d$, $s$ and $c$ quarks in the sea at multiple values of the lattice spacing, multiple $u/d$ masses and multiple volumes that allow us to include an analysis of finite-volume effects. We obtain a result for $a_{\\mu}^{\\mathrm{HVP,LO}}$ of $667(6)(12)$, where the first error is from the lattice calculation and the second includes systematic errors from missing QED and isospin-breaking effects and from quark-line disconnected diagrams. Our result implies a discrepancy between the experimental determination of $a_{\\mu}$ and the Standard Model of 3$\\sigma$.
Remarks on the static potential driven by vacuum nonlinearities in $D=3$ models
Gaete, Patricio
2016-01-01
Within the framework of the gauge-invariant, but path-dependent, variables formalism, we study the manifestations of vacuum electromagnetic nonlinearities in $D=3$ models. For this we consider both generalized Born-Infeld and Pagels-Tomboulis-like electrodynamics, as well as, an Euler-Heisenberg-like electrodynamics. We explicitly show that generalized Born-Infeld and Pagels-Tomboulis-like electrodynamics are equivalent, where the static potential profile contains a long-range (${\\raise0.5ex\\hbox{$\\scriptstyle 1$}\\kern-0.1em/\\kern-0.15em\\lower0.25ex\\hbox{$\\scriptstyle {{r^2}}$}}$-type) correction to the Coulomb potential. Interestingly enough, for an Euler-Heisenberg-like electrodynamics the interaction energy contains a linear potential, leading to the confinement of static charges.
On causality in nonlinear vacuum electrodynamics of the Pleba\\'nski class
Schellstede, Gerold O; Lämmerzahl, Claus
2016-01-01
We investigate the Pleba\\'nski class of electrodynamical theories, i.e., theories of nonlinear vacuum electrodynamics that derive from a Lorentz-invariant Lagrangian (or Hamiltonian). In any such theory the light rays are the lightlike geodesics of two optical metrics that depend on the electromagnetic background field. A set of necessary and sufficient conditions is found whose fulfillment secures that the optical metrics are causal in the sense that the light rays are lightlike or timelike with respect to the underlying space-time metric. Thereupon we derive conditions on the Lagrangian, or the Hamiltonian, of the theory such that the causality conditions are satisfied for all background fields. (The allowed values of the field strength tensor are those for which the excitation tensor is finite and real.) The general results are illustrated with several examples.
Directory of Open Access Journals (Sweden)
G.S. Vorobyov
2014-04-01
Full Text Available The article describes the experimental equipment and the results of investigations of nonlinear processes occurring during the excitation of electromagnetic oscillations in the resonant electron beam devices such as an orotron-generator of diffraction radiation. These devices are finding wide application in physics and microwave technology, now. A technique for experimental research, which bases on the using of the universal electro vacuum equipment diffraction radiation analyzer and the microprocessor system for collecting and processing data. The experimental investigations results of the energy and frequency characteristics for the most common modes of the excitation oscillations in the open resonant systems such as an orotron. The implementations on the optimum modes for the oscillations excitation in such devices were recommended.
SCOUT: a small vacuum chamber for nano-wire grid polarizer tests in the ultraviolet band
Landini, F.; Pancrazzi, M.; Totaro, M.; Pennelli, G.; Romoli, M.
2012-01-01
Within the Section of Astronomy of the Department of Physics and Astronomy of the University of Firenze, Italy), the XUVLab laboratory is active since 1998 dedicated to technological development, mainly UV oriented. The technological research is focused both on electronics and optics. Our last approach is dedicated to the development of innovative wiregrid polarizers optimized to work in transmission at 121.6 nm. The manufacturing of such optical devices requires advanced technological expertise and suitable experimental structures. First, nanotechnology capability is necessary, in order to build several tiny parallel conductive lines separated by tens of nanometers on wide areas to be macroscopically exploitable in an optical laboratory. Moreover, the characterization of such an advanced optical device has to be performed in vacuum, being air absorptive at 121.6 nm. A dedicated small vacuum chamber, SCOUT (Small Chamber for Optical UV Tests) was developed within our laboratory in order to perform practical and fast measurements. SCOUT hosts an optical bench and is equipped with several opening flanges, in order to be as flexible as possible. The flexibility that has been reached with SCOUT allows us to use the chamber beyond the goals it was thought for. It is exploitable by whatever compact (within 1 m) optical experiment that investigates the UV band of the spectrum.
Nonlinear observer to estimate polarization phenomenon in membrane distillation
Directory of Open Access Journals (Sweden)
Khoukhi Billal
2015-01-01
Full Text Available This paper presents a bi-dimensional dynamic model of Direct Contact Membrane Desalination (DCMD process. Most of the MD configuration processes have been modeled as steady-state one-dimensional systems. Stationary two-dimensional MD models have been considered only in very few studies. In this work, a dynamic model of a DCMD process is developed. The model is implemented using Matlab/Simulink environment. Numerical simulations are conducted for different operational parameters at the module inlets such as the feed and permeate temperature or feed and permeate flow rate. The results are compared with experimental data published in the literature. The work presents also a feed forward control that compensates the possible decrease of the temperature gradient by increasing the flow rate. This work also deals with a development of nonlinear observer to estimate temperature polarization inside the membrane. The observer gives a good profile and longitudinal temperature estimations and shows a good prediction of pure water flux production.
Olivier, Michel; Gagnon, Marc-Daniel; Piché, Michel
2015-03-09
A strategy to align a mode-locked fiber laser with nonlinear polarization rotation is presented. This strategy is based on measurements of the output polarization state. It is shown that, as the angle of a motorized polarization controller inside the cavity is swept, the laser eventually reaches a mode-locked regime and the values of the Stokes parameters undergo an abrupt change. The sensing of this sudden variation is thus used to detect the mode-locking condition and a feedback mechanism drives the alignment of the polarization controller to force mode locking.
Aoyama, T; Kinoshita, T; Nio, M
2008-01-01
This paper reports the tenth-order QED contribution to the g-2 of electron and muon from two gauge-invariant sets, Set I(g) and Set I(h). In the case of electron g-2 Set I(g) consists of 9 Feynman diagrams which have 4th-order vacuum-polarization loop containing another 4th-order vacuum-polarization loop. Set I(h) consists of 30 Feynman diagrams which have proper 6th-order vacuum-polarization loop containing a second-order vacuum-polarization loop. The results of numerical integration, including mass-dependent terms containing one closed loop of muon, are 0.028 597 (4) (alpha/pi)^5 for Set I(g) and 0.001 685 (13) (alpha/pi)^5 for Set I(h), respectively. We also report the contributions of Set I(g) and Set I(h) to the muon anomaly. Diagrams included are those containing electron, muon, and tau-lepton loops. Their sums are 2.640 9 (4) (alpha/pi)^5 and -0.564 8 (11) (alpha/pi)^5, respectively. The sum of contributions of Sets I(g) and I(h) containing only electron loops are in fair agreement with the recently ob...
Adkins, Gregory S; Salinger, M D; Wang, Ruihan
2015-01-01
We have calculated all contributions to the energy levels of parapositronium at order $m \\alpha^7$ coming from vacuum polarization corrections to processes involving virtual annihilation to two photons. This work is motivated by ongoing efforts to improve the experimental determination of the positronium ground-state hyperfine splitting.
Directory of Open Access Journals (Sweden)
Gregory S. Adkins
2015-07-01
Full Text Available We have calculated all contributions to the energy levels of parapositronium at order mα7 coming from vacuum polarization corrections to processes involving virtual annihilation to two photons. This work is motivated by ongoing efforts to improve the experimental determination of the positronium ground-state hyperfine splitting.
The Epstein–Glaser causal approach to the light-front QED{sub 4}. II: Vacuum polarization tensor
Energy Technology Data Exchange (ETDEWEB)
Bufalo, R., E-mail: rodrigo.bufalo@helsinki.fi [Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki (Finland); Instituto de Física Teórica (IFT/UNESP), UNESP - São Paulo State University, Rua Dr. Bento Teobaldo Ferraz 271, Bloco II Barra Funda, CEP 01140-070 São Paulo, SP (Brazil); Pimentel, B.M., E-mail: pimentel@ift.unesp.br [Instituto de Física Teórica (IFT/UNESP), UNESP - São Paulo State University, Rua Dr. Bento Teobaldo Ferraz 271, Bloco II Barra Funda, CEP 01140-070 São Paulo, SP (Brazil); Soto, D.E., E-mail: danielsb@ift.unesp.br [Instituto de Física Teórica (IFT/UNESP), UNESP - São Paulo State University, Rua Dr. Bento Teobaldo Ferraz 271, Bloco II Barra Funda, CEP 01140-070 São Paulo, SP (Brazil)
2014-12-15
In this work we show how to construct the one-loop vacuum polarization for light-front QED{sub 4} in the framework of the perturbative causal theory. Usually, in the canonical approach, it is considered for the fermionic propagator the so-called instantaneous term, but it is known in the literature that this term is controversial because it can be omitted by computational reasons; for instance, by compensation or vanishing by dimensional regularization. In this work we propose a solution to this paradox. First, in the Epstein–Glaser causal theory, it is shown that the fermionic propagator does not have instantaneous term, and with this propagator we calculate the one-loop vacuum polarization, from this calculation it follows the same result as those obtained by the standard approach, but without reclaiming any extra assumptions. Moreover, since the perturbative causal theory is defined in the distributional framework, we can also show the reason behind our obtaining the same result whether we consider or not the instantaneous fermionic propagator term. - Highlights: • We develop the Epstein–Glaser causal approach for light-front field theory. • We evaluate in detail the vacuum polarization at one-loop for the light-front QED. • We discuss the subtle issues of the Instantaneous part of the fermionic propagator in the light-front. • We evaluate the vacuum polarization at one-loop for the light-front QED with the Instantaneous fermionic part.
In-vacuum figure-8 undulator for hard X-rays with both horizontal and vertical polarization.
Tanaka, T; Maréchal, X M; Hara, T; Tanabe, T; Kitamura, H
1998-05-01
A figure-8 undulator of the in-vacuum type has been adopted as an insertion device for BL24XU, the Hyogo Beamline at SPring-8, to provide hard X-rays with both horizontal and vertical polarization instead of a tandem undulator consisting of horizontal and vertical undulators. The undulator will be operated with the gap almost fixed at 11.6 mm to provide the fundamental radiation with horizontal polarization at 9.5 keV and the 1.5th harmonic with vertical polarization at 14 keV.
Nonlinear response of metallic acGNR to an elliptically-polarized terahertz excitation field
Wang, Yichao
2016-01-01
We present a theoretical description of the nonlinear response induced by an elliptically-polarized terahertz beam normally-incident on intrinsic and extrinsic metallic armchair graphene nanorib- bons. Our results show that using a straightforward experimental setup, it should be possible to observe novel polarization-dependent nonlinearities at low excitation field strengths of the or- der of 10 4 V/m. At low temperatures the Kerr nonlinearities in extrinsic nanoribbons persist to significantly higher excitation frequencies than they do for linear polarizations, and at room tem- peratures, the third-harmonic nonlinearities are enhanced by 2-3 orders of magnitude. Finally, the Fermi-level and temperature dependence of the nonlinear response is characterized.
Tian, Jiajun; Yao, Yong; Sun, Yunxu; Yu, Xuelian; Chen, Deying
2009-08-17
A new multiwavelength Erbium-doped fiber laser is proposed and demonstrated. The intensity-dependent loss induced by nonlinear polarization rotation in a power-symmetric nonlinear optical loop mirror (NOLM) suppresses the mode competition of an Erbium-doped fiber and ensures stable multiwavelength operation at room temperature. The polarization state and its evolution conditions for stable multiwavelength operation in the ring laser cavity are discussed. The number and spectra region of output wavelength can be controlled by adjusting the work states of NOLM. (c) 2009 Optical Society of America
Shiraishi, Maresuke; Hikage, Chiaki; Namba, Ryo; Namikawa, Toshiya; Hazumi, Masashi
2016-08-01
The B -mode polarization in the cosmic microwave background (CMB) anisotropies at large angular scales provides compelling evidence for the primordial gravitational waves (GWs). It is often stated that a discovery of the GWs establishes the quantum fluctuation of vacuum during the cosmic inflation. Since the GWs could also be generated by source fields, however, we need to check if a sizable signal exists due to such source fields before reaching a firm conclusion when the B mode is discovered. Source fields of particular types can generate non-Gaussianity (NG) in the GWs. Testing statistics of the B mode is a powerful way of detecting such NG. As a concrete example, we show a model in which gauge field sources chiral GWs via a pseudoscalar coupling and forecast the detection significance at the future CMB satellite LiteBIRD. Effects of residual foregrounds and lensing B mode are both taken into account. We find the B -mode bispectrum "BBB" is in particular sensitive to the source-field NG, which is detectable at LiteBIRD with a >3 σ significance. Therefore the search for the BBB will be indispensable toward unambiguously establishing quantum fluctuation of vacuum when the B mode is discovered. We also introduced the Minkowski functional to detect the NGs. While we find that the Minkowski functional is less efficient than the harmonic-space bispectrum estimator, it still serves as a useful cross-check. Finally, we also discuss the possibility of extracting clean information on parity violation of GWs and new types of parity-violating observables induced by lensing.
Cross-polarized wave generation by effective cubic nonlinear optical interaction.
Petrov, G I; Albert, O; Etchepare, J; Saltiel, S M
2001-03-15
A new cubic nonlinear optical effect in which a linearly polarized wave propagating in a single quadratic medium is converted into a wave that is cross polarized to the input wave is observed in BBO crystal. The effect is explained by cascading of two different second-order processes: second-harmonic generation and difference frequency mixing.
Polarization of a probe laser beam due to nonlinear QED effects
Shakeri, Soroush; Kalantari, Seyed Zafarollah; Xue, She-Sheng
2017-01-01
Nonlinear QED interactions induce different polarization properties on a given probe beam. We consider the polarization effects caused by the photon-photon interaction in laser experiments, when a laser beam propagates through a constant magnetic field or collides with another laser beam. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian for both time-dependent and constant background field to explore the time evolution of the Stokes parameters Q, U, and V describing polarization. Assuming an initially linearly polarized probe laser beam, we also calculate the induced ellipticity and rotation of the polarization plane.
Non-self-conjugate mesons in a potential model with vacuum-polarization corrections
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Jena, S.N.
1980-10-01
We present a unified approach to the study of non-self-conjugate mesons including both light and heavy mesons in the framework of the vacuum-polarization-corrected flavor-independent potential. We have found that the quark-confining potential in the form of an almost equal admixture of vector and scalar parts successfully explains the S-wave hyperfine levels of the observed light and heavy mesons. Finally we calculate the electromagnetic mass differences of the heavy-quark mesons and obtain (K-bar*/sup 0/-K*/sup -/)=3.79 MeV, (K-bar/sup 0/-K/sup -/)=6 MeV, (D*/sup +//sub c/-D*/sup 0//sub c/)=2.4 MeV, (D/sup +//sub c/-D/sup 0//sub c/)=5.8 MeV, (D*/sup 0//sub b/-D*/sup -//sub b/)=3.547 MeV, and (D/sup 0//sub b/-D/sup -//sub b/)=3.558 MeV.
Shiraishi, Maresuke; Namba, Ryo; Namikawa, Toshiya; Hazumi, Masashi
2016-01-01
The B-mode polarization in the cosmic microwave background (CMB) anisotropies at large angular scales provides a smoking-gun evidence for the primordial gravitational waves (GWs). It is often stated that a discovery of the GWs establishes the quantum fluctuation of vacuum during the cosmic inflation. Since the GWs could also be generated by source fields, however, we need to check if a sizable signal exists due to such source fields before reaching a firm conclusion when the B-mode is discovered. Source fields of particular types can generate non-Gaussianity (NG) in the GWs. Testing statistics of the B-mode is a powerful way of detecting such NG. As a concrete example, we show a model in which a gauge field sources chiral GWs via a pseudoscalar coupling, and forecast the detection significance at the future CMB satellite LiteBIRD. Effects of residual foregrounds and lensing B-mode are both taken into account. We find the B-mode bispectrum "BBB" is in particular sensitive to the source-field NG, which is detec...
Why do non-gauge invariant terms appear in the vacuum polarization tensor?
Solomon, Dan
2015-01-01
It is will known that quantum field theory at the formal level is gauge invariant. However a calculation of the vacuum polarization tensor will include non-gauge invariant terms. These terms must be removed from the calculation in order to get a physically correct result. One common way to do this today is the technique of "dimensional regularization". It has recently been noted [2] that at one time a supersymmetric-like solution to the problem was explored - that is, the right combination of fields would cause the offending terms to cancel out. I will examine some of this early work and pose the question - why do the non-gauge invariant terms appear in the first place? I will show that this is due to an improper mathematical step in the formulation of the pertubative expansion. I will then show that when this step is corrected the result is gauge invariant. However a supersymmetric-like solution is still required to cancel out a divergent term.
Institute of Scientific and Technical Information of China (English)
Xiao Li; Zhang Wei; Huang Yi-Dong; Peng Jiang-De
2008-01-01
High nonlinear microstructure fibre (HNMF) is preferred in nonlinear fibre optics, especially in the applications of optical parametric effects, due to its high optical nonlinear coefficient. However, polarization dependent dispersion will impact the nonlinear optical parametric process in HNMFs. In this paper, modulation instability (MI) method is used to measure the polarization dependent dispersion of a piece of commercial HNMF, including the group velocity dispersion, the dispersion slope, the fourth-order dispersion and group birefringence. It also experimentally demonstrates the impact of the polarization dependent dispersion on the continuous wave supercontinuum (SC) generation. On one axis MI sidebands with symmetric frequency dctunings are generated, while on the other axis with larger MI frequency detuning, SC is generated by soliton self-frequency shift.
Yogo, A; Mori, M; Ogura, K; Esirkepov, T Zh; Pirozhkov, A S; Kanasaki, M; Sakaki, H; Fukuda, Y; Bolton, P R; Nishimura, H; Kondo, K
2015-01-01
Dependence of the energy of ions accelerated during interaction of the laser pulse obliquelly incident on the thin foil target on the laser polarization is studied experimentally and theoretically. We found that the ion energy being maximal for the p-polarization gradually decreases when the pulse becomes s-polarized. The experimentally found dependences of the ion energy are explained by invoking the anomalous electron heating which results in high electrostatic potential formation at the target surface. Anomalous heating of electrons beyond the energy of quiver motion in the laser field is described within the framework of theoretical model of driven oscillator with a step-like nonlinearity. We have demonstrated that the electron anomalous heating can be realized in two regimes: nonlinear resonance and stochastic heating, depending on the extent of stochasticity. We have found the accelerated ion energy scaling determined by the laser intensity, pulse duration, polarization angle and incident angle.
Nonlinear coupling of left and right handed circularly polarized dispersive Alfvén wave
Energy Technology Data Exchange (ETDEWEB)
Sharma, R. P., E-mail: rpsharma@ces.iitd.ac.in; Sharma, Swati, E-mail: swati.sharma704@gmail.com; Gaur, Nidhi, E-mail: nidhiphysics@gmail.com [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India)
2014-07-15
The nonlinear phenomena are of prominent interests in understanding the particle acceleration and transportation in the interplanetary space. The ponderomotive nonlinearity causing the filamentation of the parallel propagating circularly polarized dispersive Alfvén wave having a finite frequency may be one of the mechanisms that contribute to the heating of the plasmas. The contribution will be different of the left (L) handed mode, the right (R) handed mode, and the mix mode. The contribution also depends upon the finite frequency of the circularly polarized waves. In the present paper, we have investigated the effect of the nonlinear coupling of the L and R circularly polarized dispersive Alfvén wave on the localized structures formation and the respective power spectra. The dynamical equations are derived in the presence of the ponderomotive nonlinearity of the L and R pumps and then studied semi-analytically as well as numerically. The ponderomotive nonlinearity accounts for the nonlinear coupling between both the modes. In the presence of the adiabatic response of the density fluctuations, the nonlinear dynamical equations satisfy the modified nonlinear Schrödinger equation. The equations thus obtained are solved in solar wind regime to study the coupling effect on localization and the power spectra. The effect of coupling is also studied on Faraday rotation and ellipticity of the wave caused due to the difference in the localization of the left and the right modes with the distance of propagation.
Nishida, Yusuke
2014-10-01
We study massless Dirac fermions in a supercritical Coulomb potential with the emphasis on that its low-energy physics is universal and parametrized by a single quantity per supercritical angular momentum channel. This low-energy parameter with the dimension of length is defined only up to multiplicative factors and thus each supercritical channel exhibits the discrete scale invariance. In particular, we show that the induced vacuum polarization has a power-law tail whose coefficient is a sum of log-periodic functions with respect to the distance from the potential center. This coefficient can also be expressed in terms of the energy and width of so-called atomic collapse resonances. Our universal predictions on the vacuum polarization and its relationship to atomic collapse resonances shed light on the longstanding fundamental problem of quantum electrodynamics and can in principle be tested by graphene experiments with charged impurities.
Polarization effects in the non-linear Compton scattering
Ivanov, D Y; Serbo, V G
2005-01-01
We consider emission of a photon by an electron in the field of a strong laser wave. A probability of this process for circularly or linearly polarized laser photons and for arbitrary polarization of all other particles is calculated. We obtain the complete set of functions which describe such a probability in a compact invariant form. Besides, we discuss in some detail the polarization effects in the kinematics relevant to the problem of electron to photon conversion at photon-photon and electron-photon colliders.
THEORY OF ELECTROMAGNETIC DRIVE WITH ELEMENTARY PARTICLES CURRENT AND VACUUM POLARIZATION
Directory of Open Access Journals (Sweden)
Trunev A. P.
2016-01-01
Full Text Available The article discusses a model of rocket motor of electromagnetic type, consisting of a source of electromagnetic radio frequency oscillations and the conical cavity, in which electromagnetic waves are excited. We have created a multi-dimensional transient numerical model describing the process of establishing electromagnetic oscillations in the resonator, taking into account the finite conductivity of the walls. Separately, the standing waves in the cavity with conducting walls have been simulated. It is shown that the oscillations mode in the conducting resonator different from that in an ideal resonator, both in a case of steady and unsteady waves. We have built a dynamic model taking into account the thermal conductivity and electrical conductivity of the walls, waves and particles emission and vacuum polarization. We have also developed a dynamic model enables to optimize a thrust force on a considerable number of parameters without the involvement of the hypotheses about the physics of the phenomenon. We run the optimization of the operating parameters of the device, namely by the excitation frequency, the frequency of the modulating signal, the magnitude of heat losses of electromagnetic energy by thermal radiation in the IR spectrum, the parameters of forced heat transfer and the temperature dependence of the resistance of the material of the cavity walls. It is found that the pulse modulation greatly improves the efficiency of conversion of electromagnetic energy into thrust. The mechanism of formation of traction, adjusting the metrics of space-time, the current contribution of elementary particles, the Yang-Mills and electromagnetic fields is proposed. It is shown that the contribution of the elementary particles in the thrust force is proportional to the electrical conductivity of the system multiplied by Abraham force
Solookinejad, G.
2016-09-01
In this study, the linear and nonlinear susceptibility of a single-layer graphene nanostructure driven by a weak probe light and an elliptical polarized coupling field is discussed theoretically. The Landau levels of graphene can be separated in infrared or terahertz regions under the strong magnetic field. Therefore, by using the density matrix formalism in quantum optic, the linear and nonlinear susceptibility of the medium can be derived. It is demonstrated that by adjusting the elliptical parameter, one can manipulate the linear and nonlinear absorption as well as Kerr nonlinearity of the medium. It is realized that the enhanced Kerr nonlinearity can be possible with zero linear absorption and nonlinear amplification at some values of elliptical parameter. Our results may be having potential applications in quantum information science based on Nano scales devices.
Energy Technology Data Exchange (ETDEWEB)
Solookinejad, G., E-mail: ghsolooki@gmail.com
2016-09-15
In this study, the linear and nonlinear susceptibility of a single-layer graphene nanostructure driven by a weak probe light and an elliptical polarized coupling field is discussed theoretically. The Landau levels of graphene can be separated in infrared or terahertz regions under the strong magnetic field. Therefore, by using the density matrix formalism in quantum optic, the linear and nonlinear susceptibility of the medium can be derived. It is demonstrated that by adjusting the elliptical parameter, one can manipulate the linear and nonlinear absorption as well as Kerr nonlinearity of the medium. It is realized that the enhanced Kerr nonlinearity can be possible with zero linear absorption and nonlinear amplification at some values of elliptical parameter. Our results may be having potential applications in quantum information science based on Nano scales devices.
Energy Technology Data Exchange (ETDEWEB)
Tanaka, Masahito, E-mail: masahito-tanaka@aist.go.j [Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan); Yagi-Watanabe, Kazutoshi; Kaneko, Fusae [Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568 (Japan); Nakagawa, Kazumichi [Graduate School of Human Development and Environment, Kobe University, Tsurukabuto 3-11, Nada-ku, Kobe 657-8501 (Japan)
2010-08-15
The study of natural circular dichroism (CD) in the vacuum and extreme ultraviolet (VUV and EUV) regions has been providing us with chirality and structural information on biomolecules. We have developed the beamline BL5 at TERAS, Tsukuba, which is equipped with a compact Onuki-type polarizing undulator. This beamline is dedicated to measuring the CD spectra in the VUV and EUV regions for the photon energy region of 5-40 eV. The use of a polarization modulation technique with a polarizing undulator is essential for detecting a weak CD signal. Using this CD system, the natural CD spectrum has been measured in the EUV region up to 40 eV for the first time. In addition, the differences and the similarities between the CD spectra of four amino acid films (alanine, valine, leucine, and phenylalanine) in the VUV region up to 9.5 eV are determined.
Ivanov, D Y; Serbo, V G
2003-01-01
We consider emission of a photon by an electron in the field of a strong laser wave. Polarization effects in this process are important for a number of physical problems. We discuss a probability of this process for linearly polarized laser photons and for arbitrary polarization of all other particles. We obtain the complete set of functions which describe such a probability in a compact form.
Quantum nonlinear optics with polar J-aggregates in microcavities
Herrera, Felipe; Pachon, Leonardo A; Saikin, Semion K; Aspuru-Guzik, Alán
2014-01-01
We show that an ensemble of organic dye molecules with permanent electric dipole moments embedded in a microcavity can lead to strong optical nonlinearities at the single photon level. The strong long-range electrostatic interaction between chromophores due to their permanent dipoles introduces the desired nonlinearity of the light-matter coupling in the microcavity. We obtain the absorption spectra of a weak probe field under the influence of strong exciton-photon coupling with the cavity field. Using realistic parameters, we demonstrate that a single cavity photon can significantly modify the absorptive and dispersive response of the medium to a probe photon at a different frequency. Finally, we show that the system is in the regime of cavity-induced transparency with a broad transparency window for dye dimers. We illustrate our findings using pseudoisocyanine chloride (PIC) J-aggregates in currently-available optical microcavities.
Martin, D A
2015-01-01
We study evolution equations and stationary homogeneous solutions for electric and magnetic field amplitudes in a ring cavity with flat mirrors. The cavity is filled with a positive or negative refraction index material with third order Kerr-like electric nonlinearities and also magnetic nonlinearities, which can be relevant in metamaterials. We consider the degree of freedom of polarization in the incident beam. It is found that considering a magnetic nonlinearity increases the variety of possible qualitatively different solutions. A classification of solutions is proposed in terms of the number of bifurcations. The analysis can be useful for the implementation of optical switching or memory storage using ring cavities with non linear materials.
Four wave mixing as a probe of the vacuum
Tennant, Daniel M.
2016-06-01
Much attention has been paid to the quantum structure of the vacuum. Higher order processes in quantum electrodynamics are strongly believed to cause polarization and even breakdown of the vacuum in the presence of strong fields soon to be accessible in high intensity laser experiments. Less explored consequences of strong field electrodynamics include effects from Born-Infeld type of electromagnetic theories, a nonlinear electrodynamics that follows from classical considerations as opposed to coupling to virtual fluctuations. In this article, I will demonstrate how vacuum four wave mixing has the possibility to differentiate between these two types of vacuum responses: quantum effects on one hand and nonlinear classical extensions on the other.
Photon-photon interaction in structured QED vacuum
Hatsagortsyan, K Z
2012-01-01
In spatially structured strong laser fields, quantum electrodynamical vacuum behaves like a nonlinear Kerr medium with modulated third-order susceptibility where new coherent nonlinear effects arise due to modulation. We consider the enhancement of vacuum polarization and magnetization via coherent spatial vacuum effects in the photon-photon interaction process during scattering of a probe laser beam on parallel focused laser beams. Both processes of elastic and inelastic four wave-mixing in structured QED vacuum accompanied with Bragg interference are investigated. The phase-matching conditions and coherent effects in the presence of Bragg grating are analyzed for photon-photon scattering.
Electron acceleration in vacuum by a linearly-polarized ultra-short tightly-focused THz pulse
Salamin, Yousef I.
2017-09-01
The analytic expressions for the electric and magnetic fields of an ultra-short, tightly-focused, linearly-polarized laser pulse propagating in vacuum, derived elsewhere (Salamin, 2015) [13] to lowest-order of a truncated power-series expansion from vector and scalar potentials, are employed here for single electron acceleration calculations by THz radiation. It is shown that, while currently available THz peak powers cannot accelerate electrons appreciably, yet they result in substantial energy gradients. The field equations are used to show that an electron can be accelerated, in vacuum, from rest to 4.83 MeV by interaction with a single THz pulse of 1 TW power. Similarly, a 1 GW power pulse focused to sub-wavelength waist radius at focus is shown to accelerate the electron from rest to 5.76 keV.
High intensity polarization entangled source with a 2D nonlinear photonic crystal
DEFF Research Database (Denmark)
Wang, Qin
2009-01-01
We gave a proposal on how to use a piece of two-dimension (2D) nonlinear photonic crystal to generate a polarization entangled source. It provides not only has a high stability, but also a high entangled quality and a high intensity. Moreover, our scheme involves only practical experimental...
Cascaded Optical Buffer Based on Nonlinear Polarization Rotation in Semiconductor Optical Amplifiers
Institute of Scientific and Technical Information of China (English)
CHENG Mu; WU Chong-Qing; LIU Hua
2008-01-01
A cascaded buffer based on nonlinear polarization rotation in semiconductor optical amplifiers is proposed, which is suitable for fast reconfiguration of buffering time at picoseconds. With the proposed buffer, sixty different buffer times are demonstrated at 2.5 Gb/s.
Yan, Xiao-Qing; Liu, Zhi-Bo; Zhang, Xiao-Liang; Zang, Wei-Ping; Tian, Jian-Guo
2010-05-10
The normal elliptically polarized light Z-scan method is modified by adding a quarter-wave plate and an analyzer before the detector. The normalized transmittance formulas of modified elliptically polarized light Z-scan are obtained for media with negligible nonlinear absorption. Compared with normal linearly and elliptically polarized light Z-scan methods, an increase of sensitivity by a factor of larger than 4 is achieved for the real part of third-order susceptibility component's measurements using this modified elliptically polarized light Z-scan method. The analytical results are verified by studying the real part of independent susceptibility components of CS(2) liquid. Moreover, the potential application for cross-polarized wave generation is discussed. (c) 2010 Optical Society of America.
Electronic control of nonlinear-polarization-rotation mode locking in Yb-doped fiber lasers.
Shen, Xuling; Li, Wenxue; Yan, Ming; Zeng, Heping
2012-08-15
We demonstrate a convenient approach to precisely tune the polarization state of a nonlinear-polarization-rotation mode-locked Yb-doped fiber laser by using an electronic polarization controller. It is shown to benefit self-starting of mode-locking states, with precise tuning of the spectral profile, pulse width, and carrier-envelope offset frequency. The pulse width changed linearly by 0.78 ps in the time domain, and the carrier-envelope offset frequency shifted ~77.5 MHz in the frequency domain with a slight change of the driving voltage of 30.7 mV applied on the controller, corresponding to a polarization rotation of 0.0135π. This facilitated precise and automatic regeneration of a particular mode-locking state by setting an accurate voltage at the polarization controller with a programmed microprocessor control unit.
Doyuran, Adnan; Joshi, Chandrashekhar; Lim, Jae; Rosenzweig, James E; Tochitsky, Sergei Ya; Travish, Gil; Williams, Oliver
2005-01-01
An Inverse Compton Scattering (ICS) experiment investigating the polarized harmonic production in the nonlinear regime has begun which will utilize the existing terawatt CO2 laser system and 15 MeV photoinjector in the Neptune Laboratory at UCLA. A major motivation for a source of high brightness polarized x-rays is the production of polarized positrons for use in future linear collider experiments. Analytical calculations have been performed to predict the angular and frequency spectrums for various polarizations and different scattering angles. Currently, the experiment is running and we report the set-up and initial results. The advantages and limitations of using a high laser vector potential, ao, in an ICS-based polarized positron source are expected to be revealed with further measurement of the harmonic spectrum and angular characteristics.
Ivanov, D Y; Serbo, V G
2003-01-01
We consider emission of a photon by an electron in the field of a strong laser wave. Polarization effects in this process are important for a number of physical problems. We discuss a probability of this process for circularly polarized laser photons and for arbitrary polarization of all other particles. We obtain the complete set of functions which describe such a probability in a compact covariant form. Besides, we discuss an application of the obtained formulas to the problem of electron -> photon conversion at photon-photon and photon-electron colliders.
Large amplitude nonlinear structures in the nighttime polar mesosphere
Maharaj, Shimul K.; Bharuthram, Ramashwar; Singh Lakhina, Gurbax; Muralikrishna, Polinaya; Singh, Satyavir
2016-07-01
The existence of large amplitude potential structures will be investigated for a plasma composed of negative ions, positive ions, electrons and an additional fourth component of charged (usually positive) nano-sized ions in an attempt to model the plasma composition in the nighttime polar mesosphere (˜80 - 90 km altitude) [1]. The fourth ionic component becomes positively charged if there is a high enough concentration of negative ions which are sufficiently heavy. The positive charge on the fourth component can be explained by the capture of currents, and is not a result of photo-emission and secondary electron emission processes. Consequently, if the negative ions are much lighter, then the fourth ion component will become negatively charged. The charged ion species will be treated as inertial species which are cold or adiabatic, whilst the electrons will be considered to be Boltzmann-distributed (isothermal). Taking into consideration not only the dynamics of the heaviest species (dust-acoustic) but also the lighter ions (ion-acoustic), the theoretical study will use the Sagdeev pseudo-potential formalism to explore the existence of arbitrary amplitude solitons and double layer potential structures. [1] Observations of positively charged nanoparticles in the nighttime polar mesosphere, M. Rapp, J. Hedin, I. Strelnikova, M. Friederich, J. Gumbel, and F.˜J. Lübken, Geophys. Res. Letters. 32, L23821, doi:10.1029/2005GL024676 (2005).
S-polarized nonlinear surface and guided waves in an asymmetric layered structure
Energy Technology Data Exchange (ETDEWEB)
Mihalache, D.; Totia, H.
1983-08-01
An exact solution of Maxwell's equations is found, corresponding to s-polarized nonlinear surface and guided waves in an asymmetric layered structure. The system under consideration consists of a film with dielectric constant epsilon/sub 2/ bounded at the negative-z side by a linear medium with dielectric constant epsilon/sub 1/ and at the positive -z side by a nonlinear substrate characterized by the diagonal dielectric tensor epsilon/sub 11/ = epsilon/sub 22/ = epsilon/sub 33/ = epsilon/sub 0/ + ..cap alpha.. absolute value of E-vector/sup 2/, ..cap alpha.. > 0 (a selffocussing medium). We predict bistable states of s-polarized nonlinear surface and guided waves provided that the power flow in the wave is the control parameter.
Castro-Lopez, Marta; Brinks, Daan; Sapienza, Riccardo; van Hulst, Niek F
2011-11-09
Resonant optical antennas are ideal for nanoscale nonlinear optical interactions due to their inherent strong local field enhancement. Indeed second- and third-order nonlinear response of gold nanoparticles has been reported. Here we compare the on- and off-resonance properties of aluminum, silver, and gold nanoantennas, by measuring two-photon photoluminescence. Remarkably, aluminum shows 2 orders of magnitude higher luminescence efficiency than silver or gold. Moreover, in striking contrast to gold, the aluminum emission largely preserves the linear incident polarization. Finally, we show the systematic resonance control of two-photon excitation and luminescence polarization by tuning the antenna width and length independently. Our findings point to aluminum as a promising metal for nonlinear plasmonics.
