Biggs, Jason D
2009-01-01
The preceding paper describes a strategy for externally influencing the course of short-time electronic excitation transfer (EET) in molecular dimers and observing the process by nonlinear wave-packet interferometry (nl-WPI). Within a sample of isotropically oriented dimers having a specified internal geometry, a vibrational mode internal to the acceptor chromophore can be preferentially driven by electronically nonresonant impulsive stimulated Raman (or resonant infrared) excitation with a short polarized control pulse. A subsequent electronically resonant polarized pump then preferentially excites the donor, and EET ensues. Here we test both the control strategy and its spectroscopic investigation-with some sacrifice of amplitude-level detail-by calculating the pump-probe difference signal. That signal is the limiting case of the control-influenced nl-WPI signal in which the two pulses in the pump pulse-pair coincide, as do the two pulses in the probe pulse-pair. We present calculated pump-probe difference ...
Stienkemeier, Frank
2017-06-01
Time-resolved coherent spectroscopy has opened many new directions to study ultrafast dynamics in complex quantum systems. While most applications have been achieved in the condensed phase, we are focusing on dilute gas phase samples, in particular, on doped helium droplet beams. Isolation in such droplets at millikelvin temperatures provides unique opportunities to synthesize well-defined complexes, to prepare specific ro-vibronic states, and study their dynamics. To account for the small densities in our samples, we apply a phase modulation technique in order to reach enough sensitivity and a high spectral resolution in electronic wave packet interferometry experiments. The combination with mass-resolved ion detection enabled us e.g. to characterize vibrational structures of excimer molecules. By extending this technique we have observed collective resonances in samples of very low density (10^8 cm^{-3}). With a variant of this method, we are currently elaborating the implementation of nonlinear all-XUV spectroscopy.
Quantum Interferometry and Correlated Two-Electron Wave-Packet Observation in Helium
Ott, Christian; Raith, Philipp; Meyer, Kristina; Laux, Martin; Zhang, Yizhu; Hagstotz, Steffen; Ding, Thomas; Heck, Robert; Pfeifer, Thomas
2012-01-01
The concerted motion of two or more bound electrons governs atomic and molecular non-equilibrium processes and chemical reactions. It is thus a long-standing scientific dream to measure the dynamics of two bound correlated electrons in the quantum regime. Quantum wave packets were previously observed for single-active electrons on their natural attosecond timescales. However, at least two active electrons and a nucleus are required to address the quantum three-body problem. This situation is realized in the helium atom, but direct time-resolved observation of two-electron wave-packet motion remained an unaccomplished challenge. Here, we measure a 1.2-femtosecond quantum beating among low-lying doubly-excited states in helium to evidence a correlated two-electron wave packet. Our experimental method combines attosecond transient-absorption spectroscopy at unprecedented high spectral resolution (20 meV near 60 eV) with an intensity-tuneable visible laser field to couple the quantum states from the perturbative ...
Bruder, Lukas; Stienkemeier, Frank
2015-01-01
Phase-modulated wave-packet interferometry is combined with mass-resolved photoion detection to investigate rubidium atoms attached to helium nanodroplets in a molecular beam experiment. The spectra of atomic Rb electronic states show a vastly enhanced sensitivity and spectral resolution when compared to conventional pump-probe wave-packet interferometry. Furthermore, the formation of Rb*He exciplex molecules is probed and for the first time a fully resolved vibrational spectrum for transitions between the lowest excited $5\\Pi_{3/2}$ and the high-lying electronic states $2^2\\Pi$, $4^2\\Delta$, $6^2\\Sigma$ is obtained and compared to theory. The feasibility of applying coherent multidimensional spectroscopy to dilute cold gas phase samples is demonstrated in these experiments.
Robinett, R W
2004-01-01
The numerical prediction, theoretical analysis, and experimental verification of the phenomenon of wave packet revivals in quantum systems has flourished over the last decade and a half. Quantum revivals are characterized by initially localized quantum states which have a short-term, quasi-classical time evolution, which then can spread significantly over several orbits, only to reform later in the form of a quantum revival in which the spreading reverses itself, the wave packet relocalizes, and the semi-classical periodicity is once again evident. Relocalization of the initial wave packet into a number of smaller copies of the initial packet (`minipackets' or `clones') is also possible, giving rise to fractional revivals. Systems exhibiting such behavior are a fundamental realization of time-dependent interference phenomena for bound states with quantized energies in quantum mechanics and are therefore of wide interest in the physics and chemistry communities. We review the theoretical machinery of quantum w...
Energy Technology Data Exchange (ETDEWEB)
Robinett, R.W
2004-03-01
The numerical prediction, theoretical analysis, and experimental verification of the phenomenon of wave packet revivals in quantum systems has flourished over the last decade and a half. Quantum revivals are characterized by initially localized quantum states which have a short-term, quasi-classical time evolution, which then can spread significantly over several orbits, only to reform later in the form of a quantum revival in which the spreading reverses itself, the wave packet relocalizes, and the semi-classical periodicity is once again evident. Relocalization of the initial wave packet into a number of smaller copies of the initial packet ('minipackets' or 'clones') is also possible, giving rise to fractional revivals. Systems exhibiting such behavior are a fundamental realization of time-dependent interference phenomena for bound states with quantized energies in quantum mechanics and are therefore of wide interest in the physics and chemistry communities. We review the theoretical machinery of quantum wave packet construction leading to the existence of revivals and fractional revivals, in systems with one (or more) quantum number(s), as well as discussing how information on the classical period and revival time is encoded in the energy eigenvalue spectrum. We discuss a number of one-dimensional model systems which exhibit revival behavior, including the infinite well, the quantum bouncer, and others, as well as several two-dimensional integrable quantum billiard systems. Finally, we briefly review the experimental evidence for wave packet revivals in atomic, molecular, and other systems, and related revival phenomena in condensed matter and optical systems.
Robinett, R. W.
2004-03-01
The numerical prediction, theoretical analysis, and experimental verification of the phenomenon of wave packet revivals in quantum systems has flourished over the last decade and a half. Quantum revivals are characterized by initially localized quantum states which have a short-term, quasi-classical time evolution, which then can spread significantly over several orbits, only to reform later in the form of a quantum revival in which the spreading reverses itself, the wave packet relocalizes, and the semi-classical periodicity is once again evident. Relocalization of the initial wave packet into a number of smaller copies of the initial packet (‘minipackets’ or ‘clones’) is also possible, giving rise to fractional revivals. Systems exhibiting such behavior are a fundamental realization of time-dependent interference phenomena for bound states with quantized energies in quantum mechanics and are therefore of wide interest in the physics and chemistry communities. We review the theoretical machinery of quantum wave packet construction leading to the existence of revivals and fractional revivals, in systems with one (or more) quantum number(s), as well as discussing how information on the classical period and revival time is encoded in the energy eigenvalue spectrum. We discuss a number of one-dimensional model systems which exhibit revival behavior, including the infinite well, the quantum bouncer, and others, as well as several two-dimensional integrable quantum billiard systems. Finally, we briefly review the experimental evidence for wave packet revivals in atomic, molecular, and other systems, and related revival phenomena in condensed matter and optical systems.
Dynamics of quantum wave packets
Energy Technology Data Exchange (ETDEWEB)
Gosnell, T.R.; Taylor, A.J.; Rodriguez, G.; Clement, T.S.
1998-11-01
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to develop ultrafast laser techniques for the creation and measurement of quantum vibrational wave packets in gas phase diatomic molecules. Moreover, the authors sought to manipulate the constitution of these wave packets in terms of harmonic-oscillator basis wavefunctions by manipulating the time-dependent amplitude and phase of the incident ultrashort laser pulse. They specifically investigated gaseous diatomic potassium (K{sub 2}), and discovered variations in the shape of the wave packets as a result of changing the linear chirp in the ultrashort preparation pulse. In particular, they found evidence for wave-packet compression for a specific degree of chirp. Important ancillary results include development of new techniques for denoising and deconvolution of femtosecond time traces and techniques for diagnosing the phase and amplitude of the electric field of femtosecond laser pulses.
Causal evolution of wave packets
Eckstein, Michał
2016-01-01
Drawing from the optimal transport theory adapted to the relativistic setting we formulate the principle of a causal flow of probability and apply it in the wave packet formalism. We demonstrate that whereas the Dirac system is causal, the relativistic-Schr\\"odinger Hamiltonian impels a superluminal evolution of probabilities. We quantify the causality breakdown in the latter system and argue that, in contrast to the popular viewpoint, it is not related to the localisation properties of the states.
Particle-like wave packets in complex scattering systems
Gérardin, Benoît; Ambichl, Philipp; Prada, Claire; Rotter, Stefan; Aubry, Alexandre
2016-01-01
A wave packet undergoes a strong spatial and temporal dispersion while propagating through a complex medium. This wave scattering is often seen as a nightmare in wave physics whether it be for focusing, imaging or communication purposes. Controlling wave propagation through complex systems is thus of fundamental interest in many areas, ranging from optics or acoustics to medical imaging or telecommunications. Here, we study the propagation of elastic waves in a cavity and a disordered waveguide by means of laser interferometry. We demonstrate how the direct experimental access to the information stored in the scattering matrix of these systems allows us to selectively excite scattering states and wave packets that travel along individual classical trajectories. Due to their limited dispersion, these particle-like scattering states will be crucially relevant for all applications involving selective wave focusing and efficient information transfer through complex media.
Chirp dependence of wave packet motion in oxazine 1.
Malkmus, Stephan; Dürr, Regina; Sobotta, Constanze; Pulvermacher, Horst; Zinth, Wolfgang; Braun, Markus
2005-11-24
The motion of vibrational wave packets in the system oxazine 1 in methanol is investigated by spectrally resolved transient absorption spectroscopy. The spectral properties of the probe pulse from 600 to 700 nm were chosen to cover the overlap region where ground-state bleach and stimulated emission signals are detected. The spectral phase of the pump pulse was manipulated by a liquid crystal display based pulse-shaping setup. Chirped excitation pulses of negative and positive chirp can be used to excite vibrational modes predominantly in the ground or excited state, respectively. To distinguish the observed wave packets in oxazine 1 moving in the ground or excited state, spectrally resolved transient absorption experiments are performed for various values of the linear chirp of the pump pulses. The amplitudes of the wave packet motion show an asymmetric behavior with an optimum signal for a negative chirp of -0.75 +/- 0.2 fs/nm, which indicates that predominantly ground-state wave packets are observed.
Fictitious time wave packet dynamics: I. Nondispersive wave packets in the quantum Coulomb problem
Fabčič, T; Wunner, G
2009-01-01
Nondispersive wave packets in a fictitious time variable are calculated analytically for the field-free hydrogen atom. As is well known by means of the Kustaanheimo-Stiefel transformation the Coulomb problem can be converted into that of a four-dimensional harmonic oscillator, subject to a constraint. This regularization makes use of a fictitious time variable, but arbitrary Gaussian wave packets in that time variable in general violate that constraint. The set of "restricted Gaussian wave packets" consistent with the constraint is constructed and shown to provide a complete basis for the expansion of states in the original three-dimensional coordinate space. Using that expansion arbitrary localized Gaussian wave packets of the hydrogen atom can be propagated analytically, and exhibit a nondispersive periodic behavior as functions of the fictitious time. Restricted wave packets with and without well defined angular momentum quantum n umbers are constructed. They will be used as trial functions in time-depende...
Squeezed Wave Packets in Quantum Cosmology
Pedram, Pouria
2010-11-01
We use an appropriate initial condition for constructing squeezed wave packets in the context of Wheeler-DeWitt equation with complete classical description. This choice of initial condition does not alter the classical paths and only affect the quantum mechanical picture. To demonstrate the method, we consider an empty 4+1-dimensional Kaluza-Klein quantum cosmology in the presence of a negative cosmological constant. We show that these wave packets do not disperse and sharply peak on the classical trajectories in the whole configuration space. So, the probability of finding the corresponding physical quantities approaches zero everywhere except on the classical paths.
Wave packet dynamics and factorization of numbers
Mack, H; Haug, F; Straub, F S; Freyberger, M; Schleich, W P; Mack, Holger; Bienert, Marc; Haug, Florian; Straub, Frank S.; Freyberger, Matthias; Schleich, Wolfgang P.
2002-01-01
We connect three phenomena of wave packet dynamics: Talbot images, revivals of a particle in a box and fractional revivals. The physical origin of these effects is deeply rooted in phase factors which are quadratic in the quantum number. We show that the characteristic structures in the time evolution of these systems allow us to factorize large integers.
Relativistic suppression of wave packet spreading.
Su, Q; Smetanko, B; Grobe, R
1998-03-30
We investigate numerically the solution of Dirac equation and analytically the Klein-Gordon equation and discuss the relativistic motion of an electron wave packet in the presence of an intense static electric field. In contrast to the predictions of the (non-relativistic) Schroedinger theory, the spreading rate in the field's polarization direction as well as in the transverse directions is reduced.
Segregation of helicity in inertial wave packets
Ranjan, A.
2017-03-01
Inertial waves are known to exist in the Earth's rapidly rotating outer core and could be important for the dynamo generation. It is well known that a monochromatic inertial plane wave traveling parallel to the rotation axis (along positive z ) has negative helicity while the wave traveling antiparallel (negative z ) has positive helicity. Such a helicity segregation, north and south of the equator, is necessary for the α2-dynamo model based on inertial waves [Davidson, Geophys. J. Int. 198, 1832 (2014), 10.1093/gji/ggu220] to work. The core is likely to contain a myriad of inertial waves of different wave numbers and frequencies. In this study, we investigate whether this characteristic of helicity segregation also holds for an inertial wave packet comprising waves with the same sign of Cg ,z, the z component of group velocity. We first derive the polarization relations for inertial waves and subsequently derive the resultant helicity in wave packets forming as a result of superposition of two or more waves. We find that the helicity segregation does hold for an inertial wave packet unless the wave numbers of the constituent waves are widely separated. In the latter case, regions of opposite color helicity do appear, but the mean helicity retains the expected sign. An illustration of this observation is provided by (a) calculating the resultant helicity for a wave packet formed by superposition of four upward-propagating inertial waves with different wave vectors and (b) conducting the direct numerical simulation of a Gaussian eddy under rapid rotation. Last, the possible effects of other forces such as the viscous dissipation, the Lorentz force, buoyancy stratification, and nonlinearity on helicity are investigated and discussed. The helical structure of the wave packet is likely to remain unaffected by dissipation or the magnetic field, but can be modified by the presence of linearly stable stratification and nonlinearity.
Initial Dynamics of The Norrish Type I Reaction in Acetone: Probing Wave Packet Motion
DEFF Research Database (Denmark)
Brogaard, Rasmus Y.; Sølling, Theis I.; Møller, Klaus Braagaard
2011-01-01
agreement with the experimental signals. We can explain the ultrafast decay of the experimental signals in the following manner: the wave packet simply travels, mainly along the deplanarization coordinate, out of the detection window of the ionizing probe. This window is so narrow that subsequent revival...... of the signal due to the coherent deplanarization vibration is not observed, meaning that from the point of view of the experiment the wave packets travels directly to the S1 minimum. This result stresses the importance of pursuing a closer link to the experimental signal when using molecular dynamics...
Teleportation of Nonclassical Wave Packets of light
Lee, Noriyuki; Takeno, Yuishi; Takeda, Shuntaro; Webb, James; Huntington, Elanor; Furusawa, Akira
2012-01-01
We report on the experimental quantum teleportation of strongly nonclassical wave packets of light. To perform this full quantum operation while preserving and retrieving the fragile non-classicality of the input state, we have developed a broadband, zero-dispersion teleportation apparatus that works in conjunction with time-resolved state preparation equipment. Our approach brings within experimental reach a whole new set of hybrid protocols involving discrete- and continuous-variable techniques in quantum information processing for optical sciences.
Spectral Modulation by Rotational Wave Packets
Baertschy, Mark; Hartinger, Klaus
2005-05-01
Periodic rephasing of molecular rotational wave packets can create rapid fluctuations in the optical properties of a molecular gas which can be used to manipulate the temporal phase and spectral content of ultrashort light pulses. We have demonstrated spectral control of a time-delayed ultrafast probe pulse propagating through the rotational wave packet prepared by a pump laser pulse. The spectrum of the probe pulse can be either broadened or compressed, depending on the relative sign of the temporal phase modulation and the initial chirp of the probe pulse. Adjustment of the spectral phase at the output of the interaction region allows controlled temporal pulse streching^1 and compression^2. The degree to which the spectrum of an ultrafast pulse can be modified depends on the strength and shape of the rotational wavepacket. We are studying the optimization of the rotational wave packet excitation with complex, shaped pump laser pulses for the purpose of optimizing probe pulse spectra modulation. ^1 Klaus Hartinger and Randy A. Bartels, Opt. Lett., submitted (2005). ^2 R.A. Bartels, T.C. Weinacht, N. Wagner, M. Baertschy, Chris H. Greene, M.M. Murnane, and H.C. Kapteyn , Phys. Rev. Lett., 88, 013903 (2002). This work was supported by the NSF.
Analysis of wave packet motion in frequency and time domain: oxazine 1.
Braun, Markus; Sobotta, Constanze; Dürr, Regina; Pulvermacher, Horst; Malkmus, Stephan
2006-08-17
Wave packet motion in the laser dye oxazine 1 in methanol is investigated by spectrally resolved transient absorption spectroscopy. The spectral range of 600-690 nm was accessible by amplified broadband probe pulses covering the overlap region of ground-state bleach and stimulated emission signal. The influence of vibrational wave packets on the optical signal is analyzed in the frequency domain and the time domain. For the analysis in the frequency domain an algorithm is presented that accounts for interference effects of neighbored vibrational modes. By this method amplitude, phase and decay time of vibrational modes are retrieved as a function of probe wavelength and distortions due to neighbored modes are reduced. The analysis of the data in the time domain yields complementary information on the intensity, central wavelength, and spectral width of the optical bleach spectrum due to wave packet motion.