Nonlinear polarization of ionic liquids: theory, simulations, experiments
Kornyshev, Alexei
2010-03-01
Room temperature ionic liquids (RTILs) composed of large, often asymmetric, organic cations and simple or complex inorganic or organic anions do not freeze at ambient temperatures. Their rediscovery some 15 years ago is widely accepted as a ``green revolution'' in chemistry, offering an unlimited number of ``designer'' solvents for chemical and photochemical reactions, homogeneous catalysis, lubrication, and solvent-free electrolytes for energy generation and storage. As electrolytes they are non-volatile, some can sustain without decomposition up to 6 times higher voltages than aqueous electrolytes, and many are environmentally friendly. The studies of RTILs and their applications have reached a critical stage. So many of them can be synthesized - about a thousand are known already - their mixtures can further provide ``unlimited'' number of combinations! Thus, establishing some general laws that could direct the best choice of a RTIL for a given application became crucial; guidance is expected from theory and modelling. But for a physical theory, RTILs comprise a peculiar and complex class of media, the description of which lies at the frontier line of condensed matter theoretical physics: dense room temperature ionic plasmas with ``super-strong'' Coulomb correlations, which behave like glasses at short time-scale, but like viscous liquids at long-time scale. This talk will introduce RTILs to physicists and overview the current understanding of the nonlinear response of RTILs to electric field. It will focus on the theory, simulations, and experimental characterisation of the structure and nonlinear capacitance of the electrical double layer at a charged electrode. It will also discuss pros and contras of supercapacitor applications of RTILs.
Ultra-High-Vacuum Problem for 200 keV Polarized Electron Gun with NEA-GaAs Photocathode
Nakanishi, T; Kuwahara, M; Naniwa, K; Okumi, S; Yamamoto, M; Yamamoto, N; Yasui, K
2004-01-01
For a polarized electron source based on photoemission from GaAs, a NEA (Negative Electron Affinity) surface makes an indispensable role to extract polarized electrons in conduction band into vacuum. The NEA surface is also considered as a best surface to provide a beam with a minimum initial beam-emittance. However, the NEA surface state is realized by a mono-layer of electric dipole moment (that is Ga(-)-Cs(+)) formed at the surface and thus it is easily degraded by desorption of harmful residual gas, desorption of harmful gas created by field emission from HV-cathodes and ion back-bombardment. In order to reduce the effects of (a) and (c), extremely good UHV is required. Presently total pressure of 4·10-12
Pair Production, Vacuum Polarization and Anomaly in (A)dS and Charged Black Holes
Kim, Sang Pyo
2016-01-01
We explore the connection between the distribution of particles spontaneously produced from an electric field or black hole and the vacuum persistence, twice the imaginary part of the one-loop effective action. Employing the reconstruction conjecture, we find the effective action for the Bose-Einstein or Fermi-Dirac distribution. The Schwinger effect in ${\\rm AdS}_2$ is computed via the phase-integral method in the static coordinates. The Hawking radiation and Schwinger effect of a charged black hole is rederived and interpreted via the phase-integral. Finally, we discuss the relation between the vacuum persistence and the trace or gravitational anomalies.
Misawa, Tetsuro; Yokoyama, Takehito; Murakami, Shuichi
2012-02-01
Recent photoelectron spectroscopy experiments have revealed the presence of the Dirac cone on the surface of the topological insulator and its spin-splitting due to the spin-orbit interaction. In general, on spin-orbit coupled systems, electric fields induce spin polarizations as linear and nonlinear responses. Here we investigate the inverse Faraday effect on the surface of the topological insulator. The inverse Faraday effect is a non-linear optical effect where a circularly polarized light induces a dc spin polarization. We employ the Keldysh Green's function method to calculate the induced spin polarization and discuss its frequency dependence. In particular, in the low frequency limit, our analytical result gives the spin polarization proportional to the frequency and the square of the lifetime. As for the finite frequency regime, we employ numerical methods to discuss the resonance due to interband transitions. We also discuss the photogalvanic effect, where an illumination of a circular polarized light generates the dc charge current. Lastly, we evaluate those quantities with realistic parameters.[4pt] [1] T. Misawa, T. Yokoyama, S. Murakami, Phys. Rev. B84, 165407 (2011).
De Mello, E R B
2002-01-01
In this paper we consider the presence of the Wu-Yang magnetic monopole in the global monopole spacetime and their influence on the vacuum polarization effects around these two monopoles placed together. According to Wu-Yang [Nucl. Phys. {\\bf B107}, 365 (1976)] the solution of the Klein-Gordon equation in such an external field will not be an ordinary function but, instead, {\\it section}. Because of the peculiar radial symmetry of the global monopole spacetime, it is possible to cover its space section by two overlapping regions, needed to define the singularity free vector potential, and to study the quantum effects due to a charged scalar field in this system. In order to develop this analysis we construct the explicit Euclidean scalar Green {\\it section} associated with a charged massless field in a global monopole spacetime in the presence of the Abelian Wu-Yang magnetic monopole. Having this Green section it is possible to study the vacuum polarization effects. We explicitly calculate the renormalized va...
Implication of the polarization force on the self-similar expansion of a dusty plasma into vacuum
Bentabet, Karima; Tribeche, Mouloud
2017-01-01
The effects of the polarization force on the self-similar expansion into vacuum of an unmagnetized, collisionless dusty plasma are addressed. It is found that the polarization force may drastically influence the general trends of the self-similar expansion. It is noticed that when the polarization force dominates over the electrical one, the self-similar expansion of the dusty plasma cannot set in because the net force experienced by the dust grains is not a restoring force. Dust wave breaking and inherent dust bunching then occur preventing therefore the expansion of the dust grains. For any value of the polarization parameter R ranging from zero to a critical value Rcr , the sound-speed increases as the dust number density increases. As R increases, the values of the plasma sound-speed are shifted towards higher values before decreasing beyond the critical value Rcr . As R increases from zero to Rc, the plasma expansion becomes faster compared to those of the other cases, and larger velocities are communicated to the dust grains. This is attributed to the fact that as R increases from 0 to Rcr , the electrostatic potential and thus the electric field are sustained over a larger distance allowing therefore the dust particles to expand over a much farther distance.
Colbert, Keegan; Naraghi, Mohammad; Boyd, James G.
2017-02-01
This paper presents a model and computational method to predict the steady-state performance of thermal flexure microactuators at high input powers and various levels of partial vacuum. The model accounts for nonlinear temperature dependence of material properties, heat loss due to radiation, and intra-device heat transfer by conduction across an air gap. The model is validated by comparing the model predictions with the experimentally measured voltage, current, and displacement at standard conditions, prior to adjusting for partial vacuum. In order to understand the effect of nonlinearities on model reliability, the predictions of six additional hypothetical models are considered where (1) intra-device heat transfer is neglected, (2) radiation is neglected, (3) the thermal conductivity of silicon is assumed to be temperature-independent, (4) the thermal conductivity of air is assumed to be temperature-independent, (5) the electrical resistivity of silicon is assumed to be linear in temperature, and (6) the thermal expansion coefficient of silicon is assumed to be temperature-independent. All factors except radiation were shown to have a significant influence on the device performance especially at high input powers. The experimentally validated full model is then employed to predict the effect of reduced air pressure on the displacement and heat transfer properties of the actuator. This aspect of the study targets applications of thermal actuators in controlled environments such as space applications, actuators used for in situ micropositioning and tensile testing inside electron microscopy chambers, or actuators incorporated into the design of MEMS resonators. It was demonstrated that the maximum actuator displacement is not a linear function of reduced pressure and that it reaches a maximum at a certain partial vacuum level.
Zhu, Chengjie; Huang, Guoxiang
2011-11-07
We study linear and nonlinear propagations of probe and signal pulses in a multiple quantum-well structure with a four-level, double Λ-type configuration. We show that slow, mutually matched group velocities and giant Kerr nonlinearity of the probe and the signal pulses may be achieved with nearly vanishing optical absorption. Based on these properties we demonstrate that two-qubit quantum polarization phase gates can be constructed and highly entangled photon pairs may be produced. In addition, we show that coupled slow-light soliton pairs with very low generation power can be realized in the system.
Gravitational vacuum polarization; 3, energy conditions in the (1+1) Schwarzschild spacetime
Visser, M
1996-01-01
Building on a pair of earlier papers, I investigate the various point-wise and averaged energy conditions for the quantum stress-energy tensor corresponding to a conformally-coupled massless scalar field in the in the (1+1)-dimensional Schwarzschild spacetime. Because the stress-energy tensors are analytically known, I can get exact results for the Hartle--Hawking, Boulware, and Unruh vacua. This exactly solvable model serves as a useful sanity check on my (3+1)-dimensional investigations wherein I had to resort to a mixture of analytic approximations and numerical techniques. Key results in (1+1) dimensions are: (1) NEC is satisfied outside the event horizon for the Hartle--Hawking vacuum, and violated for the Boulware and Unruh vacua. (2) DEC is violated everywhere in the spacetime (for any quantum state not just the standard vacuum states).
Hasan, Md. Rabiul; Anower, Md. Shamim; Hasan, Md. Imran
2016-05-01
A simple hexagonal photonic crystal fiber is proposed to simultaneously achieve ultrahigh birefringence, large nonlinear coefficient, and two zero dispersion wavelengths (ZDWs). The finite element method with circular perfectly matched layer boundary condition is used to simulate the designed structure. Simulation results show that it is possible to achieve two closely lying ZDWs of 1.08 and 1.29 μm for x-polarization with 0.88 and 1.20 μm for y-polarization modes, respectively. In addition, an ultrahigh birefringence of 3.15×10-2 and a high nonlinear coefficient of 58 W-1 km-1 are also obtained at the excitation wavelength of 1.55 μm. The proposed fiber can have important applications in supercontinuum generation, parametric amplification, four-wave mixing, and optical sensors design.
Derkowska-Zielinska, Beata
2017-02-01
The influence of solvent polarity on nonlinear optical properties of tris-(8-hydroxyquinoline)-aluminum (Alqsub>3sub>) was investigated by the degenerate four-wave mixing method at the 532 nm. It was obtained that the effective values of the third-order nonlinear optical susceptibility (χeff⟨3⟩) and the second-order hyperpolarizability (γsub>effsub>) of Alqsub>3sub> depend on the solvent polarity. Additionally, it was found that Alqsub>3sub> dissolved in dimethyl sulfoxide has the highest values of χeff⟨3⟩ and γsub>effsub>. Furthermore, two Stegeman's figures of merit were also calculated. The obtained results suggest that Alqsub>3sub> is also promising material for application in all-optical signal processing devices.
León-Montiel, R de J; Yuen-Zhou, Joel
2016-01-01
The classical or quantum nature of optical spectroscopy signals is a topic that has attracted great attention recently. Spectroscopic techniques have been classified as quantum or classical depending on the light-source used in their implementations. In this way, experiments performed with quantum light---such as entangled photon pairs---have been labeled as quantum spectroscopies, whereas those performed with coherent laser pulses are generally referred to as classical ones. In this work, we highlight the fact that typical laser-spectroscopy signals should sometimes be deemed quantum too, as they contain information about the quantum vacua of the modes that interact with the sample. Using a minimalistic model, namely frequency-integrated pump-probe spectroscopy, we demonstrate that vacuum contributions can be expressed as a correction term to the \\emph{classical} pump-probe signals, which scales linearly with the intensity of the pump field. Remarkably, we show that these vacuum contributions may not be negl...
Polarization effects and nonlinear switching in fiber figure-eight lasers.
Stentz, A J; Boyd, R W
1994-09-15
We have developed a novel experimental procedure that allows us to quantify how polarization effects determine the passive mode locking of an optical fiber figure-eight laser. Based on our measurements, we have performed numerical simulations demonstrating that the nonlinear switching within this laser operates in a manner contrary to that described by the conventional theory of passive mode locking with a fast saturable absorber.
Attosecond nonlinear polarization and light-matter energy transfer in solids.
Sommer, A; Bothschafter, E M; Sato, S A; Jakubeit, C; Latka, T; Razskazovskaya, O; Fattahi, H; Jobst, M; Schweinberger, W; Shirvanyan, V; Yakovlev, V S; Kienberger, R; Yabana, K; Karpowicz, N; Schultze, M; Krausz, F
2016-05-23
Electric-field-induced charge separation (polarization) is the most fundamental manifestation of the interaction of light with matter and a phenomenon of great technological relevance. Nonlinear optical polarization produces coherent radiation in spectral ranges inaccessible by lasers and constitutes the key to ultimate-speed signal manipulation. Terahertz techniques have provided experimental access to this important observable up to frequencies of several terahertz. Here we demonstrate that attosecond metrology extends the resolution to petahertz frequencies of visible light. Attosecond polarization spectroscopy allows measurement of the response of the electronic system of silica to strong (more than one volt per ångström) few-cycle optical (about 750 nanometres) fields. Our proof-of-concept study provides time-resolved insight into the attosecond nonlinear polarization and the light-matter energy transfer dynamics behind the optical Kerr effect and multi-photon absorption. Timing the nonlinear polarization relative to the driving laser electric field with sub-30-attosecond accuracy yields direct quantitative access to both the reversible and irreversible energy exchange between visible-infrared light and electrons. Quantitative determination of dissipation within a signal manipulation cycle of only a few femtoseconds duration (by measurement and ab initio calculation) reveals the feasibility of dielectric optical switching at clock rates above 100 terahertz. The observed sub-femtosecond rise of energy transfer from the field to the material (for a peak electric field strength exceeding 2.5 volts per ångström) in turn indicates the viability of petahertz-bandwidth metrology with a solid-state device.
Attosecond nonlinear polarization and light-matter energy transfer in solids
Sommer, A.; Bothschafter, E. M.; Sato, S. A.; Jakubeit, C.; Latka, T.; Razskazovskaya, O.; Fattahi, H.; Jobst, M.; Schweinberger, W.; Shirvanyan, V.; Yakovlev, V. S.; Kienberger, R.; Yabana, K.; Karpowicz, N.; Schultze, M.; Krausz, F.
2016-06-01
Electric-field-induced charge separation (polarization) is the most fundamental manifestation of the interaction of light with matter and a phenomenon of great technological relevance. Nonlinear optical polarization produces coherent radiation in spectral ranges inaccessible by lasers and constitutes the key to ultimate-speed signal manipulation. Terahertz techniques have provided experimental access to this important observable up to frequencies of several terahertz. Here we demonstrate that attosecond metrology extends the resolution to petahertz frequencies of visible light. Attosecond polarization spectroscopy allows measurement of the response of the electronic system of silica to strong (more than one volt per ångström) few-cycle optical (about 750 nanometres) fields. Our proof-of-concept study provides time-resolved insight into the attosecond nonlinear polarization and the light-matter energy transfer dynamics behind the optical Kerr effect and multi-photon absorption. Timing the nonlinear polarization relative to the driving laser electric field with sub-30-attosecond accuracy yields direct quantitative access to both the reversible and irreversible energy exchange between visible-infrared light and electrons. Quantitative determination of dissipation within a signal manipulation cycle of only a few femtoseconds duration (by measurement and ab initio calculation) reveals the feasibility of dielectric optical switching at clock rates above 100 terahertz. The observed sub-femtosecond rise of energy transfer from the field to the material (for a peak electric field strength exceeding 2.5 volts per ångström) in turn indicates the viability of petahertz-bandwidth metrology with a solid-state device.
Chen, Hong; Huang, Xuanqi; Fu, Houqiang; Lu, Zhijian; Zhang, Xiaodong; Montes, Jossue A.; Zhao, Yuji
2017-05-01
We report the basic nonlinear optical properties, namely, two-photon absorption coefficient ( β ), three-photon absorption coefficient ( γ ), and Kerr nonlinear refractive index ( n kerr), of GaN crystals in polar c-plane, nonpolar m-plane, and semipolar ( 20 21 ¯ ) plane orientations. A typical Z-scan technique was used for the measurement with a femtosecond Ti:S laser from wavelengths of 724 nm to 840 nm. For the two-photon absorption coefficient ( β ), similar values were obtained for polar, nonpolar, and semipolar samples, which are characterized to be ˜0.90 cm/GW at 724 nm and ˜0.65 cm/GW at 730 nm for all the three samples. For the Kerr nonlinear refractive index ( n kerr), self-focusing features were observed in this work, which is different from previous reports where self-defocusing features were observed on GaN in the visible and near-UV spectral regions. At 724 nm, n kerr was measured to be ˜2.5 0 × 10 - 14 cm 2 / W for all three samples. Three-photon absorption coefficients ( γ ) were also determined, which were found to be consistent with previous reports. This study provides valuable information on the basic nonlinear optical properties of III-nitride semiconductors, which are vital for a wide range of applications such as integrated photonics and quantum photonics.
Constructive role of sensors nonlinearities in the acquisition of partially polarized speckle images
Energy Technology Data Exchange (ETDEWEB)
Delahaies, Agnes; Rousseau, David; Chapeau-Blondeau, Francois [Laboratoire d' Ingenierie des Systemes Automatises (LISA), Universite d' Angers, 62 avenue Notre Dame du Lac, 49000 Angers (France); Gindre, Denis, E-mail: david.rousseau@univ-angers.f [Laboratoire des Proprietes Optiques des Materiaux et Applications (POMA), Universite d' Angers, 2 boulevard Lavoisier, 49000 Angers (France)
2010-02-01
We study the impact of the level of the speckle noise on data acquisition in a partially polarized coherent imaging system with the presence of a nonlinearity in the imaging sensor characteristic. In perfectly linear acquisition conditions, due to the essentially multiplicative action of the speckle, the image contrast is unchanged as the speckle noise level increases, and so it has no impact on the quality of the acquired images. On the contrary, in nonlinear conditions the acquisition is affected by the speckle noise level. However, this effect of the speckle is not always detrimental. We show that, in definite nonlinear conditions, there is usually an optimal level of the speckle noise that leads to a maximum quality of the acquired images. We theoretically analyze such nonlinear regimes with partially polarized speckled images. We specifically exhibit the existence of an optimal speckle noise level in the interesting case of images realized only by a depolarization contrast. Illustrations are given with a simple 1-bit hard limiter and binary images. Then, we propose and discuss as perspectives an experimental optical setup to confront theory and experiment.
Gamma ray vortices from nonlinear inverse Compton scattering of circularly polarized light
Taira, Yoshitaka; Katoh, Masahiro
2016-01-01
Inverse Compton scattering (ICS) is an elemental radiation process that produces high-energy photons both in nature and in the laboratory. Non-linear ICS is a process in which multiple photons are converted to a single high-energy photon. Here, we theoretically show that the photon produced by non-linear ICS of circularly polarized photons is a vortex, which means that it possesses a helical wave front and carries orbital angular momentum. Our work explains a recent experimental result regarding non-linear Compton scattering that clearly shows an annular intensity distribution as a remarkable feature of a vortex beam. Our work implies that gamma ray vortices should be produced in various situations in astrophysics in which high-energy electrons and intense circularly polarized light fields coexist. They should play a critical role in stellar nucleosynthesis. Non-linear ICS is the most promising radiation process for realizing a gamma ray vortex source based on currently available laser and accelerator technol...
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Jena, S.N.
1980-06-01
Within the framework of the Poggio-Schnitzer flavor-independent static-potential model with long-distance vacuum-polarization correction, we analyze the Lorentz-Dirac structure of the confinement potential with reference to the charmonium hyperfine splittings. In view of the questionable existence and/or doubtful identity of the X(2830) and chi(3455) states, we give preference to the Lorentz-Dirac character of the confinement potential in the form of an approximately equal admixture of scalar and vector components with no anomalous moment. This in turn predicts the /sup 1/S/sub 0/ partners of psi and psi' to be near the 3.0- and 3.6-GeV mass regions, respectively. This also suggests the /sup 1/P/sub 1/ state of charmonium is to be found above the /sup 3/P/sub 0/ state near the mass region of 3.48 GeV.
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Jena, S.N.
1981-08-01
Phenomenological evidence from meson spectroscopy is presented to support the view that a unified description of bound light- and heavy-quark systems is possible within the scope of a nonrelativistic-potential-model approach. The vacuum-polarization-corrected potential with its confinement part in the form of an approximately equal admixture of vector and scalar components is found to be a suitable one for the purpose. The overall systematics of the predictions based on this potential model for the meson masses, fine-hyperfine splittings, leptonic decay widths, and the Regge slopes are observed to be consistent with the premise that the forces between quarks and antiquarks are independent of the quark flavors.
Nuclear recoil and vacuum-polarization effects on the binding energies of supercritical H-like ions
Aleksandrov, Ivan A; Shabaev, Vladimir M
2015-01-01
The Dirac Hamiltonian including nuclear recoil and vacuum-polarization operators is considered in a supercritical regime Z > 137. It is found that the nuclear recoil operator derived within the Breit approximation regularizes the Hamiltonian for the point-nucleus model and allows the ground state level to go continuously down and reach the negative energy continuum at a critical value Zcr = 145. If the Hamiltonian contains both the recoil operator and the Uehling potential, the 1s level reaches the negative energy continuum at Zcr = 144. The corresponding calculations for the excited states have been also performed. This study shows that, in contrast to previous investigations, a point-like nucleus can have effectively the charge Z > 137.
Akram, F; Gutierrez-Guerrero, L X; Masud, B; Rodriguez-Quintero, J; Calcaneo-Roldan, C; Tejeda-Yeomans, M E
2012-01-01
We study chiral symmetry breaking for fundamental charged fermions coupled electromagnetically to photons with the inclusion of four-fermion contact self-interaction term. We employ multiplicatively renormalizable models for the photon dressing function and the electron-photon vertex which minimally ensures mass anomalous dimension = 1. Vacuum polarization screens the interaction strength. Consequently, the pattern of dynamical mass generation for fermions is characterized by a critical number of massless fermion flavors above which chiral symmetry is restored. This effect is in diametrical opposition to the existence of criticality for the minimum interaction strength necessary to break chiral symmetry dynamically. The presence of virtual fermions dictates the nature of phase transition. Miransky scaling laws for the electromagnetic interaction strength and the four-fermion coupling, observed for quenched QED, are replaced by a mean-field power law behavior corresponding to a second order phase transition. T...
Vacuum Polarization of Twisted Scalars in a Non-simply Connected Space-time and Its Effects
Institute of Scientific and Technical Information of China (English)
吴普训; 余洪伟
2002-01-01
The vacuum polarization due to twisted scalar fields is investigated in a non-simply connected space time. It is found that some photon modes acquire an imaginary topological mass, thus travelling at a superluminal speed.Topological bi-refringence is expected for photons propagating perpendicularly to the compactification direction.The effect of a topological photon mass on the static properties of electromagnetic fields is also considered for the cases of both twisted and untwisted scalar fields. Our result shows that in the untwisted case the magnetic field is screened along the radial direction for massive photon modes, while in the twisted case no screening occurs and the magnetic fields merely oscillate.
Vacuum polarization and classical self-action near higher-dimensional defects
Grats, Yuri V
2016-01-01
We analyze the gravity-induced effects associated with a massless scalar field in a higher-dimensional spacetime being the tensor product of $(d-n)$-dimensional Minkowski space and $n$-dimensional spherically/cylindrically-symmetric space with a solid/planar angle deficit. These spacetimes are considered as simple models for a multidimensional global monopole (if \\mbox{$n\\geqslant 3$}) or cosmic string (if $n=2$) with $(d-n-1)$ flat extra dimensions. Thus, we refer to them as conical backgrounds. In terms of the angular deficit value, we derive the perturbative expression for the scalar Green's function, valid for any $d\\geqslant 3$ and $2\\leqslant n\\leqslant d-1$, and compute it to the leading order. With the use of this Green's function we compute the renormalized vacuum expectation value of the field square $\\langle \\phi^{2}(x)\\rangle_{\\mathrm{ren}}$ and the renormalized vacuum averaged of the scalar-field's energy-momentum tensor $\\langle T_{M N}(x)\\rangle_{\\mathrm{ren}}$ for arbitrary $d$ and $n$ from th...
Institute of Scientific and Technical Information of China (English)
Su Shi-Lei; Wang Yuan; Guo Qi; Wang Hong-Fu; Zhang Shou
2012-01-01
We propose a protocol to generate a four-photon polarization-entangled cluster state with cross-Kerr nonlinearity by using the interference of polarized photons. The protocol is based on optical elements,cross-Kerr nonlinearity,and homodyne measurement,therefore it is feasible with current experimental technology.The success probability of our protocol is optimal,this property makes our protocol more efficient than others in the applications of quantum communication.
Nonlinear Dynamic Study on Geomagnetic Polarity Reversal and Cretaceous Normal Superchron
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
It is generally acknowledged that geomagnetic polarity has reversed many times in geological history and an abnormal geologic phenomenon is the Cretaceous normal superchron. However, the causes have been unknown up to now. The nonlinear theory has been applied to analyze the phenomenon in geomagnetic polarity reversal and the Cretaceous normal superchron. The Cretaceous normal superchron implies that interaction of the Earth's core-mantle and liquid movement in the outer core may be the lowest energy state and the system of Earth magnetic field maintains a sort of temporal or spatial order structure by exchanging substance and energy in the outside continuously.During 121-83 Ma, there was no impact of a celestial body that would result in a geomagnetic polarity reversal, which may be a cause for occurrence of the Cretaceous normal superchron. The randomness of geomagnetic polarity reversal has the self-reversion characteristic of chaos and the chaos theory gives a simple and clear explanation for the dynamic cause of the geomagnetic polarity reversal.
Matsas, V J; Richardson, D J; Newson, T P; Payne, D N
1993-03-01
A full characterization of a self-starting, passively mode-locked soliton ring fiber laser in terms of its various modes of mode-locked operation, cavity length, and type of fiber used is presented. Direct evidence, based on state-of-polarization measurements, that nonlinear polarization evolution is the responsible mode-locking mechanism is also given.
Vacuum birefringence in strong inhomogeneous electromagnetic fields
Karbstein, Felix; Reuter, Maria; Zepf, Matt
2015-01-01
Birefringence is one of the fascinating properties of the vacuum of quantum electrodynamics (QED) in strong electromagnetic fields. The scattering of linearly polarized incident probe photons into a perpendicularly polarized mode provides a distinct signature of the optical activity of the quantum vacuum and thus offers an excellent opportunity for a precision test of non-linear QED. Precision tests require accurate predictions and thus a theoretical framework that is capable of taking the detailed experimental geometry into account. We derive analytical solutions for vacuum birefringence which include the spatio-temporal field structure of a strong optical pump laser field and an x-ray probe. We show that the angular distribution of the scattered photons depends strongly on the interaction geometry and find that scattering of the perpendicularly polarized scattered photons out of the cone of the incident probe x-ray beam is the key to making the phenomenon experimentally accessible with the current generatio...
Fermionic vacuum polarization by a magnetic tube in the cosmic string spacetime
de Sousa, M S Maior; de Mello, E R Bezerra
2016-01-01
In this paper, we consider a charged massive fermionic quantum field in the idealized cosmic string spacetime and in the presence of a magnetic field confined in a cylindrical tube of finite radius. Three distinct configurations for the magnetic fields are taken into account: (i) a cylindrical shell of radius $a$, (ii) a magnetic field proportional to $1/r$ and (iii) a constant magnetic field. In these three cases, the axis of the infinitely long tube of radius $a$ coincides with the cosmic string. Our main objectives in this paper are to analyze the fermionic condensat (FC) e and the vacuum expectation value (VEV) of the fermionic energy-momentum tensor. In order to do that, we explicitly construct the complete set of normalized wave-functions for each configuration of magnetic field. We show that in the region outside the tube, the FC and the VEV of the energy-momentum tensor are decomposed into two parts: the first ones correspond to the zero-thickness magnetic flux contributions, and the seconds are induc...
Suleimanov, V F; Werner, K
2009-01-01
Observed X-ray spectra of some isolated magnetized neutron stars display absorption features, sometimes interpreted as ion cyclotron lines. Modeling the observed spectra is necessary to check this hypothesis and to evaluate neutron star parameters.We develop a computer code for modeling magnetized neutron star atmospheres in a wide range of magnetic fields (10^{12} - 10^{15} G) and effective temperatures (3 \\times 10^5 - 10^7 K). Using this code, we study the possibilities to explain the soft X-ray spectra of isolated neutron stars by different atmosphere models. The atmosphere is assumed to consist either of fully ionized electron-ion plasmas or of partially ionized hydrogen. Vacuum resonance and partial mode conversion are taken into account. Any inclination of the magnetic field relative to the stellar surface is allowed. We use modern opacities of fully or partially ionized plasmas in strong magnetic fields and solve the coupled radiative transfer equations for the normal electromagnetic modes in the plas...
Dispersion-insensitive low-coherent pulses emerging from nonlinear polarization switching
Mao, D.; Liu, X. M.; Lu, H.; Wang, L. R.; Duan, L. N.
2011-11-01
We have experimentally investigated low-repetition nanosecond pulses delivered from an erbium-doped fiber (EDF) laser operating in ultra-large anomalous dispersion regime. The output pulses with rectangular profile and Gaussian spectrum almost keep invariable when they propagate through either normal- or anomalous-dispersion fibers. After nanosecond pulses are amplified via a two-stage EDF amplifier, they are broken up and exhibited as flatly broadened supercontinuum from 1520 to 1700 nm if amplified pulses are launched into a 10-km single-mode fiber, whereas the pulses retain the same duration with a broadband supercontinuum from 1200 to 1750 nm if they are input into a 100-m highly-nonlinear low-dispersion photonic-crystal fiber (PCF). The experimental observations demonstrate that the nanosecond pulses result from nonlinear polarization switching and can be regarded as dispersion-insensitive low-coherent pulses rather than compressible pulses.
Polarization dependence of nonlinear wave mixing of spinor polaritons in semiconductor microcavities
Lewandowski, Przemyslaw; Baudin, Emmanuel; Chan, Chris K P; Leung, P T; Luk, Samuel M H; Galopin, Elisabeth; Lemaitre, Aristide; Bloch, Jacqueline; Tignon, Jerome; Roussignol, Philippe; Kwong, N H; Binder, Rolf; Schumacher, Stefan
2015-01-01
The pseudo-spin dynamics of propagating exciton-polaritons in semiconductor microcavities are known to be strongly influenced by TE-TM splitting. As a vivid consequence, in the Rayleigh scattering regime, the TE-TM splitting gives rise to the optical spin Hall effect (OSHE). Much less is known about its role in the nonlinear optical regime in which four-wave mixing for example allows the formation of spatial patterns in the polariton density, such that hexagons and two-spot patterns are observable in the far field. Here we present a detailed analysis of spin-dependent four-wave mixing processes, by combining the (linear) physics of TE-TM splitting with spin-dependent nonlinear processes, i.e., exciton-exciton interaction and fermionic phase-space filling. Our combined theoretical and experimental study elucidates the complex physics of the four-wave mixing processes that govern polarization and orientation of off-axis modes.
Accelerating oscillatory fronts in a nonlinear sonic vacuum with strong nonlocal effects.
Gendelman, O V; Zolotarevskiy, V; Savin, A V; Bergman, L A; Vakakis, A F
2016-03-01
We describe and explore accelerating oscillatory fronts in sonic vacua with nonlocal interactions. As an example, a chain of particles oscillating in the plane and coupled by linear springs, with fixed ends, is considered. When one end of this system is harmonically excited in the transverse direction, one observes accelerated propagation of the excitation front, accompanied by an almost monochromatic oscillatory tail. Position of the front obeys the scaling law l(t) ∼ t(4/3). The frequency of the oscillatory tail remains constant, and the wavelength scales as λ ∼ t(1/3). These scaling laws result from the nonlocal effects; we derive them analytically (including the scaling coefficients) from a continuum approximation. Moreover, a certain threshold excitation amplitude is required in order to initiate the front propagation. The initiation threshold is evaluated on the basis of a simplified discrete model, further reduced to a completely integrable nonlinear system. Given their simplicity, nonlinear sonic vacua of the type considered herein should be common in periodic lattices.
Fang, Xiaohui; Wai, P K A; Lu, Chao; Chen, Jinhua
2014-02-10
A pulse-width-tunable 10 GHz flattop pulse (FTP) train is generated based on the combined action of active mode locking and nonlinear polarization rotation pulse shaping. Although the setup was previously used for other applications, the mechanism of FTP generation based on it is first analyzed and confirmed in the experiment. An FTP with pulse width tunable from 12 to 20 ps by changing polarization controllers is generated within the wavelength tuning range of 20 nm. The generated pulse reveals good stability, with the side mode suppression ratio of 65 dB, timing jitter of 92 fs, and amplitude fluctuation of 0.36%.
Right-hand polarized 4fce auroral roar emissions: 2. Nonlinear generation theory
Yoon, P. H.; LaBelle, J.; Weatherwax, A. T.
2016-08-01
Auroral roar emissions are commonly interpreted as Z (or upper hybrid) mode naturally excited by precipitating auroral electrons. Subsequent conversion to escaping radiation makes it possible for these emissions to be detected on the ground. Most emissions are detected as having left-hand (L) circular (or ordinary O) polarization, but the companion paper presents a systematic experimental study on the rare occurrence of the right-hand polarized, or equivalently, extraordinary (X) mode 4fce emission. A similar observation was reported earlier by Sato et al. (2015). The suggested emission mechanism is the nonlinear coalescence of two upper hybrid roars at 2fce. The present paper formulates a detailed theory for such an emission mechanism.
Fermionic vacuum polarization by an Abelian magnetic tube in the cosmic string spacetime
Maior de Sousa, M. S.; Ribeiro, R. F.; Bezerra de Mello, E. R.
2017-02-01
In this paper, we consider a charged massive fermionic quantum field in the idealized cosmic string spacetime and in the presence of a magnetic field confined in a cylindrical tube of finite radius. Three distinct configurations for the magnetic fields are taken into account: (i) a cylindrical shell of radius a , (ii) a magnetic field proportional to 1 /r , and (iii) a constant magnetic field. In these three cases, the axis of the infinitely long tube of radius a coincides with the cosmic string. Our main objectives in this paper are to analyze the fermionic condensate (FC) and the vacuum expectation value (VEV) of the fermionic energy-momentum tensor. In order to do that, we explicitly construct the complete set of normalized wave functions for each configuration of the magnetic field. We show that in the region outside the tube, the FC and the VEV of the energy-momentum tensor are decomposed into two parts: The first ones correspond to the zero-thickness magnetic flux contributions, and the second ones are induced by the nontrivial structure of the magnetic field, named core-induced contributions. The latter present specific forms depending on the magnetic field configuration considered. We also show that the VEV of the energy-momentum tensor is diagonal and obeys the conservation condition, and its trace is expressed in terms of the fermionic condensate. The zero-thickness contributions to the FC and VEV of the energy-momentum tensor depend only on the fractional part of the ration of the magnetic flux inside the tube by the quantum one. As to the core-induced contributions, they depend on the total magnetic flux inside the tube and, consequently, in general, are not a periodic function of the magnetic flux.
Aoyama, Tatsumi; Kinoshita, Toichiro; Nio, Makiko
2011-01-01
This paper reports the evaluation of the tenth-order QED contribution to the lepton g-2 from the gauge-invariant set of 2072 Feynman diagrams, called Set IV, which are obtained by inserting a second-order lepton vacuum-polarization loop into 518 eighth-order vertex diagrams of four-photon exchange type. The numerical evaluation is carried out by the adaptive-iterative Monte-Carlo integration routine vegas using the fortran codes written by the automatic code-generating algorithm gencodeN. Some of the numerical results are confirmed by comparison with the values of corresponding integrals that have been obtained previously by a different method. The result for the mass-independent contribution of the Set IV to the electron g-2 is $-7.7296 (48) (\\alpha/\\pi)^5$. There is also a small mass-dependent contribution to the electron g-2 due to the muon loop: $-0.01136 (7) (\\alpha/\\pi)^5$. The contribution of the tau-lepton loop is $-0.0000937(104)(\\alpha/\\pi)^5$. The sum of all these contributions to the electron g-2 ...
Proper Eighth-Order Vacuum-Polarization Function and its Contribution to the Tenth-Order Lepton g-2
Aoyama, T; Kinoshita, T; Nio, M
2010-01-01
This paper reports the Feynman-parametric representation of the vacuum-polarization function consisting of 105 Feynman diagrams of the eighth order, and its contribution to the gauge-invariant set called Set I(i) of the tenth-order lepton anomalous magnetic moment. Numerical evaluation of this set is carried out using FORTRAN codes generated by an automatic code generation system gencodevpN developed specifically for this purpose. The contribution of diagrams containing electron loop to the electron g-2 is 0.017 47 (11) (alpha/pi)^5. The contribution of diagrams containing muon loop is 0.000~001 67 (3) (alpha/pi)^5. The contribution of tau-lepton loop is negligible at present. The sum of all these terms is 0.017 47 (11) (alpha/pi)^5. The contribution of diagrams containing electron loop to the muon g-2 is 0.087 1 (59) (alpha/pi)^5. That of tau-lepton loop is 0.000 237 (1) (alpha/pi)^5. The total contribution to a_mu, the sum of these terms and the mass-independent term, is 0.104 8 (59) (alpha/pi)^5.
Chang, You Min; Lee, Junsu; Lee, Ju Han
2010-09-13
Proposed herein is an alternative photonic scheme for the generation of a doublet UWB pulse, which is based on the nonlinear polarization rotation of an elliptically polarized probe beam. The proposed scheme is a modified optical-fiber Kerr shutter that uses an elliptically polarized probe beam together with a linearly polarized control beam. Through theoretical analysis, it was shown that the optical-fiber-based Kerr shutter is capable of producing an ideal transfer function for the successful conversion of input Gaussian pulses into doublet pulses under special elliptical polarization states of the probe beam. An experimental verification was subsequently carried out to verify the working principle. Finally, the system performance of the generated UWB doublet pulses was assessed by propagating them over a 25-km-long standard single-mode fiber link, followed by wireless transmission. Error-free transmission was successfully achieved.
A non-linear induced polarization effect on transient electromagnetic soundings
Hallbauer-Zadorozhnaya, Valeriya Yu.; Santarato, Giovanni; Abu Zeid, Nasser; Bignardi, Samuel
2016-10-01
In a TEM survey conducted for characterizing the subsurface for geothermal purposes, a strong induced polarization effect was recorded in all collected data. Surprisingly, anomalous decay curves were obtained in part of the sites, whose shape depended on the repetition frequency of the exciting square waveform, i.e. on current pulse length. The Cole-Cole model, besides being not directly related to physical parameters of rocks, was found inappropriate to model the observed distortion, due to induced polarization, because this model is linear, i.e. it cannot fit any dependence on current pulse. This phenomenon was investigated and explained as due to the presence of membrane polarization linked to constrictivity of (fresh) water-saturated pores. An algorithm for mathematical modeling of TEM data was then developed to fit this behavior. The case history is then discussed: 1D inversion, which accommodates non-linear effects, produced models that agree quite satisfactorily with resistivity and chargeability models obtained by an electrical resistivity tomography carried out for comparison.
Devi, Seema; Agarwal, Asha; Pandey, Kiran; Pradhan, Asima
2015-03-01
Reflectance spectroscopy contains information of scatterers and absorbers present inside biological tissues and has been successfully used to diagnose disease. Success of any diagnostic tool depends upon the potential of statistical algorithm to extract appropriate diagnostic features from the measured optical data. In our recent study, we have used the potential of the classification algorithm, Nonlinear Maximum Representation and Discrimination Features (NMRDF) to extract important diagnostic features from reflectance spectra of normal and dysplastic human cervical tissue. This NMRDF algorithm uses the higher order correlation information in the input data, which helps to represent the asymmetrically distributed data and provides the closed form solution of the nonlinear transform for maximum discrimination. We have recorded unpolarized, co and cross-polarized reflectance spectra from 350nm to 650nm, illuminating the human cervical tissue epithelium with white light source. A total of 139 samples were divided into training and validation data sets. The input parameters were optimized using training data sets to extract the appropriate nonlinear features from the input reflectance spectra. These extracted nonlinear features are used as input for nearest mean classifier to calculate the sensitivity and specificity for both training as well as validation data sets. We have observed that co-polarized components provide maximum sensitivity and specificity compared to cross-polarized components and unpolarized data. This is expected since co-polarized light provides subsurface information while cross-polarized and unpolarized data mask the vital epithelial information through high diffuse scattering.
Yang, X; Li, Z; Tangdiongga, E; Lenstra, D; Khoe, G; Dorren, H
2004-05-31
We demonstrate the generation of sub-picosecond optical pulses using a semiconductor optical amplifier (SOA) and a linear polarizer placed in a ring-laser configuration. Nonlinear polarization rotation in the SOA serves as the passive mode-locking mechanism. The ring cavity generates pulses with duration below 800 fs (FWHM) at a repetition rate of 14 MHz. The time -bandwidth product is 0.48. Simulation results in good agreement with the experimental results are presented.
Nonlinear Dynamics of Ion Concentration Polarization in Porous Media: The Leaky Membrane Model
Dydek, E Victoria
2013-01-01
The conductivity of highly charged membranes is nearly constant, due to counter-ions screening pore surfaces. Weakly charged porous media, or "leaky membranes", also contain a significant concentration of co-ions, whose depletion at high current leads to ion concentration polarization and conductivity shock waves. To describe these nonlinear phenomena the absence of electro-osmotic flow, a simple Leaky Membrane Model is formulated, based on macroscopic electroneutrality and Nernst-Planck ionic fluxes. The model is solved in cases of unsupported binary electrolytes: steady conduction from a reservoir to a cation-selective surface, transient response to a current step, steady conduction to a flow-through porous electrode, and steady conduction between cation-selective surfaces in cross flow. The last problem is motivated by separations in leaky membranes, such as shock electrodialysis. The article begins with a tribute to Neal Amundson, whose pioneering work on shock waves in chromatography involved similar mat...
Lian, Yudong; Ren, Guobin; Zhu, Bofeng; Gao, Yixiao; Jian, Wei; Ren, Wenhua; Jian, Shuisheng
2017-05-01
We propose and demonstrate a switchable multiwavelength fiber laser using erbium-doped twin-core fiber (ED-TCF) and nonlinear polarization rotation (NPR). The number switchability of lasing wavelengths being switched from 1 to 4 and wavelength location switchability could be achieved simultaneously in the proposed configuration with a wavelength spacing of 1.1 nm and an optical signal to noise ratio (OSNR) larger than 43 dB. The output laser powers at different wavelengths are nearly the same with a fluctuation less than 2 dB. The proposed fiber laser shows good stability with wavelength shift within 0.01 nm and peak power fluctuation less than 5 dB. The proposed fiber laser has the advantages of simple structure and stable operation.
Nonlinear effects related to circularly polarized dispersive Alfvén waves
Sharma, Swati; Gaur, Nidhi; Sharma, R. P.
2016-09-01
In situ measurements of solar wind have strongly implicated its turbulent behavior. The observed power spectra report a breakpoint around length scales of the order of ion scales. As one of the responsible mechanisms for the observed steepening in power spectrum, our approach includes a right circularly polarized dispersive Alfvén wave (DAW) with finite frequency correction which, when subjected to transverse collapse/filamentation instability, may possibly result in steepening of spectrum and progressive transfer of energy from larger scales to smaller scales. We have studied the nonlinear effects associated with coupling of DAW with kinetic Alfvén wave in solar wind at 1 A.U. The formation of localized structures provides a clue about the emergence of turbulence. Numerical simulation is performed to study localization and power spectral density of the field and density fluctuations. The results show steeper spectrum indicating transfer of large scale turbulent energy down to small scales.
Ferroelectric polarization induces electronic nonlinearity in ion-doped conducting polymers
Fabiano, Simone; Sani, Negar; Kawahara, Jun; Kergoat, Loïg; Nissa, Josefin; Engquist, Isak; Crispin, Xavier; Berggren, Magnus
2017-01-01
Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is an organic mixed ion-electron conducting polymer. The PEDOT phase transports holes and is redox-active, whereas the PSS phase transports ions. When PEDOT is redox-switched between its semiconducting and conducting state, the electronic and optical properties of its bulk are controlled. Therefore, it is appealing to use this transition in electrochemical devices and to integrate those into large-scale circuits, such as display or memory matrices. Addressability and memory functionality of individual devices, within these matrices, are typically achieved by nonlinear current-voltage characteristics and bistability—functions that can potentially be offered by the semiconductor-conductor transition of redox polymers. However, low conductivity of the semiconducting state and poor bistability, due to self-discharge, make fast operation and memory retention impossible. We report that a ferroelectric polymer layer, coated along the counter electrode, can control the redox state of PEDOT. The polarization switching characteristics of the ferroelectric polymer, which take place as the coercive field is overcome, introduce desired nonlinearity and bistability in devices that maintain PEDOT in its highly conducting and fast-operating regime. Memory functionality and addressability are demonstrated in ferro-electrochromic display pixels and ferro-electrochemical transistors. PMID:28695197
Polarization entangled photon-pair source based on quantum nonlinear photonics and interferometry
Kaiser, F.; Ngah, L. A.; Issautier, A.; Delord, T.; Aktas, D.; D'Auria, V.; De Micheli, M. P.; Kastberg, A.; Labonté, L.; Alibart, O.; Martin, A.; Tanzilli, S.
2014-09-01
We present a versatile, high-brightness, guided-wave source of polarization entangled photons, emitted at a telecom wavelength. Photon-pairs are generated using an integrated type-0 nonlinear waveguide, and subsequently prepared in a polarization entangled state via a stabilized fiber interferometer. We show that the single photon emission wavelength can be tuned over more than 50 nm, whereas the single photon spectral bandwidth can be chosen at will over more than five orders of magnitude (from 25 MHz to 4 THz). Moreover, by performing entanglement analysis, we demonstrate a high degree of control of the quantum state via the violation of the Bell inequalities by more than 40 standard deviations. This makes this scheme suitable for a wide range of quantum optics experiments, ranging from fundamental research to quantum information applications. We report on details of the setup, as well as on the characterization of all included components, previously outlined in Kaiser et al. (Laser Phys. Lett. 10 (2013) 045202).
Li, Wei; Wang, Wen Ting; Sun, Wen Hui; Liu, Jian Guo; Zhu, Ning Hua
2014-05-05
We propose a novel approach to generating millimeter-wave (MMW) ultrawideband (UWB) signal based on nonlinear polarization rotation (NPR) in a highly nonlinear fiber (HNLF). The MMW UWB signal is background-free by eliminating the baseband frequency components using an optical filter. The proposed scheme is theoretically analyzed and experimentally verified. The generated MMW UWB signal centered at 25.5 GHz has a 10-dB bandwidth of 7 GHz from 22 to 29 GHz, which fully satisfies the spectral mask regulated by the Federal Communications Commission (FCC).
Gravitational vacuum polarization
Visser, M
1997-01-01
The energy conditions of classical Einstein gravity fail once quantum effects are introduced. These quantum violations of the energy conditions are not subtle high-energy Planck scale effects. Rather the quantum violations of the energy conditions already occur in semiclassical quantum gravity and are first-order O(\\hbar) effects. Quantum violations of the energy conditions are widespread, albeit small.
Institute of Scientific and Technical Information of China (English)
SUN Xue-ming; ZHANG Hui-jian; ZUO Meng; GU Wan-yi; XU Da-xiong
2006-01-01
Dense wavelength division multiplexing (DWDM) system is the ultimate selection as an optical communication system because of its high speeds and capacities.However,the fiber nonlinear effects and polarization mode dispersion severely limit the performance of the system when signal propagates at 40 Gbit/s in a single channel.The coupled nonlinear Schr(o)dinger equations of a single channel in DWDM,which are all considered factors of group velocity dispersion (GVD),self phase modulation (SPM),cross phase modulation (XPM),four wave mixing (FWM) and polarization mode dispersion (PMD),are derived,while their number results are obtained with extended split-step Fourier method.Finally,to analyze the impacts of the fiber nonlinear effects and PMD on the optical communication system,the simulated results of an 8x40 Gbit/s DWDM system are discussed under different conditions respectively.
Luo, Ting
As optical communications approach more data bandwidth, longer transmission distance, and more reconfigurability, dispersion, nonlinearity and polarization-dependent effects are becoming key issues for future all-optical fiber optic systems and networks. For ≥10 Gbit/s optical fiber transmission systems, it is critical that chromatic dispersion and polarization-mode-dispersion be well monitored and compensated using some type of dispersion monitoring and compensation. On the other hand, dispersive and nonlinear effects in optical fiber systems can also be beneficial and have applications on pulse management, all-optical signal processing and network function, which will be essential for high bite-rate optical networks and replacing the expensive optical-electrical-optical (O/E/O) conversion. In this Ph.D. dissertation, we present a detailed research on dispersion, nonlinearity, and polarization-dependent effects in high-speed optical communication systems. We have demonstrated: (i) A dynamic channel-spacing tunable multi-wavelength Erbium-doped fiber laser; (ii) Chromatic-dispersion-insensitive PMD monitoring by tracking the radio-frequency extracted from the vestigial-sideband; (iii) A method for simultaneous chromatic and polarization-mode dispersions monitoring by adding a frequency-shifted carrier; (iv) Polarization-insensitive optical parametric amplification by depolarizing the pump; (v) All optical chromatic dispersion monitoring potential for ultra-high speed (>40 Gbit/s) optical systems using cross-phase modulation in a highly nonlinear fiber; (vi) A novel fiber-based autocorrelator using polarimetric four-wave mixing effect and a tunable differential-group-delay element; (vii) A simple all-fiber-based autocorrelator by measuring the degree-of-polarization; and (viii) Reduction of pattern dependent data distortion in a stimulated Brillouin scattering based slow light element. These techniques will play key roles in future high-speed dynamic WDM optical
Institute of Scientific and Technical Information of China (English)
Lilin Yi; Weisheng Hu; Hao He; Yi Dong; Yaohui Jin; Weiqiang Sun
2011-01-01
We demonstrate an all-optical reconfigurable logic gate based on dominant nonlinear polarization rotation accompanied with cross-gain modulation effect in a singlc semiconductor optical amplifier (SOA). Five logic functions, including NOT, OR, NOR, AND, and NAND, are realized using 10-Gb/s on-off keying signals with flexible wavelength tunability. The operation principle is explained in detail. By adjusting polarization controllers, multiple logic functions corresponding to different input polarization states are separately achieved using a single SOA with high flexibility.%@@ We demonstrate an all-optical reconfigurable logic gate based on dominant nonlinear polarization rotation accompanied with cross-gain modulation effect in a single semiconductor optical amplifier (SOA).Five logic functions, including NOT, OR, NOR, AND, and NAND, are realized using 10-Gb/s on-off keying signals with flexible wavelength tunability.The operation principle is explained in detail.By adjusting polarization controllers, multiple logic functions corresponding to different input polarization states are separately achieved using a single SOA with high flexibility.
Construction of the Pauli-Villars-Regulated Dirac Vacuum in Electromagnetic Fields
Gravejat, Philippe; Hainzl, Christian; Lewin, Mathieu; Séré, Éric
2013-05-01
Using the Pauli-Villars regularization and arguments from convex analysis, we construct solutions to the classical time-independent Maxwell equations in Dirac's vacuum, in the presence of small external electromagnetic sources. The vacuum is not an empty space, but rather a quantum fluctuating medium which behaves as a nonlinear polarizable material. Its behavior is described by a Dirac equation involving infinitely many particles. The quantum corrections to the usual Maxwell equations are nonlinear and nonlocal. Even if photons are described by a purely classical electromagnetic field, the resulting vacuum polarization coincides to first order with that of full Quantum Electrodynamics.
Energy Technology Data Exchange (ETDEWEB)
Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo; Beniya, Atsushi; Isomura, Noritake [Toyota Central R& D Labs., Inc., Yokomichi 41-1, Nagakute, Aichi 480-1192 (Japan); Uehara, Hiromitsu; Asakura, Kiyotaka; Takakusagi, Satoru [Catalysis Research Center, Hokkaido University, Kita 21-10, Sapporo, Hokkaido 001-0021 (Japan); Nimura, Tomoyuki [AVC Co., Ltd., Inada 1450-6, Hitachinaka, Ibaraki 312-0061 (Japan)
2016-03-15
A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstrated by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.
Nonlinear reflection process of linearly-polarized, broadband Alfv\\'en waves in the fast solar wind
Shoda, Munehito
2016-01-01
Using one-dimensional numerical simulations, we study the elementary process of Alfv\\'{e}n wave reflection in a uniform medium, including nonlinear effects. In the linear regime, Alfv\\'{e}n wave reflection is triggered only by the inhomogeneity of the medium, whereas in the nonlinear regime, it can occur via nonlinear wave-wave interactions. Such nonlinear reflection (backscattering) is typified by decay instability. In most studies of decay instabilities, the initial condition has been a circularly polarized Alfv\\'{e}n wave. In this study we consider a linearly polarized Alfv\\'en wave, which drives density fluctuations by its magnetic pressure force. For generality, we also assume a broadband wave with a red-noise spectrum. In the data analysis, we decompose the fluctuations into characteristic variables using local eigenvectors, thus revealing the behaviors of the individual modes. Different from circular-polarization case, we find that the wave steepening produces a new energy channel from the parent Alfv\\...
Deb Roy, Gauranga; Fazlul Karim, Md.; Ismail, Ahmad Izani M.
2007-01-01
A nonlinear shallow water model in cylindrical polar coordinate system is developed, using an explicit finite difference scheme with a very fine resolution, to compute different aspects of tsunami at North Sumatra and the adjacent island Simeulue in Indonesia, and the Penang Island in Peninsular Malaysia. The pole of the frame is placed on the mainland of Penang (100.5°E) and the model area extends up to the west of Sumatra (87.5°E). The model is applied to simulate the propagation of tsunami wave towards North Sumatra, Simeulue and Penang Islands associated with Indonesian tsunami of 26 December 2004. The model is also applied to compute water levels along the coastal belts of those islands. Computed and observed water level data are found to be in good agreement and North Sumatra is found to be vulnerable for very high surges. The computed and observed arrival times of high surges are also in reasonable agreement everywhere. Further studies are carried out to investigate the effect of convective terms and it is found that their effects are insignificant in tsunami propagation and weakly significant for wave amplitude very near to the coast.
Three-Dimensional Induced Polarization Parallel Inversion Using Nonlinear Conjugate Gradients Method
Directory of Open Access Journals (Sweden)
Huan Ma
2015-01-01
Full Text Available Four kinds of array of induced polarization (IP methods (surface, borehole-surface, surface-borehole, and borehole-borehole are widely used in resource exploration. However, due to the presence of large amounts of the sources, it will take much time to complete the inversion. In the paper, a new parallel algorithm is described which uses message passing interface (MPI and graphics processing unit (GPU to accelerate 3D inversion of these four methods. The forward finite differential equation is solved by ILU0 preconditioner and the conjugate gradient (CG solver. The inverse problem is solved by nonlinear conjugate gradients (NLCG iteration which is used to calculate one forward and two “pseudo-forward” modelings and update the direction, space, and model in turn. Because each source is independent in forward and “pseudo-forward” modelings, multiprocess modes are opened by calling MPI library. The iterative matrix solver within CULA is called in each process. Some tables and synthetic data examples illustrate that this parallel inversion algorithm is effective. Furthermore, we demonstrate that the joint inversion of surface and borehole data produces resistivity and chargeability results are superior to those obtained from inversions of individual surface data.
Yan, Zhiyu; Li, Xiaohui; Tang, Yulong; Shum, Perry Ping; Yu, Xia; Zhang, Ying; Wang, Qi Jie
2015-02-23
We propose and demonstrate a tunable and switchable dual-wavelength ultra-fast Tm-doped fiber laser. The tunability is based on nonlinear polarization evolution (NPE) technique in a passively mode-locked laser cavity. The NPE effect induces wavelength-dependent loss in the cavity to effectively alleviate mode competition and enables the multiwavelength mode locking. The laser exhibits tunable dual-wavelength mode locking over a wide range from 1852 to 1886 nm. The system has compact structure and both the wavelength tuning and switching capabilities can be realized by controlling the polarization in the fiber ring cavity.
Institute of Scientific and Technical Information of China (English)
Cao Wen-Jun; Xu Wen-Cheng; Luo Zhi-Chao; Wang Lu-Yan; Wang Hui-Yi; Dong Jiang-Li; Luo Ai-Ping
2011-01-01
We report on the generation of dual-wavelength dissipative solitons in a passively mode-locked fibre laser with a net normal dispersion using the nonlinear polarization rotation (NPR) technique.Taking the intrinsic advantage of the intracavity birefringence-induced spectral filtering effect in the NPR-based ring laser cavity,the dual-wavelength dissipative solitons are obtained.In addition,the wavelength separation and the lasing location of the dual-wavelength solitons can be flexibly tuned by changing the orientation of the polarization controller.
Mateo, Eduardo F; Zhou, Xiang; Li, Guifang
2011-01-17
An improved split-step method (SSM) for digital backward propagation (DBP) applicable to wavelength-division multiplexed (WDM) transmission with polarization-division multiplexing (PDM) is presented. A coupled system of nonlinear partial differential equations, derived from the Manakov equations, is used for DBP. The above system enables the implementation of DBP on a channel-by-channel basis, where only the effect of phase-mismatched four-wave mixing (FWM) is neglected. A novel formulation of the SSM for PDM-WDM systems is presented where new terms are included in the nonlinear step to account for inter-polarization mixing effects. In addition, the effect of inter-channel walk-off is included. This substantially reduces the computational load compared to the conventional SSM.
Influence of Ion Nonlinear Polarization Drift and Warm Ions on Solitary Kinetic Alfvén Wave
Institute of Scientific and Technical Information of China (English)
DUAN Su-Ping; LI Zhong-Yuan
2003-01-01
Considering the effects of ion nonlinear polarization drift and warm ions, we adopt two-fluid model to results derived in this paper indicate that dip SKAW and hump SKAW both exist in a wide range in magnetosphere(for the pressure parameter β ~ 10-5 ~ 0.01, where βis the ratio of thermal pressure to magnetic pressure, i.e.region 1 > β > me/mi. These results are different from previous ones. That indicates that the effects of ion nonlinear polarization drift and warm ions are important and they cannot be neglected. The SKAW has an electric field parallel to the ambient magnetic field, which makes the SKAW take an important role in the acceleration and energization of field-aligned charged particles in magnetic plasmas. And the SKAW is also important for the heating of a local plasma.So it makes a novel physical mechanism of energy transmission possible.
Trifonov, A. Yu.; Shapovalov, A. V.
2011-05-01
The two-dimensional Kolmogorov-Petrovskii-Piskunov-Fisher equation with nonlocal nonlinearity and axially symmetric coefficients in polar coordinates is considered. The method of separation of variables in polar coordinates and the nonlinear superposition principle proposed by the authors are used to construct the asymptotic solution of a Cauchy problem in a special class of smooth functions. The functions of this class arbitrarily depend on the angular variable and are semiclassically concentrated in the radial variable. The angular dependence of the function has been exactly taken into account in the solution. For the radial equation, the formalism of semiclassical asymptotics has been developed for the class of functions which singularly depend on an asymptotic small parameter, whose part is played by the diffusion coefficient. A dynamic system of Einstein-Ehrenfest equations (a system of equations in mean and central moments) has been derived. The evolution operator for the class of functions under consideration has been constructed in explicit form.
Wang, Yunzheng; Zhang, Liqiang; Zhuo, Zhuang; Guo, Songzhen
2016-07-20
We propose a cross-splicing method, for the first time to our knowledge, to compensate the effect of fiber birefringence in a polarization-maintaining fiber ring laser mode locked by nonlinear polarization evolution. This method has been investigated numerically and experimentally. The results indicate that stable mode-locking pulses can be obtained in the cavity with this method; otherwise, no mode-locking states are achieved. The design processes of the laser cavity are presented. Pulses with single pulse energy of 2.1 nJ are generated at pump power of 460 mW. The spectral bandwidth and pulse duration are 17.5 nm and 11.7 ps, respectively. The tunability of the laser is also studied. The central wavelength can be tuned from 1023.2 to 1045.9 nm.
Resonant nonlinear interactions between atmospheric waves in the polar summer mesopause region
Institute of Scientific and Technical Information of China (English)
LIU; Renqiang; (刘仁强); YI; Fan; (易帆)
2003-01-01
Data obtained from the mobile SOUSY VHF radar at And(ya/Norway in summer 1987 have been used to study the nonlinear interactions between planetary waves, tides and gravity waves in the polar mesosphere, and the instability of background atmosphere above the mesopause. It is observed that 35-h planetary wave, diurnal, semidiurnal and terdiurnal tides are the prominent perturbations in the Lomb-Scargle spectra of the zonal wind component. By inspecting the frequency combinations, several triads are identified. By bispectral analysis it is shown that most bispectral peaks stand for quadratic coupling between tidal harmonics or between tide and planetary or gravity wave, and the height dependence of bispectral peaks reflects the variation of wave-wave interactions. Above the mesopause, the occurrence heights of the maximum L-S power spectral peaks corresponding to the prominent wave components tend to increase with their frequencies. This may result from the process in which two low frequency waves interact to generate a high frequency wave. Intensities of the planetary wave and tides increase gradually, arrive at their maxima, and then decay quickly in turn with increasing height. This kind of scene correlates with a "chain" of wave-wave resonant interactions that shifts with height from lower frequency segment to higher frequency segment. By instability analysis, it is observed that above the mesopause, the Richardson number becomes smaller and smaller with height, implying that the turbulent motion grows stronger and stronger and accordingly the background atmosphere more and more instable. It is suggested that the wave-wave sum resonant interaction and the wave dissipation due to instability are two dominant dynamical processes that occur in the mesopause region. The former invokes the energy transfer from lower frequency waves to higher frequency waves. The latter results in the heating of the atmosphere and accelerating of the background flow.
Polarization-Independent High-Speed Switching in a Standard Non-Linear Optical Loop Mirror
DEFF Research Database (Denmark)
Mulvad, Hans Christian Hansen; Galili, Michael; Oxenløwe, Leif Katsuo
2008-01-01
We introduce a scheme which allows polarization-independent switching in a standard NOLM. Experimental verification is performed by switching 10 Gbit/s data with 0.2 dB polarization-dependence and by error-free demultiplexing of polarization-scrambled 320 Gbit/s OTDM data....
Tagantsev, Alexander K.; Stolichnov, Igor; Setter, Nava; Cross, Jeffrey S.
2004-12-01
The phenomenon of polarization imprint consisting of the development of a preferential polarization state in ferroelectric films is known as one of the major issues impacting the development of high density ferroelectric memories. According to the commonly accepted scenario, the imprint is related to the charge injection and charge accumulation in the nearby-electrode passive layer of the ferroelectric film. Recent studies demonstrated that the coercive voltage shift induced by the imprint exhibits a nonlinear time dependence in a logarithmic scale. This result was interpreted as the presence of two different imprint mechanisms characterized by different activation energies. In the present work, an analytical theory of the injection scenario of imprint is developed. The charge accumulation at the interface is shown to provoke a voltage offset and polarization loss which are nonlinearly dependent on the time in logarithmic scale. This result is obtained for different charge injection mechanisms including Schottky, Pool-Frenkel, and tunneling scenarios. Thus, it is shown that a single imprint mechanism can be responsible for a nolinear (in logarithmic scale) time dependence of the voltage offset and polarization loss. Additionally, the temperature dependence of the logarithmic rate of imprint is shown to be nonexponential. The developed model ties together the time and temperature dependences of imprint. For the experimental verification of the model a study of imprint has been performed on (111) Pb(Zr ,Ti)O3 film capacitors with temperatures ranging from 25 to 150°C and exposure times up to 1000h. It has been found that the theory developed adequately describes the obtained experimental data. Based upon the theoretical and experimental results a test for ferroelectric memories is proposed, which enables the long-term prediction of polarization loss caused by imprint for a wide temperature range and for different operating voltages.
DEFF Research Database (Denmark)
Tuz, Vladimir R.; Novitsky, Denis V.; Prosvirnin, Sergey L.
2014-01-01
Optical properties of one-dimensional photonic structures consisting of Kerr-type nonlinear and magnetic layers under the action of an external static magnetic field in the Faraday geometry are investigated. The structure is a periodic arrangement of alternating nonlinear and magnetic layers (a one...
Stoller, Patrick C.; Kim, Beop-Min; Rubenchik, Alexander M.; Reiser, Karen M.; Da Silva, Luiz B.
2001-05-01
The measurement of the second order nonlinear susceptibility of collagen in various biological tissues has potential applications in the detection of structural changes which are related to different pathological conditions. We investigate second harmonic generation in a rat-tail tendon, a highly organized collagen structure consisting of parallel fibers. Using an electro-optic modulator and a quarter-wave plate, we modulate the linear polarization of an ultra-short pulse laser beam that is used to measure second harmonic generation in a confocal microscopy setup. Phase-sensitive detection of the generated signal, coupled with a simple model of the collagen protein structures, allows us to measure a parameter (gamma) related to nonlinear susceptibility and to determine the relative orientation of the structures. Our preliminary results indicate that it may be possible to use this parameter to characterize the structure.
Energy Technology Data Exchange (ETDEWEB)
Stoller, P; Kim, B-M; Rubenchik, A M; Reiser, K M; Da Silva, L B
2001-03-03
The measurement of the second order nonlinear susceptibility of collagen in various biological tissues has potential applications in the detection of structural changes which are related to different pathological conditions. We investigate second harmonic generation in rat-tail tendon, a highly organized collagen structure consisting of parallel fibers. Using an electro-optic modulator and a quarter-wave plate, we modulate the linear polarization of an ultra-short pulse laser beam that is used to measure second harmonic generation (SHG) in a confocal microscopy setup. Phase-sensitive detection of the generated signal, coupled with a simple model of the collagen protein structures, allows us to measure a parameter {gamma} related to nonlinear susceptibility and to determine the relative orientation of the structures. Our preliminary results indicate that it may be possible to use this parameter to characterize the structure.
Energy Technology Data Exchange (ETDEWEB)
Nariyuki, Y. [Faculty of Human Development, University of Toyama, 3190, Toyama City, Toyama 930-8555 (Japan); Hada, T. [Department of Earth System Science and Technology, Kyushu University, 6-1, Kasuga City, Fukuoka 816-8580 (Japan); Tsubouchi, K., E-mail: nariyuki@edu.u-toyama.ac.jp [Graduate School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)
2014-10-01
The damping process of field-aligned, low-frequency right-handed polarized nonlinear Alfvén waves (NAWs) in solar wind plasmas with and without proton beams is studied by using a two-dimensional ion hybrid code. The numerical results show that the obliquely propagating kinetic Alfvén waves (KAWs) excited by beam protons affect the damping of the low-frequency NAW in low beta plasmas, while the nonlinear wave-wave interaction between parallel propagating waves and nonlinear Landau damping due to the envelope modulation are the dominant damping process in high beta plasmas. The nonlinear interaction between the NAWs and KAWs does not cause effective energy transfer to the perpendicular direction. Numerical results suggest that while the collisionless damping due to the compressibility of the envelope-modulated NAW plays an important role in the damping of the field-aligned NAW, the effect of the beam instabilities may not be negligible in low beta solar wind plasmas.
Wang, Meiyu; Yan, Fengli; Gao, Ting
2017-08-01
We present a new scheme to provide an arbitrary four-photon polarization-entangled state, which enables the encoding of single logical qubit information into a four-qubit decoherence-free subspace robustly against collective decoherence. With the assistance of the cross-Kerr nonlinearities, a spatial entanglement gate and a polarization entanglement gate are inserted into the circuit, where the X-quadrature homodyne measurement is properly performed. According to the outcomes of homodyne measurement in the spatial entanglement process, some swap gates are inserted into the corresponding paths of the photons to swap their spatial modes. Apart from Kerr media, some basic linear optical elements are necessary, which make it feasible with current experimental techniques.
Ema, S. A.; Hossen, M. R.; Mamun, A. A.
2016-04-01
The nonlinear propagation of ion-acoustic (IA) waves in a strongly coupled plasma system containing Maxwellian electrons and nonthermal ions has been theoretically and numerically investigated. The well-known reductive perturbation technique is used to derive both the Burgers and Korteweg-de Vries (KdV) equations. Their shock and solitary wave solutions have also been numerically analyzed in understanding localized electrostatic disturbances. It has been observed that the basic features (viz. polarity, amplitude, width, etc.) of IA waves are significantly modified by the effect of polarization force and other plasma parameters (e.g., the electron-to-ion number density ratio and ion-to-electron temperature ratio). This is a unique finding among all theoretical investigations made before, whose probable implications are discussed in this investigation. The implications of the results obtained from this investigation may be useful in understanding the wave propagation in both space and laboratory plasmas.
Loures, Cristian Redondo; Biancalana, Fabio
2014-01-01
We study the influence of third-harmonic generation (THG) and negative frequency polarization terms in the self-phase modulation (SPM) of short and intense pulses in Kerr media. We find that THG induces additional symmetric lobes in the SPM process. The amplitude of these new sidebands are greatly enhanced by the contributions of the negative frequency Kerr (NFK) term and the shock operator. We compare our theoretical predictions based on the analytical nonlinear phase with simulations carried out by using the full unidirectional pulse propagation equation (UPPE).
Alexandru, Andrei; Horvath, Ivan; Streuer, Thomas
2010-01-01
We propose a framework for quantitative evaluation of dynamical tendency for polarization in arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to definition of a suitable correlation coefficient with clear statistical meaning. We apply the method to the dynamics induced by pure-glue lattice QCD in local left-right components of overlap Dirac eigenmodes. It is found that, in finite physical volume, there is a non-zero physical scale in the spectrum of eigenvalues such that eigenmodes at larger (fixed) eigenvalues exhibit concave X-distribution (negative correlation), while at smaller eigenvalues the distribution is convex (positive correlation). This chiral polarization sca...
Cruz-Diaz, G. A.; Muñoz Caro, G. M.; Chen, Y.-J.; Yih, T.-S.
2014-02-01
Context. The vacuum-UV (VUV) absorption cross sections of most molecular solids present in interstellar ice mantles with the exception of H2O, NH3, and CO2 have not been reported yet. Models of ice photoprocessing depend on the VUV absorption cross section of the ice to estimate the penetration depth and radiation dose, and in the past, gas phase cross section values were used as an approximation. Aims: We aim to estimate the VUV absorption cross section of molecular ice components. Methods: Pure ices composed of CO, H2O, CH3OH, NH3, or H2S were deposited at 8 K. The column density of the ice samples was measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120-160 nm (10.33-7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. Results: We provide VUV absorption cross sections of the reported molecular ices. Our results agree with those previously reported for H2O and NH3 ices. Vacuum-UV absorption cross section of CH3OH, CO, and H2S in solid phase are reported for the first time. H2S presents the highest absorption in the 120-160 nm range. Conclusions: Our method allows fast and readily available VUV spectroscopy of ices without the need to use a synchrotron beamline. We found that the ice absorption cross sections can be very different from the gas-phase values, and therefore, our data will significantly improve models that simulate the VUV photoprocessing and photodesorption of ice mantles. Photodesorption rates of pure ices, expressed in molecules per absorbed photon, can be derived from our data. Data can be found at http://ghosst.osug.fr/
Alexandru, Andrei; Draper, Terrence; Horvath, Ivan; Streuer, Thomas
2010-01-01
We propose a framework for quantitative evaluation of dynamical tendency for polarization in arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to definiti...
Alexandru, Andrei; Draper, Terrence; Horváth, Ivan; Streuer, Thomas
2011-08-01
We propose a framework for quantitative evaluation of dynamical tendency for polarization in an arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to the definition of a suitable correlation coefficient with clear statistical meaning. We apply the method to the dynamics induced by pure-glue lattice QCD in local left-right components of overlap Dirac eigenmodes. It is found that, in finite physical volume, there exists a non-zero physical scale in the spectrum of eigenvalues such that eigenmodes at smaller (fixed) eigenvalues exhibit convex X-distribution (positive correlation), while at larger eigenvalues the distribution is concave (negative correlation). This chiral polarization scale thus separates a regime where dynamics enhances chirality relative to statistical independence from a regime where it suppresses it, and gives an objective definition to the notion of "low" and "high" Dirac eigenmode. We propose to investigate whether the polarization scale remains non-zero in the infinite volume limit, in which case it would represent a new kind of low energy scale in QCD.