Spreading of Ultrarelativistic Wave Packet and Redshift
Lev, Felix M
2012-01-01
The red shift of light coming to the Earth from distant objects is usually explained as a consequence of the fact that the Universe is expanding. Such an explanation implies that photons emitted by distant objects travel in the interstellar medium practically without interaction with interstellar matter and hence they can survive their long journey to the Earth. We analyze this assumption by considering wave-packet spreading for an ultrarelativistic particle. We derive a formula which shows that spreading in the direction perpendicular to the particle momentum is very important and cannot be neglected. The implications of the results are discussed.
Square-integrability of multivariate metaplectic wave-packet representations
Ghaani Farashahi, Arash
2017-03-01
This paper presents a systematic study for harmonic analysis of metaplectic wave-packet representations on the Hilbert function space {{L}2}≤ft({{{R}}d}\\right) . The abstract notions of symplectic wave-packet groups and metaplectic wave-packet representations will be introduced. We then present an admissibility condition on closed subgroups of the real symplectic group \\text{Sp}≤ft({{{R}}d}\\right) , which guarantees the square-integrability of the associated metaplectic wave-packet representation on {{L}2}≤ft({{{R}}d}\\right) .
Turbulent Spot Pressure Fluctuation Wave Packet Model
Energy Technology Data Exchange (ETDEWEB)
Dechant, Lawrence J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-05-01
Wave packet analysis provides a connection between linear small disturbance theory and subsequent nonlinear turbulent spot flow behavior. The traditional association between linear stability analysis and nonlinear wave form is developed via the method of stationary phase whereby asymptotic (simplified) mean flow solutions are used to estimate dispersion behavior and stationary phase approximation are used to invert the associated Fourier transform. The resulting process typically requires nonlinear algebraic equations inversions that can be best performed numerically, which partially mitigates the value of the approximation as compared to a more complete, e.g. DNS or linear/nonlinear adjoint methods. To obtain a simpler, closed-form analytical result, the complete packet solution is modeled via approximate amplitude (linear convected kinematic wave initial value problem) and local sinusoidal (wave equation) expressions. Significantly, the initial value for the kinematic wave transport expression follows from a separable variable coefficient approximation to the linearized pressure fluctuation Poisson expression. The resulting amplitude solution, while approximate in nature, nonetheless, appears to mimic many of the global features, e.g. transitional flow intermittency and pressure fluctuation magnitude behavior. A low wave number wave packet models also recover meaningful auto-correlation and low frequency spectral behaviors.
Controlling the spreading of wave packets of a dissociating molecule
DEFF Research Database (Denmark)
Tiwari, Ashwani Kumar; Møller, Klaus Braagaard; Henriksen, Niels Engholm
2007-01-01
in the Franck-Condon region whereas, as well known, the positively chirped pulses focus the wave packet in the asymptotic region. For the negatively chirped pulses, we show that the time corresponding to the minimum in the width of the wave packet can be predicted by an analytical formula. (C) 2007 Elsevier B.V...
Equations of motion for a relativistic wave packet
Indian Academy of Sciences (India)
L Kocis
2012-05-01
The time derivative of the position of a relativistic wave packet is evaluated. It is found that it is equal to the mean value of the momentum of the wave packet divided by the mass of the particle. The equation derived represents a relativistic version of the second Ehrenfest theorem.
Rotating Gaussian wave packets in weak external potentials
Goussev, Arseni
2017-07-01
We address the time evolution of two- and three-dimensional nonrelativistic Gaussian wave packets in the presence of a weak external potential of arbitrary functional form. The focus of our study is the phenomenon of rotation of a Gaussian wave packet around its center of mass, as quantified by mean angular momentum computed relative to the wave-packet center. Using a semiclassical approximation of the eikonal type, we derive an explicit formula for a time-dependent change of mean angular momentum of a wave packet induced by its interaction with a weak external potential. As an example, we apply our analytical approach to the scenario of a two-dimensional quantum particle crossing a tilted ridge potential barrier. In particular, we demonstrate that the initial orientation of the particle wave packet determines the sense of its rotation, and report a good agreement between analytical and numerical results.
Energy Technology Data Exchange (ETDEWEB)
Graham, D. B.; Robinson, P. A.; Cairns, Iver H. [School of Physics, University of Sydney, New South Wales 2006 (Australia); Skjaeraasen, O. [ProsTek, Institute for Energy Technology, P.O. Box 40, N-2027 Kjeller (Norway)
2011-07-15
Large-scale simulations of wave packet collapse are performed by numerically solving the three-dimensional (3D) electromagnetic Zakharov equations, focusing on individual wave packet collapses and on wave packets that form in continuously driven strong turbulence. The collapse threshold is shown to decrease as the electron thermal speed {nu}{sub e}/c increases and as the temperature ratio T{sub i}/T{sub e} of ions to electrons decreases. Energy lost during wave packet collapse and dissipation is shown to depend on {nu}{sub e}/c. The dynamics of density perturbations after collapse are studied in 3D electromagnetic strong turbulence for a range of T{sub i}/T{sub e}. The structures of the Langmuir, transverse, and total electric field components of wave packets during strong turbulence are investigated over a range of {nu}{sub e}/c. For {nu}{sub e}/c < or approx. 0.17, strong turbulence is approximately electrostatic and wave packets have very similar structure to purely electrostatic wave packets. For {nu}{sub e}/c > or approx. 0.17, transverse modes become trapped in density wells and contribute significantly to the structure of the total electric field. At all {nu}{sub e}/c, the Langmuir energy density contours of wave packets are predominantly oblate (pancake shaped). The transverse energy density contours of wave packets are predominantly prolate (sausage shaped), with the major axis being perpendicular to the major axes of the Langmuir component. This results in the wave packet becoming more nearly spherical as {nu}{sub e}/c increases, and in turn generates more spherical density wells during collapse. The results obtained are compared with previous 3D electrostatic results and 2D electromagnetic results.
Analysis of circular wave packets generated by pulsed electric fields
Energy Technology Data Exchange (ETDEWEB)
Yoshida, S., E-mail: shuhei@concord.itp.tuwien.ac.at [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Reinhold, C.O. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6372 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Burgdoerfer, J. [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Wyker, B.; Ye, S.; Dunning, F.B. [Department of Physics and Astronomy and the Rice Quantum Institute, Rice University, Houston, TX 77005-1892 (United States)
2012-05-15
We demonstrate that circular wave packets in high Rydberg states generated by a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wave packets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficients.
Scattering of wave packets with phases
Karlovets, Dmitry
2016-01-01
A general problem of $2\\rightarrow N_f$ scattering is addressed with all the states being wave packets with arbitrary phases. Depending on these phases, one deals with coherent states in $(3+1)$ D, vortex particles with orbital angular momentum, the Airy beams, and their generalizations. A method is developed in which a number of events represents a functional of the Wigner functions of such states. Using width of a packet $\\sigma_p/\\langle p\\rangle$ as a small parameter, the Wigner functions, the number of events, and a cross section are represented as power series in this parameter, the first non-vanishing corrections to their plane-wave expressions are derived, and generalizations for beams are made. Although in this regime the Wigner functions turn out to be everywhere positive, the cross section develops new specifically quantum features, inaccessible in the plane-wave approximation. Among them is dependence on an impact parameter between the beams, on phases of the incoming states, and on a phase of the...
Scattering of wave packets with phases
Karlovets, Dmitry V.
2017-03-01
A general problem of 2 → N f scattering is addressed with all the states being wave packets with arbitrary phases. Depending on these phases, one deals with coherent states in (3 + 1) D, vortex particles with orbital angular momentum, the Airy beams, and their generalizations. A method is developed in which a number of events represents a functional of the Wigner functions of such states. Using width of a packet σ p /p> as a small parameter, the Wigner functions, the number of events, and a cross section are represented as power series in this parameter, the first non-vanishing corrections to their plane-wave expressions are derived, and generalizations for beams are made. Although in this regime the Wigner functions turn out to be everywhere positive, the cross section develops new specifically quantum features, inaccessible in the plane-wave approximation. Among them is dependence on an impact parameter between the beams, on phases of the incoming states, and on a phase of the scattering amplitude. A model-independent analysis of these effects is made. Two ways of measuring how a Coulomb phase and a hadronic one change with a transferred momentum t are discussed.
Massachusetts Bay - Internal wave packets digitized from SAR imagery
National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery at 1:350,000 scale in Massachusetts Bay. Internal waves are nonsinusoidal waves that...
Neutrino Oscillations in Intermediate States.II -- Wave Packets
Asahara, A; Shimomura, T; Yabuki, T
2004-01-01
We analyze oscillations of intermediate neutrinos in terms of scattering of particles described by Gaussian wave packets. We study a scalar model as in the previous paper (I) but in realistic situations, where two particles of the initial state and final state are wave packets and neutrinos are in the intermediate state. The oscillation of the intermediate neutrino is found from the time evolution of the total transition probability between the initial state and final state. The effect of a finite lifetime and a finite relaxation time $\\tau$ are also studied. We find that the oscillation pattern depends on the magnitude of wave packet sizes of particles in the initial state and final state and the lifetime of the initial particle. For $\\Delta m^2=10^{-2}$ eV$^2$, the oscillation probability deviates from the standard formula, if the wave packet sizes are around $10^{-13}$ m for 0.4 MeV neutrino.
Resonance-Assisted Decay of Nondispersive Wave Packets
Wimberger, S.; Schlagheck, P.; Eltschka, C.; Buchleitner, A.
2006-01-01
We present a quantitative semiclassical theory for the decay of nondispersive electronic wave packets in driven, ionizing Rydberg systems. Statistically robust quantities are extracted combining resonance assisted tunneling with subsequent transport across chaotic phase space and a final ionization step.
Wave packet dynamics of potassium dimers attached to helium nanodroplets
Claas, P.; Droppelmann, G.; Schulz, C. P.; Mudrich, M.; Stienkemeier, F.
2006-01-01
The dynamics of vibrational wave packets excited in K$_2$ dimers attached to superfluid helium nanodroplets is investigated by means of femtosecond pump-probe spectroscopy. The employed resonant three-photon-ionization scheme is studied in a wide wavelength range and different pathways leading to K$^+_2$-formation are identified. While the wave packet dynamics of the electronic ground state is not influenced by the helium environment, perturbations of the electronically excited states are obs...
Electronic Wave Packet in a Quantized Electromagnetic Field
Institute of Scientific and Technical Information of China (English)
程太旺; 薛艳丽; 李晓峰; 吴令安; 傅盘铭
2002-01-01
We study a non-stationary electronic wave packet in a quantized electromagnetic field. Generally, the electron and field become entangled as the electronic wave packet evolves. Here we find that, when the initial photon state is a coherent one, the wavefunction of the system can be factorized if we neglect the transferred photon number. In this case, the quantized-field calculation is equivalent to the semi-classical calculation.
On wave-packet dynamics in a decaying quadratic potential
DEFF Research Database (Denmark)
Møller, Klaus Braagaard; Henriksen, Niels Engholm
1997-01-01
We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics.......We consider the time-dependent Schrodinger equation for a quadratic potential with an exponentially decaying force constant. General analytical solutions are presented and we highlight in particular, the signatures of classical mechanics in the wave packet dynamics....
Initial dynamics of the Norrish Type I reaction in acetone: probing wave packet motion.
Brogaard, Rasmus Y; Sølling, Theis I; Møller, Klaus B
2011-02-10
The Norrish Type I reaction in the S(1) (nπ*) state of acetone is a prototype case of ketone photochemistry. On the basis of results from time-resolved mass spectrometry (TRMS) and photoelectron spectroscopy (TRPES) experiments, it was recently suggested that after excitation the wave packet travels toward the S(1) minimum in less than 30 fs and stays there for more than 100 picoseconds [Chem. Phys. Lett.2008, 461, 193]. In this work we present simulated TRMS and TRPES signals based on ab initio multiple spawning simulations of the dynamics during the first 200 fs after excitation, getting quite good agreement with the experimental signals. We can explain the ultrafast decay of the experimental signals in the following manner: the wave packet simply travels, mainly along the deplanarization coordinate, out of the detection window of the ionizing probe. This window is so narrow that subsequent revival of the signal due to the coherent deplanarization vibration is not observed, meaning that from the point of view of the experiment the wave packets travels directly to the S(1) minimum. This result stresses the importance of pursuing a closer link to the experimental signal when using molecular dynamics simulations in interpreting experimental results.
Coherent structural trapping through wave packet dispersion during photoinduced spin state switching
DEFF Research Database (Denmark)
Lemke, Henrik T.; Kjær, Kasper Skov; Hartsock, Robert
2017-01-01
The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation......, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state...... is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic...
Climatology of extratropical atmospheric wave packets in the northern hemisphere
Grazzini, Federico
2010-01-01
Planetary and synoptic scale wave-packets represents one important component of the atmospheric large-scale circulation. These dissipative structures are able to rapidly transport eddy kinetic energy, generated locally (e.g. by baroclinic conversion), downstream along the upper tropospheric flow. The transported energy, moving faster than individual weather systems, will affect the development of the next meteorological system on the leading edge of the wave packet, creating a chain of connections between systems that can be far apart in time and space, with important implications on predictability. In this work we present a different and novel approach to investigate atmospheric variability, based on the objective recognition of planetary and synoptic wave packets. We have developed an objective tracking algorithm which allows to extract relevant statistical properties of the wave trains as a function of their dominant wavelength. We have applied the algorithm to the daily analysis (every 12h) from 1958-2009...
The Spatiotemporal Evolution of Wave Packets under Chaotic Condition
Institute of Scientific and Technical Information of China (English)
LIU Fang; LI Jun-Qing; LUO Yi-Xiao; XU Gong-Ou; ZUO Wei
2001-01-01
Using the minimum uncertainty state of quantum integrable system H0 as initial state,the spatiotemporal evolution of the wave packet under the action of perturbed Hamiltonian is studied causally as in classical mechanics. Due to the existence of the avoided energy level crossing in the spectrum there exist nonlinear resonances between somepairs of neighboring components of the wave packet,the deterministic dynamical evolution becomes very complicated and appears to be chaotic.It is proposed to use expectation values for the whole set of basic dynamical variables and the corresponding spreading widths to describe the topological features concisely such that the quantum chaotic motion can be studied in contrast with the quantum regular motion and well characterized with the asymptotic behaviors.It has been demonstrated with numerical results that such a wave packet has indeed quantum behaviors of ergodicity asin corresponding classical case.
Wave packet propagation across barriers by semiclassical initial value methods
Petersen, Jakob; Kay, Kenneth G.
2015-07-01
Semiclassical initial value representation (IVR) formulas for the propagator have difficulty describing tunneling through barriers. A key reason is that these formulas do not automatically reduce, in the classical limit, to the version of the Van Vleck-Gutzwiller (VVG) propagator required to treat barrier tunneling, which involves trajectories that have complex initial conditions and that follow paths in complex time. In this work, a simple IVR expression, that has the correct tunneling form in the classical limit, is derived for the propagator in the case of one-dimensional barrier transmission. Similarly, an IVR formula, that reduces to the Generalized Gaussian Wave Packet Dynamics (GGWPD) expression [D. Huber, E. J. Heller, and R. Littlejohn, J. Chem. Phys. 89, 2003 (1988)] in the classical limit, is derived for the transmitted wave packet. Uniform semiclassical versions of the IVR formulas are presented and simplified expressions in terms of real trajectories and WKB penetration factors are described. Numerical tests show that the uniform IVR treatment gives good results for wave packet transmission through the Eckart and Gaussian barriers in all cases examined. In contrast, even when applied with the proper complex trajectories, the VVG and GGWPD treatments are inaccurate when the mean energy of the wave packet is near the classical transmission threshold. The IVR expressions for the propagator and wave packet are cast as contour integrals in the complex space of initial conditions and these are generalized to potentially allow treatment of a larger variety of systems. A steepest descent analysis of the contour integral formula for the wave packet in the present cases confirms its relationship to the GGWPD method, verifies its semiclassical validity, and explains results of numerical calculations.
Analysis of Circular Wave Packets Generated by Pulsed Electric Fields
Energy Technology Data Exchange (ETDEWEB)
Yoshida, S. [Vienna University of Technology, Austria; Reinhold, Carlos O [ORNL; Burgdorfer, J. [Vienna University of Technology, Austria; Wyker, B. [Rice University; Ye, S. [Rice University; Dunning, F. B. [Rice University
2011-01-01
We demonstrate that circular wave packets in high Rydberg states generated using a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wavepackets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficient.
Wave packet dynamics under effect of a pulsed electric field
da Silva, A. R. C. B.; de Moura, F. A. B. F.; Dias, W. S.
2016-06-01
We studied the dynamics of an electron in a crystalline one-dimensional model under effect of a time-dependent Gaussian field. The time evolution of an initially Gaussian wave packet it was obtained through the numerical solution of the time-dependent Schrödinger equation. Our analysis consists of computing the electronic centroid as well as the mean square displacement. We observe that the electrical pulse is able to promote a special kind of displacement along the chain. We demonstrated a direct relation between the group velocity of the wave packet and the applied electrical pulses. We compare those numerical calculations with a semi-classical approach.
Wave packets and initial conditions in quantum cosmology
Gousheh, S S
2000-01-01
We discuss the construction of wave packets resulting from the solutions of a class of Wheeler-DeWitt equations in Robertson-Walker type cosmologies. We present an ansatz for the initial conditions which leads to a unique determination of the expansion coefficients in the construction of the wave packets with probability distributions which, in an interesting contrast to some of the earlier works, agree well with all possible classical paths. The possible relationship between these initial conditions and signature transition in the context of classical cosmology is also discussed.
Symmetry and conservation laws in semiclassical wave packet dynamics
Energy Technology Data Exchange (ETDEWEB)
Ohsawa, Tomoki, E-mail: tomoki@utdallas.edu [Department of Mathematical Sciences, The University of Texas at Dallas, 800 W Campbell Rd., Richardson, Texas 75080-3021 (United States)
2015-03-15
We formulate symmetries in semiclassical Gaussian wave packet dynamics and find the corresponding conserved quantities, particularly the semiclassical angular momentum, via Noether’s theorem. We consider two slightly different formulations of Gaussian wave packet dynamics; one is based on earlier works of Heller and Hagedorn and the other based on the symplectic-geometric approach by Lubich and others. In either case, we reveal the symplectic and Hamiltonian nature of the dynamics and formulate natural symmetry group actions in the setting to derive the corresponding conserved quantities (momentum maps). The semiclassical angular momentum inherits the essential properties of the classical angular momentum as well as naturally corresponds to the quantum picture.