Energy Technology Data Exchange (ETDEWEB)
Rompotis, Dimitrios
2016-02-15
In this work, a single-shot temporal metrology scheme operating in the vacuum-extreme ultraviolet spectral range has been designed and experimentally implemented. Utilizing an anti-collinear geometry, a second-order intensity autocorrelation measurement of a vacuum ultraviolet pulse can be performed by encoding temporal delay information on the beam propagation coordinate. An ion-imaging time-of-flight spectrometer, offering micrometer resolution has been set-up for this purpose. This instrument enables the detection of a magnified image of the spatial distribution of ions exclusively generated by direct two-photon absorption in the combined counter-propagating pulse focus and thus obtain the second-order intensity autocorrelation measurement on a single-shot basis. Additionally, an intense VUV light source based on high-harmonic generation has been experimentally realized. It delivers intense sub-20 fs Ti:Sa fifth-harmonic pulses utilizing a loose-focusing geometry in a long Ar gas cell. The VUV pulses centered at 161.8 nm reach pulse energies of 1.1 μJ per pulse, while the corresponding pulse duration is measured with a second-order, fringe-resolved autocorrelation scheme to be 18 ± 1 fs on average. Non-resonant, two-photon ionization of Kr and Xe and three-photon ionization of Ne verify the fifth-harmonic pulse intensity and indicate the feasibility of multi-photon VUV pump/VUV probe studies of ultrafast atomic and molecular dynamics. Finally, the extended functionally of the counter-propagating pulse metrology approach is demonstrated by a single-shot VUV pump/VUV probe experiment aiming at the investigation of ultrafast dissociation dynamics of O{sub 2} excited in the Schumann-Runge continuum at 162 nm.
Nonlinear dust acoustic waves with polarization force effects in Kappa distribution plasma
Chen, Hui; Zhou, Suyun; Luo, Rongxiang; Liu, Sanqiu
2017-01-01
The propagation characteristics of dust acoustic solitary waves (DASWs) in dusty plasmas with the effects of polarization force and superthermal ions are studied. First, the polarization force induced by superthermal ions is obtained. It is shown that the superthermality of background ions affect the Debye screening of dust grains as well as the polarization force significantly. Then for small amplitude solitary waves, the KdV equation is obtained by applying the reductive perturbation technique. And for the arbitrary amplitude solitary waves, the Sagdeev potential method is employed and the Sagdeev potential is analyzed. In both case, the effects of the polarization force associated the ions’ superthermality on the characteristic of the DASWs are analyzed.
Cruz-Diaz, G A; Chen, Y -J; Yih, T -S
2014-01-01
The VUV absorption cross sections of most molecular solids present in interstellar ice mantles with the exception of H2O, NH3, and CO2 have not been reported yet. Models of ice photoprocessing depend on the VUV absorption cross section of the ice to estimate the penetration depth and radiation dose, and in the past, gas phase cross section values were used as an approximation. We aim to estimate the VUV absorption cross section of molecular ice components. Pure ices composed of CO, H2O, CH3OH, NH3, or H2S were deposited at 8 K. The column density of the ice samples was measured in situ by infrared spectroscopy in transmittance. VUV spectra of the ice samples were collected in the 120-160 nm (10.33-7.74 eV) range using a commercial microwave-discharged hydrogen flow lamp. We provide VUV absorption cross sections of the reported molecular ices. Our results agree with those previously reported for H2O and NH3 ices. Vacuum-UV absorption cross section of CH3OH, CO, and H2S in solid phase are reported for the first...
2014-12-18
300.6420) Spectroscopy, nonlinear; (190.3270) Kerr effect; (320.7110) Ultrafast nonlinear optics. http://dx.doi.org/10.1364/ OPTICA .1.000436 1...10$15/0$15.00 © 2014 Optical Society of America Research Article Vol. 1, No. 6 / December 2014 / Optica 436 Report Documentation Page Form ApprovedOMB...described by rd t Cd 1 − e− t τr;d e − tτf ;dΘt ; (5) Research Article Vol. 1, No. 6 / December 2014 / Optica 437 where the subscript d
Nonlinear Electromagnetic Waves and Spherical Arc-Polarized Waves in Space Plasmas
Tsurutani, B.; Ho, Christian M.; Arballo, John K.; Lakhina, Gurbax S.; Glassmeier, Karl-Heinz; Neubauer, Fritz M.
1997-01-01
We review observations of nonlinear plasma waves detected by interplanetary spacecraft. For this paper we will focus primarily on the phase-steepened properties of such waves. Plasma waves at comet Giacobini-Zinner measured by the International Cometary Explorer (ICE), at comets Halley and Grigg-Skjellerup measured by Giotto, and interplanetary Alfven waves measured by Ulysses, will be discussed and intercompared.
Energy Technology Data Exchange (ETDEWEB)
Gao, Tao [Fundamental Science on EHF Laboratory, University of Electronic Science and Technology of China (UESTC), Chengdu 611731 (China); Science and Technology on Monolithic Integrated Circuits and Modules Laboratory, Nanjing Electronic Devices Institute, Nanjing 210016 (China); Xu, Ruimin [Fundamental Science on EHF Laboratory, University of Electronic Science and Technology of China (UESTC), Chengdu 611731 (China); Kong, Yuechan, E-mail: kycfly@163.com; Zhou, Jianjun; Kong, Cen; Dong, Xun; Chen, Tangsheng [Science and Technology on Monolithic Integrated Circuits and Modules Laboratory, Nanjing Electronic Devices Institute, Nanjing 210016 (China)
2015-06-15
We demonstrate highly improved linearity in a nonlinear ferroelectric of Pb(Zr{sub 0.52}Ti{sub 0.48})-gated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT). Distinct double-hump feature in the transconductance-gate voltage (g{sub m}-V{sub g}) curve is observed, yielding remarkable enhancement in gate voltage swing as compared to MIS-HEMT with conventional linear gate dielectric. By incorporating the ferroelectric polarization into a self-consistent calculation, it is disclosed that in addition to the common hump corresponding to the onset of electron accumulation, the second hump at high current level is originated from the nonlinear polar nature of ferroelectric, which enhances the gate capacitance by increasing equivalent dielectric constant nonlinearly. This work paves a way for design of high linearity GaN MIS-HEMT by exploiting the nonlinear properties of dielectric.
Nonlinear electrodynamics with birefringence
Kruglov, S I
2015-01-01
A new model of nonlinear electrodynamics with three parameters is suggested. The phenomena of vacuum birefringence takes place when there is the external constant magnetic field. We calculate the indices of refraction for two polarizations of electromagnetic waves, parallel and perpendicular to the magnetic induction field. From the Bir\\'{e}fringence Magn\\'{e}tique du Vide (BMV) experiment one of the coefficients, $\\gamma\\approx 10^{-20}$ T$^{-2}$, was estimated. The canonical, symmetrical Belinfante energy-momentum tensors and dilatation current were obtained. The dilatation symmetry and the dual symmetry are broken in the model considered.
Gubarkova, Ekaterina V.; Kirillin, Mikhail Yu.; Dudenkova, Varvara V.; Timashev, Peter S.; Kotova, Svetlana L.; Kiseleva, Elena B.; Timofeeva, Lidia B.; Belkova, Galina V.; Solovieva, Anna B.; Moiseev, Alexander A.; Gelikonov, Gregory V.; Fiks, Ilya I.; Feldchtein, Felix I.; Gladkova, Natalia D.
2016-12-01
A combination of approaches to the image analysis in cross-polarization optical coherence tomography (CP OCT) and high-resolution imaging by nonlinear microscopy and atomic force microscopy (AFM) at the different stages of atherosclerotic plaque development is studied. This combination allowed us to qualitatively and quantitatively assess the disorganization of collagen in the atherosclerotic arterial tissue (reduction and increase of CP backscatter), at the fiber (change of the geometric distribution of fibers in the second-harmonic generation microscopy images) and fibrillar (violation of packing and different nature of a basket-weave network of fibrils in the AFM images) organization levels. The calculated CP channel-related parameters are shown to have a statistically significant difference between stable and unstable (also called vulnerable) plaques, and hence, CP OCT could be a potentially powerful, minimally invasive method for vulnerable plaques detection.
Aoyama, T; Kinoshita, T; Nio, M
2011-01-01
This paper reports the tenth-order contributions to the g-2 of the electron a_e and those of the muon a_mu from the gauge-invariant Set II(c), which consists of 36 Feynman diagrams, and Set II(d), which consists of 180 Feynman diagrams. Both sets are obtained by insertion of sixth-order vacuum-polarization diagrams in the fourth-order anomalous magnetic moment. The mass-independent contributions from Set II(c) and Set II(d) are -0.116 489 (32)(alpha/pi)^5 and -0.243 00 (29)(alpha/pi)^5, respectively. The leading contributions to a_mu, which involve electron loops only, are -3.888 27 (90)(alpha/pi)^5 and 0.4972 (65)(alpha/pi)^5 for Set II(c) and Set II(d), respectively. The total contributions of the electron, muon, and tau-lepton loops to a_e are -0.116 874 (32) (alpha/pi)^5 for Set II(c) and -0.243 10 (29) (alpha/pi)^5 for Set II(d). The contributions of electron, muon, and tau-lepton loops to a_mu are -5.5594 (11) (alpha/pi)^5 for Set II(c) and 0.2465 (65) (alpha/pi)^5 for Set II(d).
Aoyama, T; Kinoshita, T; Nio, M; Watanabe, N
2008-01-01
We have evaluated the contribution to the anomalous magnetic moment of the electron from six tenth-order Feynman diagrams which contain eighth-order vacuum-polarization function formed by two light-by-light scattering diagrams connected by three photons. The integrals are constructed by two different methods. In the first method the subtractive counter terms are used to deal with ultraviolet (UV) singularities together with the requirement of gauge-invariance. In the second method, the Ward-Takahashi identity is applied to the light-by-light scattering amplitudes to eliminate UV singularities. Numerical evaluation confirms that the two methods are consistent with each other within their numerical uncertainties. Combining the two results statistically and adding small contribution from the muons and/or tau leptons, we obtain $ 0.000 399 9 (18) (\\alpha/\\pi)^5$. We also evaluated the contribution to the muon $g-2$ from the same set of diagrams and found $ -1.263 44 (14) (\\alpha/\\pi)^5$.
Energy Technology Data Exchange (ETDEWEB)
Baher, S. [Department of Physics, Lorestan University, Khoramabad (Iran, Islamic Republic of) and Research Institute of Applied Sciences (ACECR), Shahid Beheshti University (Iran, Islamic Republic of)]. E-mail: bahersalar@yahoo.com; Baharvand, A. [Department of Physics, Lorestan University, Khoramabad (Iran, Islamic Republic of); Sepahvand, R. [Department of Physics, Lorestan University, Khoramabad (Iran, Islamic Republic of); Badraghi, J. [Research Institute of Applied Sciences (ACECR), Shahid Beheshti University (Iran, Islamic Republic of)
2007-04-30
The propagation of nonlinear s-polarized polariton waves (TE modes) in an infinitely extended superlattice is considered. The periodic system is composed of two different components where the layers are arranged in an alternating fashion so that each layer of material 1 is bounded by two layers of material 2 and vice versa. In general, each of the individual layers may be characterized by a Kerr-type nonlinear dielectric function with a frequency-dependent characteristic of either the plasmons in a metal/semiconductor or the optical phonons in an ionic crystal. To investigate the propagation of polariton modes in such a system, a theoretical model is formulated leading to Jacobi elliptic functions for the electric field amplitude across the layers. Subsequently, the application of boundary conditions at the interfaces gives rise to dispersion relations. Numerical examples are given for plasmon-polariton and phonon-polariton modes and a comparison is made with phonon-polariton modes propagating in a three layered system.
Wang, Xiong; Zhou, Pu; Wang, Xiaolin; Xiao, Hu; Liu, Zejin
2014-03-10
We demonstrate the nanosecond-level pulses in Tm-doped fiber laser generated by passively harmonic mode-locking. Nonlinear polarization rotation performed by two polarization controllers (PCs) is employed to induce the self-starting harmonic mode-locking. The fundamental repetition rate of the laser is 448.8 kHz, decided by the length of the cavity. Bundles of pulses with up to 17 uniform subpulses are generated due to the split of pulse when the pump power increases and the PCs are adjusted. Continuous harmonic mode-locked pulse trains are obtained with 1st to 6th and even more than 15th order when the positions of the PCs are properly fixed and the pump power is scaled up. The widths of all the uniform individual pulses are mostly 3-5 ns, and pulse with width of 304 ns at fundamental repetition rate can also be generated by adjusting the PCs. Hysteresis phenomenon of the passively harmonic mode-locked pulses' repetition frequency versus pump power is observed. The rather wide 3dB spectral bandwidth of the pulse train (25 nm) indicates that they may resemble noise-like pulses.
Almaiman, Ahmed; Ziyadi, Morteza; Mohajerin-Ariaei, Amirhossein; Cao, Yinwen; Chitgarha, Mohammad Reza; Liao, Peicheng; Bao, Changjing; Shamee, Bishara; Ahmed, Nisar; Alishahi, Fatemeh; Fallahpour, Ahmad; Akasaka, Youichi; Yang, Jeng-Yuan; Sekiya, Motoyoshi; Touch, Joseph D; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Willner, Alan E
2016-06-15
This Letter proposes a method for tunable automatically locked homodyne detection of wavelength-division multiplexing (WDM) dual-polarization (DP) phase-shift keyed (PSK) channels using nonlinear mixing. Two stages of periodically poled lithium niobate (PPLN) waveguides and an LCoS filter enable automatic phase locking of the channels to a local laser.
Directory of Open Access Journals (Sweden)
M. Komanec
2014-09-01
Full Text Available We have developed a data transparent optical packet switch prototype employing wavelength conversion based on four-wave mixing. The switch is composed of an electro-optical control unit and an all-optical switching segment. To achieve higher switching efficiencies, Ge-doped silica suspended-core and chalcogenide arsenicselenide single-mode fibers were experimentally evaluated and compared to conventional highly-nonlinear fiber. Improved connectorization technology has been developed for Ge-doped suspended-core fiber, where we achieved connection losses of 0.9 dB. For the arsenic-selenide fiber we present a novel solid joint technology, with connection losses of only 0.25 dB, which is the lowest value presented up-to-date. Conversion efficiency of -13.7 dB was obtained for the highly-nonlinear fiber, which is in perfect correlation with previously published results and thus verifies the functionality of the prototype. Conversion efficiency of -16.1 dB was obtained with arsenic-selenide fiber length reduced to five meters within simulations, based on measurement results with a 26 m long component. Employment of such a short arsenic-selenide fiber segment allows significant broadening of the wavelength conversion spectral range due to possible neglection of dispersion.
Simulations of light-light scattering in quantum vacuum
Carneiro, Pedro; Grismayer, Thomas; Silva, LuíS.; Fonseca, Ricardo
2016-10-01
Facilities such as the Extreme Light Infrastructure (ELI) or the VULCAN 20 PW project, as well as the Petta-Watt SLAC project, coupled with the x-ray LCLSII source will allow to perform the first experiments on the probing of quantum vacuum. In our work, we developed a numerical method to self-consistently solve the nonlinear system of Maxwell's equations including quantum corrections of vacuum polarization. The robustness of our algorithm allied to the ability to integrate this tool within a particle-in-cell (PIC) method, represents an important milestone in modeling future planned experiments to prove the existence of the quantum vacuum. Such experiments aim to measure the induced ellipticity on a x-ray pulse after probing a strong optical pump due to the quantum vacuum fluctuations. We present simulation results of both the ellipticity induced and polarization rotation, using realistic laser parameters of the Petta-Watt SLAC project, and the x-ray LCLSII source, whilst taking into account all finite-size multi-dimensional effects. We show how the ellipticity induced varies as a function of the distance to the axis of the beam, proving the importance of taking into account finite-size effects. This work serves as an important tool to complement existing efforts within the community to probe the effects of the quantum vacuum, in the strong field regime, for the first time.
Halevy, A; Dovrat, L; Eisenberg, H S; Becker, P; Bohatý, L
2011-01-01
We describe the full characterization of the biaxial nonlinear crystal BiB3O6 (BiBO) as a polarization entangled photon source using non-collinear type-II parametric down-conversion. We consider the relevant parameters for crystal design, such as cutting angles, polarization of the photons, effective nonlinearity, spatial and temporal walk-offs, crystal thickness and the effect of the pump laser bandwidth. Experimental results showing entanglement generation with high rates and a comparison to the well investigated beta-BaB2O4 (BBO) crystal are presented as well. Changing the down-conversion crystal of a polarization entangled photon source from BBO to BiBO enhances the generation rate as if the pump power was increased by more than three times. Such an improvement is currently required for the generation of multiphoton entangled states.
Halevy, A; Megidish, E; Dovrat, L; Eisenberg, H S; Becker, P; Bohatý, L
2011-10-10
We describe the full characterization of the biaxial nonlinear crystal BiB₃O₆ (BiBO) as a polarization entangled photon source using non-collinear type-II parametric down-conversion. We consider the relevant parameters for crystal design, such as cutting angles, polarization of the photons, effective nonlinearity, spatial and temporal walk-offs, crystal thickness and the effect of the pump laser bandwidth. Experimental results showing entanglement generation with high rates and a comparison to the well investigated β-BaB₂O₄ (BBO) crystal are presented as well. Changing the down-conversion crystal of a polarization entangled photon source from BBO to BiBO enhances the generation rate as if the pump power was increased by 2.5 times. Such an improvement is currently required for the generation of multiphoton entangled states.
Marder, Seth R.; Gorman, Christopher B.; Cheng, Lap-Tak A.; Tiemann, Bruce G.
1993-02-01
We recently reported that there is an optimal combination of donor and acceptor strengths for a given molecular length and bridge structure that maximizes (beta) . For this combination, there is the correct degree of bond length alternation and asymmetry in the molecule. Our recent findings suggest that molecules that can be viewed as asymmetric cyanines with relatively small amounts of bond length alternation are nearly optimal. In this manner, we have identified molecules with nonlinearities many times that of conventional chromophores for a given length. In this paper, we will present a new computational analysis that allows the correlation of bond length alternation with hyperpolarizabilities and will present EFISH data on simple donor-acceptor polyene chromophores.
Energy Technology Data Exchange (ETDEWEB)
Zhang Xiaofei [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Xu Qing, E-mail: xuqing@whut.edu.c [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Liu Hanxing; Chen Wen [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Chen Min; Kim, Bok-Hee [Faculty of Advanced Materials Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)
2011-04-01
Nonlinear dielectric properties of Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} ceramics prepared by citrate method were investigated under bias electric field with respect to field history. X-ray diffraction analysis and temperature dependence of the dielectric constant ({epsilon}{sub r}) confirmed a macroscopically paraelectric state for the specimen at room temperature. A slim polarization versus electric field (P-E) hysteresis loop of the specimen at room temperature indicated the existence of polar nano-regions (PNRs) superimposed on the paraelectric background. The nonlinear dielectric properties in continuous cycles of bias field sweep displayed a strong sensitivity to the field history. This phenomenon was qualitatively explained in terms of an irreversible polarization evolution of the PNRs under the bias fields. A considerable decline of the tunability with the cycle number suggests an appreciable contribution of the PNRs to the dielectric nonlinearity. The polarization and size of the PNRs were determined by fitting the dielectric constants to a multipolarization mechanism model.
Schäfer, Christoph; Fries, Christian; Theobald, Christian; L'huillier, Johannes A
2013-01-15
Continuous-wave mode-locking of a laser exploiting the nonlinear polarization rotation (NPR) technique via Type I second harmonic generation is demonstrated for the first time. The NPR is generated by a lithium triborate crystal and transformed into nonlinear cavity losses of a 888 nm pumped Nd:YVO4 laser. Self-starting, reliable mode-locking has been achieved at a high average output power of 20.6 W and a pulse duration of 7.3 ps. Furthermore, transform limited pulses down to 2.7 ps have been demonstrated at 9.9 W.
Institute of Scientific and Technical Information of China (English)
2011-01-01
With its pure aperture up to 985mm, the New Vacuum Solar Telescope of China （NVST） has become the world＇s biggest vacuum solar telescope. The main science task of NVST is the high-resolution observation of photosphere and chromosphere including their fine structure of magnetic field on the sun. The NVST was equipped with many new technologies and powerful instruments, such as an adaptive optical system, a polarization analyzer, two vertical spectrographs, a high-resolution image system and a very narrow Ha filter （0.125A）.
Energy Technology Data Exchange (ETDEWEB)
Lorenci, V.A. de; Svaiter, N.F. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)
1996-11-01
It was investigated which mapping has to be used to compare measurements made in a rotating frame to those made in an inertial frame. Using a non-Galilean coordinate transformation, the creation-annihilation operators of a massive scalar field in the rotating frame are not the same as those of an inertial observer. This leads to a new vacuum state(a rotating vacuum) which is a superposition of positive and negative frequency Minkowski particles. Polarization effects in circular accelerators in the proper frame of the electron making a connection with the inertial frame point of view were analysed. 65 refs.
Polarizable vacuum analysis of electromagnetic fields
Ye, Xing-Hao
2009-01-01
By examining the electric displacement in a dielectric medium and in a vacuum, the polarization property of quantum vacuum is discussed. Both the electric and magnetic fields are analysed in the framework of polarizable vacuum. It is found that the energy and force generated by the electric and magnetic fields can then be understood in a natural way. As an application, the electromagnetic wave is also investigated, which reaches a polarizable vacuum interpretation of the energy and spin of a photon.
Gordon, H.S.
1959-09-15
An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.
Karbstein, Felix
2016-01-01
The focus of these lectures is on the quantum vacuum subjected to classical electromagnetic fields. To this end we explicitly derive the renowned Heisenberg-Euler effective action in constant electromagnetic fields in a rather pedagogical and easy to conceive way. As an application, we use it to study vacuum birefringence constituting one of the most promising optical signatures of quantum vacuum nonlinearity.
Energy Technology Data Exchange (ETDEWEB)
Biltoft, P J
2004-10-15
The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.
Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo
1989-01-01
The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.
DEFF Research Database (Denmark)
Maagaard, Mathilde; Oestergaard, Jeanett; Johansen, Marianne
2012-01-01
Objectives. To develop and validate an Objective Structured Assessment of Technical Skills (OSATS) scale for vacuum extraction. Design. Two part study design: Primarily, development of a procedure-specific checklist for vacuum extraction. Hereafter, validationof the developed OSATS scale for vacuum...... extraction in a prospective observational study. Setting. Rigshospitalet, University Hospital of Copenhagen. Population. For development an obstetric expert from each labor ward in Denmark (28 departments) were invited to participate. For validation nine first-year residents and ten chief physicians...... with daily work in the obstetric field were tested. Methods. The Delphi method was used for development of the scale. In a simulated vacuum extraction scenario first-year residents and obstetric chief physicians were rated using the developed OSATS scale for vacuum extraction to test construct validity...
DEFF Research Database (Denmark)
Maagaard, Mathilde; Oestergaard, Jeanett; Johansen, Marianne
2012-01-01
Objectives. To develop and validate an Objective Structured Assessment of Technical Skills (OSATS) scale for vacuum extraction. Design. Two part study design: Primarily, development of a procedure-specific checklist for vacuum extraction. Hereafter, validationof the developed OSATS scale for vacuum...... extraction in a prospective observational study. Setting. Rigshospitalet, University Hospital of Copenhagen. Population. For development an obstetric expert from each labor ward in Denmark (28 departments) were invited to participate. For validation nine first-year residents and ten chief physicians...... with daily work in the obstetric field were tested. Methods. The Delphi method was used for development of the scale. In a simulated vacuum extraction scenario first-year residents and obstetric chief physicians were rated using the developed OSATS scale for vacuum extraction to test construct validity...
Grigoryan, L. S.; Saakyan, G. S.
1984-09-01
The existence of a special gravitational vacuum is considered in this paper. A phenomenological method differing from the traditional Einsteinian formalization is utilized. Vacuum, metric and matter form a complex determined by field equations and at great distances from gravitational masses vacuum effects are small but could be large in powerful fields. Singularities and black holes justify the approach as well as the Ambartsmyan theory concerning the existence of supermassive and superdense prestallar bodies that then disintegrate. A theory for these superdense bodies is developed involving gravitational field equations that describe the vacuum by an energy momentum tensor and define the field and mass distribution. Computations based on the theory for gravitational radii with incompressible liquid models adequately reflecting real conditions indicate that a gravitational vacuum could have considerable effects on superdense stars and could have radical effects for very large masses.
Park, Q H
1999-01-01
Using the Painlevé analysis, we investigate the integrability properties of a system of two coupled nonlinear Schrödinger equations that describe the propagation of orthogonally polarized optical waves in an isotropic medium. Besides the well-known integrable vector nonlinear Schrödinger equation, we show that there exist a new set of equations passing the Painlevé test where the self and cross phase modulational terms are of different magnitude. We introduce the Hirota bilinearization and the Bãcklund transformation to obtain soliton solutions and prove integrability by making a change of variables. The conditions on the third-order susceptibility tensor $\\chi^{(3)} $ imposed by these new integrable equations are explained.
Wu, Wenjue; Zhou, Yue; Sun, Ji; Dai, Yitang; Yin, Feifei; Dai, Jian; Xu, Kun
2016-11-01
We proposed a mode-locked all-polarization-maintaining erbium-doped fiber laser base on a nonlinear amplifying loop mirror (NALM). The laser can generate 1.6 ps pulses at 1550 nm with the energy of 1 nJ that can be compressed down to 100 fs with the compressor outside the cavity. The repetition rate of the output pulse is 12MHz. Such configuration of laser is easier controlled and self starting long term operation, and is highly desirable for industrial applications, such as micro-machining.
Xiao, Xiaosheng; Hua, Yi
2016-10-01
All-normal-dispersion (ANDi) mode-locked Yb-doped fiber laser is a promising seed source for supercontinuum (SC) generation, due to its compact structure and broadband output. The influences of output ports of the ANDi laser mode-locked by nonlinear polarization rotation (NPR), on the generated SC are investigated. Two output ports of ANDi laser are considered, one of which is the conventional nonlinear polarization rotation (NPR) port and the other is extracted from a coupler after the NPR port. It is found that, the SC originated from the coupler port is much broader than that from the NPR port, which is validated by lots of experiments with different output parameters. Furthermore, the conclusion is verified and generalized to general ANDi lasers by numerical simulations, because the output pulse from coupler port could be cleaner than that from NPR port. Besides, there are no significant differences in the phase coherence and temporal stability between the SCs generated from both ports. Hence for the SC generation based on ANDi laser, it is preferred to use the pulse of coupler port (i.e. pulse after NPR port) serving as the seed source.
Yuan, Jinhui; Kang, Zhe; Li, Feng; Zhou, Guiyao; Zhang, Xianting; Mei, Chao; Sang, Xinzhu; Wu, Qiang; Yan, Binbin; Zhou, Xian; Zhong, Kangping; Wang, Kuiru; Yu, Chongxiu; Lu, Chao; Tam, Hwa Yaw; Wai, P K A
2017-08-23
Deep-ultraviolet (UV) second-harmonics (SHs) have important applications in basic physics and applied sciences. However, it still remains challenging to generate deep-UV SHs especially in optical fibers. Here, for the first time, we experimentally demonstrate the deep-UV SH generations (SHGs) by combined degenerate four-wave mixing (FWM) and surface nonlinearity polarization in an in-house designed and fabricated air-silica photonic crystal fiber (PCF). When femtosecond pump pulses with average input power P av of 650 mW and center wavelength λ p of 810, 820, 830, and 840 nm are coupled into the normal dispersion region close to the zero-dispersion wavelength of the fundamental mode of the PCF, the anti-Stokes waves induced by degenerate FWM process are tunable from 669 to 612 nm. Then, they serve as the secondary pump, and deep-UV SHs are generated within the wavelength range of 334.5 to 306 nm as a result of surface nonlinearity polarization at the core-cladding interface of the PCF. The physical mechanism of the SHGs is confirmed by studying the dependences of the output power P SH of the SHs on the PCF length and time. Finally, we also establish a theoretical model to analyze the SHGs.
Directory of Open Access Journals (Sweden)
Mustapha Lahmar
2015-04-01
Full Text Available On the basis of the V. K. Stokes micro-continuum theory, the effects of couple stresses on the nonlinear dynamic response of the unbalanced Jeffcott’s flexible rotor supported by layered hydrodynamic journal bearings is presented in this paper. A nonlinear transient modified Reynolds’ equation is derived and discretized by the finite element method to obtain the fluid-film pressure field as well as the film thickness by means of the implicit Euler method. The nonlinear orbits of the rotor center are determined by solving the nonlinear differential equations of motion with the explicit Euler’s scheme taking into account the flexibility of rotor. According to the obtained results, the combined effects of couple stresses due to the presence of polymer additives in lubricant and the pressure dependent viscosity on the nonlinear dynamic response of the rotor-bearing system are significant and cannot be ignored or overlooked. As expected, these effects are more noticeable for polymers characterized by higher length molecular chains.
Intravaia, F
2016-01-01
In quantum theory the vacuum is defined as a state of minimum energy that is devoid of particles but still not completely empty. It is perhaps more surprising that its definition depends on the geometry of the system and on the trajectory of an observer through space-time. Along these lines we investigate the case of an atom flying at constant velocity near a planar surface. Using general concepts of statistical mechanics it is shown that the motion-modified interaction with the electromagnetic vacuum is formally equivalent to the interaction with a thermal field having an effective temperature determined by the atom's velocity and distance from the surface. This result suggests new ways to experimentally investigate the properties of the quantum vacuum in non-equilibrium systems and effects such as quantum friction.
De Lorenci, V A
1996-01-01
We investigate which mapping we have to use to compare measurements made in a rotating frame to those made in an inertial frame. Using a "Lorentz-like" coordinate transformation we obtain that creation-anihilation operators of a massless scalar field in the rotating frame are not the same as those of an inertial observer. This leads to a new vacuum state (a rotating vacuum) which is a superposition of positive and negative frequency Minkowski particles. After this, introducing an apparatus device coupled linearly with the field we obtain that there is a strong correlation between number of rotating particles (in a given state) obtained via canonical quantization and via response function of the rotating detector. Finally, we analyse polarization effects in circular accelerators in the proper frame of the electron making a connection with the inertial frame point of view.
Ngoko Djiokap, J M; Manakov, N L; Meremianin, A V; Hu, S X; Madsen, L B; Starace, Anthony F
2014-11-28
Control of double ionization of He by means of the polarization and carrier-envelope phase (CEP) of an intense, few-cycle extreme ultraviolet (XUV) pulse is demonstrated numerically by solving the six-dimensional two-electron, time-dependent Schrödinger equation for He interacting with an elliptically polarized XUV pulse. Guided by perturbation theory (PT), we predict the existence of a nonlinear dichroic effect (∝I^{3/2}) that is sensitive to the CEP, ellipticity, peak intensity I, and temporal duration of the pulse. This dichroic effect (i.e., the difference of the two-electron angular distributions for opposite helicities of the ionizing XUV pulse) originates from interference of first- and second-order PT amplitudes, allowing one to probe and control S- and D-wave channels of the two-electron continuum. We show that the back-to-back in-plane geometry with unequal energy sharing is an ideal one for observing this dichroic effect that occurs only for an elliptically polarized, few-cycle attosecond pulse.
1974-01-01
This valve was used in the Intersecting Storage Rings (ISR) to protect against the shock waves that would be caused if air were to enter the vacuum tube. Some of the ISR chambers were very fragile, with very thin walls - a design required by physicists on the lookout for new particles.
Deligny, O
2002-01-01
The cosmic rays spectrum has been shown to extend well beyond 10^20 eV. With nearly 20 events observed in the last 40 years, it is now established that particles with energies near or above 10^21 eV. No nearby astrophysical object has been shown to correlate with the arrival directions of the highest energy events, yet the exponential cut-off in the high energy end of the spectrum one expects to see in the case of far sources is not visible. It was recently pointed out that the influence of the vacuum of quantum electrodynamics on particle propagation could explain qualitatively this mystery. This note is a critic to these ideas.
Energy Technology Data Exchange (ETDEWEB)
Maxwell, R.J. (Deaprtment of Agriculture, Philadelphia, PA (USA)); Rady, A.H. (Nuclear Research Centre, Inshas (Egypt))
1989-01-01
Chicken muscle and skin were separately irradiated in air and under vacuum packaging at 0, 1, 3, 6 and 10 kGy using {sup 137}Cs (dose rate 0.1 kGy/min). Lipids were isolated as neutral and polar subclasses from muscle samples and as total lipid extracts from skin. Lipids were converted to fatty acid methyl esters, analyzed by capillary gas chromatography and the data compiled as fatty acid profiles by statistical computer analysis. Normalized reports were assembled from this data for the three lipid extract types. Only negligible changes in fatty acid profiles were observed for the neutral lipids of muscle and for the fatty acyl residues of skin lipids. Minor changes of interest, however, were observed for the polyunsaturated fatty acyl residues in the polar lipid fractions of muscle tissue, especially at higher irradiation doses (6 and 10 kGy). Comparisons were made between these results and those of an earlier study were similar tissues were irradiated at -20{sup 0}C. No new fatty acyl residues or other artifacts due to {gamma}-irradiation were found in detectable amounts by gas chromatography in any of the lipid fractions isolated. (author).
Petrov, E. Yu.; Kudrin, A. V.
2016-09-01
The problem of longitudinal oscillations of an electric field and a charge polarization density in a quantum electrodynamics (QED) vacuum is considered. Within the framework of semiclassical analysis, we calculate time-periodic solutions of bosonized (1 +1 )-dimensional QED (massive Schwinger model). Applying the Bohr-Sommerfeld quantization condition, we determine the mass spectrum of charge-zero bound states (plasmons) which correspond in quantum theory to the found classical solutions. We show that the existence of such plasmons does not contradict any fundamental physical laws and study qualitatively their excitation in a (3 +1 )-dimensional real world.
Vacuum measurement on vacuum packaged MEMS devices
Energy Technology Data Exchange (ETDEWEB)
Gan Zhiyin; Lin Dong; Wang Xuefang; Chenggang; Zhang Honghai; Liu Sheng [Institute of Microsystems and Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, China, 430074 (China)
2007-07-15
This paper investigates the relationship between the resonance impedance of a tuning fork quartz oscillator and the small size cavity vacuum pressure and develops an on-line vacuum measurement system to track real-time vacuum pressure in MEMS devices. Furthermore, authors completely analyze all facts that affect the resonance impedance. A set of metal vacuum packaged devices have been monitored for more than 10 months using this on-line vacuum measurement system. The results indicate that it is very critical to investigate vacuum packaging processes, reliability and durability of the vacuum devices by using this on-line vacuum measurement system.
Yan, Ming; Li, Wenxue; Yang, Kangwen; Zhou, Hui; Shen, Xuling; Zhou, Qian; Ru, Qitian; Bai, Dongbi; Zeng, Heping
2012-05-01
We report on a simple scheme to precisely control carrier-envelope phase of a nonlinear-polarization-rotation mode-locked self-started Yb-fiber laser system with an average output power of ∼7 W and a pulse width of 130 fs. The offset frequency was locked to the repetition rate of ∼64.5 MHz with a relative linewidth of ∼1.4 MHz by using a self-referenced feed-forward scheme based on an acousto-optic frequency shifter. The phase noise and timing jitter were calculated to be 370 mrad and 120 as, respectively.
Novikov, A; Odoulov, S; Jungen, R; Tschudi, T
1991-12-15
The development of a spatial subharmonic, i.e., of a light wave propagating at the bisector of two pump waves, with orthogonal polarizations incident upon a BaTiO(3) crystal in a plane normal to the optical axis is observed and studied. Parametric amplification of a seed wave meeting the phase-matching condition in the presence of two pump waves is shown to be the main reason for subharmonic generation in this crystal.