Short-time Chebyshev wave packet method for molecular photoionization
Sun, Zhaopeng; Zheng, Yujun
2016-08-01
In this letter we present the extended usage of short-time Chebyshev wave packet method in the laser induced molecular photoionization dynamics. In our extension, the polynomial expansion of the exponential in the time evolution operator, the Hamiltonian operator can act on the wave packet directly which neatly avoids the matrix diagonalization. This propagation scheme is of obvious advantages when the dynamical system has large Hamiltonian matrix. Computational simulations are performed for the calculation of photoelectronic distributions from intense short pulse ionization of K2 and NaI which represent the Born-Oppenheimer (BO) model and Non-BO one, respectively.
Electron acceleration by Landau resonance with whistler mode wave packets
Gurnett, D. A.; Reinleitner, L. A.
1983-01-01
Recent observations of electrostatic waves associated with whistler mode chorus emissions provide evidence that electrons are being trapped by Landau resonance interactions with the chorus. In this paper, the trapping, acceleration and escape of electrons in Landau resonance with a whistler mode wave packet are discussed. It is shown that acceleration can occur by both inhomogeneous and dispersive effects. The maximum energy gained is controlled by the points where trapping and escape occur. Large energy changes are possible if the frequency of the wave packet or the magnetic field strength increase between the trapping and escape points. Various trapping and escape mechanisms are discussed.
Massachusetts Bay - Internal Wave Packets Digitized from SAR Imagery and Intersected with Bathymetry
National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with bathymetry for Massachusetts Bay. The internal wave packets were...
National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with tidal zones for Massachusetts Bay. The internal wave packets were...
Weisskopf-Wigner model for wave packet excitation
Paloviita, A; Stenholm, S; Paloviita, Asta; Suominen, Kalle-Antti; Stenholm, Stig
1997-01-01
We consider a laser induced molecular excitation process as a decay of a single energy state into a continuum. The analytic results based on Weisskopf-Wigner approach and perturbation calculations are compared with numerical wave packet results. We find that the decay model describes the excitation process well within the expected parameter region.
Propagation of gravity wave packet near critical level
Institute of Scientific and Technical Information of China (English)
YUE Xianchang; YI Fan
2005-01-01
A couple of two-dimensional linear and fully nonlinear numerical models for compressible atmosphere are used to numerically study the propagation of the gravity wave packet into a mean wind shear. For a linear propagation wave packet, the critical level interactions are in good agreement with the linear critical level theory. The dynamically and convectively unstable regions are formed due to the critical level interaction of a finite-amplitude wave packet, but they would not break. The free exchange of potential energy with kinetic energy in the background atmosphere at rest ceases after entering the mean wind shear. However, it still goes on in the nonlinear propagation. It is shown that the nonlinear effects modify the mean flow markedly, reduce the momentum and energy propagation velocity and drop the elevation of the critical level.The gravity wave packet becomes unstable and breaks down into smaller scales in some regions. It expends much more kinetic energy than potential energy in the early phase of the breakdown. This means that the wave breakdown sets up due to the action of the shear instability rather than a convective one.
Non-linear wave packet dynamics of coherent states
Indian Academy of Sciences (India)
J Banerji
2001-02-01
We have compared the non-linear wave packet dynamics of coherent states of various symmetry groups and found that certain generic features of non-linear evolution are present in each case. Thus the initial coherent structures are quickly destroyed but are followed by Schrödinger cat formation and revival. We also report important differences in their evolution.
Wave packet dynamics in the optimal superadiabatic approximation
Betz, Volker; Manthe, Uwe
2016-01-01
We explain the concept of superadiabatic approximations and show how in the context of the Born- Oppenheimer approximation they lead to an explicit formula that can be used to predict transitions at avoided crossings. Based on this formula, we present a simple method for computing wave packet dynamics across avoided crossings. Only knowledge of the adiabatic electronic energy levels near the avoided crossing is required for the computation. In particular, this means that no diabatization procedure is necessary, the adiabatic energy levels can be computed on the fly, and they only need to be computed to higher accuracy when an avoided crossing is detected. We test the quality of our method on the paradigmatic example of photo-dissociation of NaI, finding very good agreement with results of exact wave packet calculations.
Stochastic Acceleration of Ions Driven by Pc1 Wave Packets
Khazanov, G. V.; Sibeck, D. G.; Tel'nikhin, A. A.; Kronberg, T. K.
2015-01-01
The stochastic motion of protons and He(sup +) ions driven by Pc1 wave packets is studied in the context of resonant particle heating. Resonant ion cyclotron heating typically occurs when wave powers exceed 10(exp -4) nT sq/Hz. Gyroresonance breaks the first adiabatic invariant and energizes keV ions. Cherenkov resonances with the electrostatic component of wave packets can also accelerate ions. The main effect of this interaction is to accelerate thermal protons to the local Alfven speed. The dependencies of observable quantities on the wave power and plasma parameters are determined, and estimates for the heating extent and rate of particle heating in these wave-particle interactions are shown to be in reasonable agreement with known empirical data.
Inclusion of quantum fluctuations in wave packet dynamics
Ohnishi, A
1996-01-01
We discuss a method by which quantum fluctuations can be included in microscopic transport models based on wave packets that are not energy eigenstates. By including the next-to-leading order term in the cumulant expansion of the statistical weight, which corresponds to the wave packets having Poisson energy distributions, we obtain a much improved global description of the quantum statistical properties of the many-body system. In the case of atomic nuclei, exemplified by 12C and 40Ca, the standard liquid-drop results are reproduced at low temperatures and a phase transformation to a fragment gas occurs as the temperature is raised. The treatment can be extended to dynamical scenarios by means of a Langevin force emulating the transitions between the wave packets. The general form of the associated transport coefficients is derived and it is shown that the appropriate microcanonical equilibrium distribution is achieved in the course of the time evolution. Finally, invoking Fermi's golden rule, we derive spec...
Electron Rydberg wave packets in one-dimensional atoms
Indian Academy of Sciences (India)
Supriya Chatterjee; Amitava Choudhuri; Aparna Saha; B Talukdar
2010-09-01
An expression for the transition probability or form factor in one-dimensional Rydberg atom irradiated by short half-cycle pulse was constructed. In applicative contexts, our expression was found to be more useful than the corresponding result given by Landau and Lifshitz. Using the new expression for the form factor, the motion of a localized quantum wave packet was studied with particular emphasis on its revival and super-revival properties. Closed form analytical expressions were derived for expectation values of the position and momentum operators that characterized the widths of the position and momentum distributions. Transient phase-space localization of the wave packet produced by the application of a single impulsive kick was explicitly demonstrated. The undulation of the uncertainty product as a function of time was studied in order to visualize how the motion of the wave packet in its classical trajectory spreads throughout the orbit and the system becomes nonclassical. The process, however, repeats itself such that the atom undergoes a free evolution from a classical, to a nonclassical, and back to a classical state.
Rydberg Wave Packets and Half-Cycle Electromagnetic Pulses
Raman, Chandra S.
1998-05-01
This dissertation summarizes an examination of the dynamics of atomic Rydberg wave packets with coherent pulses of THz electromagnetic radiation consisting of less than a single cycle of the electric field. The bulk of the energy is contained in just a half-cycle. Previous work ( R. Jones, D. You, and P. Bucksbaum, ``Ionization of Rydberg atoms by subpicosecond half-cycle electromagnetic pulses,'' Phys. Rev. Lett.), vol. 70, 1993. had shown how these half-cycle pulses can be used to ionize the highly excited states of an atom, and that a classical view of electronic motion in the atom explains the ionization mechanism. To further probe the boundary between classical trajectories and quantum mechanics, in this work I investigate dynamical combinations of Rydberg states, or Rydberg wave packets, and how they ionize under the influence of a half-cycle electromagnetic pulse. With time-domain techniques I am able to extract the dynamics of the wave packet from the ionization rate, and to observe wave packet motion in both the electronic radial ( C. Raman, C. Conover, C. Sukenik, and P. Bucksbaum, ``Ionization of Rydberg wavepackets by sub-picosecond half-cycle electromagnetic pulses,'' Phys. Rev. Lett.), vol. 76, 1996.and angular ( C. Raman, T. Weinacht, and P. Bucksbaum, ``Stark wavepackets viewed with half cycle pulses.'' Phys. Rev. A), vol. 55, No. 6, 1997. coordinates. This is the first time a wavepacket technique has been used to view electron motion everywhere on its trajectory, and not just at the nucleus. This is the principal feature of half-cycle pulse ionization. Semiclassical ideas of ionization in conjunction with quantum descriptions of the wave packet, are capable of reproducing the main trends in the data, and in the absence of a rigorous model I rely on these. Experiments of this nature provide examples of the ongoing effort to use the coherent properties of radiation to control electronic motion in an atom, as well as to probe the boundaries between
Energy and Information Transfer Via Coherent Exciton Wave Packets
Zang, Xiaoning
Electronic excitons are bound electron-hole states that are generated when light interacts with matter. Such excitations typically entangle with phonons and rapidly decohere; the resulting electronic state dynamics become diffusive as a result. However, if the exciton-phonon coupling can be reduced, it may be possible to construct excitonic wave packets that offer a means of efficiently transmitting information and energy. This thesis is a combined theory/computation investigation to design condensed matter systems which support the requisite coherent transport. Under the idealizing assumption that exciton-phonon entanglement could be completely suppressed, the majority of this thesis focuses on the creation and manipulation of exciton wave packets in quasi-one-dimensional systems. While each site could be a silicon quantum dot, the actual implementation focused on organic molecular assemblies for the sake of computational simplicity, ease of experimental implementation, potential for coherent transport, and promise because of reduced structural uncertainty. A laser design was derived to create exciton wave packets with tunable shape and speed. Quantum interference was then exploited to manipulate these packets to block, pass, and even dissociate excitons based on their energies. These developments allow exciton packets to be considered within the arena of quantum information science. The concept of controllable excitonic wave packets was subsequently extended to consider molecular designs that allow photons with orbital angular momentum to be absorbed to create excitons with a quasi-angular momentum of their own. It was shown that a well-defined measure of topological charge is conserved in such light-matter interactions. Significantly, it was also discovered that such molecules allow photon angular momenta to be combined and later emitted. This amounts to a new way of up/down converting photonic angular momentum without relying on nonlinear optical materials. The
Coherent structural trapping through wave packet dispersion during photoinduced spin state switching
Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; van Driel, Tim B.; Chollet, Matthieu; Glownia, James M.; Song, Sanghoon; Zhu, Diling; Pace, Elisabetta; Matar, Samir F.; Nielsen, Martin M.; Benfatto, Maurizio; Gaffney, Kelly J.; Collet, Eric; Cammarata, Marco
2017-05-01
The description of ultrafast nonadiabatic chemical dynamics during molecular photo-transformations remains challenging because electronic and nuclear configurations impact each other and cannot be treated independently. Here we gain experimental insights, beyond the Born-Oppenheimer approximation, into the light-induced spin-state trapping dynamics of the prototypical [Fe(bpy)3]2+ compound by time-resolved X-ray absorption spectroscopy at sub-30-femtosecond resolution and high signal-to-noise ratio. The electronic decay from the initial optically excited electronic state towards the high spin state is distinguished from the structural trapping dynamics, which launches a coherent oscillating wave packet (265 fs period), clearly identified as molecular breathing. Throughout the structural trapping, the dispersion of the wave packet along the reaction coordinate reveals details of intramolecular vibronic coupling before a slower vibrational energy dissipation to the solution environment. These findings illustrate how modern time-resolved X-ray absorption spectroscopy can provide key information to unravel dynamic details of photo-functional molecules.
Semiclassical wave-packets emerging from interaction with an environment
Energy Technology Data Exchange (ETDEWEB)
Recchia, Carla, E-mail: carla.recchia@libero.it [D.I.S.I.M., Università di L’Aquila, Via Vetoio - Loc. Coppito - 67010 L’Aquila (Italy); Teta, Alessandro, E-mail: teta@mat.uniroma1.it [Dipartimento di Matematica, “Sapienza” Università di Roma, P.le A. Moro 5, 00185 Roma (Italy)
2014-01-15
We study the quantum evolution in dimension three of a system composed by a test particle interacting with an environment made of N harmonic oscillators. At time zero the test particle is described by a spherical wave, i.e., a highly correlated continuous superposition of states with well localized position and momentum, and the oscillators are in the ground state. Furthermore, we assume that the positions of the oscillators are not collinear with the center of the spherical wave. Under suitable assumptions on the physical parameters characterizing the model, we give an asymptotic expression of the solution of the Schrödinger equation of the system with an explicit control of the error. The result shows that the approximate expression of the wave function is the sum of two terms, orthogonal in L{sup 2}(R{sup 3(N+1)}) and describing rather different situations. In the first one, all the oscillators remain in their ground state and the test particle is described by the free evolution of a slightly deformed spherical wave. The second one consists of a sum of N terms where in each term there is only one excited oscillator and the test particle is correspondingly described by the free evolution of a wave packet, well concentrated in position and momentum. Moreover, the wave packet emerges from the excited oscillator with an average momentum parallel to the line joining the oscillator with the center of the initial spherical wave. Such wave packet represents a semiclassical state for the test particle, propagating along the corresponding classical trajectory. The main result of our analysis is to show how such a semiclassical state can be produced, starting from the original spherical wave, as a result of the interaction with the environment.
Riemann zeta function from wave-packet dynamics
DEFF Research Database (Denmark)
Mack, R.; Dahl, Jens Peder; Moya-Cessa, H.
2010-01-01
is governed by the temperature of the thermal phase state and tau is proportional to t. We use the JWKB method to solve the inverse spectral problem for a general logarithmic energy spectrum; that is, we determine a family of potentials giving rise to such a spectrum. For large distances, all potentials...... index of JWKB. We compare and contrast exact and approximate eigenvalues of purely logarithmic potentials. Moreover, we use a numerical method to find a potential which leads to exact logarithmic eigenvalues. We discuss possible realizations of Riemann zeta wave-packet dynamics using cold atoms...
Maamache, Mustapha; Bouguerra, Yacine; Choi, Jeong Ryeol
2016-06-01
A Gaussian wave packet of the inverted oscillator is investigated using the invariant operator method together with the unitary transformation method. A simple wave packet directly derived from the eigenstates of the invariant operator of the system corresponds to a plane wave that is fully delocalized. However, we can construct a weighted wave packet in terms of such plane waves, which corresponds to a Gaussian wave. This wave packet is associated with the generalized coherent state, which can be crucially utilized for investigating the classical limit of quantum wave mechanics. Various quantum properties of the system, such as fluctuations of the canonical variables, the uncertainty product, and the motion of the wave packet or quantum particle, are analyzed by means of this wave packet. We have confirmed that the time behavior of such a wave packet is very similar to the counterpart classical state. The wave packet runs away from the origin in the positive or negative direction in the 1D coordinate depending on the condition of the initial state. We have confirmed that this wave packet not only moves acceleratively but also spreads out during its propagation.
Field structure of collapsing wave packets in 3D strong Langmuir turbulence
Newman, D. L.; Robinson, P. A.; Goldman, M. V.
1989-01-01
A simple model is constructed for the electric fields in the collapsing wave packets found in 3D simulations of driven and damped isotropic strong Langmuir turbulence. This model, based on a spherical-harmonic decomposition of the electrostatic potential, accounts for the distribution of wave-packet shapes observed in the simulations, particularly the predominance of oblate wave packets. In contrast with predictions for undamped and undriven subsonic collapse of scalar fields, oblate vector-field wave packets do not flatten during collapse but, instead, remain approximately self-similar and rigid.
Wave packet molecular dynamics simulations of warm dense hydrogen
Knaup, M; Toepffer, C; Zwicknagel, G
2003-01-01
Recent shock-wave experiments with deuterium in a regime where a plasma phase-transition has been predicted and their theoretical interpretation are the matter of a controversial discussion. In this paper, we apply 'wave packet molecular dynamics' (WPMD) simulations to investigate warm dense hydrogen. The WPMD method was originally used by Heller for a description of the scattering of composite particles such as simple atoms and molecules; later it was applied to Coulomb systems by Klakow et al. In the present version of our model the protons are treated as classical point-particles, whereas the electrons are represented by a completely anti-symmetrized Slater sum of periodic Gaussian wave packets. We present recent results for the equation of state of hydrogen at constant temperature T = 300 K and of deuterium at constant Hugoniot E - E sub 0 + 1/2(1/n - 1/n sub 0)(p + p sub 0) = 0, and compare them with the experiments and several theoretical approaches.
Qualitative dynamics of wave packets in turbulent jets
Semeraro, Onofrio; Lusseyran, François; Pastur, Luc; Jordan, Peter
2017-09-01
We analyze the temporal dynamics associated with axisymmetric coherent structures in a turbulent jet. It has long been established that turbulent jets comprise large-scale coherent structures, now more commonly referred to as "wave packets" [Jordan and Colonius, Annu. Rev. Fluid Mech. 45, 173 (2013), 10.1146/annurev-fluid-011212-140756]. These structures exhibit a marked spatiotemporal organization, despite turbulence, and we aim to characterize their temporal dynamics by means of nonlinear statistical tools. The analysis is based on data presented Breakey et al., in Proceedings of the 19th AIAA/CEAS Aeroacoustics Conference, AIAA Paper 2013-2083 (AIAA, Reston, VA, 2013), where time series of the wave-packet signatures are extracted at different streamwise locations. The experiment runs at Ma=0.6 and Re=5.7 ×105 . A thorough analysis is performed. Statistical tools are used to estimate the embedding and correlation dimensions that characterize the dynamical system. Input-output transfer functions are designed as control-oriented models; and for this special case, consistent with other recent studies, we find that linear models can reproduce much of the convective input-ouput behavior. Finally, we show how surrogate models can partially reproduce the nonlinear dynamics.