Boyd, Robert W
2013-01-01
Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q
DEFF Research Database (Denmark)
Kwok, C.H.; Chow, C.W.; Tsang, H.K.;
2006-01-01
We study the conversion bandwidth of the cross-polarization-modulation (YPoIM)-based wavelength conversion scheme with a dispersion-flattened highly nonlinear photonic-crystal fiber for signals with a nonreturn-to-zero (NRZ) modulation format. Both theoretical and experimental results show...... using the YPoIM approach compared with the four-wave mixing approach previously reported is demonstrated....
Influence of Photon Mass on Vacuum Birefringence Experiment
Institute of Scientific and Technical Information of China (English)
CHEN Min; SHAO Cheng-Gang
2007-01-01
Influence of photon mass on vacuum birefringence experiment is analysed according to the nonlinearities of vacuum quantum electrodynamics for the light propagation through an intense electromagnetic field.It is shown that although the photon mass will cause a change of the refractive indices n⊥ and n(‖) of vacuum birefringence,the difference n(‖)-n⊥is unchanged,which means that the effect of photon mass cannot be observed in vacuum birefringence experiment.
Vacuum systems for the ILC helical undulator
Malyshev, O B; Clarke, J A; Bailey, I R; Dainton, J B; Malysheva, L I; Barber, D P; Cooke, P; Baynham, E; Bradshaw, T; Brummitt, A; Carr, S; Ivanyushenkov, Y; Rochford, J; Moortgat-Pick, G A
2007-01-01
The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of ∼10MeV∼10MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of ∼100nTorr∼100nTorr in a narrow chamber of 4–6mm4–6mm inner diameter, with a long length of 100–200m100–200m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.
NONLINEAR EFFECTS OF THIRD-AND FIFTH-ORDER ON POLARIZATION BEATS IN AFOUR-LEVEL SYS-TEM
Institute of Scientific and Technical Information of China (English)
Zhang Yan-peng; Lu Ke-qing; Wu Hong-cai; Xu Jiao; Fu Pan-ming
2000-01-01
We have employed second-order coherence function theory to study thenonlinear effects of third-and fifth-order on polarization beats in afour-level system (TPBFS and FPBFS). It is found that the differenttemporal behavior of the beat signal in TPBFS and FPBFS depends on thestochastic properties of the lasers and transverse relaxation rate ofthe transition. We have considered the cases that pump beams have eithernarrow band or broadband linewidth and found that for both cases aDoppler-free precision can be achieved in the measurement of theenergy-level difference between two excited states which are dipolarforbidden from the ground state. We also discussed the spatiallmodulation behavior of the beat signal.
Modified Nonlinear Model of Arcsin-Electrodynamics
Kruglov, S. I.
2016-07-01
A new modified model of nonlinear arcsin-electrodynamics with two parameters is proposed and analyzed. We obtain the corrections to the Coulomb law. The effect of vacuum birefringence takes place when the external constant magnetic field is present. We calculate indices of refraction for two perpendicular polarizations of electromagnetic waves and estimate bounds on the parameter γ from the BMV and PVLAS experiments. It is shown that the electric field of a point-like charge is finite at the origin. We calculate the finite static electric energy of point-like particles and demonstrate that the electron mass can have the pure electromagnetic nature. The symmetrical Belinfante energy-momentum tensor and dilatation current are found. We show that the dilatation symmetry and dual symmetry are broken in the model suggested. We have investigated the gauge covariant quantization of the nonlinear electrodynamics fields as well as the gauge fixing approach based on Dirac's brackets.
2016-01-01
Modeling and prediction of polar organic chemical integrative sampler (POCIS) sampling rates (Rs) for 73 compounds using artificial neural networks (ANNs) is presented for the first time. Two models were constructed: the first was developed ab initio using a genetic algorithm (GSD-model) to shortlist 24 descriptors covering constitutional, topological, geometrical and physicochemical properties and the second model was adapted for Rs prediction from a previous chromatographic retention model (RTD-model). Mechanistic evaluation of descriptors showed that models did not require comprehensive a priori information to predict Rs. Average predicted errors for the verification and blind test sets were 0.03 ± 0.02 L d–1 (RTD-model) and 0.03 ± 0.03 L d–1 (GSD-model) relative to experimentally determined Rs. Prediction variability in replicated models was the same or less than for measured Rs. Networks were externally validated using a measured Rs data set of six benzodiazepines. The RTD-model performed best in comparison to the GSD-model for these compounds (average absolute errors of 0.0145 ± 0.008 L d–1 and 0.0437 ± 0.02 L d–1, respectively). Improvements to generalizability of modeling approaches will be reliant on the need for standardized guidelines for Rs measurement. The use of in silico tools for Rs determination represents a more economical approach than laboratory calibrations. PMID:27363449
Lokstein, Heiko; Krikunova, Maria; Teuchner, Klaus; Voigt, Bernd
2011-08-15
Photosynthetically active pigments are usually organized into pigment-protein complexes. These include light-harvesting antenna complexes (LHCs) and reaction centers. Site energies of the bound pigments are determined by interactions with their environment, i.e., by pigment-protein as well as pigment-pigment interactions. Thus, resolution of spectral substructures of the pigment-protein complexes may provide valuable insight into structure-function relationships. By means of conventional (linear) and time-resolved spectroscopic techniques, however, it is often difficult to resolve the spectral substructures of complex pigment-protein assemblies. Nonlinear polarization spectroscopy in the frequency domain (NLPF) is shown to be a valuable technique in this regard. Based on initial experimental work with purple bacterial antenna complexes as well as model systems NLPF has been extended to analyse the substructure(s) of very complex spectra, including analyses of interactions between chlorophylls and "optically dark" states of carotenoids in LHCs. The paper reviews previous work and outlines perspectives regarding the application of NLPF spectroscopy to disentangle structure-function relationships in pigment-protein complexes.
Knippenberg, S; Rehn, D R; Wormit, M; Starcke, J H; Rusakova, I L; Trofimov, A B; Dreuw, A
2012-02-14
An earlier proposed approach to molecular response functions based on the intermediate state representation (ISR) of polarization propagator and algebraic-diagrammatic construction (ADC) approximations is for the first time employed for calculations of nonlinear response properties. The two-photon absorption (TPA) spectra are considered. The hierarchy of the first- and second-order ADC∕ISR computational schemes, ADC(1), ADC(2), ADC(2)-x, and ADC(3/2), is tested in applications to H(2)O, HF, and C(2)H(4) (ethylene). The calculated TPA spectra are compared with the results of coupled cluster (CC) models and time-dependent density-functional theory (TDDFT) calculations, using the results of the CC3 model as benchmarks. As a more realistic example, the TPA spectrum of C(8)H(10) (octatetraene) is calculated using the ADC(2)-x and ADC(2) methods. The results are compared with the results of TDDFT method and earlier calculations, as well as to the available experimental data. A prominent feature of octatetraene and other polyene molecules is the existence of low-lying excited states with increased double excitation character. We demonstrate that the two-photon absorption involving such states can be adequately studied using the ADC(2)-x scheme, explicitly accounting for interaction of doubly excited configurations. Observed peaks in the experimental TPA spectrum of octatetraene are assigned based on our calculations.
Vacuum Lightcone Fluctuations in a Dielectric
Bessa, C H G; Ford, L H; Svaiter, N F
2014-01-01
A model for observable effects of electromagnetic vacuum fluctuations is presented. The model involves a probe pulse which traverses a slab of nonlinear optical material with a nonzero second order polarizability. We argue that the pulse interacts with the ambient vacuum fluctuations of other modes of the quantized electric field, and these vacuum fluctuations cause variations in the flight time of the pulse through the material. The geometry of the slab of material defines a sampling function for the quantized electric field, which in turn determines that vacuum modes whose wavelengths are of the order of the thickness of the slab give the dominant contribution. Some numerical estimates are made, which indicate that fractional fluctuations in flight time of the order of $10^{-9}$ are possible in realistic situations. The model presented here is both an illustration of a physical effect of vacuum fluctuations, and an analog model for the lightcone fluctuations predicted by quantum gravity.
Yanagawa, Youichi; Ohsaka, Hiromichi; Jitsuiki, Kei; Yoshizawa, Toshihiko; Takeuchi, Ikuto; Omori, Kazuhiko; Oode, Yasumasa; Ishikawa, Kouhei
2016-08-01
This article describes the theory of the formation of the vacuum phenomenon (VP), the detection of the VP, the different medical causes, the different locations of the presentation of the VP, and the differential diagnoses. In the human body, the cavitation effect is recognized on radiological studies; it is called the VP. The mechanism responsible for the formation of the VP is as follows: if an enclosed tissue space is allowed to expand as a rebound phenomenon after an external impact, the volume within the enclosed space will increase. In the setting of expanding volume, the pressure within the space will decrease. The solubility of the gas in the enclosed space will decrease as the pressure of the space decreases. Decreased solubility allows a gas to leave a solution. Clinically, the pathologies associated with the VP have been reported to mainly include the normal joint motion, degeneration of the intervertebral discs or joints, and trauma. The frequent use of CT for trauma patients and the high spatial resolution of CT images might produce the greatest number of chances to detect the VP in trauma patients. The VP is observed at locations that experience a traumatic impact; thus, an analysis of the VP may be useful for elucidating the mechanism of an injury. When the VP is located in the abdomen, it is important to include perforation of the digestive tract in the differential diagnosis. The presence of the VP in trauma patients does not itself influence the final outcome.
Ortega, Alejandra; Perez-Martinez, Ana Laura; Ogawa, Takeshi; Smith, Francis; Walser, Ardie; Dorsinville, Roger
A highly-conjugated polar dye with three aromatic rings connected with azo groups was prepared and it was incorporated in polycinnamate. It showed a third-order nonlinear susceptibility of 8 × 10-10 esu determined by a Z-scan technique. The unpoled and poled films show the same susceptibility indicating the polymer film could not be poled. The open aperture Z-scan showed negligible two-photon absorption at 1064 nm.
Nonlinearity-reduced interferometer
Wu, Chien-ming
2007-12-01
Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as the frequency mixing, polarization mixing, polarization-frequency mixing, and the ghost reflections. An interferometer having accuracy in displacement measurement of less than one-nanometer is necessary in nanometrology. To meet the requirement, the periodic nonlinearity should be less than deep sub-nanometer. In this paper, a nonlinearity-reduced interferometry has been proposed. Both the linear- and straightness-interferometer were tested. The developed interferometer demonstrated of a residual nonlinearity less than 25 pm.
Vacuum mechatronics. Proceedings.
Belinski, S. E.; Shirazi, M.; Hackwood, S.; Beni, G.
The discipline of vacuum mechatronics is the design and development of vacuum-compatible, computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. Vacuum mechantronics is relevant to research engineers in integrated circuit manufacturing, surface physics, food processing, biotechnology, materials handling, space sciences and manufacturing.
Lin, Sheng-Fong; Lin, Gong-Ru
2014-09-08
With the combining effects of the fiber birefringence induced round-trip phase variation and the gain profile reshaping induced spectral filtering in the Erbium-doped fiber laser (EDFL) cavity, the mechanism corresponding to the central wavelength tunability of the EDFL passively mode-locked by nonlinear polarization rotation is explored. Bending the intracavity fiber induces the refractive index difference between orthogonal axes, which enables the dual-band central wavelength shift of 2.9 nm at 1570 nm region and up to 10.2 nm at 1600 nm region. The difference between the wavelength shifts at two bands is attributed to the gain dispersion decided by the gain spectral curvature of the EDFA, and the spacing between two switchable bands is provided by the birefringence induced variation on phase delay which causes transmittance variation. In addition, the central wavelength shift can also be controlled by varying the pumping geometry. At 1570 nm regime, an offset of up to 5.9 nm between the central wavelengths obtained under solely forward or backward pumping condition is observed, whereas the bidirectional pumping scheme effectively compensates the gain spectral reshaping effects to minimize the central wavelength shift. In contrast, the wavelength offset shrinks to only 1.1 nm when mode-locking at 1600 nm under single-sided pumping, as the gain profile strongly depends on the spatial distribution of the excited erbium ions under different pumping schemes. Except the birefringence variation and the gain spectral filtering phenomena, the gain-saturation mechanism induced refractive index change and its influence to the dual-band central wavelength tunability are also observed and analyzed.
Vacuum high harmonic generation in the shock regime
Böhl, P; Ruhl, H
2015-01-01
Electrodynamics becomes nonlinear and permits the self-interaction of fields when the quantised nature of vacuum states is taken into account. The effect on a plane probe pulse propagating through a stronger constant crossed background is calculated using numerical simulation and by analytically solving the corresponding wave equation. The electromagnetic shock resulting from vacuum high harmonic generation is investigated and a nonlinear shock parameter identified.
Sahoo, Sushree S.; Bhowmick, Arup; Mohapatra, Ashok K.
2017-03-01
We have studied the rotation of an elliptically polarized light propagating through thermal rubidium vapor with efficient four-wave mixing (FWM) and cross-phase modulation (XPM). These nonlinear processes are enhanced by Zeeman coherence within the degenerate sub-levels of the two-level atomic system. The elliptically polarized light with small ellipticity is considered as the superposition of a strong-linearly-polarized pump beam and a weak-orthogonal-polarized probe beam. The interference of the probe and the newly generated light field due to degenerate FWM and their gain in the medium due to a large XPM induced by the pump beam leads to the rotation of the elliptical polarized light. A theoretical analysis of the probe propagation through the nonlinear medium was used to explain the experimental observation and the fitting of the experimental data gives the estimates of the third-order non-linear susceptibilities associated with FWM and XPM. Our study can provide useful parameters for the generation of efficient squeezed vacuum states and squeezed polarization states of light. Furthermore our study finds application in controlling the diffraction of a linearly-polarized light beam traversing the medium.
A method to measure vacuum birefringence at FCC-ee
Uggerhøj, Ulrik I
2016-01-01
It is well-known that the Heisenberg-Euler-Schwinger effective Lagrangian predicts that a vacuum with a strong static electromagnetic field turns birefringent. We propose a scheme that can be implemented at the planned FCC-ee, to measure the nonlinear effect of vacuum birefringence in electrodynamics arising from QED corrections. Our scheme employs a pulsed laser to create Compton backscattered photons off a high energy electron beam, with the FCC-ee as a particularly interesting example. These photons will pass through a strong static magnetic field, which changes the state of polarization of the radiation - an effect proportional to the photon energy. This change will be measured by the use of an aligned single-crystal, where a large difference in the pair production cross-sections can be achieved. In the proposed experimental setup the birefringence effect gives rise to a difference in the number of pairs created in the analyzing crystal, stemming from the fact that the initial laser light has a varying st...
Indian Vacuum Society: The Indian Vacuum Society
Saha, T. K.
2008-03-01
The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of
Modified nonlinear model of arcsin-electrodynamics
Kruglov, S I
2015-01-01
A new modified model of nonlinear arcsin-electrodynamics with two parameters is proposed and analyzed. We obtain the corrections to the Coulomb law. The effect of vacuum birefringence takes place when the external constant magnetic field is present. We calculate indices of refraction for two perpendicular polarizations of electromagnetic waves and estimate bounds on the parameter $\\gamma$ from the BMV and PVLAS experiments. It is shown that the electric field of a point-like charge is finite at the origin. We calculate the finite static electric energy of point-like particles and demonstrate that the electron mass can have the pure electromagnetic nature. The symmetrical Belinfante energy-momentum tensor and dilatation current are found. We show that the dilatation symmetry and dual symmetry are broken in the model suggested.
Non-linear effects for cylindrical gravitational two-soliton
Tomizawa, Shinya
2015-01-01
Using a cylindrical soliton solution to the four-dimensional vacuum Einstein equation, we study non-linear effects of gravitational waves such as Faraday rotation and time shift phenomenon. In the previous work, we analyzed the single-soliton solution constructed by the Pomeransky's improved inverse scattering method. In this work, we construct a new two-soliton solution with complex conjugate poles, by which we can avoid light-cone singularities unavoidable in a single soliton case. In particular, we compute amplitudes of such non-linear gravitational waves and time-dependence of the polarizations. Furthermore, we consider the time shift phenomenon for soliton waves, which means that a wave packet can propagate at slower velocity than light.
Chughtai, Mohsan Niaz; Forzati, Marco; Mårtensson, Jonas; Rafique, Danish
2012-03-26
In this paper we numerically investigate nonlinear impairments in a WDM system with mixed PM (D)QPSK and OOK channels. First we analyze the dependence of XPM and XPolM on SOP and baud rate in absence of PMD. In this case we find that the nonlinear impairments are highly dependent on relative SOP between the PM (D)QPSK and neighbouring OOK channels. The dependence on relative SOP is more pronounced in differential detection than in coherent detection. However, with increasing values of PMD this dependence decreases, and non-linear tolerance improves.
Construction of the Pauli-Villars-regulated Dirac vacuum in electromagnetic fields
Gravejat, Philippe; Lewin, Mathieu; Séré, Eric
2012-01-01
Using the Pauli-Villars regularization and arguments from convex analysis, we construct the polarized Dirac vacuum, in the presence of small external electromagnetic fields. We describe the electrons by a Hartree-Fock-type theory and the photons by a self-consistent classical magnetic potential. The resulting vacuum polarization coincides on first order with that of full Quantum Electrodynamics.
Catalysis of Schwinger Vacuum Pair Production
Dunne, Gerald V; Schützhold, Ralf
2009-01-01
We propose a new catalysis mechanism for non-perturbative vacuum electron-positron pair production, by superimposing a plane-wave X-ray probe beam with a strongly focused optical laser pulse, such as is planned at the Extreme Light Infrastructure (ELI) facility. We compute the absorption coefficient arising from vacuum polarization effects for photons below threshold in a strong electric field. This set-up should facilitate the (first) observation of this non-perturbative QED effect with planned light sources such as ELI yielding an envisioned intensity of order 10^{26}W/cm^2.
Plane density of induced vacuum charge in a supercritical Coulomb potential
Khalilov, V R
2016-01-01
An expression for the density of a planar induced vacuum charge is obtained in a strong Coulomb potential in coordinate space. Treatment is based on a self-adjoint extension approach for constructing of the Green's function of a charged fermion in this potential. Induced vacuum charge density is calculated and analyzed at the subcritical and supercritical Coulomb potentials for massless and massive fermions. The behavior of the obtained vacuum charge density is investigated at long and short distances from the Coulomb center. The induced vacuum charge has a screening sign. Screening of a Coulomb impurity in graphene is briefly discussed. We calculate the real vacuum polarization charge density that acquires the quantum electrodynamics vacuum in the supercritical Coulomb potential due to the so-called real vacuum polarization. It is shown that the vacuum charge densities essentially differ in massive and massless cases. We expect that our results can, as a matter of principle, be tested in graphene with a supe...
Vacuum Energy: Myths and Reality
Volovik, G. E.
2006-01-01
We discuss the main myths related to the vacuum energy and cosmological constant, such as: ``unbearable lightness of space-time''; the dominating contribution of zero point energy of quantum fields to the vacuum energy; non-zero vacuum energy of the false vacuum; dependence of the vacuum energy on the overall shift of energy; the absolute value of energy only has significance for gravity; the vacuum energy depends on the vacuum content; cosmological constant changes after the phase transition...
Physical Vacuum in Superconductors
de Matos, Clovis Jacinto
2009-01-01
Although experiments carried out by Jain et al. showed that the Cooper pairs obey the strong equivalence principle, The measurement of the Cooper pairs inertial mass by Tate et al. revealed an anomalous excess of mass. In the present paper we interpret these experimental results in the framework of an electromagnetic model of dark energy for the superconductors' vacuum. We argue that this physical vacuum is associated with a preferred frame. Ultimately from the conservation of energy for Cooper pairs we derive a model for a variable vacuum speed of light in the superconductors physical vacuum in relation with a possible breaking of the weak equivalence principle for Cooper pairs.
Vacuum Birefringence as a Vacuum Emission Process
Karbstein, Felix
2015-01-01
We argue that the phenomenon of vacuum birefringence in strong inhomogeneous electromagnetic fields can be most efficiently analyzed in terms of a vacuum emission process. In this contribution, we exemplarily stick to the case of vacuum birefringence in a stationary perpendicularly directed, purely magnetic background field extending over a finite spatial extent. Similar field configurations are realized in the BMV and PVLAS experiments. We demonstrate that we can reproduce the conventional constant field result. Our focus is on effects which arise when the probe photons originate in the field free region, are directed towards the magnetic field region, and detected well after the interaction with the magnetic field has taken place, again at zero field.
Electron Cyclotron Waves Polarization in the TJII Stellarator
Energy Technology Data Exchange (ETDEWEB)
Cappa, A.; Martinez-Fernandez, J.; Wagner, D.
2013-05-01
This report describes the theoretical calculations related with the electron cyclotron (EC) waves polarization control in the TJII stellarator. Two main aspects will be distinguished: the determination of the vacuum polarization that the wave must exhibit if a given propagation mode in a cold plasma is desired and the calculation of the behavior of the grooved polarizers and other transmission systems used to launch the vacuum wave with the required polarization. (Author) 13 refs.
Bogusławski, Jakub; Kowalczyk, Maciej; Iwanowski, Przemysław; Hruban, Andrzej; Diduszko, Ryszard; Piotrowski, Kazimierz; Dybko, Krzysztof; Wojciechowski, Tomasz; Aleszkiewicz, Marta; Sotor, Jarosław
2017-08-07
Due to their broadband nonlinear optical properties, low-dimensional materials are widely used for pulse generation in fiber and solid-state lasers. Here we demonstrate novel materials, Bi2Te2Se (BTS) and Sn-doped Bi2Te2Se (BSTS), which can be used as a universal saturable absorbers for distinct spectral regimes. The material was mechanically exfoliated from a bulk single-crystal and deposited onto a side-polished fiber. We have performed characterization of the fabricated devices and employed them in polarization-maintaining ytterbium- and erbium-doped fiber lasers. This enabled us to obtain self-starting passively Q-switched regime at 1 µm and 1.56 µm. The oscillators emitted stable, linearly polarized radiation with the highest single pulse energy approaching 692 nJ. Both lasers are characterized by the best performance observed in all-polarization maintaining Q-switched fiber lasers with recently investigated new saturable absorbers, which was enabled by a very high damage threshold of the devices. This demonstrates the great potential of the investigated materials for the ultrafast photonics community.
Effective "Gluon" Dynamics in a Stochastic Vacuum
Magpantay, J A
2002-01-01
Using the new scalar and vector degrees of freedom derived from the non-linear gauge condition (grad-dot-D)(grad-dot-A)=0, we show that the effective dynamics of the vector fields (identified as ``gluons'') in the stochastic vacuum defined by the scalars result in the vector fields acquiring a mass. We also find the vector fields losing their self-interactions.
DEFF Research Database (Denmark)
Olsson, Per-Ivar; Fiandaca, Gianluca; Larsen, Jakob Juul;
This paper presents an advanced signal processing scheme for time-domain induced polarization full waveform data. The scheme includes several steps with an improved induced polarization (IP) response gating design using convolution with tapered windows to suppress high frequency noise...... of noise model parameters for each segment, a full harmonic noise model is subtracted. Furthermore, the uncertainty of the background drift removal is estimated which together with the gating uncertainty estimate and a uniform uncertainty gives a total, data-driven, error estimate for each IP gate...
Cervical spine annulus vacuum.
Bohrer, S P; Chen, Y M
1988-01-01
Thirty-eight annulus vacuums in 27 patients were analyzed with regard to location, configuration, and associated vertebral abnormalities such as degenerative changes, absent and compressed anterosuperior vertebral body corners, and annulus calcification. It is concluded that most annulus vacuums are a degenerative phenomenon at the attachment of the annulus to bone. These vacuums may be associated with other degenerative changes such as osteophytes and annulus calcification. Vacuums have a strong association with compressed anterosuperior corners. These deformed corners are thought to be early osteophytes and may be related to previous trauma, a vertebra with an absent corner, and/or normal motion. Small annulus vacuums adjacent to vertebral corners with a normal appearance are more likely to result from acute trauma.
Bernardini, M.
1991-08-01
A status report of the vacuum system of ELETTRA, the 2 GeV, 400 mA light source under construction in Trieste, will be described. The Vacuum project, presented at ``Synchrotron Radiation Vacuum Workshop'' at Riken (Japan 22-24 March 1990) and more recently at EVC-2, the European Vacuum Conference at Trieste (Italy 21-26 May 1990), is now in the phase of testing a prototype sector, which is 1/24 of the ring circumference. Details and some technological aspects of the fabrication will be reviewed together with the vacuum performances. Results of laboratory experiments on components, standard or not, allowed us to finalize the main choices in light of the general philosophy of the project and will be properly summarized.
Energy Technology Data Exchange (ETDEWEB)
Bohrer, S.P.; Chen, Y.M.
1988-07-01
Thirty-eight annulus vacuums in 27 patients were analyzed with regard to location, configuration, and associated vertebral abnormalities such as degenerative changes, absent and compressed anterosuperior vertebral body corners, and annulus calcification. It is concluded that most annulus vacuums are a degenerative phenomenon at the attachment of the annulus to bone. These vacuums may be associated with other degenerative changes such as osteophytes and annulus calcification. Vacuums have a strong association with compressed anterosuperior corners. These deformed corners are thought to be early osteophytes and may be related to previous trauma, a vertebra with an absent corner, and/or normal motion. Small annulus vacuums adjacent to vertebral corners with a normal appearance are more likely to result from acute trauma.
Vacuum controls and interlocks
Strubin, P
2007-01-01
The vacuum control system is, in most cases, a subset of the general control system of an accelerator. As such, it shares the architecture and communication infrastructure of the main control system. Considered as a ‘slow process’ to control in the frame of accelerators, the vacuum control system can be built using commercial industrial controllers (PLCs). A data driven approach allows for changes in configuration without changing the software code but at the expense of a solid database. Modelling the equipment allows for easy adaptation of a variety of control units with the same functionality but different physical interfaces. It also allows for a uniform display of the available data and status values. Interlocks are required to protect the vacuum equipment itself against abnormal conditions, but also to protect other systems, like RF, which need a good vacuum to operate. They are an integral part of any vacuum control system.
Microfabricated triggered vacuum switch
Roesler, Alexander W.; Schare, Joshua M.; Bunch, Kyle
2010-05-11
A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.
Nonlinear elastic waves in materials
Rushchitsky, Jeremiah J
2014-01-01
The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...
Suprathermal electrons in a vacuum spark discharge
Energy Technology Data Exchange (ETDEWEB)
Bashutin, O. A., E-mail: boa308@mail.ru; Savjolov, A. S., E-mail: savjolov@plasma.mephi.ru [National Research Nuclear University MEPhI (Russian Federation)
2016-04-15
Results of experiments on the detection of suprathermal electron beams in the plasma of a highcurrent low-inductance vacuum spark by means of space-resolved spectral X-ray polarimetry are presented. It is shown that the observed polarization of bremsstrahlung may be caused by an ~100-keV electron beam propagating along the discharge axis from the pinching region toward the anode. The influence of the discharge initiation conditions on the parameters of the generated electron beams is analyzed.
Numerical Simulation of Vacuum Heat Treatment Thermal Hysteresis Time of GH4169 Superalloy Workpiece
Institute of Scientific and Technical Information of China (English)
WANGMing-wei; ZHANGLi-wen; JIANGGuo-dong; ZHANGFan-yun; LiChen-hui; ZHANGLi-sheng; ZHANGZun-li
2004-01-01
A nonlinear finite element model of vacuum heat treatment process was developed. In this model, influence of many factors, such as nonlinear heat radiation, temperature-dependent thermal physical properties of material are considered. The temperature field of GH4169 alloy workpiece during vacuum heat treatment process was calculated using finite element software MSC.Marc, and the thermal hysteresis time of the workpiece was predicted. An experiment of vacuum heat treatment of GH4169 superalloy workpiece was carried out to verify the calculation. The experimental results of temperature profile agree well with the simulated results. This work lays a theoretical foundation for optimizing technical parameter of vacuum heat treatment process.
Polarized electrogowdy spacetimes censored
Energy Technology Data Exchange (ETDEWEB)
Nungesser, Ernesto, E-mail: ernesto.nungesser@aei.mpg.d [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1, 14476 Potsdam (Germany)
2010-05-01
A sketch of the proof of strong cosmic censorship is presented for a class of solutions of the Einstein-Maxwell equations, those with polarized Gowdy symmetry. A key element of the argument is the observation that by means of a suitable choice of variables the central equations in this problem can be written in a form where they are identical to the central equations for general (i.e. non-polarized) vacuum Gowdy spacetimes. Using this it is seen that the results of Ringstroem on strong cosmic censorship in the vacuum case have implications for the Einstein-Maxwell case. Working out the geometrical meaning of these analytical results leads to the main conclusion.
Institute of Scientific and Technical Information of China (English)
WEN Jing; JIANG Hong-Bing; YU Jing; YANG Hong; GONG Qi-Huang
2011-01-01
@@ We investigate the propagation of femtosecond laser pulses in a 5-mm-thick BBO crystal along the direction of type-Ⅰ phase-matched second-harmonic generation.An intensity-asymmetric broadband conical emission (500- 2000 nm) is demonstrated when a suitable chirp is introduced.It is generated by optical parametric amplification pumped by the second-harmonic light and seeded by the fundamental light which is broadened by cascaded nonlinear processes during second-harmonic generation.
Yumura, Takashi; Yamamoto, Wataru
2017-09-20
We employed density functional theory (DFT) calculations with dispersion corrections to investigate energetically preferred alignments of certain p,p'-dimethylaminonitrostilbene (DANS) molecules inside an armchair (m,m) carbon nanotube (n × DANS@(m,m)), where the number of inner molecules (n) is no greater than 3. Here, three types of alignments of DANS are considered: a linear alignment in a parallel fashion and stacking alignments in parallel and antiparallel fashions. According to DFT calculations, a threshold tube diameter for containing DANS molecules in linear or stacking alignments was found to be approximately 1.0 nm. Nanotubes with diameters smaller than 1.0 nm result in the selective formation of linearly aligned DANS molecules due to strong confinement effects within the nanotubes. By contrast, larger diameter nanotubes allow DANS molecules to align in a stacking and linear fashion. The type of alignment adopted by the DANS molecules inside a nanotube is responsible for their second-order non-linear optical properties represented by their static hyperpolarizability (β0 values). In fact, we computed β0 values of DANS assemblies taken from optimized n × DANS@(m,m) structures, and their values were compared with those of a single DANS molecule. DFT calculations showed that β0 values of DANS molecules depend on their alignment, which decrease in the following order: linear alignment > parallel stacking alignment > antiparallel stacking alignment. In particular, a linear alignment has a β0 value more significant than that of the same number of isolated molecules. Therefore, the linear alignment of DANS molecules, which is only allowed inside smaller diameter nanotubes, can strongly enhance their second-order non-linear optical properties. Since the nanotube confinement determines the alignment of DANS molecules, a restricted nanospace can be utilized to control their second-order non-linear optical properties. These DFT findings can assist in the design
Kwok, C H; Chow, C W; Tsang, H K; Lin, Chinlon; Bjarklev, A
2006-06-15
We study the conversion bandwidth of the cross-polarization-modulation (XPoIM)-based wavelength conversion scheme with a dispersion-flattened highly nonlinear photonic-crystal fiber for signals with a nonreturn-to-zero (NRZ) modulation format. Both theoretical and experimental results show that the conversion bandwidth can be extended to cover a very wide band, including S-, C-, and L-bands for 10 Gbit/s NRZ signals (a total bandwidth of 120 nm is experimentally demonstrated). We also study the theoretical bandwidth limit for 40 Gbit/s NRZ signals. A significant extension of the conversion bandwidth using the XPoIM approach compared with the four-wave mixing approach previously reported is demonstrated.
Klebanoff, Leonard Elliott; Rader, Daniel John
2000-01-01
A thermophoretic vacuum wand that is particularly suited for transporting articles in a cleanroom environment so that potential particle contaminants in the air do not become adhered to the surface of the article is described. The wand includes a housing having a platen with a front surface with suction port(s) through the platen; a vacuum source for applying a negative pressure to the suction port(s); and heating device for the object. Heating the article when it is held by the vacuum wand affords thermophoretic protection that effectively prevents particles in the air from depositing onto the article.
Energy Technology Data Exchange (ETDEWEB)
Barroso, A. [Universidade de Lisboa, Centro de Fisica Teorica e Computacional, Faculdade de Ciencias, Lisboa (Portugal); Ferreira, P.M.; Santos, Rui [Universidade de Lisboa, Centro de Fisica Teorica e Computacional, Faculdade de Ciencias, Lisboa (Portugal); Instituto Superior de Engenharia de Lisboa, Lisboa (Portugal); Ivanov, I.P. [Universite de Liege, IFPA, Liege (Belgium); Sobolev Institute of Mathematics, Novosibirsk (Russian Federation); Silva, Joao P. [Instituto Superior de Engenharia de Lisboa, Lisboa (Portugal); Universidade Tecnica de Lisboa, Centro de Fisica Teorica de Particulas (CFTP), Instituto Superior Tecnico, Lisboa (Portugal)
2013-09-15
In the Standard Model, the Higgs potential allows only one minimum at tree level. But the open possibility that there might be two scalar doublets enriches the vacuum structure, allowing for the risk that we might now be in a metastable state, which we dub the panic vacuum. Current experiments at the LHC are probing the Higgs particle predicted as a result of the spontaneous symmetry breaking. Remarkably, in the two Higgs model with a softly broken U(1) symmetry, the LHC experiments already allow to exclude many panic vacuum solutions. (orig.)
Agrawal, Govind P
2001-01-01
The Optical Society of America (OSA) and SPIE - The International Society for Optical Engineering have awarded Govind Agrawal with an honorable mention for the Joseph W. Goodman Book Writing Award for his work on Nonlinear Fiber Optics, 3rd edition.Nonlinear Fiber Optics, 3rd Edition, provides a comprehensive and up-to-date account of the nonlinear phenomena occurring inside optical fibers. It retains most of the material that appeared in the first edition, with the exception of Chapter 6, which is now devoted to the polarization effects relevant for light propagation in optical
Vacuum mechatronics first international workshop
Energy Technology Data Exchange (ETDEWEB)
Belinski, S.E.; Shirazi, M.; Hackwood, S.; Beni, G. (eds.) (California Univ., Santa Barbara, CA (USA))
1989-01-01
This report contains papers on the following topics: proposed epitaxial thin film growth in the ultra-vacuum of space; particle monitoring and control in vacuum processing equipment; electrostatic dust collector for use in vacuum systems; materials evaluation of an electrically noisy vacuum slip ring assembly; an overview of lubrication and associated materials for vacuum service; the usage of lubricants in a vacuum environment; guidelines and practical applications for lubrication in vacuum; recent development in leak detector and calibrator designs; the durability of ballscrews for ultrahigh vacuum; vacuum-compatible robot for self-contained manufacturing systems; the design, fabrication, and assembly of an advanced vacuum robotics system for space payload calibration; design criteria for mechanisms used in space; and concepts and requirements for semiconductor multiprocess integration in vacuum. These papers are indexed separately elsewhere.
Federal Laboratory Consortium — Located near the K-Basins (see K-Basins link) in Hanford's 100 Area is a facility called the Cold Vacuum Drying Facility (CVDF).Between 2000 and 2004, workers at the...
Cosmology of gravitational vacuum
Burdyuzha, V; Pacheco, J
2008-01-01
Production of gravitational vacuum defects and their contribution to the energy density of our Universe are discussed. These topological microstructures (defects) could be produced in the result of creation of the Universe from "nothing" when a gravitational vacuum condensate has appeared. They must be isotropically distributed over the isotropic expanding Universe. After Universe inflation these microdefects are smoothed, stretched and broken up. A part of them could survive and now they are perceived as the structures of Lambda-term and an unclustered dark matter. It is shown that the parametrization noninvariance of the Wheeler-De Witt equation can be used to describe phenomenologically vacuum topological defects of different dimensions (worm-holes, micromembranes, microstrings and monopoles). The mathematical illustration of these processes may be the spontaneous breaking of the local Lorentz-invariance of the quasi-classical equations of gravity. Probably the gravitational vacuum condensate has fixed tim...