Vibrational wave packet induced oscillations in two-dimensional electronic spectra. I. Experiments
Nemeth, Alexandra; Mancal, Tomas; Lukes, Vladimir; Hauer, Juergen; Kauffmann, Harald F; Sperling, Jaroslaw
2010-01-01
This is the first in a series of two papers investigating the effect of electron-phonon coupling in two-dimensional Fourier transformed electronic spectroscopy. We present a series of one- and two-dimensional nonlinear spectroscopic techniques for studying a dye molecule in solution. Ultrafast laser pulse excitation of an electronic transition coupled to vibrational modes induces a propagating vibrational wave packet that manifests itself in oscillating signal intensities and line-shapes. For the two-dimensional electronic spectra we can attribute the observed modulations to periodic enhancement and decrement of the relative amplitudes of rephasing and non-rephasing contributions to the total response. Different metrics of the two-dimensional signals are shown to relate to the frequency-frequency correlation function which provides the connection between experimentally accessible observations and the underlying microscopic molecular dynamics. A detailed theory of the time-dependent two-dimensional spectral li...
High Precision Signal Processing Algorithm for White Light Interferometry
Kim, Jeonggon Harrison
2008-01-01
A new signal processing algorithm for absolute temperature measurement using white light interferometry has been proposed and investigated theoretically. The proposed algorithm determines the phase delay of an interferometer with very high precision (≪ one fringe) by identifying the zero order fringe peak of cross-correlation of two fringe scans of white light interferometer. The algorithm features cross-correlation of interferometer fringe scans, hypothesis testing and fine tuning. The hypot...
The pump-probe coupling of matter wave packets to remote lattice states
DEFF Research Database (Denmark)
Sherson, Jacob F; Park, Sung Jong; Pedersen, Poul Lindholm;
2012-01-01
containing a Bose–Einstein condensate. The evolution of these wave packets is monitored in situ and their six-photon reflection at a band gap is observed. In direct analogy with pump–probe spectroscopy, a probe pulse allows for the resonant de-excitation of the wave packet into states localized around...
Wave analysis of the evolution of a single wave packet in supersonic boundary layer
Yermolaev, Yury G.; Yatskikh, Aleksey A.; Kosinov, Alexander D.; Semionov, Nickolay V.
2016-10-01
The evolution of the artificial wave packet in laminar flat-plate boundary layer was experimentally studied by hot-wire measurements at M=2. The localized disturbances were generated by pulse glow discharge. The wave analysis of evolution of wave packet was provided. It was found, that the most unstable waves are oblique, that consistent with results of linear theory.
Simulation on the electronic wave packet cyclotron motion in a Weyl semimetal slab.
Yao, Haibo; Zhu, Mingfeng; Jiang, Liwei; Zheng, Yisong
2017-04-20
We perform a numerical simulation on the time evolution of an electronic wave packet in a Weyl semimetal (WSM) slab driven by a magnetic field. We find that the evolution trajectory of the wave packet depends sensitively on its initial spin state. Only with initial spin state identical to that of the Fermi arc state at the surface it localized, does the wave packet evolution demonstrate the characteristic cyclotron orbit of WSM previously predicted from a semiclassical viewpoint. By analyzing the eigen-expansion of the electronic wave packet, we find the chiral Landau levels (LLs) of the WSM slab, as ingredients of the wave packet, to be responsible for establishing the characteristic WSM cyclotron orbit. In contrast, the nonchiral LLs contribute irregular oscillations to the wave packet evolution, going against the formation of a well-defined cyclotron orbit. In addition, the tilted magnetic field does not affect the motion of the electronic wave packet along the Fermi arcs in the momentum space. It does, however, alter the evolution trajectory of the electronic wave packet in real space and spin space. Finally, the energy disalignment of the Weyl nodes results in a 3D cyclotron orbit in real space.
Cho, Jungyeon
2011-05-13
Electron magnetohydrodynamics (EMHD) provides a fluidlike description of small-scale magnetized plasmas. An EMHD wave propagates along magnetic field lines. The direction of propagation can be either parallel or antiparallel to the magnetic field lines. We numerically study propagation of three-dimensional (3D) EMHD wave packets moving in one direction. We obtain two major results. (1) Unlike its magnetohydrodynamic (MHD) counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave packets traveling in one direction create opposite-traveling wave packets via self-interaction and cascade energy to smaller scales. (2) EMHD wave packets traveling in one direction clearly exhibit inverse energy cascade. We find that the latter is due to conservation of magnetic helicity. We compare inverse energy cascade in 3D EMHD turbulence and two-dimensional (2D) hydrodynamic turbulence.
Cho, Jungyeon
2011-01-01
Electron magnetohydrodynamics (EMHD) provides a fluid-like description of small-scale magnetized plasmas. An EMHD wave (also known as whistler wave) propagates along magnetic field lines. The direction of propagation can be either parallel or anti-parallel to the magnetic field lines. We numerically study propagation of 3-dimensional (3D) EMHD wave packets moving in one direction. We obtain two major results: 1. Unlike its magnetohydrodynamic (MHD) counterpart, an EMHD wave packet is dispersive. Because of this, EMHD wave packets traveling in one direction create opposite traveling wave packets via self-interaction and cascade energy to smaller scales. 2. EMHD wave packets traveling in one direction clearly exhibit inverse energy cascade. We find that the latter is due to conservation of magnetic helicity. We compare inverse energy cascade in 3D EMHD turbulence and 2-dimensional (2D) hydrodynamic turbulence.
Flavor entanglement in neutrino oscillations in the wave packet description
Blasone, Massimo; Dell'Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio
2015-10-01
The wave packet approach to neutrino oscillations provides an enlightening description of quantum decoherence induced, during propagation, by localization effects. Within this approach, we show that a deeper insight into the dynamical aspects of particle mixing can be obtained if one investigates the behavior of quantum correlations associated to flavor oscillations. By identifying the neutrino three-flavor modes with (suitably defined) three-qubit modes, the exploitation of tools of quantum information theory for mixed states allows a detailed analysis of the dynamical behavior of flavor entanglement during free propagation. This provides further elements leading to a more complete understanding of the phenomenon of neutrino oscillations, and a basis for possible applicative implementations. The analysis is carried out by studying the distribution of the flavor entanglement; to this aim, we perform combined investigations of the behaviors of the two-flavor concurrence and of the logarithmic negativities associated with specific bipartitions of the three flavors.
Discrete Wave-Packet Representation in Nuclear Matter Calculations
Müther, H; Kukulin, V I; Pomerantsev, V N
2016-01-01
The Lippmann-Schwinger equation for the nucleon-nucleon $t$-matrix as well as the corresponding Bethe-Goldstone equation to determine the Brueckner reaction matrix in nuclear matter are reformulated in terms of the resolvents for the total two-nucleon Hamiltonians defined in free space and in medium correspondingly. This allows to find solutions at many energies simultaneously by using the respective Hamiltonian matrix diagonalization in the stationary wave packet basis. Among other important advantages, this approach simplifies greatly the whole computation procedures both for coupled-channel $t$-matrix and the Brueckner reaction matrix. Therefore this principally novel scheme is expected to be especially useful for self-consistent nuclear matter calculations because it allows to accelerate in a high degree single-particle potential iterations. Furthermore the method provides direct access to the properties of possible two-nucleon bound states in the nuclear medium. The comparison between reaction matrices f...
Nonlinear single Compton scattering of an electron wave-packet
Angioi, A; Di Piazza, A
2016-01-01
In the presence of a sufficiently intense electromagnetic laser field, an electron can absorb on average a large number of photons from the laser and emit a high-energy one (nonlinear single Compton scattering). The case of nonlinear single Compton scattering by an electron with definite initial momentum has been thoroughly investigated in the literature. Here, we consider a more general initial state of the electron and use a wave-packet obtained as a superposition of Volkov wave functions. In particular, we investigate the energy spectrum of the emitted radiation at fixed observation direction and show that in typical experimental situations the sharply peaked structure of nonlinear single Compton scattering spectra of an electron with definite initial energy is almost completely washed out. Moreover, we show that at comparable uncertainties, the one in the momentum of the incoming electron has a larger impact on the photon spectra at a fixed observation direction than the one on the laser frequency, relate...
Information Geometry of Quantum Entangled Gaussian Wave-Packets
Kim, D -H; Cafaro, C; Mancini, S
2011-01-01
Describing and understanding the essence of quantum entanglement and its connection to dynamical chaos is of great scientific interest. In this work, using information geometric (IG) techniques, we investigate the effects of micro-correlations on the evolution of maximal probability paths on statistical manifolds induced by systems whose microscopic degrees of freedom are Gaussian distributed. We use the statistical manifolds associated with correlated and non-correlated Gaussians to model the scattering induced quantum entanglement of two spinless, structureless, non-relativistic particles, the latter represented by minimum uncertainty Gaussian wave-packets. Knowing that the degree of entanglement is quantified by the purity P of the system, we express the purity for s-wave scattering in terms of the micro-correlation coefficient r - a quantity that parameterizes the correlated microscopic degrees of freedom of the system; thus establishing a connection between entanglement and micro-correlations. Moreover, ...
Recovery time in quantum dynamics of wave packets
Energy Technology Data Exchange (ETDEWEB)
Strekalov, M. L., E-mail: strekalov@kinetics.nsc.ru [Russian Academy of Sciences, Voevodskii Institute of Chemical Kinetics and Combustion, Siberian Branch (Russian Federation)
2017-01-15
A wave packet formed by a linear superposition of bound states with an arbitrary energy spectrum returns arbitrarily close to the initial state after a quite long time. A method in which quantum recovery times are calculated exactly is developed. In particular, an exact analytic expression is derived for the recovery time in the limiting case of a two-level system. In the general case, the reciprocal recovery time is proportional to the Gauss distribution that depends on two parameters (mean value and variance of the return probability). The dependence of the recovery time on the mean excitation level of the system is established. The recovery time is the longest for the maximal excitation level.
Slow-light Airy wave packets and their active control via electromagnetically induced transparency
Hang, Chao
2014-01-01
We propose a scheme to generate (3+1)-dimensional slow-light Airy wave packets in a resonant $\\Lambda$-type three-level atomic gas via electromagnetically induced transparency. We show that in the absence of dispersion the Airy wave packets formed by a probe field consist of two Airy wave packets accelerated in transverse directions and a longitudinal Gaussian pulse with a constant propagating velocity lowered to $10^{-5}\\,c$ ($c$ is the light speed in vacuum). We also show that in the presence of dispersion it is possible to generate another type of slow-light Airy wave packets consisting of two Airy beams in transverse directions and an Airy wave packet in the longitudinal direction. In this case, the longitudinal velocity of the Airy wave packet can be further reduced during propagation. Additionally, we further show that the transverse accelerations (or bending) of the both types of slow-light Airy wave packets can be completely eliminated and the motional trajectories of them can be actively manipulated ...
Propagation of General Wave Packets in Some Classical and Quantum Systems
Institute of Scientific and Technical Information of China (English)
LIN Qiong-Gui
2006-01-01
In quantum mechanics the center of a wave packet is precisely defined as the center of probability. The center-of-probability velocity describes the entire motion of the wave packet. In classical physics there is no precise counterpart to the center-of-probability velocity of quantum mechanics, in spite of the fact that there exist in the literature at least eight different velocities for the electromagnetic wave. We propose a center-of-energy velocity to describe the entire motion of general wave packets in classical physical systems. It is a measurable quantity, and is well defined for both continuous and discrete systems. For electromagnetic wave packets it is a generalization of the velocity of energy transport. General wave packets in several classical systems are studied and the center-of-energy velocity is calculated and expressed in terms of the dispersion relation and the Fourier coefficients. These systems include string subject to an external force, monatomic chain and diatomic chain in one dimension, and classical Heisenberg model in one dimension. In most cases the center-of-energy velocity reduces to the group velocity for quasi-monochromatic wave packets. Thus it also appears to be the generalization of the group velocity. Wave packets of the relativistic Dirac equation are discussed briefly.
Chan, Yat-Long; Tsui, Ka Ming; Wong, Chan Fai; Xu, Jianyi
2015-01-01
We derive the neutrino flavor transition probabilities with the neutrino treated as a wave packet. The decoherence and dispersion effects from the wave-packet treatment show up as damping and phase-shifting of the plane-wave neutrino oscillation patterns. If the energy uncertainty in the initial neutrino wave packet is larger than around 0.01 of the neutrino energy, the decoherence and dispersion effects would degrade the sensitivity of reactor neutrino experiments to mass hierarchy measurement to lower than 3 $\\sigma$ confidence level.
Wave packet approach to the Jayne-Cummings and Rabi models
Larson, J
2006-01-01
This paper numerically studies the Jaynes-Cummings model with and without the rotating wave approximation in a non-standard way. Expressing the models with field quadrature operators, instead of the typically used boson ladder operators, a wave packet propagation approach is applied. The obtained evolved wave packets are then used to calculate various quantities, such as, Rabi oscillations, squeezing and entanglement. Many of the phenomenon can be explained from the wave packet evolution, either in the adiabatic or diabatic frames. Different behaviours of the two models are discussed.
Quantum wave packet dynamics with trajectories: reflections on a downhill ramp potential
Lopreore, Courtney L.; Wyatt, Robert E.
2000-07-01
The quantum trajectory method (QTM) for wave packet dynamics involves solving discretized hydrodynamic equations-of-motion in the Lagrangian picture (C. Lopreore, R.E. Wyatt, Phys. Rev. Lett. 82 (1999) 5190). In this Letter, results are presented which illustrate the dynamics of an initial Gaussian wave packet on a downhill ramp potential. Plots are shown for the time evolving probability density, as well as phase space plots and force diagrams. The mechanism, deduced from these plots, surprisingly shows some of the transmitted fluid elements of the wave packet making a U-turn before they head downhill on the ramp potential.
Inversion of an Atomic Wave Packet in a Circularly Polarized Electromagnetic Wave
Institute of Scientific and Technical Information of China (English)
ZENG Gao-Jian
2001-01-01
We study behavior of an atomic wave packet in a circularly polarized electromagnetic wave, and particularly calculate the atomic inversion of the wave packet. A general method of calculation is presented. The results are interesting. For example, if the wave packet is very narrow or/and the interaction is very strong, no matter the atom is initially in its ground state or excited state, the atomic inversion approaches zero as time approaches infinity. If the atom is initially in its ground state and excited state with the probability 1/2 respectively, and if the momentum density is an even function, then the atomic inversion equals zero at any time.``
Coriolis-coupled wave packet dynamics of H + HLi reaction.
Padmanaban, R; Mahapatra, S
2006-05-11
We investigated the effect of Coriolis coupling (CC) on the initial state-selected dynamics of H+HLi reaction by a time-dependent wave packet (WP) approach. Exact quantum scattering calculations were obtained by a WP propagation method based on the Chebyshev polynomial scheme and ab initio potential energy surface of the reacting system. Partial wave contributions up to the total angular momentum J=30 were found to be necessary for the scattering of HLi in its vibrational and rotational ground state up to a collision energy approximately 0.75 eV. For each J value, the projection quantum number K was varied from 0 to min (J, K(max)), with K(max)=8 until J=20 and K(max)=4 for further higher J values. This is because further higher values of K do not have much effect on the dynamics and also because one wishes to maintain the large computational overhead for each calculation within the affordable limit. The initial state-selected integral reaction cross sections and thermal rate constants were calculated by summing up the contributions from all partial waves. These were compared with our previous results on the title system, obtained within the centrifugal sudden and J-shifting approximations, to demonstrate the impact of CC on the dynamics of this system.
Discrete wave-packet representation in nuclear matter calculations
Müther, H.; Rubtsova, O. A.; Kukulin, V. I.; Pomerantsev, V. N.
2016-08-01
The Lippmann-Schwinger equation for the nucleon-nucleon t matrix as well as the corresponding Bethe-Goldstone equation to determine the Brueckner reaction matrix in nuclear matter are reformulated in terms of the resolvents for the total two-nucleon Hamiltonians defined in free space and in medium correspondingly. This allows one to find solutions at many energies simultaneously by using the respective Hamiltonian matrix diagonalization in the stationary wave-packet basis. Among other important advantages, this approach simplifies greatly the whole computation procedures both for the coupled-channel t matrix and the Brueckner reaction matrix. Therefore this principally novel scheme is expected to be especially useful for self-consistent nuclear matter calculations because it allows one to accelerate in a high degree single-particle potential iterations. Furthermore the method provides direct access to the properties of possible two-nucleon bound states in the nuclear medium. The comparison between reaction matrices found via the numerical solution of the Bethe-Goldstone integral equation and the straightforward Hamiltonian diagonalization shows a high accuracy of the method suggested. The proposed fully discrete approach opens a new way to an accurate treatment of two- and three-particle correlations in nuclear matter on the basis of the three-particle Bethe-Faddeev equation by an effective Hamiltonian diagonalization procedure.
Pulse-induced focusing of Rydberg wave packets
Arbó, D. G.; Reinhold, C. O.; Burgdörfer, J.; Pattanayak, A. K.; Stokely, C. L.; Zhao, W.; Lancaster, J. C.; Dunning, F. B.
2003-06-01
We demonstrate that strong transient phase-space localization can be achieved by the application of a single impulsive “kick” in the form of a short (600 ps) unidirectional electric-field pulse to a strongly polarized, quasi-one-dimensional Rydberg atom. The underlying classical dynamics is analyzed and it is shown that phase-space localization results from a focusing effect analogous to rainbow scattering. Moreover, it is shown that the essential features of the classical analysis remain valid in a quantum-mechanical treatment of the system in terms of its phase-space Husimi distribution. The degree of phase-space localization is characterized by the coarse-grained Renyi entropy. Transient phase-space localization is demonstrated experimentally using extreme redshifted m=0 potassium Stark states in the n=351 manifold and a short probe pulse. The experimental data are in good agreement with theoretical predictions. The localized state provides an excellent starting point for further control and manipulation of the electron wave packet.
Statistical behavior of Langmuir wave packets observed inside the electron foreshock of Saturn
Pisa, David; Hospodarsky, George B.; Kurth, Willam S.; Gurnett, Donald A.; Santolik, Ondrej; Soucek, Jan
2014-05-01
We present a statistical study of Langmuir wave packets in the Saturnian foreshock using Cassini Wideband Receiver electric field waveforms. We analyzed all foreshock crossings from 2004 to 2012 using an automatic method for the identification of Langmuir wave signatures. Observed waveforms exhibit a shape similar to Langmuir solitons or monochromatic wave packets with a slowly varying envelope. This is in agreement with a variety of previous observations of Langmuir waves in the terrestrial foreshock and associated with Type III radio bursts. We determined the peak amplitude for all wave packets, and found the distributions of amplitude appeared to follow a power law with P(E) ≈ E-2. We confirm that the most intense electron plasma waves are observed near the foreshock boundary. We estimated the energy density ratio to be about one order below previously reported values at Saturn. Finally, we discuss the properties of the Langmuir wave packets at different locations in the foreshock.
Signatures of wave packet revival phenomena in the expectation values of observables
Sudheesh, C; Balakrishnan, V
2004-01-01
Wave packet revivals and fractional revivals are striking quantum interference phenomena that can occur under suitable conditions in a system with a nonlinear spectrum. In the framework of a specific model (the propagation of an initially coherent wave packet in a Kerr-like medium), it is shown that distinctive signatures of these revivals and fractional revivals are displayed by the time evolution of the expectationWave packet revivals and fractional revivals are striking quantum interference phenomena that can occur under suitable conditions in a system with a nonlinear spectrum. In the framework of a specific model (the propagation of an initially coherent wave packet in a Kerr-like medium), it is shown that distinctive signatures of these revivals and fractional revivals are displayed by the time evolution of the expectation values of physical observables and their powers, i.e., by experimentally measurable quantities. Moreover, different fractional revivals can be selectively identified by examining appr...
Stability and evolution of wave packets in strongly coupled degenerate plasmas
Misra, A P
2011-01-01
We study the nonlinear propagation of electrostatic wave packets in a collisional plasma composed of strongly coupled ions and relativistically degenerate electrons. The equilibrium of ions is maintained by an effective temperature associated with their strong coupling, whereas that of electrons is provided by the relativistic degeneracy pressure. Using a multiple scale technique, a (3+1)-dimensional coupled set of nonlinear Schr\\"{o}dinger-like equations with nonlocal nonlinearity is derived from a generalized viscoelastic hydrodynamic model. These coupled equations, which govern the dynamics of wave packets, are used to study the oblique modulational instability of a Stoke's wave train to a small plane wave perturbation. We show that the wave packets, though stable to the parallel modulation, becomes unstable against oblique modulations. In contrast to the long-wavelength carrier modes, the wave packets with short-wavelengths are shown to be stable in the weakly relativistic case, whereas they can be stable...
Nonlinear dynamics of Airy-Vortex 3D wave packets: Emission of vortex light waves
Driben, Rodislav
2014-01-01
The dynamics of 3D Airy-vortex wave packets is studied under the action of strong self-focusing Kerr nonlinearity. Emissions of nonlinear 3D waves out of the main wave packets with the topological charges were demonstrated. Due to the conservation of the total angular momentum, charges of the emitted waves are equal to those carried by the parental light structure. The rapid collapse imposes a severe limitation on the propagation of multidimensional waves in Kerr media. However, the structure of the Airy beam carrier allows the coupling of light from the leading, most intense peak into neighboring peaks and consequently strongly postpones the collapse. The dependence of the critical input amplitude for the appearance of a fast collapse on the beam width is studied for wave packets with zero and non-zero topological charges. Wave packets carrying angular momentum are found to be much more resistant to the rapid collapse, especially those having small width.
Nonlinear dynamics of Airy-vortex 3D wave packets: emission of vortex light waves.
Driben, Rodislav; Meier, Torsten
2014-10-01
The dynamics of 3D Airy-vortex wave packets is studied under the action of strong self-focusing Kerr nonlinearity. Emissions of nonlinear 3D waves out of the main wave packets with the topological charges were demonstrated. Because of the conservation of the total angular momentum, charges of the emitted waves are equal to those carried by the parental light structure. The rapid collapse imposes a severe limitation on the propagation of multidimensional waves in Kerr media. However, the structure of the Airy beam carrier allows the coupling of light from the leading, most intense peak into neighboring peaks and consequently strongly postpones the collapse. The dependence of the critical input amplitude for the appearance of a fast collapse on the beam width is studied for wave packets with zero and nonzero topological charges. Wave packets carrying angular momentum are found to be much more resistant to the rapid collapse.
Annular wave packets at Dirac points and probability oscillation in graphene
Luo, Ji; Valencia, Daniel
2011-01-01
Wave packets in graphene whose central wave vector is at Dirac points are investigated by numerical calculations. Starting from an initial Gaussian function, these wave packets form into annular peaks that propagate to all directions like ripple-rings on water surface. At the beginning, electronic probability alternates between the central peak and the ripple-rings and transient oscillation occurs at the center. As time increases, the ripple-rings propagate at the fixed Fermi speed, and their widths remain unchanged. The axial symmetry of the energy dispersion leads to the circular symmetry of the wave packets. The fixed speed and widths, however, are attributed to the linearity of the energy dispersion. Interference between states that respectively belong to two branches of the energy dispersion leads to multiple ripple-rings and the probability-density oscillation. In a magnetic field, annular wave packets become confined and no longer propagate to infinity. If the initial Gaussian width differs greatly fro...
On the classical limit of Bohmian mechanics for Hagedorn wave packets
Dürr, Detlef
2010-01-01
We consider the classical limit of quantum mechanics in terms of Bohmian trajectories. For wave packets as defined by Hagedorn we show that the Bohmian trajectories converge to Newtonian trajectories in probability.
Goos-Haenchen and Imbert-Fedorov shifts for bounded wave packets of light
Ornigotti, Marco
2012-01-01
We present precise expressions of the spatial and angular Goos-Haenchen and Imbert-Fedorov shifts experienced by a longitudinally and transversally limited beam of light (wave packet) upon reflection from a dielectric interface, as opposed to the well-known case of a monochromatic beam which is bounded in transverse directions but infinitely extended along the direction of propagation. This is done under the assumption that the detector time is longer than the temporal length of the wave packet (wave packet regime). Our results will be applied to the case of a Gaussian wave packet and show that, at the leading order in the Taylor expansion of reflected-field amplitudes, the results are the same of the monochromatic case.
Nonlinear dynamics of wave packets in PT-symmetric optical lattices near the phase transition point
Nixon, Sean; Yang, Jianke
2012-01-01
Nonlinear dynamics of wave packets in PT-symmetric optical lattices near the phase-transition point are analytically studied. A nonlinear Klein-Gordon equation is derived for the envelope of these wave packets. A variety of novel phenomena known to exist in this envelope equation are shown to also exist in the full equation including wave blowup, periodic bound states and solitary wave solutions.
Trajectory description of the quantum–classical transition for wave packet interference
Energy Technology Data Exchange (ETDEWEB)
Chou, Chia-Chun, E-mail: ccchou@mx.nthu.edu.tw
2016-08-15
The quantum–classical transition for wave packet interference is investigated using a hydrodynamic description. A nonlinear quantum–classical transition equation is obtained by introducing a degree of quantumness ranging from zero to one into the classical time-dependent Schrödinger equation. This equation provides a continuous description for the transition process of physical systems from purely quantum to purely classical regimes. In this study, the transition trajectory formalism is developed to provide a hydrodynamic description for the quantum–classical transition. The flow momentum of transition trajectories is defined by the gradient of the action function in the transition wave function and these trajectories follow the main features of the evolving probability density. Then, the transition trajectory formalism is employed to analyze the quantum–classical transition of wave packet interference. For the collision-like wave packet interference where the propagation velocity is faster than the spreading speed of the wave packet, the interference process remains collision-like for all the degree of quantumness. However, the interference features demonstrated by transition trajectories gradually disappear when the degree of quantumness approaches zero. For the diffraction-like wave packet interference, the interference process changes continuously from a diffraction-like to collision-like case when the degree of quantumness gradually decreases. This study provides an insightful trajectory interpretation for the quantum–classical transition of wave packet interference.
Afraimovich, E.; Lesyuta, O.; Lipko, Yu.; Perevalova, N.; Voyeikov, S.; Vodyannikov, V.; Yakovets, A.; Jacobi, Ch.
This report discusses the experimental research results on the morphology and physi- cal origin of total electron content (TEC) pulsations as measured using the data from the global GPS network. Periodic electron density oscillations of the type of wave packets were investigated previously in terms of the hypothesis of their association with geomagnetic field (GP) pulsations. The greater part of evidence of the association between GP ad periodic electron density oscillations in the ionosphere was obtained by recording the frequency Doppler shift if the ionosphere-reflected radio signal and TEC variations measured using signals from geostationary satellites. However, many years of investigations have not yet provided thorough insight into the mechanisms ac- counting for the linkage between GP and ionospheric variations. One reason for that is the difficulty associated with obtaining statistically significant sets of experimental data. The use of the international ground-based network of two-frequency receivers of the navigation GPS system which comprised no less than 900 site as of August 2001 and is currently placing the data on the Internet, opens up a new era of a global, con- tinuous and fully computerized monitoring of ionospheric disturbances of a different class. This report presents a global morphology of TEC pulsations for 50 days with a different level of geomagnetic activity and the number of stations of the global GPS network from 100 to 300. A total number of the "receiver - GPS satellites" radio paths used in the analysis is about 500,000. Quasi-periodic TEC variations in the range of periods from 10 to 20 min are investigated, which is dictated by the fact that the data from the global GPS network are placed on the Internet with a standard temporal res- olution of 30 s. Most often, the observed TEC pulsations represent wave packets with a duration on the order of 1 hour. It was found that such TEC pulsations are a rela- tively rare event and are
Disentangling stellar activity from exoplanetary signals with interferometry
Directory of Open Access Journals (Sweden)
Ligi Roxanne
2015-01-01
Full Text Available Stellar activity can express as many forms at stellar surfaces: dark spots, convective cells, bright plages. Particularly, dark spots and bright plages add noise on photometric data or radial velocity measurements used to detect exoplanets, and thus lead to false detection or disrupt their derived parameters. Since interferometry provides a very high angular resolution, it may constitute an interesting solution to distinguish the signal of a transiting exoplanet and that of stellar activity. It has also been shown that granulation adds bias in visibility and closure phase measurements, aﬀecting in turn the derived stellar parameters. We analyze the noises generated by dark spots on interferometric observables and compare them to exoplanet signals. We investigate the current interferometric instruments able to measure and disentangle these signals, and show that there is a lack in spatial resolution. We thus give a prospective of the improvements to be brought on future interferometers, which would also significantly extend the number of available targets.
High Precision Signal Processing Algorithm for White Light Interferometry
Directory of Open Access Journals (Sweden)
Jeonggon Harrison Kim
2008-12-01
Full Text Available A new signal processing algorithm for absolute temperature measurement using white light interferometry has been proposed and investigated theoretically. The proposed algorithm determines the phase delay of an interferometer with very high precision (<< one fringe by identifying the zero order fringe peak of cross-correlation of two fringe scans of white light interferometer. The algorithm features cross-correlation of interferometer fringe scans, hypothesis testing and fine tuning. The hypothesis test looks for a zero order fringe peak candidate about which the cross-correlation is symmetric minimizing the uncertainty of mis-identification. Fine tuning provides the proposed algorithm with high precision subsample resolution phase delay estimation capability. The shot noise limited performance of the proposed algorithm has been analyzed using computer simulations. Root-mean-square (RMS phase error of the estimated zero order fringe peak has been calculated for the changes of three different parameters (SNR, fringe scan sample rate, coherence length of light source. Computer simulations showed that the proposed signal processing algorithm identified the zero order fringe peak with a miss rate of 3 x 10-4 at 31 dB SNR and the extrapolated miss rate at 35 dB was 3 x 10-8. Also, at 35 dB SNR, RMS phase error less than 10-3 fringe was obtained. The proposed signal processing algorithm uses a software approach that is potentially inexpensive, simple and fast.
Phase Structure of Strong-Field Tunneling Wave Packets from Molecules.
Liu, Ming-Ming; Li, Min; Wu, Chengyin; Gong, Qihuang; Staudte, André; Liu, Yunquan
2016-04-22
We study the phase structure of the tunneling wave packets from strong-field ionization of molecules and present a molecular quantum-trajectory Monte Carlo model to describe the laser-driven dynamics of photoelectron momentum distributions of molecules. Using our model, we reproduce and explain the alignment-dependent molecular frame photoelectron spectra of strong-field tunneling ionization of N_{2} reported by M. Meckel et al. [Nat. Phys. 10, 594 (2014)]. In addition to modeling the low-energy photoelectron angular distributions quantitatively, we extract the phase structure of strong-field molecular tunneling wave packets, shedding light on its physical origin. The initial phase of the tunneling wave packets at the tunnel exit depends on both the initial transverse momentum distribution and the molecular internuclear distance. We further show that the ionizing molecular orbital has a critical effect on the initial phase of the tunneling wave packets. The phase structure of the photoelectron wave packet is a key ingredient for modeling strong-field molecular photoelectron holography, high-harmonic generation, and molecular orbital imaging.
Einstein-de Broglie relations for wave packet: the acoustic world
Simaciu, Ion; Dumitrescu, Gheorghe; Georgeta, Nan
2015-01-01
In this paper we study the relations of Einstein-de Broglie type for the wave packets. We assume that the wave packet is a possible model of particle . When studying the behaviour of the wave packet for standing waves, in relation to an accelerated observer (i.e. Rindler observer), there can be demonstrated that the equivalent mass of the packet is the inertial mass. In our scenario, the waves and of the wave packets are depicted by the strain induced/produced in the medium. The properties of the waves, of the wave packet and, generally, of the perturbations in a material medium suggest the existence of an acoustic world. The acoustic world has mechanical and thermodynamical properties. The perturbations that are generated and propagated in the medium are correlated by means of acoustic waves with maximum speed. The observers of this world of disturbances (namely the acoustic world) have senses that are based on the perception of mechanical waves (disturbance of any kind) and apparatus for detecting and acqui...
Phase Structure of Strong-Field Tunneling Wave Packets from Molecules
Liu, Ming-Ming; Li, Min; Wu, Chengyin; Gong, Qihuang; Staudte, André; Liu, Yunquan
2016-04-01
We study the phase structure of the tunneling wave packets from strong-field ionization of molecules and present a molecular quantum-trajectory Monte Carlo model to describe the laser-driven dynamics of photoelectron momentum distributions of molecules. Using our model, we reproduce and explain the alignment-dependent molecular frame photoelectron spectra of strong-field tunneling ionization of N2 reported by M. Meckel et al. [Nat. Phys. 10, 594 (2014)]. In addition to modeling the low-energy photoelectron angular distributions quantitatively, we extract the phase structure of strong-field molecular tunneling wave packets, shedding light on its physical origin. The initial phase of the tunneling wave packets at the tunnel exit depends on both the initial transverse momentum distribution and the molecular internuclear distance. We further show that the ionizing molecular orbital has a critical effect on the initial phase of the tunneling wave packets. The phase structure of the photoelectron wave packet is a key ingredient for modeling strong-field molecular photoelectron holography, high-harmonic generation, and molecular orbital imaging.
Principle of stationary phase for propagating wave packets in the unidimensional scattering problem
Energy Technology Data Exchange (ETDEWEB)
Bernardini, A.E. [Universidade Federal de Sao Carlos, Departamento de Fisica, PO Box 676, Sao Carlos, SP (Brazil)
2008-08-15
We point out some incompatibilities which appear when one applies the stationary phase method for deriving phase times to obtain the spatial localization of wave packets scattered by a unidimensional potential barrier. We concentrate on the above barrier diffusion problem where the wave packet collision implies the possibility of multiple reflected and transmitted wave packets, which, depending on the boundary conditions, can overlap or stand in relative separation in space. We demonstrate that the indiscriminate use of the method for such a particular configuration leads to paradoxical results for which the correct interpretation, confirmed by analytical/numerical calculations, imposes the necessity of the appearance of multiple peaks as a consequence of multiple reflections by the barrier steps. (orig.)
Test particle simulation study of whistler wave packets observed near Comet Giacobini-Zinner
Kaya, N.; Matsumoto, H.; Tsurutani, B. T.
1989-01-01
Nonlinear interactions of water group ions with large-amplitude whistler wave packets detected at the leading edge of steepened magnetosonic waves observed near Comet Giacobini-Zinner (GZ) are studied using test particle simulations of water-ion interactions with a model wave based on GZ data. Some of the water ions are found to be decelerated in the steepened portion of the magnetosonic wave to the resonance velocity with the whistler wave packets. Through resonance and related nonlinear interaction with the large-amplitude whistler waves, the water ions become trapped by the packet. An energy balance calculation demonstrates that the trapped ions lose their kinetic energy during the trapped motion in the packet. Thus, the nonlinear trapping motion in the wave structure leads to effective energy transfer from the water group ions to the whistler wave packets in the leading edge of the steepened MHD waves.
Resonance-Radiation Force Exerted by a Circularly Polarized Light on an Atomic Wave Packet
Institute of Scientific and Technical Information of China (English)
YE Yong-Hua; ZENG Gao-Jian; LI Jin-Hui
2006-01-01
We study the behaviour of an atomic wave packet in a circularly polarized light, and especially give the calculation of the radiative force exerted by the circularly polarized light on the atomic wave packet under the resonance condition. A general method of the calculation is presented and the result is interesting. For example, under the condition that the wave packet is very narrow or/and the interaction is very strong, no matter whether the atom is initially in its ground state or excited state, as time approaches to infinity, the resonance-radiation force exerted by the light on the atom approaches to zero. If the atom is initially in its ground state and excited state with the probability 1/2 respectively, and if the momentum density is a even function, then the resonance-radiation force exerted by the light on the atom is equal to zero.