2016-01-01
This comprehensive, standard work has been updated to remain an important resource for all those needing detailed knowledge of the theory and applications of vacuum technology. With many numerical examples and illustrations to visualize the theoretical issues.
Laugen, Geoffrey A.
2011-01-01
Acquiring cheap, moving video was impossible in a vacuum environment, due to camera overheating. This overheating is brought on by the lack of cooling media in vacuum. A water-jacketed camera cooler enclosure machined and assembled from copper plate and tube has been developed. The camera cooler (see figure) is cup-shaped and cooled by circulating water or nitrogen gas through copper tubing. The camera, a store-bought "spy type," is not designed to work in a vacuum. With some modifications the unit can be thermally connected when mounted in the cup portion of the camera cooler. The thermal conductivity is provided by copper tape between parts of the camera and the cooled enclosure. During initial testing of the demonstration unit, the camera cooler kept the CPU (central processing unit) of this video camera at operating temperature. This development allowed video recording of an in-progress test, within a vacuum environment.
ISR Intersection Vacuum Chamber
1975-01-01
This special vacuum chamber presenting a lateral opening at the beam crossing point is one of the many chambers specifically designed for a particular experiment. Here it is shown during assembly at the ISR mechanical worshop.
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2009-04-01
Full Text Available Both the big-bang and the quasi-steady-state cosmologies originate in some type of Planck state. This paper presents a new cosmological theory based on the Planck- vacuum negative-energy state, a state consisting of a degenerate collection of negative- energy Planck particles. A heuristic look at the Einstein field equation provides a con- vincing argument that such a vacuum state could provide a theoretical explanation for the visible universe.
Whitaker, Jerry
2012-01-01
Providing examples of applications, Power Vacuum Tubes Handbook, Third Edition examines the underlying technology of each type of power vacuum tube device in common use today. The author presents basic principles, reports on new development efforts, and discusses implementation and maintenance considerations. Supporting mathematical equations and extensive technical illustrations and schematic diagrams help readers understand the material. Translate Principles into Specific Applications This one-stop reference is a hands-on guide for engineering personnel involved in the design, specification,
Institute of Scientific and Technical Information of China (English)
韩文君; 刘松玉; 章定文; 刘维正
2013-01-01
考虑真空荷载实际边界条件，引入对土体压缩曲线线性化的双对数坐标，建立了真空预压砂井地基非线性固结近似解答；利用模型试验结果验证了解答的可靠性，并分析了真空度衰减和土性参数对固结性状的影响。研究结果表明，考虑了真空荷载衰减及双对数坐标的解答计算得到的土体沉降、超静孔压与实测值最为接近。对于超固结土而言，基于变形计算的固结度随着压缩指数与渗透指数比值的增大而减小，随着真空荷载衰减系数的减小而减小；当压缩指数与渗透指数比值大于1时，正常固结状态中基于孔压计算的固结度随真空荷载衰减系数的减小而增大。随着压缩指数与回弹指数比值的增大，地基超静孔压消散速率也随之增加，沉降速率在超固结状态时随之减缓，在正常固结状态时则随之加快，土体由超固结状态进入正常固结状态的时间随之变长。%Based on the bi-logarithmic coordinate compression model and actual vacuum pressure along the drain for normally consolidated and over-consolidated clays, a new analytical solution of the radial consolidation of subsoil by vacuum preloading was derived.The analytical solution was verified by the model test, and the influences of vacuum pressure attenuation and soil parameters on consolidation were analyzed.The results show that the calculated settlement and the excess pore wa-ter pressure are most close to the measured data in model tests.For over-consolidated clays, the con-solidation degree calculated by deformation decreases with the increase of the ratio of the compres-sion index and the permeability index and with the decease of the vacuum pressure attenuation coeffi-cient.When the ratio of the compression index and the permeability index is more than one, the con-solidation degree in normal consolidation state calculated by pore water pressure increases with the decrease of
Nonlinear diffusion and superconducting hysteresis
Energy Technology Data Exchange (ETDEWEB)
Mayergoyz, I.D. [Univ. of Maryland, College Park, MD (United States)
1996-12-31
Nonlinear diffusion of electromagnetic fields in superconductors with ideal and gradual resistive transitions is studied. Analytical results obtained for linear and nonlinear polarizations of electromagnetic fields are reported. These results lead to various extensions of the critical state model for superconducting hysteresis.
Kannajosyula, H.; Lissenden, C. J.; Rose, J. L.
2012-05-01
Ultrasonic guided wave mode control and steering using phased array transducers (PATs) is studied. A PAT with elements arranged on a cylindrical-polar grid is proposed to overcome the problem of large side-lodes associated with a rectangular grid PAT. The PAT is visualized as a spatio-temporal filter to calculate phase delays. Wavenumber bands resulting from the radial rows enable constructive interfere only in the vicinity of the desired wavenumber and angle of propagation. Finite element simulations are presented to study PAT performance.
Structure and decay in the QED vacuum
Labun, Lance Andrew
This thesis is a guide to a selection of the author's published work that connect and contribute to understanding the vacuum of quantum electrodynamics in strong, prescribed electromagnetic fields. This theme is elaborated over the course of two chapters: The first chapter sets the context, defining the relevant objects and conditions of the study and reviewing established knowledge upon which this study builds. The second chapter organizes and explains important results appearing in the published work. The papers 1. (Labun and Rafelski, 2009) "Vacuum Decay Time in Strong External Fields" 2. (Labun and Rafelski, 2010a) "Dark Energy Simulacrum in Nonlinear Electrodynamics" 3. (Labun and Rafelski, 2010b) "QED Energy-Momentum Trace as a Force in Astrophysics" 4. (Labun and Rafelski, 2010c) "Strong Field Physics: Probing Critical Acceleration and Inertia with Laser Pulses and Quark-Gluon Plasma" 5. (Labun and Rafelski, 2010d) "Vacuum Structure and Dark Energy" 6. (Labun and Rafelski, 2011) "Spectra of Particles from Laser-Induced Vacuum Decay" are presented in their published format as appendices. Related literature is cited throughout the body where it directly supports the content of this overview; more extensive references are found within the attached papers. This study begins with the first non-perturbative result in quantum electrodynamics, a result obtained by Heisenberg and Euler (1936) for the energy of a zero-particle state in a prescribed, long-wavelength electromagnetic field. The resulting Euler-Heisenberg effective potential generates a nonlinear theory of electromagnetism and exhibits the ability of the electrical fields to decay into electron-positron pairs. Context for phenomena arising from the Euler-Heisenberg effective potential is established by considering the energy-momentum tensor of a general nonlinear electromagnetic theory. The mass of a field configuration is defined, and I discuss two of its consequences pertinent to efforts to observe
On polarization in biomembranes
DEFF Research Database (Denmark)
Zecchi, Karis Amata
close to physiological conditions, making these effects biologically relevant. In this work, we consider the case of asymmetric membranes which can display spontaneous polarization in the absence of a field. Close to the phase transition, we find that the membrane displays piezoelectric, flexoelectric...... and thermoelectric behaviour. In particular, the membrane capacitance is a nonlinear function of the applied voltage. Furthermore, in the presence of spontaneous polarization, our thermodynamical description is able to explain the outward rectified current-voltage relationship measured on synthetic lipid bilayers....... Due to the nonlinear dependence of the membrane capacitance and conductance on voltage and the presence of spontaneous polarization, the traditional equivalent circuit of the membrane is not an accurate description in physiological conditions. An updated equivalent circuit of the lipid bilayer is here...
Calibrating System for Vacuum Gauges
Institute of Scientific and Technical Information of China (English)
MengJun; YangXiaotian; HaoBinggan; HouShengjun; HuZhenjun
2003-01-01
In order to measure the vacuum degree, a lot of vacuum gauges will be used in CSR vacuum system. We bought several types of vacuum gauges. We know that different typos of vacuum gauges or even one type of vacuum gauges have different measure results in same condition, so they must be calibrated. But it seems impossible for us to send so many gauges to the calibrating station outside because of the high price. So the best choice is to build a second class calibrating station for vacuum gauges by ourselves (Fig.l).
Energy Technology Data Exchange (ETDEWEB)
Matter, Regina S.
2000-06-27
During the Summer of 1999 the vacuum in LER was studied in order to answer a few questions: (1) how fast is the vacuum system cleaning; (2) when will the required operating pressure 10 nTorr be reached; (3) how fast do the TSP's saturate; and (4) what is the present average pressure in LER and what is the corresponding beam lifetime? Once {Delta}P/I, the coefficient relating the pressure to beam current and the base pressure is calculated, it is easy to find the time constants associated with the cleaning of the vacuum system and the saturation of the TSP's. In addition, these calculations showed that vertical steering of the LER orbit affects the vacuum and that leaks cause the TSP's to saturate. It is difficult to calculate the average pressure in the ring because most of the ion pumps in the straight sections do not read pressure accurately. Secondly, how do you calculate the conductance between the chamber and the anti-chamber? Thirdly, the gas load is unevenly distributed along the ring because of photon stops and leaks. However, the average vacuum pressure seen by the beam in the arcs is roughly three times higher than the pressure measured at the ion pumps, according to Artem Kulikov. Instead of calculating the average pressure in the ring, the author has calculated the coefficient relating the inverse beam lifetime to the beam current to see the long term improvement of the LER beam lifetime as the vacuum system is scrubbed. These calculations showed that the lifetime, including the low intensity lifetime, is limited by the vacuum pressure. The results reported here are obtained from numerical calculations.
Classical enhancement of quantum vacuum fluctuations
De Lorenci, V A
2016-01-01
We propose a mechanism for the enhancement of vacuum fluctuations by means of a classical field. The basic idea is that if an observable quantity depends quadratically upon a quantum field, such as the electric field, then the application of a classical field produces a cross term between the classical and quantum fields. This cross term may be significantly larger than the purely quantum part, but also undergoes fluctuations driven by the quantum field. We illustrate this effect in a model for lightcone fluctuations involving pulses in a nonlinear dielectric. Vacuum electric field fluctuations produce fluctuations in the speed of a probe pulse, and form an analog model for quantum gravity effects. If the material has a nonzero third-order susceptibility, then the fractional light speed fluctuations are proportional to the square of the fluctuating electric field. Hence the application of a classical electric field can enhance the speed fluctuations. We give an example where this enhancement can be an increas...
Institute of Scientific and Technical Information of China (English)
Hitoshi Iwata
2004-01-01
Almost 30 years has passed since the publication of materials on vacuum carburizing technology, and is attracting a great deal of attention as a technology capable of being used as a substitute for gas carburizing technology.However, the technology was not popular except in specific fields. The main reason for this is due to a variety of harmful influences accompanying the sooting problems caused by CH4 or C3H8. We have succeeded in that the occurrence of sooting was suppressed by utilizing acetylene, at extremely low pressure for carburizing (below 1 kPa). This process is now showing the excellent quality and prospects for this technology in terms of quality, economy and safety. At present almost 70 practical mass production furnaces are used in production lines, in Japan and abroad. At this time, we will report summary of the present acetylene vacuum carbufizing process and the actual results obtained by these acetylene vacuum carbufizing furnaces for mass production.
1964-01-01
Handbook of Vacuum Physics, Volume 3: Technology is a handbook of vacuum physics, with emphasis on the properties of miscellaneous materials such as mica, oils, greases, waxes, and rubber. Accurate modern tables of physical constants, properties of materials, laboratory techniques, and properties of commercial pumps, gauges, and leak detectors are presented. This volume is comprised of 12 chapters and begins with a discussion on pump oils, divided into rotary pump oils and vapor pump oils. The next chapter deals with the properties and applications of greases, including outgassing and vapor pr
Hamada, Yuta
2016-01-01
The null result in the LHC may indicate that the standard model is not drastically modified up to very high scale such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops the large vacuum expectation value in the early universe, the lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with a second Higgs doublet and a singlet scalar.
Superoleophobicity under vacuum
Liu, Xinjie; Wang, Xiaolong; Liang, Yongmin; Bell, Steven E. J.; Liu, Weimin; Zhou, Feng
2011-05-01
By using superoleophobic alumina and low vapor pressure oils we have been able to study wetting behavior at high vacuum. Here, we show that a superoleophobic state can exist for some probe liquids, even under high vacuum. However, with other liquids the surfaces are only superoloephobic because air is trapped beneath the droplet and the contact angle decreases dramatically (150°-120°) if this air is removed. These observations open up the possibility of designing materials which fully exploit the potential of physically trapped air to achieve extreme oleophobicity and/or hydrophobicity.
Phenomenology of the vacuum in quantum electrodynamics and beyond
Energy Technology Data Exchange (ETDEWEB)
Doebrich, Babette
2011-09-30
Determining forces that arise by the restriction of the fluctuation modes of the vacuum by the insertion of boundaries or the observation of altered light propagation in external fields is a versatile means to investigate the vacuum structure of quantum electrodynamics. For these quantum vacuum probes, the vacuum can be understood and effectively modeled as a medium. Investigating the properties of this medium cannot only test and broaden our understanding of known interactions but can also be a valuable tool in the search for particles at low energy scales which arise in extensions of the standard model. In this thesis, we first study the geometry dependence of fluctuation modes in the Dirichlet-scalar analog of Casimir-Polder forces between an atom and a surface with arbitrary uniaxial corrugations. To this end we employ a technique which is fully nonperturbative in the height profile. We parameterize the differences to the distance dependencies in the planar limit in terms of an anomalous dimension quantifying the power-law deviation from the planar case. In numerical studies of experimentally relevant corrugations, we identify a universal regime of the anomalous dimension at larger distances. We argue that this universality arises as the relevant fluctuations average over corrugation structures smaller than the atom-wall distance. Turning to modified light propagation as a probe of the quantum vacuum, we show that a combination of strong, pulsed magnets and gravitational-wave interferometers can not only facilitate the detection of strong-field QED phenomena, but also significantly enlarges the accessible parameter space of hypothetical hidden-sector particles. We identify pulsed magnets as a suitable strong-field source to induce quantum nonlinearities, since their pulse frequency can be perfectly matched with the domain of highest sensitivity of modern gravitational-wave interferometers. Pushing current laboratory field-strengths to their limits, we suggest a
Chiral vacuum fluctuations in quantum gravity
Magueijo, Joao
2010-01-01
We examine tensor perturbations around a deSitter background within the framework of Ashtekar's variables and cousins parameterized by the Immirzi parameter $\\gamma$. At the classical level we recover standard cosmological perturbation theory, with illuminating insights. Quantization leads to real novelties. In the low energy limit we find a second quantized theory of gravitons which displays different vacuum fluctuations for right and left gravitons. Nonetheless right and left gravitons have the same (positive) energies, resolving a number of paradoxes suggested in the literature. The right-left asymmetry of the vacuum fluctuations depends on $\\gamma$ and the ordering of the Hamiltonian constraint, and it would leave a distinctive imprint in the polarization of the cosmic microwave background, thus opening quantum gravity to observational test.
Chiral Vacuum Fluctuations in Quantum Gravity
Magueijo, João; Benincasa, Dionigi M. T.
2011-03-01
We examine tensor perturbations around a de Sitter background within the framework of Ashtekar’s variables and its cousins parameterized by the Immirzi parameter γ. At the classical level we recover standard cosmological perturbation theory, with illuminating insights. Quantization leads to real novelties. In the low energy limit we find a second quantized theory of gravitons which displays different vacuum fluctuations for right and left gravitons. Nonetheless right and left gravitons have the same (positive) energies, resolving a number of paradoxes suggested in the literature. The right-left asymmetry of the vacuum fluctuations depends on γ and the ordering of the Hamiltonian constraint, and it would leave a distinctive imprint in the polarization of the cosmic microwave background, thus opening quantum gravity to observational test.
Ferroelectric Domain Imaging Mechanism in High-Vacuum Scanning Force Microscopy
Institute of Scientific and Technical Information of China (English)
ZENG Hua-Rong; YU Han-Feng; CHU Rui-Qing; LI Guo-Rong; YIN Qing-Rui
2005-01-01
@@ High-vacuum scanning force microscopy of the domain structures in PMN-PT single crystals is investigated. It has been shown that under high vacuum conditions, the polarization charges are not effectively compensated for by intrinsic screening charges from the ferroelectrics. This result suggests that the electrostatic tip-sample interaction plays a great contribution to the domain imaging mechanism in PMN-PT ferroelectric single crystals under high vacuum conditions.
Technology handbook of vacuum physics
Beck, A H
2013-01-01
Handbook of Vacuum Physics, Volume 3: Technology is part of a series of publications that presents articles featuring the whole spectrum of vacuum physics. This particular volume presents materials that deal with technology concerns in vacuum mechanics. The first material talks about the utilization of ceramic materials in the construction of vacuum devices. The next paper details the application of vacuum physics in soldering and brazing process. The last article deals with the utilization of vacuum technology in high frequency heating. The book will be of great use to professionals involved
No-go theorem for false vacuum black holes
Galtsov, D V; Galtsov, Dmitri V.; Lemos, José P. S.
2001-01-01
We study the possibility of non-singular black hole solutions in the theory of general relativity coupled to a non-linear scalar field with a positive potential possessing two minima: a `false vacuum' with positive energy and a `true vacuum' with zero energy. Assuming that the scalar field starts at the false vacuum at the origin and comes to the true vacuum at spatial infinity, we prove a no-go theorem by extending a no-hair theorem to the black hole interior: no smooth solutions exist which interpolate between the local de Sitter solution near the origin and the asymptotic Schwarzschild solution through a regular event horizon or several horizons.
2007-01-01
"Modern physics has shown that the vacuum, previously thought of as a stated of total nothingness, is really a seething background of virtual particles springing in and out of eixstence until they can seize enough energy to materialize as "real" particles." (1,5 page)
1971-01-01
Some of the most important components of the vacuum system are shown. At the left, the rectangular box is a sputter-ion pump inside its bake-out oven. The assembly in the centre includes a sector valve, three roughing valves, a turbomolecular pump, a rotary backing pump and auxiliary equipment. At the right, the small elbow houses a Bayard-
1983-01-01
This is a cut-out of a LEP vacuum chamber for dipole magnets showing the beam channel and the pumping channel with the getter (NEG) strip and its insulating supports. A water pipe connected to the cooling channel can also be seen at the back.The lead radiation shield lining is also shown. See also 8305563X.
... a handle on the cup to move the baby through the birth canal. When is Vacuum-assisted Delivery Needed? Even after your cervix is fully dilated ( ... delivers the baby's head, you will push the baby the rest of the way out. After delivery, you can hold your baby on your tummy ...
1970-01-01
A pressure of 5 x 10-11 Torr has been obtained repreatedly in this pilot section of the ISR vacuum system. The pilot section is 45 m long is pumped by 9 sputter-ion pumps pf 350 l/s pumping speed, and is baked out at 200 degrees C before each pump down.
CERN PhotoLab
1983-01-01
Final prototype for the LEP vacuum chamber, see 8305170 for more details. Here we see the strips of the NEG pump, providing "distributed pumping". The strips are made from a Zr-Ti-Fe alloy. By passing an electrical current, they were heated to 700 deg C.
Davies, Paul Charles William; Manogue, C A; Davies, Paul C W; Dray, Tevian; Manogue, Corinne A
1996-01-01
We derive conditions for rotating particle detectors to respond in a variety of bounded spacetimes and compare the results with the folklore that particle detectors do not respond in the vacuum state appropriate to their motion. Applications involving possible violations of the second law of thermodynamics are briefly addressed.
CPT-odd Photon in Vacuum-Orthogonal Model
Albayrak, Soner
2015-01-01
Lorentz and CPT violation in the photon sector with the operators of arbitrary mass dimension has been proposed in the context of Standard-Model Extension. The CPT-odd subset of this enlarged model is investigated from a quantum-field theoretical point of view. The generic forms of dispersion relations, polarization vectors and the propagators are obtained for this special subset. Particularly, the general vacuum-orthogonal model is analyzed and it is demonstrated that the vacuum orthogonal model remains vacuum orthogonal at all orders. Although the model has birefringent solutions, they are shown to be spurious. Furthermore, the relevant polarization vectors are shown to be conventional. Leading order model is explicitly analyzed and it is demonstrated that there exists a nontrivial coefficient space satisfying above properties.
Nonlocal homogenization for nonlinear metamaterials
Gorlach, Maxim A; Lapine, Mikhail; Kivshar, Yuri S; Belov, Pavel A
2016-01-01
We present a consistent theoretical approach for calculating effective nonlinear susceptibilities of metamaterials taking into account both frequency and spatial dispersion. Employing the discrete dipole model, we demonstrate that effects of spatial dispersion become especially pronounced in the vicinity of effective permittivity resonance where nonlinear susceptibilities reach their maxima. In that case spatial dispersion may enable simultaneous generation of two harmonic signals with the same frequency and polarization but different wave vectors. We also prove that the derived expressions for nonlinear susceptibilities transform into the known form when spatial dispersion effects are negligible. In addition to revealing new physical phenomena, our results provide useful theoretical tools for analysing resonant nonlinear metamaterials.
Gas bearing operates in vacuum
Perkins, G. S.
1975-01-01
Bearing has restrictions to reduce air leaks and is connected to external pumpout facility which removes exhausted air. Token amount of air which is lost to vacuum is easily removed by conventional vacuum pump.
Tritium handling in vacuum systems
Energy Technology Data Exchange (ETDEWEB)
Gill, J.T. [Monsanto Research Corp., Miamisburg, OH (United States). Mound Facility; Coffin, D.O. [Los Alamos National Lab., NM (United States)
1986-10-01
This report provides a course in Tritium handling in vacuum systems. Topics presented are: Properties of Tritium; Tritium compatibility of materials; Tritium-compatible vacuum equipment; and Tritium waste treatment.
Profile optimization for an HV insulator in vacuum
Energy Technology Data Exchange (ETDEWEB)
Egiziano, L.; Spagnuolo, G.; Tucci, V. [Univ. di Salerno, Fisciano (Italy). Dipt. di Ingegneria dell`Informazione e Ingegneria Elettrica; Lupo, G.; Petrarca, C. [Univ. di Napoli Federico II (Italy). Dipt. di Ingegneria Elettrica
1996-12-31
The exposition of HV solid insulators in vacuum to relevant voltage differences could determine the surface flashover along the solid dielectric-vacuum interface. Insulator holdoff capabilities can be significantly improved by limiting the field intensity in proximity of the electrodes by means of a Geometrical Field Control, namely designing the insulator profile so that the region subjected to high field is shifted away from the regions where the electrodes join the solid dielectric-vacuum interface. In this paper a new profile for an HV insulator in vacuum is presented. An axially symmetrical configuration constituted by a couple of coaxial cylindrical electrodes is considered, with the insulator shape designed to guarantee similar performances for both field polarities. The effectiveness of the design is validated by means of numerical simulations and by experimental results involving D.C. and impulse flashover performances.
Park, Jesung; Kemp, Nate J; Rylander, H Grady; Milner, Thomas E
2009-08-03
Complex polarization ratio (CPR) in materials with birefringence and biattenuance is shown as a logarithmic spiral in the complex plane. A multi-state Levenberg-Marquardt nonlinear fitting algorithm using the CPR trajectory collected by polarization sensitive optical coherence tomography (PS-OCT) was developed to determine polarization properties of an anisotropic scattering medium. The Levenberg-Marquardt nonlinear fitting algorithm using the CPR trajectory is verified using simulated PS-OCT data with speckle noise. Birefringence and biattenuance of a birefringent film, ex-vivo rodent tail tendon and in-vivo primate retinal nerve fiber layer were determined using measured CPR trajectories and the Levenberg-Marquardt nonlinear fitting algorithm.
Nonlinear metrology with a quantum interface
Napolitano, M.; Mitchell, M. W.
2009-01-01
We describe nonlinear quantum atom-light interfaces and nonlinear quantum metrology in the collective continuous variable formalism. We develop a nonlinear effective Hamiltonian in terms of spin and polarization collective variables and show that model Hamiltonians of interest for nonlinear quantum metrology can be produced in $^{87}$Rb ensembles. With these Hamiltonians, metrologically relevant atomic properties, e.g. the collective spin, can be measured better than the "Heisenberg limit" $\\...
Bullock, Jack C.; Kelly, Benjamin E.
1980-01-01
A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.
Stability analysis of polarization attraction in optical fibers
Turitsyn, K S
2013-01-01
The nonlinear cross-polarization interaction among two intense counterpropagating beams in a span of lossless randomly birefringent telecom optical fiber may lead to the attraction an initially polarization scrambled signal towards wave with a well-defined state of polarization at the fiber output. By exploiting exact analytical solutions of the nonlinear polarization coupling process we carry out a linear stability study which reveals that temporally stable stationary solutions are only obtained whenever the output signal polarization is nearly orthogonal to the input pump polarization. Moreover, we predict that polarization attraction is acting in full strength whenever equally intense signal and pump waves are used.
UV Nano-Lights: Nonlinear Quantum Dot-Plasmon Coupling
2014-08-01
method is also applicable to bare nanoparticles in polar solvents. 15. SUBJECT TERMS Quantum Dots, Nonlinear Optical Materials , Energy...TERMS Quantum Dots, Nonlinear Optical Materials , Energy Conservation, Up-conversion 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT
Vacuum squeezing in atomic media with self-rotation
Matsko, A B; Scully, M O; Welch, G R; Budker, D; Kimball, D F; Rochester, S M; Yashchuk, V V
2002-01-01
When linearly polarized light propagates through a medium which causes self-rotation of elliptically polarized light, squeezed vacuum is produced in the orthogonal polarization. A simple relationship between the self-rotation angle for a given ellipticity and the degree of squeezing is developed. Taking into account absorption, we find the optimum condition for squeezing for any medium which causes self-rotation. Next, we analyze squeezing when the medium consists of a vapor of idealized, four-level atoms. Finally, we consider a medium consisting of a gas of multi-level Rb atoms, and analyze squeezing for light tuned near the D-lines under realistic conditions.
Energy Technology Data Exchange (ETDEWEB)
Wang, Shuao; Alekseev, Evgeny V.; Ling, Jie; Liu, Guokui; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.
2010-03-23
Four new sodium uranyl borates, α-Na[(UO{sub 2}){sub 2}B{sub 10}O{sub 15}(OH){sub 5})] (NaUBO-1), β-Na[(UO{sub 2}){sub 2}B{sub 10}O{sub 15}(OH){sub 5}] (NaUBO-2), Na[(UO{sub 2}){sub 2}B{sub 10}O{sub 15}(OH){sub 5}]·3H{sub 2}O (NaUBO-3), and Na[(UO{sub 2})B{sub 6}O{sub 10}(OH)]·2H{sub 2}O (NaUBO-4), and four new thallium uranyl borates, α-Tl{sub 2}[(UO{sub 2}){sub 2}B{sub 11}O{sub 18}(OH){sub 3}] (TlUBO-1), β-Tl{sub 2}[(UO{sub 2}){sub 2}B{sub 11}O{sub 18}(OH){sub 3}] (TlUBO-2), Tl[(UO{sub 2}){sub 2}B{sub 10}O{sub 16}(OH){sub 3}] (TlUBO-3), and Tl{sub 2}[(UO{sub 2}){sub 2}B{sub 11}O{sub 19}(OH)] (TlUBO-4), have been prepared via the reaction of sodium nitrate or thallium nitrate, uranyl nitrate, and excess boric acid at 190 °C. These compounds share a common structural motif consisting of a linear uranyl, UO{sub 2}{sup 2+}, cation surrounded by BO{sub 3} triangles and BO{sub 4} tetrahedra to create a UO{sub 8} hexagonal bipyramidal environment around uranium. The borate anions bridge between uranyl units to create sheets. Additional BO{sub 3} triangles extend from the polyborate layers and are directed approximately perpendicular to the sheets. In some compounds, these units can link the layers together to yield three-dimensional networks with large pores to house the Na{sup +} or Tl{sup+} cations and water molecules. The structures are all noncentrosymmetric and are either polar or chiral. While the uranyl borate layers are noncentrosymmetric in and of themselves, there is also twisting of the interlayer BO{sub 3} groups to reduce the interlayer spacing, producing helical features in some structures. Na[(UO{sub 2})B{sub 6}O{sub 10}(OH)]·2H{sub 2}O and β-Tl{sub 2}[(UO{sub 2}){sub 2}B{sub 11}O{sub 18}(OH){sub 3}], which can be obtained as pure phases, display second-harmonic generation of 532 nm light from 1064 nm light.
Paraxial Theory of Direct Electro-optic Sampling of the Quantum Vacuum
Moskalenko, A. S.; Riek, C.; Seletskiy, D. V.; Burkard, G.; Leitenstorfer, A.
2015-12-01
Direct detection of vacuum fluctuations and analysis of subcycle quantum properties of the electric field are explored by a paraxial quantum theory of ultrafast electro-optic sampling. The feasibility of such experiments is demonstrated by realistic calculations adopting a thin ZnTe electro-optic crystal and stable few-femtosecond laser pulses. We show that nonlinear mixing of a short near-infrared probe pulse with the multiterahertz vacuum field leads to an increase of the signal variance with respect to the shot noise level. The vacuum contribution increases significantly for appropriate length of the nonlinear crystal, short pulse duration, tight focusing, and a sufficiently large number of photons per probe pulse. If the vacuum input is squeezed, the signal variance depends on the probe delay. Temporal positions with a noise level below the pure vacuum may be traced with subcycle resolution.
Sibuet, R.
2008-05-01
For decades and for ultimate pressure below 1 mbar, oil-sealed Rotary Vane Pumps have been the most popular solution for a wide range of vacuum applications. In the late 80ies, Semiconductor Industry has initiated the development of the first dry roughing pumps. Today SC applications are only using dry pumps and dry pumping packages. Since that time, pumps manufacturers have developed dry vacuum pumps technologies in order to make them attractive for other applications. The trend to replace lubricated pumps by dry pumps is now spreading over many other market segments. For the Semiconductor Industry, it has been quite easy to understand the benefits of dry pumps, in terms of Cost of Ownership, process contamination and up-time. In this paper, Technology of Dry pumps, its application in R&D/industries, merits over conventional pumps and future growth scope will be discussed.
A squeezed light source operated under high vacuum
Wade, Andrew R.; Mansell, Georgia L.; Chua, Sheon S. Y.; Ward, Robert L.; Slagmolen, Bram J. J.; Shaddock, Daniel A.; McClelland, David E.
2015-01-01
Non-classical squeezed states of light are becoming increasingly important to a range of metrology and other quantum optics applications in cryptography, quantum computation and biophysics. Applications such as improving the sensitivity of advanced gravitational wave detectors and the development of space-based metrology and quantum networks will require robust deployable vacuum-compatible sources. To date non-linear photonics devices operated under high vacuum have been simple single pass systems, testing harmonic generation and the production of classically correlated photon pairs for space-based applications. Here we demonstrate the production under high-vacuum conditions of non-classical squeezed light with an observed 8.6 dB of quantum noise reduction down to 10 Hz. Demonstration of a resonant non-linear optical device, for the generation of squeezed light under vacuum, paves the way to fully exploit the advantages of in-vacuum operations, adapting this technology for deployment into new extreme environments. PMID:26657616
PARAFFIN SEPARATION VACUUM DISTILLATION
Directory of Open Access Journals (Sweden)
Zaid A. Abdulrahman
2013-05-01
Full Text Available Simulated column performance curves were constructed for existing paraffin separation vacuum distillation column in LAB plant (Arab Detergent Company/Baiji-Iraq. The variables considered in this study are the thermodynamic model option, top vacuum pressure, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates composition were constructed. Four different thermodynamic model options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.The simulated results show that about 2% to 8 % of paraffin (C10, C11, C12, & C13 present at the bottom stream which may cause a problem in the LAB plant. The major variations were noticed for the top temperature & the paraffin weight fractions at bottom section with top vacuum pressure. The bottom temperature above 240 oC is not recommended because the total bottom flow rate decreases sharply, where as the weight fraction of paraffins decrease slightly. The study gives evidence about a successful simulation with CHEMCAD
Nonlinear Metamaterials for Holography
Almeida, Euclides; Prior, Yehiam
2015-01-01
A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multi-layer metamaterial holograms where by the nonlinear process of Third Harmonic Generation, a background free image is formed at a new frequency which is the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analyzed and prospects for future device applications are discussed.
Sesia, Sergio
2016-01-01
Background For specific therapy to correct pectus excavatum (PE), conservative treatment with the vacuum bell (VB) was introduced more than 10 years ago in addition to surgical repair. Preliminary results using the VB were encouraging. We report on our 13-year experience with the VB treatment including the intraoperative use during the Nuss procedure and present some technical innovations. Methods A VB with a patient-activated hand pump is used to create a vacuum at the anterior chest wall. Three different sizes of vacuum bells, as well as a model fitted for young women, exist. The appropriate size is selected according to the individual patient’s age and ventral surface. The device should be used at home for a minimum of 30 minutes (twice a day), and may be used up to a maximum of several hours daily. The intensity of the applied negative pressure can be evaluated with an integrated pressure gauge during follow-up visits. A prototype of an electronic model enables us to measure the correlation between the applied negative pressure and the elevation of the anterior chest wall. Results Since 2003, approx. 450 patients between 2 to 61 years of age started the VB therapy. Age and gender specific differences, depth of PE, symmetry or asymmetry, and concomitant malformations such as scoliosis and/or kyphosis influence the clinical course and success of VB therapy. According to our experience, we see three different groups of patients. Immediate elevation of the sternum was confirmed thoracoscopically during the Nuss procedure in every patient. Conclusions The VB therapy has been established as an alternative therapeutic option in selected patients suffering from PE. The initial results up to now are encouraging, but long-term results comprising more than 15 years are so far lacking, and further evaluation and follow-up studies are necessary. PMID:27747177
Vacuum ultraviolet spectroscopy I
Samson, James A; Lucatorto, Thomas
1998-01-01
This volume is for practitioners, experimentalists, and graduate students in applied physics, particularly in the fields of atomic and molecular physics, who work with vacuum ultraviolet applications and are in need of choosing the best type of modern instrumentation. It provides first-hand knowledge of the state-of-the-art equipment sources and gives technical information on how to use it, along with a broad reference bibliography.Key Features* Aimed at experimentalists who are in need of choosing the best type of modern instrumentation in this applied field* Contains a detailed chapter on la
Energy Technology Data Exchange (ETDEWEB)
Mapes, M.; Smart, L.; Weiss, D.; Steszyn, A.; Todd, R.
2010-01-01
The ERL Vacuum systems are depicted in a figure. ERL has eight vacuum volumes with various sets of requirements. A summary of vacuum related requirements is provided in a table. Five of the eight volumes comprise the electron beamline. They are the 5-cell Superconducting RF Cavity, Superconducting e-gun, injection, loop and beam dump. Two vacuum regions are the individual cryostats insulating the 5-cell Superconducting RF Cavity and the Superconducting e-gun structures. The last ERL vacuum volume not shown in the schematic is the laser transport line. The beamline vacuum regions are separated by electropneumatic gate valves. The beam dump is common with loop beamline but is considered a separate volume due to geometry and requirements. Vacuum in the 5-cell SRF cavity is maintained in the {approx}10{sup -9} torr range at room temperature by two 20 l/s ion pumps and in the e-gun SRF cavity by one 60 l/s ion pump. Vacuum in the SRF cavities operated at 2{sup o}K is reduced to low 10{sup -11} torr via cryopumping of the cavity walls. The cathode of the e-gun must be protected from poisoning, which can occur if vacuum adjacent to the e-gun in the injection line exceeds 10-11 torr range in the injection warm beamline near the e-gun exit. The vacuum requirements for beam operation in the loop and beam dump are 10-9 torr range. The beamlines are evacuated from atmospheric pressure to high vacuum level with a particulate free, oil free turbomolecular pumping cart. 25 l/s shielded ion pumps distributed throughout the beamlines maintain the vacuum requirement. Due to the more demanding vacuum requirement of the injection beamline proximate to the e-gun, a vacuum bakeout of the injection beamline is required. In addition, two 200 l/s diode ion pumps and supplemental pumping provided by titanium sublimation pumps are installed in the injection line just beyond the exit of the e-gun. Due to expected gas load a similar pumping arrangement is planned for the beam dump. The
Bloembergen, Nicolaas
1996-01-01
Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe
Katarina Anthony
2015-01-01
A new LHCb programme is delving into uncharted waters for the LHC: exploring how protons interact with noble gases inside the machine pipe. While, at first glance, it may sound risky for the overall quality of the vacuum in the machine, the procedure is safe and potentially very rich in rewards. The results could uncover the high-energy helium-proton cross-section (with all the implications thereof), explore new boundaries of the quark-gluon plasma and much more. As the beam passes through LHCb, interactions with neon gas allow the experiment to measure the full beam profile. In this diagram, beam 1 (blue) and beam 2 (red) are measured by the surrounding VELO detector. It all begins with luminosity. In 2011, LHCb set out to further improve its notoriously precise measurements of the beam profile, using the so-called Beam-Gas Imaging (BGI) method. BGI does exactly what it says on the tin: a small amount of gas is inserted into the vacuum, increasing the rate of collisions around the interaction ...