Indian Academy of Sciences (India)
Maninder Kaur; Bindiya Arora; Mahmood Mian
2016-01-01
We examine the dynamical evolution of wave packets in a cubical billiard where three quantum numbers (, , ) determine its energy spectrum and consequently its dynamical behaviour. We have constructed the wave packet in the cubical billiard and have observed its time evolution for various closed orbits. The closed orbits are possible for certain specific values of quantum numbers (, , ) and initial momenta (, , ). We observe that a cubical billiard exhibits degenerate energy levels and the path lengths of the closed orbits for these degenerate energy levels are identical. In spite of the identical path lengths, the shapes of the closed orbits for degenerate levels are different and depend upon angles and which we term as the sweep and the elevation angles, respectively. These degenerate levels owe their origin to the symmetries prevailing in the cubical billiard and these levels disappear completely or partially for a parallelepiped billiard as the symmetry breaks due to commensurate or incommensurate ratio of sides.
Time delay of wave packets during their tunnelling through a quantum diode
Energy Technology Data Exchange (ETDEWEB)
Ivanov, N A; Skalozub, V V [Dnipropetrovsk National University Oles Honchar (Ukraine)
2014-04-28
A modified saddle-point method is used to investigate the process of propagation of a wave packet through a quantum diode. A scattering matrix is constructed for the structure in question. The case of tunnelling of a packet with a Gaussian envelope through the diode is considered in detail. The time delay and the shape of the wave packet transmitted are calculated. The dependence of the delay time on the characteristics of the input packet and the internal characteristics of the quantum diode is studied. Possible applications of the results obtained are discussed. (laser applications and other topics in quantum electronics)
Strong field dissociative ionization of the D2+: Nuclear wave packet analysis
Tóth, A.; Borbély, S.; Halász, G. J.; Vibók, Á.
2017-09-01
Theoretical ab initio investigation of strong field dissociative ionization of the D2+ molecule in the multiphoton regime is reported. The dynamics is initiated by ultrashort laser pulses for fixed molecular axis orientations. Nuclear wave packet calculations are performed to provide the joint energy spectra (JES): ionization-dissociation probability density via electron (Ee) and nuclear (En) kinetic energy. Analyzing the time-dependent nuclear wave packet densities we have successfully identified the exact path followed by the D2+ target for each multiphoton peak.
Karlovets, D V; Serbo, V G
2015-01-01
Laser photons carrying non-zero orbital angular momentum are known and exploited during the last twenty years. Recently it has been demonstrated experimentally that such (twisted) electrons can be produced and even focused to a subnanometer scale. Thus, twisted electrons emerge as a new tool in atomic physics. The state of a twisted electron can be considered as a specific wave packet of plane waves. In the present paper-I we consider elastic scattering of the wave packets of fast non-relativistic particles on a potential field. We obtain simple and convenient formulae for a number of events in such a scattering. The equations derived represent, in fact, generalization of the well-known Born approximation for the case when finite sizes and inhomogeneity of the initial packet should be taken into account. To illustrate the obtained results, we consider two simple models corresponding to scattering of a Gaussian wave packet on the Gaussian potential and on the hydrogen atom. The scattering of twisted electrons ...
Wave packet dynamics of the matter wave field of a Bose-Einstein condensate
Sudheesh, C; Lakshmibala, S
2004-01-01
We show in the framework of a tractable model that revivals and fractional revivals of wave packets afford clear signatures of the extent of departure from coherence and from Poisson statistics of the matter wave field in a Bose-Einstein condensate, or of a suitably chosen initial state of the radiation field propagating in a Kerr-like medium.
Gaussian and Airy wave-packets of massive particles with orbital angular momentum
Karlovets, Dmitry V
2014-01-01
While wave-packet solutions for relativistic wave equations are oftentimes thought to be approximate (paraxial), we demonstrate that there is a family of such solutions, which are exact, by employing a null-plane (light-cone) variables formalism. A scalar Gaussian wave-packet in transverse plane is generalized so that it acquires a well-defined z-component of the orbital angular momentum (OAM), while may not acquire a typical "doughnut" spatial profile. Such quantum states and beams, in contrast to the Bessel ones, may have an azimuthal-angle-dependent probability density and finite quantum uncertainty of the OAM, which is determined by the packet's width. We construct a well-normalized Airy wave-packet, which can be interpreted as a one-particle state for relativistic massive boson, show that its center moves along the same quasi-classical straight path and, what is more important, spreads with time and distance exactly as a Gaussian wave-packet does, in accordance with the uncertainty principle. It is expla...
Bai, Xiao-Dong; Malomed, Boris A.; Deng, Fu-Guo
2016-09-01
We consider the transfer of lattice wave packets through a tilted discrete breather (TDB) in opposite directions in the discrete nonlinear Schrödinger model with asymmetric defects, which may be realized as a Bose-Einstein condensate trapped in a deep optical lattice, or as optical beams in a waveguide array. A unidirectional transport mode is found, in which the incident wave packets, whose energy belongs to a certain interval between full reflection and full passage regions, pass the TDB only in one direction, while in the absence of the TDB, the same lattice admits bidirectional propagation. The operation of this mode is accurately explained by an analytical consideration of the respective energy barriers. The results suggest that the TDB may emulate the unidirectional propagation of atomic and optical beams in various settings. In the case of the passage of the incident wave packet, the scattering TDB typically shifts by one lattice unit in the direction from which the wave packet arrives, which is an example of the tractor-beam effect, provided by the same system, in addition to the rectification of incident waves.
Program for quantum wave-packet dynamics with time-dependent potentials
Dion, C M; Rahali, G
2014-01-01
We present a program to simulate the dynamics of a wave packet interacting with a time-dependent potential. The time-dependent Schr\\"odinger equation is solved on a one-, two-, or three-dimensional spatial grid using the split operator method. The program can be compiled for execution either on a single processor or on a distributed-memory parallel computer.
Frame properties of wave packet systes in L^2 (R^d)
DEFF Research Database (Denmark)
Christensen, Ole; Rahimi, Asghar
2008-01-01
Extending work by Hernandez, Labate and Weiss, we present a sufficent condition for a generalized shift-invariant system to be a Bessel sequence or even a frame forL(2)(R-d). In particular, this leads to a sufficient condition for a wave packet system to form a frame. On the other hand, we show...
Monte Carlo Wave Packet Theory of Dissociative Double Ionization
DEFF Research Database (Denmark)
Leth, Henriette Astrup; Madsen, Lars Bojer; Mølmer, Klaus
2009-01-01
Nuclear dynamics in strong-field double ionization processes is predicted using a stochastic Monte Carlo wave packet technique. Using input from electronic structure calculations and strong-field electron dynamics the description allows for field-dressed dynamics within a given molecule as well...
Quantum Chaos and Exponential Growth of Spreading Width of a Wave Packet in Chaotic Systems
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The quantum correspondence of one particular signature of classical chaos———the exponential instability f motion can be characterized by the initial exponential growth rate of the spreading width of the propagating quantum wave packet.In a former study~[1] a one to one correspondence has been found between the initial
Energy Technology Data Exchange (ETDEWEB)
Zhang, Jianxin; Zhang, Zhenjun [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Tong, Peiqing, E-mail: pqtong@njnu.edu.cn [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems, Nanjing Normal University, Nanjing 210023 (China)
2013-07-15
We investigate the spreading of an initially localized wave packet in one-dimensional generalized Fibonacci (GF) lattices by solving numerically the discrete nonlinear Schrödinger equation (DNLSE) with a delayed cubic nonlinear term. It is found that for short delay time, the wave packet is self-trapping in first class of GF lattices, that is, the second moment grows with time, but the corresponding participation number does not grow. However, both the second moment and the participation number grow with time for large delay time. This illuminates that the wave packet is delocalized. For the second class of GF lattices, the dynamic behaviors of wave packet depend on the strength of on-site potential. For a weak on-site potential, the results are similar to the case of the first class. For a strong on-site potential, both the second moment and the participation number does not grow with time in the regime of short delay time. In the regime of large delay time, both the second moment and the participation number exhibit stair-like growth.
Recollision dynamics of electron wave packets in high-order harmonic generation
Yuan, Kai-Jun; Bandrauk, André D.
2009-11-01
We numerically investigate the dynamics of recollision of an electron in high-order harmonic generation (HHG) for an H atom and a molecular ion H2+ using a short (ten optical cycles), and intense (I0≥1014W/cm2) , z -polarized linear laser pulse with wavelength 800 nm by accurately solving the three-dimensional time-dependent Schrödinger equation. A time-frequency analysis obtained via Gabor transforms is employed to identify electron recollision and recombination times responsible for the generation of harmonics. We find that the HHG spectra are mainly attributed to the recollision of an inner electron wave packet with the parent ion in agreement with the classical recollision model. A time delay of the electron recollision occurs between wave packets in inner and outer regions, near to and far from the parent ion, due to different phase of the acceleration (as well as dipole velocity) of the electron. Inner wave packets at recollision contain mainly short and long trajectories whereas outer wave packets contain only single trajectories. Lower-order harmonics are generated mainly by single recollisions near field extrema, i.e., in strong electric fields whereas higher-order harmonics are generated by double trajectories with different intensities. In the case of H2+ at a critical nuclear distance for charge resonance enhanced ionization, we also find that HHG mainly comes from contributions of the inner electron wave packet, but with more complex recollision trajectories due to the presence of more than one Coulomb center. Triple recollision trajectories are shown to occur generally for the latter.
Propagation of Gaussian wave packets in complex media and application to fracture characterization
Ding, Yinshuai; Zheng, Yingcai; Zhou, Hua-Wei; Howell, Michael; Hu, Hao; Zhang, Yu
2017-08-01
Knowledge of the subsurface fracture networks is critical in probing the tectonic stress states and flow of fluids in reservoirs containing fractures. We propose to characterize fractures using scattered seismic data, based on the theory of local plane-wave multiple scattering in a fractured medium. We construct a localized directional wave packet using point sources on the surface and propagate it toward the targeted subsurface fractures. The wave packet behaves as a local plane wave when interacting with the fractures. The interaction produces multiple scattering of the wave packet that eventually travels up to the surface receivers. The propagation direction and amplitude of the multiply scattered wave can be used to characterize fracture density, orientation and compliance. Two key aspects in this characterization process are the spatial localization and directionality of the wave packet. Here we first show the physical behaviour of a new localized wave, known as the Gaussian Wave Packet (GWP), by examining its analytical solution originally formulated for a homogenous medium. We then use a numerical finite-difference time-domain (FDTD) method to study its propagation behaviour in heterogeneous media. We find that a GWP can still be localized and directional in space even over a large propagation distance in heterogeneous media. We then propose a method to decompose the recorded seismic wavefield into GWPs based on the reverse-time concept. This method enables us to create a virtually recorded seismic data using field shot gathers, as if the source were an incident GWP. Finally, we demonstrate the feasibility of using GWPs for fracture characterization using three numerical examples. For a medium containing fractures, we can reliably invert for the local parameters of multiple fracture sets. Differing from conventional seismic imaging such as migration methods, our fracture characterization method is less sensitive to errors in the background velocity model
Tsurutani, Bruce T.; Smith, Edward J.; Brinca, Armando L.; Thorne, Richard M.; Matsumoto, Hiroshi
1989-01-01
The physical characteristics of high-frequency wave packets detected at the steepened edge of magnetosonic waves near Comet Giacobini-Zinner are explored, based on an examination of over 45 well-defined events. The results suggest that the wave packets play an important role in the reorientation and reduction in field magnitude from the steepened magnetosonic waves to the upstream ambient field. The observed properties of the wave packets are shown to be consistent with anomalously Doppler-shifted right-hand polarized waves.
Energy Technology Data Exchange (ETDEWEB)
Chan, Yat-Long; Chu, M.C.; Xu, Jianyi [The Chinese University of Hong Kong, Department of Physics, Shatin (China); Tsui, Ka Ming [University of Tokyo, RCCN, ICRR, Kashiwa, Chiba (Japan); Wong, Chan Fai [Sun Yat-Sen University, Guangzhou (China)
2016-06-15
We derive the neutrino flavor transition probabilities with the neutrino treated as a wave packet. The decoherence and dispersion effects from the wave-packet treatment show up as damping and phase-shifting of the plane-wave neutrino oscillation patterns. If the energy uncertainty in the initial neutrino wave packet is larger than around 0.01 of the neutrino energy, the decoherence and dispersion effects would degrade the sensitivity of reactor neutrino experiments to mass hierarchy measurement to lower than 3 σ confidence level. (orig.)
Kaur, Maninder; Main, M
2015-01-01
We examine the dynamical evolution of wave packets in a cubical billiard where three quantum numbers ($n_x,n_y,n_z$) determine its energy spectrum and consequently its dynamical behavior. We have constructed the wave packet in the cubical billiard and have observed its time evolution for various closed orbits. The closed orbits are possible for certain specific values of quantum numbers ($n_x,n_y,n_z$) and initial momenta ($k_x,k_y,k_z$). We observe that a cubical billiard exhibits degenerate energy levels and the path lengths of the closed orbits for these degenerate energy levels are identical. In spite of the identical path lengths, the shapes of the closed orbits for degenerate levels are different and depend upon angles $\\theta$ and $\\phi$ which we term as the sweep and the elevation angle respectively. These degenerate levels owe their origin to the symmetries prevailing in the cubical billiard and degenerate levels disappear completely or partially for a parallelepiped billiard as the symmetry breaks d...
Abdel-Latif, Mahmoud K
2011-01-01
The excitation of the degenerate $E_1$ carbonyl stretching vibrations in dimanganese decacarbonyl is shown to trigger wave packet circulation in the subspace of these two modes. On the time scale of about 5 picoseconds intramolecular anharmonic couplings do not cause appreciable disturbance, even under conditions where the two $E_1$ modes are excited by up to about two vibrational quanta each. The compactness of the circulating wave packet is shown to depend strongly on the excitation conditions such as pulse duration and field strength. Numerical results for the solution of the seven-dimensional vibrational Schr\\"odinger equation are obtained for a density functional theory based potential energy surface and using the multi-configuration time-dependent Hartree method.
Monte Carlo wave packet approach to dissociative multiple ionization in diatomic molecules
DEFF Research Database (Denmark)
Leth, Henriette Astrup; Madsen, Lars Bojer; Mølmer, Klaus
2010-01-01
A detailed description of the Monte Carlo wave packet technique applied to dissociative multiple ionization of diatomic molecules in short intense laser pulses is presented. The Monte Carlo wave packet technique relies on the Born-Oppenheimer separation of electronic and nuclear dynamics...... and provides a consistent theoretical framework for treating simultaneously both ionization and dissociation. By simulating the detection of continuum electrons and collapsing the system onto either the neutral, singly ionized or doubly ionized states in every time step the nuclear dynamics can be solved....... The computational effort is restricted and the model is applicable to any molecular system where electronic Born-Oppenheimer curves, dipole moment functions, and ionization rates as a function of nuclear coordinates can be determined....
Institute of Scientific and Technical Information of China (English)
WU; Shaoping(吴少平); YI; Fan(易帆)
2002-01-01
By using FICE scheme, a numerical simulation of nonlinear propagation of gravity wave packet in three-dimension compressible atmosphere is presented. The whole nonlinear propagation process of the gravity wave packet is shown; the basic characteristics of nonlinear propagation and the influence of the ambient winds on the propagation are analyzed. The results show that FICE scheme can be extended in three-dimension by which the calculation is steady and kept for a long time; the increase of wave amplitude is faster than the exponential increase according to the linear gravity theory; nonlinear propagation makes the horizontal perturbation velocity increase greatly which can lead to enhancement of the local ambient winds; the propagation path and the propagation velocity of energy are different from the results expected by the linear gravity waves theory, the nonlinearity causes the change in propagation characteristics of gravity wave; the ambient winds alter the propagation path and group velocity of gravity wave.
Space-time evolution of Gaussian wave packets through superlattices containing left-handed layers
Energy Technology Data Exchange (ETDEWEB)
Pereyra, P; Romero-Serrano, M [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana-Azcapotzalco, Mexico DF (Mexico); Robledo-Martinez, A, E-mail: ppereyra@correo.azc.uam.m, E-mail: a.robledo@mailaps.or [Departamento de EnergIa, Universidad Autonoma Metropolitana-Azcapotzalco, Mexico DF (Mexico)
2009-05-01
We study the space-time evolution of Gaussian electromagnetic wave packets moving through (L/R){sup n} superlattices, containing alternating layers of left and right-handed materials. We show that the time spent by the wave packet moving through arbitrary (L/R){sup n} superlattices are well described by the phase time. We show that in the particular case where the thicknesses d{sub L,R} and indices n{sub l,r} of the layers satisfy the condition d{sub L}|n{sub L}| = d{sub R}n{sub R}, the usual band structure becomes a sequence of isolated and equidistant peaks with negative phase times.
High frequency wave packets for the Schr\\"odinger equation and its numerical approximations
Marica, Aurora-Mihaela
2010-01-01
We build Gaussian wave packets for the linear Schr\\"odinger equation and its finite difference space semi-discretization and illustrate the lack of uniform dispersive properties of the numerical solutions as established in Ignat, Zuazua, Numerical dispersive schemes for the nonlinear Schr\\"odinger equation, SIAM. J. Numer. Anal., 47(2) (2009), 1366-1390. It is by now well known that bigrid algorithms provide filtering mechanisms allowing to recover the uniformity of the dispersive properties as the mesh size goes to zero. We analyze and illustrate numerically how these high frequency wave packets split and propagate under these bigrid filtering mechanisms, depending on how the fine grid/coarse grid filtering is implemented.
System-level physics of autonomous nanorobots for hard chemistry and wave packet engineering
Santoli, Salvatore
1994-08-01
The operation of the prospective autonomous molecular robots that would represent the most advanced achievement of the molecular manufacturing conception is examined at various levels of physical description: the thermodynamic, the hydrodynamic, and the kinetic (Boltzmann) level down to local nonequilibrium thermodynamical and/or mechanical conditions possibly arising in work in some circumstances. The concept of wave packet engineering is suggested as a special technique in the exploitation of molecular robots possibilities, which are generally characterized as 'hard chemistry'.