Gröbner, Oswald
1999-01-01
The Large Hadron Collider (LHC) project, now in the advanced construction phase at CERN, comprises two proton storage rings with colliding beams of 7-TeV energy. The machine is housed in the existing LEP tunnel with a circumference of 26.7 km and requires a bending magnetic field of 8.4 T with 14-m long superconducting magnets. The beam vacuum chambers comprise the inner 'cold bore' walls of the magnets. These magnets operate at 1.9 K, and thus serve as very good cryo-pumps. In order to reduce the cryogenic power consumption, both the heat load from synchrotron radiation emitted by the proton beams and the resistive power dissipation by the beam image currents have to be absorbed on a 'beam screen', which operates between 5 and 20 K and is inserted inside the vacuum chamber. The design of this beam screen represents a technological challenge in view of the numerous and often conflicting requirements and the very tight mechanical tolerances imposed. The synchrotron radiation produces strong outgassing from the...
Vacuum metastability with black holes
Energy Technology Data Exchange (ETDEWEB)
Burda, Philipp [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Gregory, Ruth [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Perimeter Institute, 31 Caroline Street North,Waterloo, ON, N2L 2Y5 (Canada); Moss, Ian G. annd [School of Mathematics and Statistics, Newcastle University,Newcastle Upon Tyne, NE1 7RU (United Kingdom)
2015-08-24
We consider the possibility that small black holes can act as nucleation seeds for the decay of a metastable vacuum, focussing particularly on the Higgs potential. Using a thin-wall bubble approximation for the nucleation process, which is possible when generic quantum gravity corrections are added to the Higgs potential, we show that primordial black holes can stimulate vacuum decay. We demonstrate that for suitable parameter ranges, the vacuum decay process dominates over the Hawking evaporation process. Finally, we comment on the application of these results to vacuum decay seeded by black holes produced in particle collisions.
Energy Technology Data Exchange (ETDEWEB)
Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)
2003-05-07
A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.
Spatial solitons in nonlinear liquid waveguides
Indian Academy of Sciences (India)
R Barillé; G Rivoire
2001-11-01
Spatial solitons are studied in a planar waveguide ﬁlled with nonlinear liquids. Spectral and spatial measurements for different geometries and input power of the laser beam show the inﬂuence of different nonlinear effects as stimulated scatterings on the soliton propagation and in particular on the beam polarization. The stimulated scattering can be used advantageously to couple the two polarization components. This effect can lead to multiple applications in optical switching.
Topological nature of nonlinear optical effects in solids
Morimoto, Takahiro; Nagaosa, Naoto
2015-01-01
There are a variety of nonlinear optical effects including higher harmonic generations, photovoltaic effects, and nonlinear Kerr rotations. They are realized by the strong light irradiation to materials that results in nonlinear polarizations in the electric field. These are of great importance in studying the physics of excited states of the system as well as for applications to optical devices and solar cells. Nonlinear properties of materials are usually described by the nonlinear suscepti...
Price, G.W.
1954-08-01
A protector device is described for use in controlling the pressure within a cyclotron. In particular, an electrical circuit functions to actuate a vacuum pump when a predetermined low pressure is reached and disconnect the pump when the pressure increases abcve a certain value. The principal feature of the control circuit lies in the use of a voltage divider network at the input to a relay control tube comprising two parallel, adjustable resistances wherein one resistor is switched into the circuit when the relay connects the pump to a power source. With this arrangement the relay is energized at one input level received from a sensing element within the cyclotron chamber and is de-energized when a second input level, representing the higher pressure limit, is reached.
Anomalous CMB polarization and gravitational chirality
Contaldi, Carlo R.; Magueijo, Joao; Smolin, Lee
2008-01-01
We consider the possibility that gravity breaks parity, with left and right handed gravitons coupling to matter with a different Newton's constant and show that this would affect their zero-point vacuum fluctuations during inflation. Should there be a cosmic background of gravity waves, the effect would translate into anomalous CMB polarization. Non-vanishing TB (and EB) polarization components emerge, revealing interesting experimental targets. Indeed if reasonable chirality is present a TB ...
Vacuum Rabi spectra of a single quantum emitter
Ota, Yasutomo; Kumagai, Naoto; Iwamoto, Satoshi; Arakawa, Yasuhiko
2015-01-01
We report the observation of the vacuum Rabi splitting of a single quantum emitter by measuring its direct spontaneous emission into free space. We used a semiconductor quantum dot inside a photonic crystal nanocavity, in conjunction with an appropriate cavity design and filtering with a polarizer and an aperture, enabling the extraction of the inherently-weak emitter's signal. The emitter's vacuum Rabi spectra exhibit clear differences to those measured by detecting the cavity photon leakage. Moreover, we observed an asymmetric vacuum Rabi spectrum induced by interference between the emitter and cavity detection channels. Our observations lay the groundwork for accessing various cavity quantum electrodynamics phenomena that manifest themselves only in the emitter's direct spontaneous emission.
Vacuum Energy Sequestering and Graviton Loops
Kaloper, Nemanja
2016-01-01
We recently formulated a local mechanism of vacuum energy sequester. This mechanism automatically removes all matter loop contributions to vacuum energy from the stress energy tensor which sources the curvature. Here we adapt the local vacuum energy sequestering mechanism to also cancel all the vacuum energy loops involving virtual gravitons, in addition to the vacuum energy generated by matter fields alone.
High Vacuum Furnace for HIRFL-CSR
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In order to satisfy the requirement of ultra-high vacuum and low out-gassing rate of materials which are used to make HIIRFL-CSR vacuum chambers, a high vacuum furnace for degassing the beam chambers, flanges, and the other vacuum components has been designed and manufactured by IMP and Vacuum Equipment Factory in Lanzhou.
Vacuum Energy Sequestering and Graviton Loops
Kaloper, Nemanja; Padilla, Antonio
2016-01-01
We recently formulated a local mechanism of vacuum energy sequester. This mechanism automatically removes all matter loop contributions to vacuum energy from the stress energy tensor which sources the curvature. Here we adapt the local vacuum energy sequestering mechanism to also cancel all the vacuum energy loops involving virtual gravitons, in addition to the vacuum energy generated by matter fields alone.
Vacuum Gas Tungsten Arc Welding
Weeks, J. L.; Todd, D. T.; Wooten, J. R.
1997-01-01
A two-year program investigated vacuum gas tungsten arc welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. After a vacuum chamber and GTAW power supply were modified, several difficult-to-weld materials were studied and key parameters developed. Finally, Incoloy 903 weld overlays were produced without microfissures.
Vacuum enhanced cutaneous biopsy instrument
Collins, Joseph
2000-01-01
A syringe-like disposable cutaneous biopsy instrument equipped with a tubular blade at its lower end, and designed so that a vacuum is created during use, said vacuum serving to retain undeformed a plug of tissue cut from a patient's skin.
ULTRARAPID VACUUM-MICROWAVE HISTOPROCESSING
KOK, LP; BOON, ME
1995-01-01
A novel histoprocessing method for paraffin sections is presented in which the combination of vacuum and microwave exposure is the key element. By exploiting the decrease in boiling temperature under vacuum, the liquid molecules in the tissues have been successfully extracted and exchanged at relati
ULTRARAPID VACUUM-MICROWAVE HISTOPROCESSING
KOK, LP; BOON, ME
A novel histoprocessing method for paraffin sections is presented in which the combination of vacuum and microwave exposure is the key element. By exploiting the decrease in boiling temperature under vacuum, the liquid molecules in the tissues have been successfully extracted and exchanged at
Breather cloth for vacuum curing
Reed, M. W.
1979-01-01
Finely-woven nylon cloth that has been treated with Teflon improves vacuum adhesive bonding of coatings to substrates. Cloth is placed over coating; entire assembly, including substrate, coating, and cloth, is placed in plastic vacuum bag for curing. Cloth allows coating to "breathe" when bag is evacuated. Applications include bonding film coatings to solar concentrators and collectors.
Bubnov, Andrey; Gubina, Nadezda; Zhukovsky, Vladimir
2016-05-01
We study vacuum polarization effects in the model of Dirac fermions with additional interaction of an anomalous magnetic moment with an external magnetic field and fermion interaction with an axial-vector condensate. The proper time method is used to calculate the one-loop vacuum corrections with consideration for different configurations of the characteristic parameters of these interactions.
Metamaterials with tailored nonlinear optical response.
Husu, Hannu; Siikanen, Roope; Mäkitalo, Jouni; Lehtolahti, Joonas; Laukkanen, Janne; Kuittinen, Markku; Kauranen, Martti
2012-02-08
We demonstrate that the second-order nonlinear optical response of noncentrosymmetric metal nanoparticles (metamolecules) can be efficiently controlled by their mutual ordering in an array. Two samples with minor change in ordering have nonlinear responses differing by a factor of up to 50. The results arise from polarization-dependent plasmonic resonances modified by long-range coupling associated with metamolecular ordering. The approach opens new ways for tailoring the nonlinear responses of metamaterials and their tensorial properties.
Energy Technology Data Exchange (ETDEWEB)
Prescott, C.Y.
1993-07-01
Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist.
Optical Levitation of Nanodiamonds by Doughnut Beams in Vacuum
Zhou, Lei-Ming; Chen, Jun; Zhao, Nan
2016-01-01
Optically levitated nanodiamonds with nitrogen-vacancy centers promise a high-quality hybrid spin-optomechanical system. However, the trapped nanodiamond absorbs energy form laser beams and causes thermal damage in vacuum. We propose to solve the problem by trapping a composite particle (a nanodiamond core coated with a less absorptive silica shell) at the center of strongly focused doughnut-shaped laser beams. Systematical study on the trapping stability, heat absorption, and oscillation frequency concludes that the azimuthally polarized Gaussian beam and the linearly polarized Laguerre-Gaussian beam ${\\rm LG}_{03}$ are the optimal choices. With our proposal, particles with strong absorption coefficients can be trapped without obvious heating and, thus, the spin-optomechanical system based on levitated nanodiamonds are made possible in high vacuum with the present experimental techniques.
Detection of vacuum birefringence using intense laser pulses
Energy Technology Data Exchange (ETDEWEB)
Luiten, Andre N. [School of Physics M013, University of Western Australia, Nedlands, Western Australia 6009 (Australia)]. E-mail: andre@physics.uwa.edu.au; Petersen, Jesse C. [School of Physics M013, University of Western Australia, Nedlands, Western Australia 6009 (Australia)
2004-10-04
We propose a novel technique that promises hope of being the first to directly detect a polarization of the quantum electrodynamic (QED) vacuum. The technique exploits the high fields associated with ultra-short pulses of light stored in low dispersion optical resonators. We show that the technique circumvents the need for large-scale liquid helium cooled magnets, and more importantly avoids the experimental pitfalls that plague existing experimental approaches that use these magnets. The new technique has a predicted birefringence measurement sensitivity of {delta}n{approx}10-20 in a 1 s measurement. Currently available optics and lasers will enable observation of vacuum polarization in an experiment of only a few days in duration.
Detection of vacuum birefringence using intense laser pulses
Luiten, Andre N.; Petersen, Jesse C.
2004-10-01
We propose a novel technique that promises hope of being the first to directly detect a polarization of the quantum electrodynamic (QED) vacuum. The technique exploits the high fields associated with ultra-short pulses of light stored in low dispersion optical resonators. We show that the technique circumvents the need for large-scale liquid helium cooled magnets, and more importantly avoids the experimental pitfalls that plague existing experimental approaches that use these magnets. The new technique has a predicted birefringence measurement sensitivity of Δn∼10 in a 1 s measurement. Currently available optics and lasers will enable observation of vacuum polarization in an experiment of only a few days in duration.
Hadron Contribution to Vacuum Polarisation
Davier, M.; Hoecker, A.; Malaescu, B.; Zhang, Z.
2016-10-01
Precision tests of the Standard Theory require theoretical predictions taking into account higher-order quantum corrections. Among these vacuum polarisation plays a predominant role. Vacuum polarisation originates from creation and annihilation of virtual particle-antiparticle states. Leptonic vacuum polarisation can be computed from quantum electrodynamics. Hadronic vacuum polarisation cannot because of the non-perturbative nature of QCD at low energy. The problem is remedied by establishing dispersion relations involving experimental data on the cross section for e+ e- annihilation into hadrons. This chapter sets the theoretical and experimental scene and reviews the progress achieved in the last decades thanks to more precise and complete data sets. Among the various applications of hadronic vacuum polarisation calculations, two are emphasised: the contribution to the anomalous magnetic moment of the muon, and the running of the fine structure constant α to the Z mass scale. They are fundamental ingredients to high precision tests of the Standard Theory.
Hadron Contribution to Vacuum Polarisation
Davier, M; Malaescu, B; Zhang, Z
2016-01-01
Precision tests of the Standard Theory require theoretical predictions taking into account higher-order quantum corrections. Among these vacuum polarisation plays a predominant role. Vacuum polarisation originates from creation and annihilation of virtual particle–antiparticle states. Leptonic vacuum polarisation can be computed from quantum electrodynamics. Hadronic vacuum polarisation cannot because of the non-perturbative nature of QCD at low energy. The problem is remedied by establishing dispersion relations involving experimental data on the cross section for e+ e− annihilation into hadrons. This chapter sets the theoretical and experimental scene and reviews the progress achieved in the last decades thanks to more precise and complete data sets. Among the various applications of hadronic vacuum polarisation calculations, two are emphasised: the contribution to the anomalous magnetic moment of the muon, and the running of the fine structure constant α to the Z mass scale. They are fundamental ingre...
Albareti, F. D.; Cembranos, J. A. R.; Maroto, A. L.
2014-12-01
We consider the vacuum energy of massive quantum fields in an expanding universe. We define a conserved renormalized energy-momentum tensor by means of a comoving cutoff regularization. Using exact solutions for de Sitter space-time, we show that in a certain range of mass and renormalization scales there is a contribution to the vacuum energy density that scales as nonrelativistic matter and that such a contribution becomes dominant at late times. By means of the WKB approximation, we find that these results can be extended to arbitrary Robertson-Walker geometries. We study the range of parameters in which the vacuum energy density would be compatible with current limits on dark matter abundance. Finally, by calculating the vacuum energy in a perturbed Robertson-Walker background, we obtain the speed of sound of density perturbations and show that the vacuum energy density contrast can grow on sub-Hubble scales as in standard cold dark matter scenarios.
Albareti, F D; Maroto, A L
2014-01-01
We consider the vacuum energy of massive quantum fields in an expanding universe. We define a conserved renormalized energy-momentum tensor by means of a comoving cutoff regularization. Using exact solutions for de Sitter space-time, we show that in a certain range of mass and renormalization scales there is a contribution to the vacuum energy density that scales as non-relativistic matter and that such a contribution becomes dominant at late times. By means of the WKB approximation, we find that these results can be extended to arbitrary Robertson-Walker geometries. We study the range of parameters in which the vacuum energy density would be compatible with current limits on dark matter abundance. Finally, by calculating the vacuum energy in a perturbed Robertson-Walker background, we obtain the speed of sound of density perturbations and show that the vacuum energy density contrast can grow on sub-Hubble scales as in standard cold dark matter scenarios.
Vacuum Energy and Its Consequences
Hewett, Lionel
2009-10-01
Intuitively one would think that a perfect vacuum should contain no energy. However, quantum mechanics asserts that virtual particles popping in and out of existence too fast to be observed directly should produce a non-zero average energy density for empty space. This presentation discusses how quantum mechanics predicts too large a value for this energy density, how the Casimir effect correctly predicts the measured value of the vacuum energy between closely spaced objects, how time-symmetric cosmology predicts the energy density of interstellar space, how vacuum energy produces negative pressure, how vacuum energy causes the current universe to accelerate its expansion, and why vacuum energy cannot be tapped so as to produce an inexhaustible source of energy for all mankind.
2016-07-01
Advanced Research Projects Agency (DARPA) Dynamics-Enabled Frequency Sources (DEFYS) program is focused on the convergence of nonlinear dynamics and...Early work in this program has shown that nonlinear dynamics can provide performance advantages. However, the pathway from initial results to...dependent nonlinear stiffness observed in these devices. This work is ongoing, and will continue through the final period of this program . Reference 9
The cosmological origins of nonlinear Electrodynamics
Novello, M
2016-01-01
We present a mechanism that allows to describe any nonlinear theory of Electrodynamics as a consequence of the coupling of the electromagnetic field to gravity in the presence of a vacuum represented by the cosmological constant. We emphasize gravity\\rq s exclusive role of catalysis.
Heinrici, Axel; Bjelajac, Goran; Jonkers, Jeroen; Jakobs, Stefan; Olschok, Simon; Reisgen, Uwe
2017-02-01
Research and development carried out by the ISF Welding and Joining Institute of RWTH Aachen University has proven that combining high power laser and low vacuum atmosphere provides a welding performance and quality, which is comparable to electron beam welding. The developed welding machines are still using a beam forming which takes place outside the vacuum and the focusing laser beam has to be introduced to the vacuum via a suitable window. This inflexible design spoils much of the flexibility of modern laser welding. With the target to bring a compact, lightweight flying optics with flexible laser transport fibers into vacuum chambers, a high power fiber-fiber coupler has been adapted by II-VI HIGHYAG that includes a reliable vacuum interface. The vacuum-fiber-fiber coupler (V-FFC) is tested with up to 16 kW sustained laser power and the design is flexible in terms of a wide variety of laser fiber plug systems and vacuum flanges. All that is needed to implement the V-FFC towards an existing or planned vacuum chamber is an aperture of at least 100 mm (4 inch) diameter with any type of vacuum or pressure flange. The V-FFC has a state-of-the-art safety interface which allows for fast fiber breakage detection for both fibers (as supported by fibers) by electric wire breakage and short circuit detection. Moreover, the System also provides connectors for cooling and electric signals for the laser beam optics inside the vacuum. The V-FFC has all necessary adjustment options for coupling the laser radiation to the receiving fiber.
Nayfeh, Ali Hasan
1995-01-01
Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim
Yoshida, Zensho
2010-01-01
This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl
Nanda, Sudarsan
2013-01-01
"Nonlinear analysis" presents recent developments in calculus in Banach space, convex sets, convex functions, best approximation, fixed point theorems, nonlinear operators, variational inequality, complementary problem and semi-inner-product spaces. Nonlinear Analysis has become important and useful in the present days because many real world problems are nonlinear, nonconvex and nonsmooth in nature. Although basic concepts have been presented here but many results presented have not appeared in any book till now. The book could be used as a text for graduate students and also it will be useful for researchers working in this field.
New Mathematical Functions for Vacuum System Analysis
Woronowicz, Michael S.
2017-01-01
A new bivariate function has been found that provides solutions of integrals having the form u (sup minus eta) e (sup u) du which arise when developing predictions for the behavior of pressure within a rigid volume under high vacuum conditions in the presence of venting as well as sources characterized by power law transient decay over the range [0,1] for eta and for u greater than or equal to 0. A few properties of the new function are explored in this work. For instance the eta equals 1/2 case reproduces the Dawson function. In addition, a slight variation of the solution technique reproduces the exponential integral for eta equals 1. The technique used to generate these functions leads to an approach for solving a more general class of nonlinear ordinary differential equations, with the potential for identifying other new functions that solve other integrals.
Vacuum polarization around a three-dimensional black hole
Shiraishi, Kiyoshi
2015-01-01
We calculate the Euclidean propagator for a conformally coupled massless scalar field in the background of the three-dimensional black hole. The expectation value $\\langle\\varphi^2\\rangle$ in the Hartle-Hawking state is obtained in the spacetime.
Muon g-2 and Hadronic Vacuum Polarization: Recent Developments
Eidelman, Simon
2016-04-01
We discuss various experiments on e+e- annihilation into hadrons relevant to the problem of the muon anomalous magnetic moment. They include a status of the ISR measurements of the e+e- → π+π- as well as studies of numerous hadronic final states in experiments with the CMD-3 and SND detectors at the VEPP-2000 e+e- collider.
Muon g-2 and Hadronic Vacuum Polarization: Recent Developments
Directory of Open Access Journals (Sweden)
Eidelman Simon
2016-01-01
Full Text Available We discuss various experiments on e+e− annihilation into hadrons relevant to the problem of the muon anomalous magnetic moment. They include a status of the ISR measurements of the e+e− → π+π− as well as studies of numerous hadronic final states in experiments with the CMD-3 and SND detectors at the VEPP-2000 e+e− collider.
Quantum gravitational corrections to vacuum polarization during inflation
Leonard, Katie Elizabeth
Pompeii suffered a famous volcanic disaster in 79 AD. This led to a tremendous loss of life. This thesis examines that loss of life and the geography of death left behind by the eruption. Where did the citizens of Pompeii die, and how could they have avoided their fate? These are issues that are examined through geographic methodologies and the use of GIS. The results indicate a people that could have been spared with proper hazards management, and one that shows through mapping the large loss of life that accompanied one of history's most famous volcanic eruptions.
Institute of Scientific and Technical Information of China (English)
通拉嘎; 贾卫国; 杨军; 张俊萍
2012-01-01
通过对低双折射非线性相干耦合模传输方程引入斯托克斯参量表达式,利用庞加莱球图示法,分析了非线性相干耦合波在低双折射光纤中偏振态的衍化规律,并运用相图法数学几何法给出了双折射差与偏振不稳定性的关系,临街功率表达式.当两个运动常量满足关系时,偏振态围绕庞加莱球上的P1,P2稳定点旋转的闭合曲线衍化,并呈现椭圆偏振态；当两个运动常量满足关系时,出现保偏现象；当两个运动常量满足关系时,偏振态围绕P1,P3稳定点旋转的闭合曲线衍化.%Nonlinear polarization evolution for different birefringence regions in a weakly birefringent fiber was analysed by using Poincaré sphere.It was derived by quoting the Stoke's parameters formalism in the nonlinear coupled differential equations for the nonlinear coupled-mode.The phase plane method shows how the evolution of polarization was governed by refringence.Three conditions was derived for different initial values.While the two constants of motion allow for the inequality-R＞Γ,the polarization state would either be elliptical or spin around the stable singular points P1 and P2 on the Poincaré sphere.For the inequality-R=Γ,the linear polarization maintaing phenomenon would occur,the critical power for polarization instability was obtained by using geometrical methods.For the inequality-R＜Γ＜R,the evolution of polarization state would spin around the two points fixed point P and P3 on the Poincaré sphere.
49 CFR 570.56 - Vacuum brake assist unit and vacuum brake system.
2010-10-01
... 49 Transportation 6 2010-10-01 2010-10-01 false Vacuum brake assist unit and vacuum brake system... Vehicles With GVWR of More Than 10,000 Pounds § 570.56 Vacuum brake assist unit and vacuum brake system. The following requirements apply to vehicles with vacuum brake assist units and vacuum brake systems...
Non-linear Vacuum Phenomena in Non-commutative QED
Alvarez-Gaumé, Luís
2001-01-01
We show that the classic results of Schwinger on the exact propagation of particles in the background of constant field-strengths and plane waves can be readily extended to the case of non-commutative QED. It is shown that non-perturbative effects on constant backgrounds are the same as their commutative counterparts, provided the on-shell gauge invariant dynamics is referred to a non-perturbatively related space-time frame. For the case of the plane wave background, we find evidence of the effective extended nature of non-commutative particles, producing retarded and advanced effects in scattering. Besides the known `dipolar' character of non-commutative neutral particles, we find that charged particles are also effectively extended, but they behave instead as `half-dipoles'.
M. Wojcieszak
2015-01-01
Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass pol
2014-12-01
QPSK Gaussian channels . .......................................................................... 39 vi 1. INTRODUCTION Forward error correction (FEC...Capacity of BSC. 7 Figure 5. Capacity of AWGN channel . 8 4. INTRODUCTION TO POLAR CODES Polar codes were introduced by E. Arikan in [1]. This paper...Under authority of C. A. Wilgenbusch, Head ISR Division EXECUTIVE SUMMARY This report describes the results of the project “More reliable wireless
Stimulated photon emission from the vacuum
Karbstein, Felix
2014-01-01
We study the effect of stimulated photon emission from the vacuum subjected to strong space-time dependent electromagnetic fields as generated in the focal spot of two counter-propagating, linearly polarized high-intensity laser pulses. The superposition of the two counter-propagating electromagnetic waves results in a standing electromagnetic wave which - in contrast to a single plane wave - is characterized by at least one nonzero electromagnetic field invariant. Focusing on a comparably simple electromagnetic field profile, which should nevertheless capture the essential features of the electromagnetic fields generated in the focal spots of real high-intensity laser beams, we provide estimates for the numbers of emitted photons attainable with present and near future high-intensity laser facilities.
Vacuum Brazing of Accelerator Components
Singh, Rajvir; Pant, K. K.; Lal, Shankar; Yadav, D. P.; Garg, S. R.; Raghuvanshi, V. K.; Mundra, G.
2012-11-01
Commonly used materials for accelerator components are those which are vacuum compatible and thermally conductive. Stainless steel, aluminum and copper are common among them. Stainless steel is a poor heat conductor and not very common in use where good thermal conductivity is required. Aluminum and copper and their alloys meet the above requirements and are frequently used for the above purpose. The accelerator components made of aluminum and its alloys using welding process have become a common practice now a days. It is mandatory to use copper and its other grades in RF devices required for accelerators. Beam line and Front End components of the accelerators are fabricated from stainless steel and OFHC copper. Fabrication of components made of copper using welding process is very difficult and in most of the cases it is impossible. Fabrication and joining in such cases is possible using brazing process especially under vacuum and inert gas atmosphere. Several accelerator components have been vacuum brazed for Indus projects at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore using vacuum brazing facility available at RRCAT, Indore. This paper presents details regarding development of the above mentioned high value and strategic components/assemblies. It will include basics required for vacuum brazing, details of vacuum brazing facility, joint design, fixturing of the jobs, selection of filler alloys, optimization of brazing parameters so as to obtain high quality brazed joints, brief description of vacuum brazed accelerator components etc.
DEFF Research Database (Denmark)
Nikolova, L.; Ramanujam, P.S.
Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...
DEFF Research Database (Denmark)
Nikolova, L.; Ramanujam, P.S.
properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication......Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... and characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...
Green laser interferometric metrology system with sub-nanometer periodic nonlinearity.
Zhao, Shijie; Wei, Haoyun; Zhu, Minhao; Li, Yan
2016-04-10
This paper describes the design and realization of a heterodyne laser interferometer system that is applicable to metrology comparison. In this research, an iodine-stabilized Nd:YAG laser at 532 nm served as the light source. Two spatially separated beams with different offset frequencies are generated by two acousto-optic modulators to prevent any source mixing and polarization leakage. The interferometry components are integrated to a monolithic prism to reduce the difficulty of the light path adjustment and to guarantee the measuring accuracy. The experimental results show there is a sub-nanometer periodic nonlinearity, which mainly results from the ghost reflection. Placed in a vacuum chamber, the interferometer is applicable for measuring comparison using a piezo nanopositioner and a precision translation stage. Finally, a commercial interferometer is calibrated with the interferometer system.
Primordial gravitational waves in running vacuum cosmologies
Tamayo, D. A.; Lima, J. A. S.; Alves, M. E. S.; de Araujo, J. C. N.
2017-01-01
We investigate the cosmological production of gravitational waves in a nonsingular flat cosmology powered by a "running vacuum" energy density described by ρΛ ≡ ρΛ(H), a phenomenological expression potentially linked with the renormalization group approach in quantum field theory in curved spacetimes. The model can be interpreted as a particular case of the class recently discussed by Perico et al. (2013) [25] which is termed complete in the sense that the cosmic evolution occurs between two extreme de Sitter stages (early and late time de Sitter phases). The gravitational wave equation is derived and its time-dependent part numerically integrated since the primordial de Sitter stage. The generated spectrum of gravitons is also compared with the standard calculations where an abrupt transition, from the early de Sitter to the radiation phase, is usually assumed. It is found that the stochastic background of gravitons is very similar to the one predicted by the cosmic concordance model plus inflation except at higher frequencies (ν ≳ 100 kHz). This remarkable signature of a "running vacuum" cosmology combined with the proposed high frequency gravitational wave detectors and measurements of the CMB polarization (B-modes) may provide a new window to confront more conventional models of inflation.
NCSX Vacuum Vessel Fabrication
Energy Technology Data Exchange (ETDEWEB)
Viola, M. E.; Brown, T.; Heitzenroeder, P.; Malinowski, F.; Reiersen, W.; Sutton, L.; Goranson, P.; Nelson, B.; Cole, M.; Manuel, M.; McCorkle, D.
2005-10-07
The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in conjunction with the Oak Ridge National Laboratory (ORNL). The goal of this experiment is to develop a device which has the steady state properties of a traditional stellarator along with the high performance characteristics of a tokamak. A key element of this device is its highly shaped Inconel 625 vacuum vessel. This paper describes the manufacturing of the vessel. The vessel is being fabricated by Major Tool and Machine, Inc. (MTM) in three identical 120º vessel segments, corresponding to the three NCSX field periods, in order to accommodate assembly of the device. The port extensions are welded on, leak checked, cut off within 1" of the vessel surface at MTM and then reattached at PPPL, to accommodate assembly of the close-fitting modular coils that surround the vessel. The 120º vessel segments are formed by welding two 60º segments together. Each 60º segment is fabricated by welding ten press-formed panels together over a collapsible welding fixture which is needed to precisely position the panels. The vessel is joined at assembly by welding via custom machined 8" (20.3 cm) wide spacer "spool pieces." The vessel must have a total leak rate less than 5 X 10-6 t-l/s, magnetic permeability less than 1.02μ, and its contours must be within 0.188" (4.76 mm). It is scheduled for completion in January 2006.
Directory of Open Access Journals (Sweden)
E. D. Chertov
2015-01-01
Full Text Available The work is devoted to the creation of a new type of mixer to produce homogeneous mixtures of dissimilar materials applied to recycling of housing and communal services waste. The article describes the design of a dual-chamber device of the original high-temperature vacuum mixer, there investigated the processes occurring in the chambers of such devices. The results of theoretical and experimental research of the process of mixing recycled polyethylene with a mixture of "grinded food waste – Eco wool” are presented. The problem of the optimum choice of bending the curvilinear blades in the working volume of the seal, which is achieved by setting their profile in the form of involute arc of several circles of different radii, is examined . The dependences, allowing to define the limits of the changes of the main mode parameters the angular velocity of rotation of the working body of the mixer using two ways of setting the profile of the curvilinear blade mixer are obtained. Represented design of the mixer is proposed to use for a wide range of tasks associated with the mixing of the components with a strongly pronounced difference of physic al chemical properties and, in particular, in the production of composites out of housing and communal services waste.
Holmes, Richard R.; Mckechnie, Timothy N.
1989-01-01
Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.
Nonlinear metamaterials for holography
Almeida, Euclides; Bitton, Ora; Prior, Yehiam
2016-08-01
A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three-dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years, it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multilayer metamaterial holograms. A background free image is formed at a new frequency--the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analysed and prospects for future device applications are discussed.
Nonlinear metamaterials for holography
Almeida, Euclides; Bitton, Ora
2016-01-01
A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three-dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years, it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multilayer metamaterial holograms. A background free image is formed at a new frequency—the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analysed and prospects for future device applications are discussed. PMID:27545581
The vacuum universe the vacuum deposit and the dimensional hierarchy
Chung Ding Yu
2001-01-01
In this paper, it is proposed that the universe not only gains its existence from the vacuum but also fattens itself with the vacuum. It is the vacuum universe. The vacuum is deposited in the inflationary universe before the inflation. During the inflation, the deposited vacuum is spent to acquire space. In terms of elementary particles, the deposited vacuum is spent to dilute (fractionalize) the primordial high mass mixed 9-branes to form the low mass hierarchical mixed branes from 9 to 3 whose masses decrease with the space-time dimension numbers. This formation of the hierarchical mixed branes is followed by the internal empty space formation. The internal empty space is generate internally by the annihilation of some of the mixed branes through charge symmetry. The energy released is cosmic radiation. The inflationary emergence of the hierarchical mixed branes and the non-inflationary emergence of cosmic radiation after the inflation constitute the hybrid inflation. The mixed 3-brane is the mixture of lep...
Optical Search for QED vacuum magnetic birefringence, Axions and photon Regeneration
Pugnat, P; Hryczuk, A; Slunecka, M; Finger, M; Finger, M; Jary, V; Kral, M
2007-01-01
Since its prediction in 1936 by Euler, Heisenberg and Weisskopf in the earlier development of the Quantum Electrodynamic (QED) theory, the Vacuum Magnetic Birefringence (VMB) is still a challenge for optical metrology techniques. According to QED, the vacuum behaves as an optically active medium in the presence of an external magnetic field. It can be experimentally probed with a linearly polarized laser beam. After propagating through the vacuum submitted to a transverse magnetic field, the polarization of the laser beam will change to elliptical and the parameters of the polarization are directly related to fundamental constants such as the fine structure constant and the electron Compton wavelength. Contributions to the VMB could also arise from the existence of light scalar or pseudo-scalar particles like axions that couple to two photons and this would manifest itself as a sizeable deviation from the initial QED prediction. On one side, the interest in axion search, providing an answer to the strong-CP p...
In-situ measurement of vacuum window birefringence by atomic spectroscopy
Steffen, Andreas; Genske, Maximilian; Meschede, Dieter; Robens, Carsten; Alberti, Andrea
2013-01-01
We present an in-situ method to measure the birefringence of a single vacuum window by means of microwave spectroscopy on an ensemble of cold atoms. Stress-induced birefringence can cause an ellipticity in the polarization of an initially linearly-polarized laser beam. The amount of ellipticity can be reconstructed by measuring the differential vector light shift of an atomic hyperfine transition. Measuring the ellipticity as a function of the linear polarization angle allows us to infer the amount of birefringence $\\Delta n$ at the level of $10^{-8}$ and identify the orientation of the optical axes. The key benefit of this method is the ability to separately characterize each vacuum window, allowing the birefringence to be precisely compensated in existing vacuum apparatuses.
Polarization in free electron lasers
Energy Technology Data Exchange (ETDEWEB)
Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)
1995-12-31
Polarization of electromagnetic radiation is required very often in numerous scientific and industrial applications: studying of crystals, molecules and intermolecular interaction high-temperature superconductivity, semiconductors and their transitions, polymers and liquid crystals. Using polarized radiation allows to obtain important data (otherwise inaccessible) in astrophysics, meteorology and oceanology. It is promising in chemistry and biology for selective influence on definite parts of molecules in chain synthesis reactions, precise control of various processes at cell and subcell levels, genetic engineering etc. Though polarization methods are well elaborated in optics, they can fail in far-infrared, vacuum-ultraviolet and X-ray regions because of lack of suitable non-absorbing materials and damaging of optical elements at high specific power levels. Therefore, it is of some interest to analyse polarization of untreated FEL radiation obtained with various types of undulators, with and without axial magnetic field. The polarization is studied using solutions for electron orbits in various cases: plane or helical undulator with or without axial magnetic field, two plane undulators, a combination of right- and left-handed helical undulators with equal periods, but different field amplitudes. Some examples of how a desired polarization (elliptical circular or linear) can be obtained or changed quickly, which is necessary in many experiments, are given.