Spreading of wave packets, Uncertainty Relations and the de Broglie Frequency
Caldas, H C G
1998-01-01
The spreading of quantum mechanical wave packets are studied in two cases. Firstly we look at the time behavior of the packet width of a free particle confined in the observable Universe. Secondly, by imposing the conservation of the time average of the packet width of a particle driven by a harmonic oscillator potential, we find a zero-point energy which frequency is the de Broglie frequency.
Expansion of a wave-packet in lattices with disorder and nonlinearity
Naether, Uta; Martinez, Alejandro J; Sützer, Simon; Tünnermann, Andreas; Nolte, Stefan; Molina, Mario I; Vicencio, Rodrigo A; Szameit, Alexander
2012-01-01
We show, theoretically and experimentally, the counterintuitive result that an increase of disorder can result in an enhanced spreading of an initially localized excitation. Moreover, we find that adding a focusing nonlinearity facilitates the expansion of the wave-packet even further by increasing its effective size. We find a clear transition between between the regions of enhanced spreading (weak disorder) and localization (strong localization) described by a "diffusion peak".
Quantum control of electron wave packets in bound molecules by trains of half-cycle pulses
Energy Technology Data Exchange (ETDEWEB)
Persson, Emil; Pichler, Markus; Wachter, Georg; Hisch, Thomas; Burgdoerfer, Joachim; Graefe, Stefanie [Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, A-1040 Vienna (Austria); Jakubetz, Werner [Institute for Theoretical Chemistry, University of Vienna, Waehringerstr. 38, A-1090 Vienna (Austria)
2011-10-15
We investigate protocols for transient localization of electrons in homodiatomic molecules, as well as permanent localization via population inversion in polar molecules. By examining three different model systems with one electronic and one nuclear degree of freedom, we identify mechanisms leading to control over the localization of the electronic wave packets. We show that electronic states dressed by the quasi-dc component of the train of half-cycle pulses steer the combined electronic and nuclear motion toward the targeted state.
Massachusetts Bay - Internal Wave Packets Extracted from SAR Imagery Binned in 1x1 minute grid cells
National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets extracted from SAR imagery that were binned in 1x1 minute latitude/longitude polygon grid cells. Statistics were...
National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets digitized from SAR imagery and intersected with a bathymetrically derived slope surface for Massachusetts Bay. The...
Frequencies of wave packets of whistler-mode chorus inside its source region: a case study
Directory of Open Access Journals (Sweden)
O. Santolik
2008-06-01
Full Text Available Whistler-mode chorus is a structured wave emission observed in the Earth's magnetosphere in a frequency range from a few hundreds of Hz to several kHz. We investigate wave packets of chorus using high-resolution measurements recorded by the WBD instrument on board the four Cluster spacecraft. A night-side chorus event observed during geomagnetically disturbed conditions is analyzed. We identify lower and upper frequencies for a large number of individual chorus wave packets inside the chorus source region. We investigate how these observations are related to the central position of the chorus source which has been previously estimated from the Poynting flux measurements. We observe typical frequency bandwidths of chorus of approximately 10% of the local electron cyclotron frequency. Observed time scales are around 0.1 s for the individual wave packets. Our results indicate a lower occurrence probability for lower frequencies in the vicinity of the central position of the source compared to measurements recorded closer to the outer boundaries of the source. This is in agreement with recent research based on the backward wave oscillator theory.
Wave packet dynamics in one-dimensional linear and nonlinear generalized Fibonacci lattices.
Zhang, Zhenjun; Tong, Peiqing; Gong, Jiangbin; Li, Baowen
2011-05-01
The spreading of an initially localized wave packet in one-dimensional linear and nonlinear generalized Fibonacci (GF) lattices is studied numerically. The GF lattices can be classified into two classes depending on whether or not the lattice possesses the Pisot-Vijayaraghavan property. For linear GF lattices of the first class, both the second moment and the participation number grow with time. For linear GF lattices of the second class, in the regime of a weak on-site potential, wave packet spreading is close to ballistic diffusion, whereas in the regime of a strong on-site potential, it displays stairlike growth in both the second moment and the participation number. Nonlinear GF lattices are then investigated in parallel. For the first class of nonlinear GF lattices, the second moment of the wave packet still grows with time, but the corresponding participation number does not grow simultaneously. For the second class of nonlinear GF lattices, an analogous phenomenon is observed for the weak on-site potential only. For a strong on-site potential that leads to an enhanced nonlinear self-trapping effect, neither the second moment nor the participation number grows with time. The results can be useful in guiding experiments on the expansion of noninteracting or interacting cold atoms in quasiperiodic optical lattices.
Multi-resolution schemes for time scaled propagation of wave packets
Frapiccini, Ana Laura; Mota-Furtado, Francisca; O'Mahony, Patrick F; Piraux, Bernard
2014-01-01
We present a detailed analysis of the time scaled coordinate approach and its implementation for solving the time-dependent Schr\\"odinger equation describing the interaction of atoms or molecules with radiation pulses. We investigate and discuss the performance of multi-resolution schemes for the treatment of the squeezing around the origin of the bound part of the scaled wave packet. When the wave packet is expressed in terms of B-splines, we consider two different types of breakpoint sequences: an exponential sequence with a constant density and an initially uniform sequence with a density of points around the origin that increases with time. These two multi-resolution schemes are tested in the case of a one-dimensional gaussian potential and for atomic hydrogen. In the latter case, we also use Sturmian functions to describe the scaled wave packet and discuss a multi-resolution scheme which consists in working in a sturmian basis characterized by a set of non-linear parameters. Regarding the continuum part ...
Wu, Yue-Chao; Zhao, Bin; Lee, Soo-Y.
2016-02-01
Femtosecond stimulated Raman spectroscopy (FSRS) on the Stokes side arises from a third order polarization, P(3)(t), which is given by an overlap of a first order wave packet, |" separators=" Ψ2 ( 1 ) ( p u , t ) > , prepared by a narrow band (ps) Raman pump pulse, Epu(t), on the upper electronic e2 potential energy surface (PES), with a second order wave packet, resembles the zeroth order wave packet |" separators=" Ψ1 ( 0 ) ( t ) > on the lower PES spatially, but with a force on |" separators=" Ψ2 ( 1 ) ( p u , t ) > along the coordinates of the reporter modes due to displacements in the equilibrium position, so that . The observable FSRS Raman gain is related to the imaginary part of P(3)(ω). The imaginary and real parts of P(3)(ω) are related by the Kramers-Kronig relation. Hence, from the FSRS Raman gain, we can obtain the complex P(3)(ω), whose Fourier transform then gives us the complex P(3)(t) to analyze for ω ¯ j ( t ) . We apply the theory, first, to a two-dimensional model system with one conformational mode of low frequency and one reporter vibrational mode of higher frequency with good results, and then we apply it to the time-resolved FSRS spectra of the cis-trans isomerization of retinal in rhodopsin [P. Kukura et al., Science 310, 1006 (2005)]. We obtain the vibrational frequency up-shift time constants for the C12-H wagging mode at 216 fs and for the C10-H wagging mode at 161 fs which are larger than for the C11-H wagging mode at 127 fs, i.e., the C11-H wagging mode arrives at its final frequency while the C12-H and C10-H wagging modes are still up-shifting to their final values, agreeing with the findings of Yan et al. [Biochemistry 43, 10867 (2004)].
Asymmetric acoustic propagation of wave packets via the self-demodulation effect
Devaux, Thibaut; Richoux, Olivier; Pagneux, Vincent
2015-01-01
This article presents the experimental characterization of nonreciprocal elastic wave transmission in a single-mode elastic waveguide. This asymmetric system is obtained by coupling a selection layer with a conversion layer: the selection component is provided by a phononic crystal, while the conversion is achieved by a nonlinear self-demodulation effect in a 3D unconsolidated granular medium. A quantitative experimental study of this acoustic rectifier indicates a high rectifying ratio, up to $10^6$, with wide band (10 kHz) and an audible effect. Moreover, this system allows for wave-packet rectification and extends the future applications of asymmetric systems.
Wave-Packet Collapse Based on Weak Repeatability or Covariant Condition
Wu, Zhao-Qi; Zhu, Chuan-Xi; Wang, Jian-Hui
2016-02-01
The conflict between the dynamics postulate (unitary evolution) and the measurement postulate (wave-packet collapse) of quantum mechanics has been reconciled by Zurek from an information transfer perspective [Phys. Rev. A 76 (2007) 052110], and has further been extended to a more general scenario [Phys. Rev. A 87 (2013) 052111]. In this paper, we reconsider Zurek's new derivation by using weak repeatability postulate or covariant condition instead of repeatability postulate. Supported by National Natural Science Foundation of China under Grant Nos. 11461045, 11326099, 11361042, 11265010, and Natural Science Foundation of Jiangxi Province of China under Grant Nos. 20142BAB211016, 20132BAB201001, 20132BAB212009
Evolution of spin-dependent atomic wave packets in a harmonic potential
Institute of Scientific and Technical Information of China (English)
Wen Ling-Hua; Liu Min; Kong Ling-Bo; Chen Ai-Xi; Zhan Ming-Sheng
2005-01-01
We have investigated theoretically the evolution of spin-dependent atomic wave packets in a harmonic magnetic trapping potential. For a Bose-condensed gas, which undergoes a Mott insulator transition and a spin-dependent transport, the atomic wavefunction can be described by an entangled single-atom state. Due to the confinement of the -harmonic potential, the density distributions exhibit periodic decay and revival, which is different from the case of free expansion after switching off the combined harmonic and optical lattice potential.
Irreversible Behaviour and Collapse of Wave Packets in a Quantum System with Point Interactions
Guarneri, Italo
2011-01-01
A system of a particle and a harmonic oscillator, which have pure point spectrum if uncoupled, is known to acquire absolutely continuous spectrum when the particle and the oscillator are coupled by a sufficiently strong point interaction. Here the simple dynamical mechanism underlying this phenomenon is exposed. The energy of the oscillator is proven to exponentially diverge in time, while the spatial probability distribution of the particle collapses into a delta function in the interaction point. On account of this result, a generalized model with many oscillators which interact with the particle at different points is argued to provide a formal model for approximate measurement of position, and collapse of wave packets.
Irreversible behaviour and collapse of wave packets in a quantum system with point interactions
Energy Technology Data Exchange (ETDEWEB)
Guarneri, Italo [Center for Nonlinear and Complex Systems, Universita dell' Insubria, via Valleggio 11, I-22100 Como (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, via Bassi 6, I-27100 Pavia (Italy)
2011-12-02
A system of a particle and a harmonic oscillator, which have pure point spectra if uncoupled, is known to acquire an absolutely continuous spectrum when they are coupled by a sufficiently strong point interaction. Here, the dynamical mechanism underlying this spectral phenomenon is exposed. The energy of the oscillator is proven to exponentially diverge in time, while the spatial probability distribution of the particle collapses into a {delta}-function at the interaction point. On account of this result, a generalized model with many oscillators which interact with the particle at different points is argued to provide a formal model for the approximate measurement of position and collapse of wave packets. (paper)
Wave packet evolution approach to ionization of hydrogen molecular ion by fast electrons
Serov, V V; Joulakian, B B; Vinitsky, S I; Serov, Vladislav V.; Derbov, Vladimir L.; Joulakian, Boghos B.; Vinitsky, Sergue I.
2000-01-01
The multiply differential cross section of the ionization of hydrogen molecular ion by fast electron impact is calculated by a direct approach, which involves the reduction of the initial 6D Schr\\"{o}dinger equation to a 3D evolution problem followed by the modeling of the wave packet dynamics. This approach avoids the use of stationary Coulomb two-centre functions of the continuous spectrum of the ejected electron which demands cumbersome calculations. The results obtained, after verification of the procedure in the case atomic hydrogen, reveal interesting mechanisms in the case of small scattering angles.
A preliminary study on sea wave packet equations on slowly varying topography
Institute of Scientific and Technical Information of China (English)
朱首贤; 丁平兴; 孔亚珍; 沙文钰
2001-01-01
There is a common hypothesis for the presently popular mild-slope equations that wave particle motion is irrotational. In this paper, an attempt is made to abandon the irrotational assumption and to set up new sea wave packet equations on slowly varying topography by use of the WKBJ method. To simplify the deduction, the two-dimensional shallow water equations are used to describe the sea wave particle motion in the very shallow nearshore area. The established equations can give some characteristics of wave propagation near shore.
Wave packet dynamics in energy space, random matrix theory, and the quantum-classical correspondence
Cohen; Izrailev; Kottos
2000-03-06
We apply random-matrix-theory (RMT) to the analysis of evolution of wave packets in energy space. We study the crossover from ballistic behavior to saturation, the possibility of having an intermediate diffusive behavior, and the feasibility of strong localization effect. Both theoretical considerations and numerical results are presented. Using quantal-classical correspondence considerations we question the validity of the emerging dynamical picture. In particular, we claim that the appearance of the intermediate diffusive behavior is possibly an artifact of the RMT strategy.
Aharonovich, Igal
2016-01-01
We present a simple method to expedite simulation of quantum wave-packet dynamics by more than a factor of $2$ with the Strang split-operator propagation. Dynamics of quantum wave-packets are often evaluated using the the \\emph{Strang} split-step propagation, where the kinetic part of the Hamiltonian $\\hat{T}$ and the potential part $\\hat{V}$ are piecewise integrated according to $e^{- i \\hat{H} \\delta t} \\approx e^{- i \\hat{V} \\delta t/2} e^{- i \\hat{T}\\delta t} e^{- i \\hat{V} \\delta t/2}$, which is accurate to second order in the propagation time $\\delta t$. In molecular quantum dynamics, the potential propagation occurs over multiple coupled potential surfaces and requires matrix exponentiation for each position in space and time which is computationally demanding. Our method employs further splitting of the potential matrix $\\hat{V}$ into a diagonal space dependent part $\\hat{V}_{D}(R)$ and an off-diagonal time-dependent coupling-field $\\hat{V}_{OD}(t)$, which then requires only a single matrix exponentia...
Time-dependent quantum wave packet dynamics to study charge transfer in heavy particle collisions
Zhang, Song Bin; Wu, Yong; Wang, Jian Guo
2016-12-01
The method of time-dependent quantum wave packet dynamics has been successfully extended to study the charge transfer/exchange process in low energy two-body heavy particle collisions. The collision process is described by coupled-channel equations with diabatic potentials and (radial and rotational) couplings. The time-dependent coupled equations are propagated with the multiconfiguration time-dependent Hartree method and the modulo squares of S-matrix is extracted from the wave packet by the flux operator with complex absorbing potential (FCAP) method. The calculations of the charge transfer process 12Σ+ H-(1s2) +Li(1 s22 s ) →22Σ+ /32 Σ+ /12 Π H(1 s ) +Li-(1s 22 s 2 l ) (l =s ,p ) at the incident energy of about [0.3, 1.3] eV are illustrated as an example. It shows that the calculated reaction probabilities by the present FCAP reproduce that of quantum-mechanical molecular-orbital close-coupling very well, including the peak structures contributed by the resonances. Since time-dependent external interactions can be directly included in the present FCAP calculations, the successful implementation of FCAP provides us a powerful potential tool to study the quantum control of heavy particle collisions by lasers in the near future.
The phase delay and its complex time: From stationary states up to wave packets
Energy Technology Data Exchange (ETDEWEB)
Grossel, Ph., E-mail: philippe.grossel@univ-reims.fr
2013-03-15
Complex time is often invoked about tunneling effect where the classical phase delay is completed with a crucial filter effect. Usually the complex times are obtained by considering the flux-flux correlation function, but this can be obtained by a very simple approach using the search of the maximum of the generalized complex phase function, including the amplitude of the wave function. Various aspects of the phase delay are presented in the case of wave packets impinging on simple or resonant quantum barriers. Formal links with the classical mechanics give birth to quasi-trajectories of the quantum particle, totally compatible with the quantum mechanics. - Highlights: Black-Right-Pointing-Pointer The stationary phase method is extended in including the variations of the spectra. Black-Right-Pointing-Pointer The complex phase delay leads to a complex trajectory inside and out-side the barrier. Black-Right-Pointing-Pointer Examples of quasi-trajectories are given in case of different quantum barriers. Black-Right-Pointing-Pointer Phase delays are specified for resonant tunneling or above-barrier wave-packets. Black-Right-Pointing-Pointer The coherence between the quasi-trajectories and quantum mechanics is shown.
Quantum optimal control of wave packet dynamics under the influence of dissipation
Energy Technology Data Exchange (ETDEWEB)
Ohtsuki, Yukiyoshi; Nakagami, Kazuyuki; Zhu, Wusheng; Rabitz, Herschel
2003-02-01
Optimal control within the density matrix formalism is applied to the production of desired non-equilibrium distributions in condensed phases. The time evolution of a molecular system modeled by a displaced harmonic oscillator is assumed to be described by the Markoffian master equation with phenomenological relaxation parameters. The physical objectives of concern are the creation of a specified vibronic state, population inversion and wave packet shaping. The effects of an initial thermal distribution and dissipation on these targets are examined. In order to transfer a large amount of population (i.e., the strong-field regime) to a target wave packet in an electronic excited state, it is shown that creating a shaped packet in the ground state is often required to achieve high yield. This control pathway cannot be taken into account within the weak-field approximation, and is especially important when the target state includes vibrational states that are weakly accessible from the initial state or that have preferential indirect excitation paths from the initial state. Although relaxation effects usually reduce the control efficiency, under certain conditions, the bath-induced dynamics can help to create an objective state.