DEFF Research Database (Denmark)
Hu, Hao; Mulvad, Hans Christian Hansen; Galili, Michael
2010-01-01
Polarization-insensitive 640 Gbit/s demultiplexing for OTDM data signals is demonstrated using a 100 m polarization-maintaining highly non-linear fibre. The scheme is based on four wave mixing (FWM) in a polarization-maintaining fibre loop (PMFL) with bidirectional operation. Less than 0.2 d...
SILICON REFINING BY VACUUM TREATMENT
Directory of Open Access Journals (Sweden)
André Alexandrino Lotto
2014-12-01
Full Text Available This work aims to investigate the phosphorus removal by vacuum from metallurgical grade silicon (MGSi (98.5% to 99% Si. Melting experiments were carried out in a vacuum induction furnace, varying parameters such as temperature, time and relation area exposed to the vacuum / volume of molten silicon. The results of chemical analysis were obtained by inductively coupled plasma (ICP, and evaluated based on thermodynamic and kinetic aspects of the reaction of vaporization of the phosphorus in the silicon. The phosphorus was decreased from 33 to approximately 1.5 ppm after three hours of vacuum treatment, concluding that the evaporation step is the controlling step of the process for parameters of temperature, pressure and agitation used and refining by this process is technically feasible.
Inhomogeneous and interacting vacuum energy
De-Santiago, Josue; Wang, Yuting
2012-01-01
Vacuum energy is a simple model for dark energy driving an accelerated expansion of the universe. If the vacuum energy is inhomogeneous in spacetime then it must be interacting. We present the general equations for a spacetime-dependent vacuum energy in cosmology, including inhomogeneous perturbations. We show how any dark energy cosmology can be described by an interacting vacuum+matter. Different models for the interaction can lead to different behaviour (e.g., sound speed for dark energy perturbations) and hence could be distinguished by cosmological observations. As an example we present the cosmic microwave microwave background anisotropies and the matter power spectrum for two different versions of a generalised Chaplygin gas cosmology.
APS storage ring vacuum system
Energy Technology Data Exchange (ETDEWEB)
Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Goeppner, G.A.; Gonczy, J.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B.
1990-01-01
The Advanced Photon Source synchrotron radiation facility, under construction at the Argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components. The vacuum system, which is designed to operate at a pressure of 1 n Torr, consists of 240 connected sections, the majority of which are fabricated from an aluminum alloy extrusion. The sections are equipped with distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. The details of the vacuum system design, selected results of the development program and general construction plans are presented. 11 refs., 6 figs., 3 tabs.
Nonlinear opto-mechanical pressure
Conti, Claudio
2014-01-01
A transparent material exhibits ultra-fast optical nonlinearity and is subject to optical pressure if irradiated by a laser beam. However, the effect of nonlinearity on optical pressure is often overlooked, even if a nonlinear optical pressure may be potentially employed in many applications, as optical manipulation, biophysics, cavity optomechanics, quantum optics, optical tractors, and is relevant in fundamental problems as the Abraham-Minkoswky dilemma, or the Casimir effect. Here we show that an ultra-fast nonlinear polarization gives indeed a contribution to the optical pressure that also is negative in certain spectral ranges; the theoretical analysis is confirmed by first-principles simulations. An order of magnitude estimate shows that the effect can be observable by measuring the deflection of a membrane made by graphene.
Vacuum production; Produccion de vacio
Energy Technology Data Exchange (ETDEWEB)
Segovia, J. L. de
2010-07-01
Since the advent of ultra high vacuum in 1958 has been a great demand for new as means of production and to meet the process needs to be done: industry heavy, high technology and space research areas, large accelerator systems particles or nuclear fusion. In this paper we explore the modern media production: dry vacuum pumps, turbo pumps, pump status diffusion ion pumps and cryopumps. (Author)
Decoherence delays false vacuum decay
Bachlechner, Thomas C.
2012-01-01
We show that gravitational interactions between massless thermal modes and a nucleating Coleman-de Luccia bubble may lead to efficient decoherence and strongly suppress metastable vacuum decay for bubbles that are small compared to the Hubble radius. The vacuum decay rate including gravity and thermal photon interactions has the exponential scaling $\\Gamma\\sim\\Gamma_{CDL}^{2}$, where $\\Gamma_{CDL}$ is the Coleman-de Luccia decay rate neglecting photon interactions. For the lowest metastable i...
ITER diagnostic system: Vacuum interface
Energy Technology Data Exchange (ETDEWEB)
Patel, K.M., E-mail: Kaushal.Patel@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France); Udintsev, V.S.; Hughes, S.; Walker, C.I.; Andrew, P.; Barnsley, R.; Bertalot, L. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France); Drevon, J.M. [Bertin Technologies, BP 22, 13762 Aix-en Provence cedex 3 (France); Encheva, A. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France); Kashchuk, Y. [Institution “PROJECT CENTER ITER”, 1, Akademika Kurchatova pl., Moscow (Russian Federation); Maquet, Ph. [Bertin Technologies, BP 22, 13762 Aix-en Provence cedex 3 (France); Pearce, R.; Taylor, N.; Vayakis, G.; Walsh, M.J. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France)
2013-10-15
Diagnostics play an essential role for the successful operation of the ITER tokamak. They provide the means to observe control and to measure plasma during the operation of ITER tokamak. The components of the diagnostic system in the ITER tokamak will be installed in the vacuum vessel, in the cryostat, in the upper, equatorial and divertor ports, in the divertor cassettes and racks, as well as in various buildings. Diagnostic components that are placed in a high radiation environment are expected to operate for the life of ITER. There are approx. 45 diagnostic systems located on ITER. Some diagnostics incorporate direct or independently pumped extensions to maintain their necessary vacuum conditions. They require a base pressure less than 10{sup −7} Pa, irrespective of plasma operation, and a leak rate of less than 10{sup −10} Pa m{sup 3} s{sup −1}. In all the cases it is essential to maintain the ITER closed fuel cycle. These directly coupled diagnostic systems are an integral part of the ITER vacuum containment and are therefore subject to the same design requirements for tritium and active gas confinement, for all normal and accidental conditions. All the diagnostics, whether or not pumped, incorporate penetration of the vacuum boundary (i.e. window assembly, vacuum feedthrough etc.) and demountable joints. Monitored guard volumes are provided for all elements of the vacuum boundary that are judged to be vulnerable by virtue of their construction, material, load specification etc. Standard arrangements are made for their construction and for the monitoring, evacuating and leak testing of these volumes. Diagnostic systems are incorporated at more than 20 ports on ITER. This paper will describe typical and particular arrangements of pumped diagnostic and monitored guard volume. The status of the diagnostic vacuum systems, which are at the start of their detailed design, will be outlined and the specific features of the vacuum systems in ports and extensions
Vacuum Frying: A nutritional approach
Manuel Coronel
2014-01-01
(Received: 2014/08/07 - Accepted: 2014/09/22)One of the largest areas of the food industry is the production of snacks, but these have generally an inadequate nutritional profile in healthy eating. The vacuum frying technology is presented as a clear option processing for the development of new products and existing ones. This review article presents the advantages of using technology in Vacuum frying different types of food, especially in relation to the contents of some micronutrients and f...
Synthesis of a polar ordered oxynitride perovskite
Energy Technology Data Exchange (ETDEWEB)
Vadapoo, Rajasekarakumar; Ahart, Muhtar; Somayazulu, Maddury; Holtgrewe, Nicholas; Meng, Yue; Konopkova, Zuzana; Hemley, Russell J.; Cohen, R. E.
2017-06-01
For decades, numerous attempts have been made to produce polar oxynitride perovskites, where some of the oxygen is replaced by nitrogen, but a polar ordered oxynitride has never been demonstrated. Caracas and Cohen [Appl. Phys. Lett. 91, 092902 (2007)] studied possible ordered polar oxynitrides within density-functional theory (DFT) and found a few candidates that were predicted to be insulating and at least metastable. YSi O 2 N stood out with huge predicted polarization and nonlinear optic coefficients. In this study, we demonstrate the synthesis of perovskite-structured YSi O 2 N by using a combination of a diamond-anvil cell and in situ laser-heating techniques. Subsequent in situ x-ray diffraction, second-harmonic generation, and Raman-scattering measurements confirm that it is polar and a strong nonlinear optical material, with structure and properties similar to those predicted by DFT.
Zhu, Hong-Ming; Pen, Ue-Li; Chen, Xuelei; Yu, Hao-Ran
2016-01-01
We present a direct approach to non-parametrically reconstruct the linear density field from an observed non-linear map. We solve for the unique displacement potential consistent with the non-linear density and positive definite coordinate transformation using a multigrid algorithm. We show that we recover the linear initial conditions up to $k\\sim 1\\ h/\\mathrm{Mpc}$ with minimal computational cost. This reconstruction approach generalizes the linear displacement theory to fully non-linear fields, potentially substantially expanding the BAO and RSD information content of dense large scale structure surveys, including for example SDSS main sample and 21cm intensity mapping.
Vacuum-assisted cesarean section
Directory of Open Access Journals (Sweden)
McQuivey RW
2017-03-01
Full Text Available Ross W McQuivey,1 Jon E Block2 1Clinical Innovations, Salt Lake City, UT, 2Independent consultant, San Francisco, CA, USA Abstract: There has been a dramatic rise in the frequency of cesarean sections, surpassing 30% of all deliveries in the US. This upsurge, coupled with a decreasing willingness to allow vaginal birth after cesarean section, has resulted in an expansion of the use of vacuum assistance to safely extract the fetal head. By avoiding the use of a delivering hand or forceps blade, the volume being delivered through the uterine incision can be decreased when the vacuum is used properly. Reducing uterine extensions with their associated complications (eg, excessive blood loss in difficult cases is also a theoretical advantage of vacuum delivery. Maternal discomfort related to excessive fundal pressure may also be lessened. To minimize the risk of neonatal morbidity, proper cup placement over the “flexion point” remains essential to maintain vacuum integrity and reduce the chance of inadvertent detachment and uterine extensions. Based on the published literature and pragmatic clinical experience, utilization of the vacuum device is a safe and effective technique to assist delivery during cesarean section. Keywords: cesarean section, vacuum, forceps, birth, delivery
Edge conduction in vacuum glazing
Energy Technology Data Exchange (ETDEWEB)
Simko, T.M.; Collins, R.E. [Sydney Univ., NSW (Australia). Dept. of Applied Physics; Beck, F.A.; Arasteh, D. [Lawrence Berkeley Lab., CA (United States)
1995-03-01
Vacuum glazing is a form of low-conductance double glazing using in internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. An array of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation. Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge effects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.
Technical specification for vacuum systems
Energy Technology Data Exchange (ETDEWEB)
Khaw, J. (ed.)
1987-01-01
The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10/sup -5/ to 10/sup -11/ Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing and designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components. (LEW)
DEFF Research Database (Denmark)
Guo, Hairun; Zeng, Xianglong; Zhou, Binbin
2013-01-01
We interpret the purely spectral forward Maxwell equation with up to third-order induced polarizations for pulse propagation and interactions in quadratic nonlinear crystals. The interpreted equation, also named the nonlinear wave equation in the frequency domain, includes quadratic and cubic...
Nicholson, Stephen P
2012-01-01
People categorize themselves and others, creating ingroup and outgroup distinctions. In American politics, parties constitute the in- and outgroups, and party leaders hold sway in articulating party positions. A party leader's endorsement of a policy can be persuasive, inducing co-partisans to take the same position. In contrast, a party leader's endorsement may polarize opinion, inducing out-party identifiers to take a contrary position. Using survey experiments from the 2008 presidential election, I examine whether in- and out-party candidate cues—John McCain and Barack Obama—affected partisan opinion. The results indicate that in-party leader cues do not persuade but that out-party leader cues polarize. This finding holds in an experiment featuring President Bush in which his endorsement did not persuade Republicans but it polarized Democrats. Lastly, I compare the effect of party leader cues to party label cues. The results suggest that politicians, not parties, function as polarizing cues.
Kim, Jong-Kook
2005-01-01
Nonlinear fiber devices have been attracting considerable attention in recent years, due to their inherent ultrafast response time and potential applications in optical communication systems. They usually require long fibers to generate sufficient nonlinear phase shifts, since nonlinearities of conventional silica-core silica-clad fibers are too low. These long devices, however, cause the serious problems of pulse walk-off, pulse broadening, and polarization fluctuation which are major limiti...
Mišković, Olivera; Olea, Rodrigo
2011-01-01
Motivated by possible applications within the framework of anti-de Sitter gravity/conformal field theory correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by nonlinear electrodynamics are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary nonlinear electrodynamic Lagrangian in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Falloff conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass and vacuum energy as conserved quantities associated to an asymptotic timelike Killing vector are computed using a background-independent regularization of the gravitational action based on the addition of counterterms which are a given polynomial in the intrinsic and extrinsic curvatures.
Ruszczynski, Andrzej
2011-01-01
Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates t
Development of vacuum glazing with advanced thermal properties - Final report
Energy Technology Data Exchange (ETDEWEB)
Koebel, M.; Manz, H.
2009-03-15
Windows constitute a weak link in the building envelope and hence contribute significantly to the total heating energy demand in buildings. By evacuating the glazing cavity a vacuum glazing is created and heat transfer can be significantly reduced. This project was designed to build knowledge and technology necessary to fabricate vacuum glazing with advanced thermal properties. More specifically, various strategies for improvement of conventional technology were investigated. Of central importance was the development of a novel edge sealing approach which can in theory circumvent the main limitation of conventional glass soldering technology. This approach which is rapid, low temperature, low cost and completely vacuum compatible was filed for patenting in 2008. With regards to thermal insulation performance and glazing deflection, numerical studies were performed demonstrating the importance of nonlinear behavior with glazing size and the results published. A detailed service life prediction model was elaborated which defines a set of parameters necessary to keep the expected pressure increase below a threshold value of 0.1 Pa after 30 years. The model takes into account four possible sources of pressure increase and a getter material which acts as a sink. For the production of 0.5 m by 0.5 m glazing assembly prototypes, a high vacuum chamber was constructed and a first sealing prototype realized therein. The manufacture of improved prototypes and optimization of the anodic bonding edge sealing technology with emphasis on process relevant aspects is the goal of a follow-up project. (authors)
Vacuum high-harmonic generation and electromagnetic shock
Böhl, P.; King, B.; Ruhl, H.
2016-04-01
> When one takes into account the presence of virtual charged states in the quantum vacuum, a nonlinear self-interaction can arise in the propagation of electromagnetic fields. This self-interaction is often referred to as `real photon-photon scattering'. When the centre-of-mass energy of colliding photons is much lower than the rest energy of an electron-positron pair, this quantum effect can be included in the classical field equations of motion as a vacuum current and charge density using the Heisenberg-Euler Lagrangian. Using analytical and numerical methods for subcritical fields, the intrinsic solution to Maxwell's equations has been found for counterpropagating probe and pump plane waves in the presence of vacuum four- and six-wave mixing. In the corresponding all-order solution for the scattered probe, a route to vacuum high-harmonic generation is identified in which a long phase length can compensate for the weakness of interacting fields. The resulting shocks in the probe carrier wave and envelope are studied for different parameter regimes and polarisation set-ups. In this special issue, we study two additional set-ups: that of a slowly varying single-cycle background to highlight the effect of an oscillating background on the probe harmonic spectrum, and that of a few-cycle probe to highlight the smoothing of the harmonic peaks produced by a wider spectrum of probe photons. We also correct sign errors in an earlier publication.
Purification of a single photon nonlinearity
Snijders, H; Norman, J; Bakker, M P; Gossard, A; Bowers, J E; van Exter, M P; Bouwmeester, D; Löffler, W
2016-01-01
We show that the lifetime-reduced fidelity of a semiconductor quantum dot-cavity single photon nonlinearity can be restored by polarization pre- and postselection. This is realized with a polarization degenerate microcavity in the weak coupling regime, where an output polarizer enables quantum interference of the two orthogonally polarized transmission amplitudes. This allows us to transform incident coherent light into a stream of strongly correlated photons with a second-order correlation function of g2(0)~40, larger than previous experimental results even in the strong-coupling regime. This purification technique might also be useful to improve the fidelity of quantum dot based logic gates.
Mathot, S
2008-01-01
The aim of this paper is to describe the vacuum brazing procedure used at CERN for the brazing of Radio Frequency Quadrupole (RFQ). The RFQ is made of high precision machined OFE copper pieces assembled together. Vacuum brazing is one of the most promising techniques used to join the individual components leading to vacuum tightness and high precision alignment. The RFQ modules brazed at CERN are made of four 100 or 120 cm long vanes (two major and two minor vanes). Our brazing procedure consists of two steps. The first step involves the brazing of the four vanes in a horizontal position. The second step consists of brazing the vacuum stainless steel flanges to the copper structure in a vertical position. The paper describes the problems encountered with the alignment and the vacuum tightness. The difficulties related to the stress relaxation of the machined copper pieces during the brazing heat treatment are discussed. In addition, the solutions developed to improve the alignment of the brazed RFQâs are...
Herrmann, Marc
2015-01-01
Background: The vacuum in the light-front representation of quantum field theory is trivial while vacuum in the equivalent canonical representation of the same theory is non-trivial. Purpose: Understand the relation between the vacuum in light-front and canonical representations of quantum field theory and the role of zero-modes in this relation. Method: Vacuua are defined as linear functionals on an algebra of field operators. The role of the algebra in the definition of the vacuum is exploited to understand this relation. Results: The vacuum functional can be extended from the light-front Fock algebra to an algebra of local observables. The extension to the algebra of local observables is responsible for the inequivalence. The extension defines a unitary mapping between the physical representation of the local algebra and a sub-algebra of the light-front Fock algebra. Conclusion: There is a unitary mapping from the physical representation of the algebra of local observables to a sub-algebra of the light-fro...
The discovery potential of laser polarization experiments
Energy Technology Data Exchange (ETDEWEB)
Ahlers, Markus [Oxford Univ. (United Kingdom). Rudolf Peierls Centre for Theoretical Physics; Jaeckel, Joerg [Durham Univ. (United Kingdom). Inst. for Particle Physics and Phenomenology; Ringwald, Andreas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2008-12-15
Currently, a number of experiments are searching for vacuum magnetic birefringence and dichroism, i.e. for dispersive and absorptive features in the propagation of polarized light along a transverse magnetic field in vacuum. In this note we calculate the Standard Model contributions to these signatures, thereby illuminating the discovery potential of such experiments in the search for new physics. We discuss the three main sources for a Standard Model contribution to a dichroism signal: photon splitting, neutrino pair production and production of gravitons. (orig.)
In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio
2012-12-01
The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.
Vacuum energy of the Bukhvostov-Lipatov model
Bazhanov, Vladimir V.; Lukyanov, Sergei L.; Runov, Boris A.
2016-10-01
Bukhvostov and Lipatov have shown that weakly interacting instantons and anti-instantons in the O (3) non-linear sigma model in two dimensions are described by an exactly soluble model containing two coupled Dirac fermions. We propose an exact formula for the vacuum energy of the model for twisted boundary conditions, expressing it through a special solution of the classical sinh-Gordon equation. The formula perfectly matches predictions of the standard renormalized perturbation theory at weak couplings as well as the conformal perturbation theory at short distances. Our results also agree with the Bethe ansatz solution of the model. A complete proof the proposed expression for the vacuum energy based on a combination of the Bethe ansatz techniques and the classical inverse scattering transform method is presented in the second part of this work [42].
Vacuum energy of the Bukhvostov-Lipatov model
Bazhanov, Vladimir V; Runov, Boris A
2016-01-01
Bukhvostov and Lipatov have shown that weakly interacting instantons and anti-instantons in the $O(3)$ non-linear sigma model in two dimensions are described by an exactly soluble model containing two coupled Dirac fermions. We propose an exact formula for the vacuum energy of the model for twisted boundary conditions, expressing it through a special solution of the classical sinh-Gordon equation. The formula perfectly matches predictions of the standard renormalized perturbation theory at weak couplings as well as the conformal perturbation theory at short distances. Our results also agree with the Bethe ansatz solution of the model. A complete proof the proposed expression for the vacuum energy based on a combination of the Bethe ansatz techniques and the classical inverse scattering transform method is presented in the second part of this work [40].
Solutions to a nonlinear drift-diffusion model for semiconductors
Directory of Open Access Journals (Sweden)
Weifu Fang
1999-05-01
Full Text Available A nonlinear drift-diffusion model for semiconductors is analyzed to show the existence of non-vacuum global solutions and stationary solutions. The long time behavior of the solutions is studied by establishing the existence of an absorbing set and a compact attractor of the dynamical system. Parallel results on vacuum solutions are also obtained under weaker conditions on model parameters.
Microscale Digital Vacuum Electronic Gates
Manohara, Harish (Inventor); Mojarradi, Mohammed M. (Inventor)
2014-01-01
Systems and methods in accordance with embodiments of the invention implement microscale digital vacuum electronic gates. In one embodiment, a microscale digital vacuum electronic gate includes: a microscale field emitter that can emit electrons and that is a microscale cathode; and a microscale anode; where the microscale field emitter and the microscale anode are disposed within at least a partial vacuum; where the microscale field emitter and the microscale anode are separated by a gap; and where the potential difference between the microscale field emitter and the microscale anode is controllable such that the flow of electrons between the microscale field emitter and the microscale anode is thereby controllable; where when the microscale anode receives a flow of electrons, a first logic state is defined; and where when the microscale anode does not receive a flow of electrons, a second logic state is defined.
Impedances of Laminated Vacuum Chambers
Energy Technology Data Exchange (ETDEWEB)
Burov, A.; Lebedev, V.; /Fermilab
2011-06-22
First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].
Quasilinear hyperbolic Fuchsian systems and AVTD behavior in T2 symmetric vacuum spacetimes
Ames, Ellery; Isenberg, James; LeFloch, Philippe G
2012-01-01
We set up the singular initial value problem for quasilinear hyperbolic Fuchsian systems of first order and establish a well-posedness theory for this problem with smooth data and smooth coefficients. We apply this theory in order to show the existence of smooth (although not analytic) T2 symmetric solutions to the vacuum Einstein equations, which exhibit AVTD (asymptotically velocity term dominated) behavior in the neighborhood of their singularities and are polarized or half-polarized.
Energy Technology Data Exchange (ETDEWEB)
Turchetti, G. (Bologna Univ. (Italy). Dipt. di Fisica)
1989-01-01
Research in nonlinear dynamics is rapidly expanding and its range of applications is extending beyond the traditional areas of science where it was first developed. Indeed while linear analysis and modelling, which has been very successful in mathematical physics and engineering, has become a mature science, many elementary phenomena of intrinsic nonlinear nature were recently experimentally detected and investigated, suggesting new theoretical work. Complex systems, as turbulent fluids, were known to be governed by intrinsically nonlinear laws since a long time ago, but received purely phenomenological descriptions. The pioneering works of Boltzmann and Poincare, probably because of their intrinsic difficulty, did not have a revolutionary impact at their time; it is only very recently that their message is reaching a significant number of mathematicians and physicists. Certainly the development of computers and computer graphics played an important role in developing geometric intuition of complex phenomena through simple numerical experiments, while a new mathematical framework to understand them was being developed.
Particle description of zero energy vacuum; 2, Basic vacuum systems
Grandpeix, J Y
2002-01-01
We describe vacuum as a system of virtual particles, some of which have negative energies. Any system of vacuum particles is a part of a keneme, i.e. of a system of n particles which can, without violating the conservation laws, annihilate in the strict sense of the word (transform into nothing). A keneme is a homogeneous system, i.e. its state is invariant by all transformations of the invariance group. But a homogeneous system is not necessarily a keneme. In the simple case of a spin system, where the invariance group is SU(2), a homogeneous system is a system whose total spin is unpolarized; a keneme is a system whose total spin is zero. The state of a homogeneous system is described by a statistical operator with infinite trace (von Neumann), to which corresponds a characteristic distribution. The characteristic distributions of the homogeneous systems of vacuum are defined and studied. Finally it is shown how this description of vacuum can be used to solve the frame problem posed in (I).
DEFF Research Database (Denmark)
Liu, Xiang; Hu, Hao; Chandrasekhar, S.;
2014-01-01
-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled......We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all...... reach in a dispersion-managed transmission link. We further study the impact of polarization-mode dispersion on the performance gain brought by the phase-conjugated twin waves, showing a gain of ∼3.8 dB in signal quality factors....
Liu, Xiang; Hu, Hao; Chandrasekhar, S; Jopson, R M; Gnauck, A H; Dinu, M; Xie, C; Winzer, P J
2014-03-24
We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled reach in a dispersion-managed transmission link. We further study the impact of polarization-mode dispersion on the performance gain brought by the phase-conjugated twin waves, showing a gain of ~3.8 dB in signal quality factors.
Parr, Susan Resneck
1991-01-01
On college campuses, the climate is polarized because of intolerance and discrimination, censorship, factionalism, and anger among students and faculty. As a result, the campus is in danger of becoming dominated by political issues and discouraging the exchange of ideas characteristic of a true liberal arts education. (MSE)
The quantum vacuum at the foundations of classical electrodynamics
Leuchs, G; Sánchez-Soto, L L
2010-01-01
In the classical theory of electromagnetism, the permittivity and the permeability of free space are constants whose magnitudes do not seem to possess any deeper physical meaning. By replacing the free space of classical physics with the quantum notion of the vacuum, we speculate that the values of the aforementioned constants could arise from the polarization and magnetization of virtual pairs in vacuum. A classical dispersion model with parameters determined by quantum and particle physics is employed to estimate their values. We find the correct orders of magnitude. Additionally, our simple assumptions yield an independent estimate for the number of charged elementary particles based on the known values of the permittivity and the permeability, and for the volume of a virtual pair. Such interpretation would provide an intriguing connection between the celebrated theory of classical electromagnetism and the quantum theory in the weak field limit.
The Source of the Quantum Vacuum
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2009-01-01
Full Text Available The quantum vacuum consists of virtual particles randomly appearing and disappearing in free space. Ordinarily the wavenumber (or frequency spectrum of the zero-point fields for these virtual particles is assumed to be unbounded. The unbounded nature of the spectrum leads in turn to an infinite energy density for the quantum vacuum and an infinite renormalization mass for the free particle. This paper argues that there is a more fundamental vacuum state, the Planck vacuum, from which the quantum vacuum emerges and that the "graininess" of this more fundamental vacuum state truncates the wavenumber spectrum and leads to a finite energy density and a finite renormalization mass.
The Source of the Quantum Vacuum
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2009-01-01
Full Text Available The quantum vacuum consists of virtual particles randomly appearing and disappearing in free space. Ordinarily the wavenumber (or frequency spectrum of the zero-point fields for these virtual particles is assumed to be unbounded. The unbounded nature of the spectrum leads in turn to an infinite energy density for the quantum vacuum and an infinite renormalization mass for the free particle. This paper argues that there is a more fundamental vacuum state, the Planck vacuum, from which the quantum vacuum emerges and that the “graininess” of this more fundamental vacuum state truncates the wavenumber spectrum and leads to a finite energy density and a finite renormalization mass.
Gases and vacua handbook of vacuum physics
Beck, A H
2013-01-01
Handbook of Vacuum Physics, Volume 1: Gases and Vacua provides information on the many aspects of vacuum technology, from material on the quantum theoretical aspects of the complex semi-conductors used for thermionic and photo-electric emission to data on the performance of commercially available pumps, gauges, and high-vacuum materials. The handbook satisfies the need of workers using vacuum apparatuses or works on the diverse applications of high-vacuum technology in research and industry. The book is a compilation of long articles prepared by experts in vacuum technology. Sufficient theoret
Gregory, Ruth
2016-01-01
This talk reviews our recent work showing how tiny black holes can act as nucleation sites for the decay of the metastable Higgs vacuum. We start by discussing the formation of thin wall bubbles of true vacuum inside a false vacuum, and show how adding a black hole lowers the action of the Euclidean tunneling solution, thus strongly enhancing the probability of vacuum decay. We then review numerical results for the Higgs vacuum showing that the decay rate is even higher for these "thick wall" bubbles. The results imply either tiny black holes are not a component of our universe, or BSM corrections to the Higgs potential must stabilise our vacuum.
Miskovic, Olivera
2010-01-01
Motivated by possible applications within the framework of anti-de Sitter gravity/Conformal Field Theory (AdS/CFT) correspondence, charged black holes with AdS asymptotics, which are solutions to Einstein-Gauss-Bonnet gravity in D dimensions, and whose electric field is described by a nonlinear electrodynamics (NED) are studied. For a topological static black hole ansatz, the field equations are exactly solved in terms of the electromagnetic stress tensor for an arbitrary NED Lagrangian, in any dimension D and for arbitrary positive values of Gauss-Bonnet coupling. In particular, this procedure reproduces the black hole metric in Born-Infeld and conformally invariant electrodynamics previously found in the literature. Altogether, it extends to D>4 the four-dimensional solution obtained by Soleng in logarithmic electrodynamics, which comes from vacuum polarization effects. Fall-off conditions for the electromagnetic field that ensure the finiteness of the electric charge are also discussed. The black hole mass...
Effect of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Temperature is one of the key parameters for BT20 titanium alloy cylindrical workpiece manufactured by vacuum hot bulge forming. A two-dimensional nonlinear thermo-mechanical coupled FE model was established. Numerical simulation of vacuum hot bulge forming process of titanium alloy cylindrical workpiece was carried out using FE analysis software MSC Marc. The effects of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece were analyzed by numerical simulation.The simulated results show that the Y-direction displacement and the equivalent plastic strain of the workpiece increase with increasing bulge temperature. The residual stress decreases with increasing bulge temperature. The optimal temperature range of BT20 titanium alloy during vacuum hot bulge forming is 750-850 ℃. The corresponding experiments were carried out. The simulated results agreed well with the experimental results.
Entropic Measure of Time, and Gas Expansion in Vacuum
Martyushev, Leonid M
2016-01-01
The study considers advantages of the introduced measure of time based on the entropy change under irreversible processes (entropy production). Using the example of non-equilibrium expansion of an ideal gas in vacuum, such a measure is introduced with the help of Boltzmann's classic entropy. It is shown that, in the general case, this measure of time proves to be nonlinearly related to the reference measure assumed uniform by convention. The connection between this result and the results of other authors investigating measure of time in some biological and cosmological problems is noted.
Seider, Warren D.; Ungar, Lyle H.
1987-01-01
Describes a course in nonlinear mathematics courses offered at the University of Pennsylvania which provides an opportunity for students to examine the complex solution spaces that chemical engineers encounter. Topics include modeling many chemical processes, especially those involving reaction and diffusion, auto catalytic reactions, phase…
Katarina Anthony
2013-01-01
Last month, the Vacuum, Surfaces and Coatings (VSC) group was tasked with an unusually delicate operation in the LHCb experiment cavern: removing the LHC beam pipe while keeping the sensitive Vertex Locator vacuum vessel (VELO) completely isolated from the action. The VSC group seal off the VELO beam pipe with a flange. Image: Gloria Corti. LHCb’s VELO detector is one of the crown jewels of the experiment. With detector elements surrounded by a vacuum, it gets as close as 5 cm from the beam. Fantastic for physics, but difficult for all-important access. “Because of the sensitivity of the VELO detector and its proximity to the beam, the collaboration decided not to bake (see box) its portion of the beam pipe,” says Giulia Lanza (TE-VSC-LBV), the expert in charge of the beam vacuum operation. “Our group was therefore asked to remove the rest of the LHC beam pipe while keeping the VELO portion of the pipe completely isolated. This work...
Entanglement in the Bogoliubov vacuum
DEFF Research Database (Denmark)
Poulsen, Uffe Vestergaard; Meyer, T.; Lewenstein, M.
2005-01-01
We analyze the entanglement properties of the Bogoliubov vacuum, which is obtained as a second-order approximation to the ground state of an interacting Bose-Einstein condensate. We work in one- and two-dimensional lattices and study the entanglement between two groups of sites as a function...
Vacuum assisted closure in coloproctology
Bemelman, W.A.
2009-01-01
Vacuum-assisted closure has earned its indications in coloproctology. It has been described with variable results in the treatment of large perineal defects after abdominoperineal excision, in the treatment of stoma dehiscence and perirectal abscesses. The most promising indication for
Vacuum barrier for excimer lasers
Energy Technology Data Exchange (ETDEWEB)
Shurter, Roger P. (Jemez Springs, NM)
1992-01-01
A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.
Vacuum barrier for excimer lasers
Energy Technology Data Exchange (ETDEWEB)
Shurter, R.P.
1992-09-15
A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput. 3 figs.
Vacuum mounting for piezoelectric transducers
Tiede, D. A.
1977-01-01
Special housing couples piezoelectric transducers to nonporous surfaces for ultrasonic or acoustic-emission testing. Device, while providing sound isolation on flat or nonflat surfaces, can be attached and detached quickly. Vacuum sealing mechanism eliminates need for permanent or semipermanent bonds, viscous coupling liquids, weights, magnets, tape, or springs ordinarily used.
Brine Distribution after Vacuum Saturation
DEFF Research Database (Denmark)
Hedegaard, Kathrine; Andersen, Bertel Lohmann
1999-01-01
Experiments with the vacuum saturation method for brine in plugs of chalk showed that a homogeneous distribution of brine cannot be ensured at saturations below 20% volume. Instead of a homogeneous volume distribution the brine becomes concentrated close to the surfaces of the plugs...
Polarization dependence of Z-scan measurement: theory and experiment.
Yan, Xiao-Qing; Liu, Zhi-Bo; Zhang, Xiao-Liang; Zhou, Wen-Yuan; Tian, Jian-Guo
2009-04-13
Here we report on an extension of common Z-scan method to arbitrary polarized incidence light for measurements of anisotropic third-order nonlinear susceptibility in isotropic medium. The normalized transmittance formulas of closed-aperture Z-scan are obtained for linearly, elliptically and circularly polarized incidence beam. The theoretical analysis is examined experimentally by studying third-order nonlinear susceptibility of CS2 liquid. Results show that the elliptically polarized light Z-scan method can be used to measure simultaneously the two third-order nonlinear susceptibility components chi(3)(xyyx) and chi(3)(xxyy). Furthermore, the elliptically polarized light Z-scan measurements of large nonlinear phase shift are also analyzed theoretically and experimentally.
High-Reflectivity Coatings for a Vacuum Ultraviolet Spectropolarimeter
Narukage, Noriyuki; Kubo, Masahito; Ishikawa, Ryohko; Ishikawa, Shin-nosuke; Katsukawa, Yukio; Kobiki, Toshihiko; Giono, Gabriel; Kano, Ryouhei; Bando, Takamasa; Tsuneta, Saku; Auchère, Frédéric; Kobayashi, Ken; Winebarger, Amy; McCandless, Jim; Chen, Jianrong; Choi, Joanne
2017-03-01
Precise polarization measurements in the vacuum ultraviolet (VUV) region are expected to be a new tool for inferring the magnetic fields in the upper atmosphere of the Sun. High-reflectivity coatings are key elements to achieving high-throughput optics for precise polarization measurements. We fabricated three types of high-reflectivity coatings for a solar spectropolarimeter in the hydrogen Lyman-α (Lyα; 121.567 nm) region and evaluated their performance. The first high-reflectivity mirror coating offers a reflectivity of more than 80 % in Lyα optics. The second is a reflective narrow-band filter coating that has a peak reflectivity of 57 % in Lyα, whereas its reflectivity in the visible light range is lower than 1/10 of the peak reflectivity (˜ 5 % on average). This coating can be used to easily realize a visible light rejection system, which is indispensable for a solar telescope, while maintaining high throughput in the Lyα line. The third is a high-efficiency reflective polarizing coating that almost exclusively reflects an s-polarized beam at its Brewster angle of 68° with a reflectivity of 55 %. This coating achieves both high polarizing power and high throughput. These coatings contributed to the high-throughput solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), which was launched on 3 September, 2015.
A New Approach for Calculating Vacuum Susceptibility
Institute of Scientific and Technical Information of China (English)
宗红石; 平加伦; 顾建中
2004-01-01
Based on the Dyson-Schwinger approach, we propose a new method for calculating vacuum susceptibilities. As an example, the vector vacuum susceptibility is calculated. A comparison with the results of the previous approaches is presented.