Wave Packet Dynamics in the Infinite Square Well with the Wigner Quasi-probability Distribution
Belloni, Mario; Doncheski, Michael; Robinett, Richard
2004-05-01
Over the past few years a number of authors have been interested in the time evolution and revivals of Gaussian wave packets in one-dimensional infinite wells and in two-dimensional infinite wells of various geometries. In all of these circumstances, the wave function is guaranteed to revive at a time related to the inverse of the system's ground state energy, if not sooner. To better visualize these revivals we have calculated the time-dependent Wigner quasi-probability distribution for position and momentum, P_W(x; p), for Gaussian wave packet solutions of this system. The Wigner quasi-probability distribution clearly demonstrates the short-term semi-classical time dependence, as well as longer-term revival behavior and the structure during the collapsed state. This tool also provides an excellent way of demonstrating the patterns of highly-correlated Schrödinger-cat-like `mini-packets' which appear at fractional multiples of the exact revival time. This research is supported in part by a Research Corporation Cottrell College Science Award (CC5470) and the National Science Foundation under contracts DUE-0126439 and DUE-9950702.
Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji
2012-02-01
Organic materials form crystals by relatively weak Van der Waals attraction between molecules, and thus differ fundamentally from covalently bonded semiconductors. Carriers in the organic semiconductors induce the drastic lattice deformation, which is called as polaron state. The polaron effect on the transport is a serious problem. Exactly what conduction mechanism applies to organic semiconductors has not been established. Therefore, we have investigated the transport properties using the Time-Dependent Wave-Packet Diffusion (TD-WPD) method [1]. To consider the polaron effect on the transport, in the methodology, we combine the wave-packet dynamics based on the quantum mechanics theory with the molecular dynamics. As the results, we can describe the electron motion modified by (electron-phonon mediated) time-dependent structural change. We investigate the transport property from an atomistic viewpoint and evaluate the mobility of organic semiconductors. We clarify the temperature dependence of mobility from the thermal activated behavior to the power law behavior. I will talk about these results in my presentation. [1] H. Ishii, N. Kobayashi, K. Hirose, Phys. Rev. B, 82 085435 (2010).
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Ba Phi [Central University of Construction, Tuy Hoa (Viet Nam); Kim, Ki Hong [Ajou University, Suwon (Korea, Republic of)
2014-02-15
We study numerically the dynamics of an initially localized wave packet in one-dimensional nonlinear Schroedinger lattices with both local and nonlocal nonlinearities. Using the discrete nonlinear Schroedinger equation generalized by including a nonlocal nonlinear term, we calculate four different physical quantities as a function of time, which are the return probability to the initial excitation site, the participation number, the root-mean-square displacement from the excitation site and the spatial probability distribution. We investigate the influence of the nonlocal nonlinearity on the delocalization to self-trapping transition induced by the local nonlinearity. In the non-self-trapping region, we find that the nonlocal nonlinearity compresses the soliton width and slows down the spreading of the wave packet. In the vicinity of the delocalization to self-trapping transition point and inside the self-trapping region, we find that a new kind of self-trapping phenomenon, which we call partial self-trapping, takes place when the nonlocal nonlinearity is sufficiently strong.
Zagoya, C; Ronto, M; Shalashilin, D V; Faria, C Figueira de Morisson
2014-01-01
We assess the suitability of quantum and semiclassical initial value representations, exemplified by the coupled coherent states (CCS) method and the Herman Kluk (HK) propagator, respectively, for modeling the dynamics of an electronic wave packet in a strong laser field, if this wave packet is initially bound. Using Wigner quasiprobability distributions and ensembles of classical trajectories, we identify signatures of over-the-barrier and tunnel ionization in phase space for static and time-dependent fields and the relevant sets of phase-space trajectories in order to model such features. Overall, we find good agreement with the full solution of the time-dependent Schr\\"odinger equation (TDSE) for Wigner distributions constructed with both initial-value representations. Our results indicate that the HK propagator does not fully account for tunneling and over-the-barrier reflections. However, it is able to partly reproduce features associated with the wave packet crossing classically forbidden regions, altho...
Determining the wavelength of Langmuir wave packets at the Earth's bow shock
Krasnoselskikh, V V; Bale, S D; 10.5194/angeo-29-613-2011
2011-01-01
The propagation of Langmuir waves in plasmas is known to be sensitive to density fluctuations. Such fluctuations may lead to the coexistence of wave pairs that have almost opposite wave-numbers in the vicinity of their reflection points. Using high frequency electric field measurements from the WIND satellite, we determine for the first time the wavelength of intense Langmuir wave packets that are generated upstream of the Earth's electron foreshock by energetic electron beams. Surprisingly, the wavelength is found to be 2 to 3 times larger than the value expected from standard theory. These values are consistent with the presence of strong inhomogeneities in the solar wind plasma rather than with the effect of weak beam instabilities.
Transport of time-varying plasma currents by whistler wave packets
Stenzel, R. L.; Urrutia, J. M.; Rousculp, C.
1992-01-01
The relationship between pulsed currents and electromagnetic waves is examined in a regime characterized by electron MHD. Pulsed currents are generated by (1) collection/emission of charged particles by/from biased electrodes and (2) induction of currents by time-varying and moving magnetic fields. Pulsed currents are observed to propagate at the speed of whistler wave packets. Their field structure forms ropelike configurations which are electromagnetically force-free. Moving sources induce 'eddy' currents which excite waves and form Cerenkov-like whistler 'wings'. The radiation patterns of moving magnetic antennas and electrodynamic tethers are investigated. Nonlinear effects of large-amplitude, antenna-launched whistler pulses are observed. These involve a new modulational instability in which a channel of high conductivity which permits the wave/currents to penetrate deeply into a collisional plasma is formed.
Wave-packet rectification in nonlinear electronic systems: A tunable Aharonov-Bohm diode
Li, Yunyun; Marchesoni, Fabio; Li, Baowen
2014-01-01
Rectification of electron wave-packets propagating along a quasi-one dimensional chain is commonly achieved via the simultaneous action of nonlinearity and longitudinal asymmetry, both confined to a limited portion of the chain termed wave diode. However, it is conceivable that, in the presence of an external magnetic field, spatial asymmetry perpendicular to the direction of propagation suffices to ensure rectification. This is the case of a nonlinear ring-shaped lattice with different upper and lower halves (diode), which is attached to two elastic chains (leads). The resulting device is mirror symmetric with respect to the ring vertical axis, but mirror asymmetric with respect to the chain direction. Wave propagation along the two diode paths can be modeled for simplicity by a discrete Schr\\"odinger equation with cubic nonlinearities. Numerical simulations demonstrate that, thanks to the Aharonov-Bohm effect, such a diode can be operated by tuning the magnetic flux across the ring.
Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets
Pullen, M G; Le, A -T; Baudisch, M; Sclafani, M; Pires, H; Schröter, C D; Ullrich, J; Moshammer, R; Pfeifer, T; Lin, C D; Biegert, J
2016-01-01
The ability to directly follow and time resolve the rearrangement of the nuclei within molecules is a frontier of science that requires atomic spatial and few-femtosecond temporal resolutions. While laser induced electron diffraction can meet these requirements, it was recently concluded that molecules with particular orbital symmetries (such as {\\pi}g) cannot be imaged using purely backscattering electron wave packets without molecular alignment. Here, we demonstrate, in direct contradiction to these findings, that the orientation and shape of molecular orbitals presents no impediment for retrieving molecular structure with adequate sampling of the momentum transfer space. We overcome previous issues by showcasing retrieval of the structure of randomly oriented O2 and C2H2 molecules, with {\\pi}g and {\\pi}u symmetries, respectively, and where their ionisation probabilities do not maximise along their molecular axes. While this removes a serious bottleneck for laser induced diffraction imaging, we find unexpec...
Tunneling wave packets of atoms from intense elliptically polarized fields in natural geometry
Han, Meng; Li, Min; Liu, Ming-Ming; Liu, Yunquan
2017-02-01
We study strong-field tunneling of atoms in intense elliptically polarized laser fields in natural tunneling geometry. We obtain the temporal- and spatial-dependent tunneling ionization rates, the transverse and longitudinal momentum distributions, and the position distributions of the tunnel exit in parabolic coordinates. The tunneling electron wave packets at the tunnel exit are three dimensionally characterized for both momentum and spatial distributions. The conjunction between the tunneling point and the classical propagation of the widely used semiclassical model are naturally connected. We further calculate the ellipticity-dependent photoelectron momentum distributions on the detector, which are validated by comparison with the exact results through numerically solving the time-dependent Schrödinger equation. The theory clarifies crucial questions about strong-field tunneling ionization, which has important implications for the attoclock with elliptical or circular fields, photoelectron holography, molecular orbital imaging, etc.
Five-wave-packet quantum error correction based on continuous-variable cluster entanglement
Hao, Shuhong; Su, Xiaolong; Tian, Caixing; Xie, Changde; Peng, Kunchi
2015-10-01
Quantum error correction protects the quantum state against noise and decoherence in quantum communication and quantum computation, which enables one to perform fault-torrent quantum information processing. We experimentally demonstrate a quantum error correction scheme with a five-wave-packet code against a single stochastic error, the original theoretical model of which was firstly proposed by S. L. Braunstein and T. A. Walker. Five submodes of a continuous variable cluster entangled state of light are used for five encoding channels. Especially, in our encoding scheme the information of the input state is only distributed on three of the five channels and thus any error appearing in the remained two channels never affects the output state, i.e. the output quantum state is immune from the error in the two channels. The stochastic error on a single channel is corrected for both vacuum and squeezed input states and the achieved fidelities of the output states are beyond the corresponding classical limit.
Quantum black hole wave packet: Average area entropy and temperature dependent width
Directory of Open Access Journals (Sweden)
Aharon Davidson
2014-09-01
Full Text Available A quantum Schwarzschild black hole is described, at the mini super spacetime level, by a non-singular wave packet composed of plane wave eigenstates of the momentum Dirac-conjugate to the mass operator. The entropy of the mass spectrum acquires then independent contributions from the average mass and the width. Hence, Bekenstein's area entropy is formulated using the 〈mass2〉 average, leaving the 〈mass〉 average to set the Hawking temperature. The width function peaks at the Planck scale for an elementary (zero entropy, zero free energy micro black hole of finite rms size, and decreases Doppler-like towards the classical limit.
Electronic excitation by short x-ray pulses: from quantum beats to wave packet revivals
Rivière, P.; Iqbal, S.; Rost, J. M.
2014-06-01
We propose a simple way to determine the periodicities of wave packets (WPs) in quantum systems directly from the energy differences of the states involved. The resulting classical periods and revival times are more accurate than those obtained with the traditional expansion of the energies about the central quantum number \\overline{n}, especially when \\overline{n} is low. The latter type of WP motion occurs upon excitation of highly charged ions with short XUV or x-ray pulses. Moreover, we formulate the WP dynamics in such a form that it directly reveals the origin of phase shifts in the maxima of the autocorrelation function, a phenomenon most prominent in the low \\overline{n} WP dynamics.
Rapid propagation of a Bloch wave packet excited by a femtosecond ultraviolet pulse
Krasovskii, E. E.; Friedrich, C.; Schattke, W.; Echenique, P. M.
2016-11-01
Attosecond streaking spectroscopy of solids provides direct observation of the dynamics of electron excitation and transport through the surface. We demonstrate the crucial role of the exciting field in electron propagation and establish that the lattice scattering of the outgoing electron during the optical pumping leads to the wave packet moving faster than with the group velocity and faster than the free electron. We solve the time-dependent Schrödinger equation for a model of laser-assisted photoemission, with inelastic scattering treated as electron absorption and alternatively by means of random collisions. For a weak lattice scattering, the phenomenological result that the photoelectron moves with the group velocity d E /d ℏ k and traverses on average the distance equal to the mean-free path is proved to hold even at very short traveling times. This offers a novel interpretation of the delay time in streaking experiment and sheds new light on tunneling in optoelectronic devices.
Five-wave-packet quantum error correction based on continuous-variable cluster entanglement.
Hao, Shuhong; Su, Xiaolong; Tian, Caixing; Xie, Changde; Peng, Kunchi
2015-10-26
Quantum error correction protects the quantum state against noise and decoherence in quantum communication and quantum computation, which enables one to perform fault-torrent quantum information processing. We experimentally demonstrate a quantum error correction scheme with a five-wave-packet code against a single stochastic error, the original theoretical model of which was firstly proposed by S. L. Braunstein and T. A. Walker. Five submodes of a continuous variable cluster entangled state of light are used for five encoding channels. Especially, in our encoding scheme the information of the input state is only distributed on three of the five channels and thus any error appearing in the remained two channels never affects the output state, i.e. the output quantum state is immune from the error in the two channels. The stochastic error on a single channel is corrected for both vacuum and squeezed input states and the achieved fidelities of the output states are beyond the corresponding classical limit.
The Liouville equation for flavour evolution of neutrinos and neutrino wave packets
Hansen, Rasmus Sloth Lundkvist
2016-01-01
We consider several aspects related to the form, derivation and applications of the Liouville equation (LE) for flavour evolution of neutrinos. To take into account the quantum nature of neutrinos we derive the evolution equation for the matrix of densities using wave packets instead of Wigner functions. The obtained equation differs from the standard LE by an additional term which is proportional to the difference of group velocities. We show that this term describes loss of the propagation coherence in the system. In absence of inelastic collisions, the LE can be reduced to a single derivative equation over a trajectory coordinate. Additional time and spacial dependence may steam from initial (production) conditions. The transition from single neutrino evolution to the evolution of a neutrino gas is considered.
Quantum dynamics of electronic transitions with Gauss-Hermite wave packets.
Borrelli, Raffaele; Peluso, Andrea
2016-03-21
A new methodology based on the superposition of time-dependent Gauss-Hermite wave packets is developed to describe the wave function of a system in which several interacting electronic states are coupled to a bath of harmonic oscillators. The equations of motion for the wave function parameters are obtained by employing the Dirac-Frenkel time-dependent variational principle. The methodology is applied to study the quantum dynamical behaviour of model systems with two interacting electronic states characterized by a relatively large reorganization energy and a range of energy biases. The favourable scaling properties make it a promising tool for the study of the dynamics of chemico-physical processes in molecular systems.
Wave-packet analysis of strong-field ionization of sodium in the quasistatic regime*
Bunjac, Andrej; Popović, Duška B.; Simonović, Nenad S.
2016-05-01
Strong field ionization of the sodium atom in the tunnelling and over-the-barrier regimes is studied by examining the valence electron wave-packet dynamics in the static electric field. The lowest state energy and the ionization rate determined by this method for different strengths of the applied field agree well with the results obtained using other methods. The initial period of the nonstationary decay after switching the field on is analyzed and discussed. It is demonstrated that, if the Keldysh parameter is significantly lower than one (quasistatic regime), the probability of ionization by a laser pulse can be obtained from the static rates. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.
Nonlinear saturation of wave packets excited by low-energy electron horseshoe distributions.
Krafft, C; Volokitin, A
2013-05-01
Horseshoe distributions are shell-like particle distributions that can arise in space and laboratory plasmas when particle beams propagate into increasing magnetic fields. The present paper studies the stability and the dynamics of wave packets interacting resonantly with electrons presenting low-energy horseshoe or shell-type velocity distributions in a magnetized plasma. The linear instability growth rates are determined as a function of the ratio of the plasma to the cyclotron frequencies, of the velocity and the opening angle of the horseshoe, and of the relative thickness of the shell. The nonlinear stage of the instability is investigated numerically using a symplectic code based on a three-dimensional Hamiltonian model. Simulation results show that the dynamics of the system is mainly governed by wave-particle interactions at Landau and normal cyclotron resonances and that the high-order normal cyclotron resonances play an essential role. Specific features of the dynamics of particles interacting simultaneously with two or more waves at resonances of different natures and orders are discussed, showing that such complex processes determine the main characteristics of the wave spectrum's evolution. Simulations with wave packets presenting quasicontinuous spectra provide a full picture of the relaxation of the horseshoe distribution, revealing two main phases of the evolution: an initial stage of wave energy growth, characterized by a fast filling of the shell, and a second phase of slow damping of the wave energy, accompanied by final adjustments of the electron distribution. The influence of the density inhomogeneity along the horseshoe on the wave-particle dynamics is also discussed.
Dynamical properties of a particle in a wave packet: Scaling invariance and boundary crisis
Energy Technology Data Exchange (ETDEWEB)
Oliveira, Diego F.M., E-mail: diegofregolente@gmail.com [CAMTP, Center For Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor (Slovenia); Robnik, Marko, E-mail: robnik@uni-mb.si [CAMTP, Center For Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor (Slovenia); Leonel, Edson D., E-mail: edleonel@rc.unesp.br [Departamento de Estatistica, Matematica Aplicada e Computacao, UNESP, Univ Estadual Paulista, Av. 24A, 1515-Bela Vista, 13506-900 Rio Claro, SP (Brazil)
2011-10-15
Highlights: > Acceleration of particles in a wave packet. > The location of the first invariant spanning curve which borders the chaotic sea. > Scaling to characterise the transition from integrability to non-integrability. > The property of area preservation is broken and attractors emerge. > After a tiny increase of the dissipation the system experience a boundary crisis. - Abstract: Some dynamical properties present in a problem concerning the acceleration of particles in a wave packet are studied. The dynamics of the model is described in terms of a two-dimensional area preserving map. We show that the phase space is mixed in the sense that there are regular and chaotic regions coexisting. We use a connection with the standard map in order to find the position of the first invariant spanning curve which borders the chaotic sea. We find that the position of the first invariant spanning curve increases as a power of the control parameter with the exponent 2/3. The standard deviation of the kinetic energy of an ensemble of initial conditions obeys a power law as a function of time, and saturates after some crossover. Scaling formalism is used in order to characterise the chaotic region close to the transition from integrability to nonintegrability and a relationship between the power law exponents is derived. The formalism can be applied in many different systems with mixed phase space. Then, dissipation is introduced into the model and therefore the property of area preservation is broken, and consequently attractors are observed. We show that after a small change of the dissipation, the chaotic attractor as well as its basin of attraction are destroyed, thus leading the system to experience a boundary crisis. The transient after the crisis follows a power law with exponent -2.
Energy Technology Data Exchange (ETDEWEB)
Vubangsi, M.; Tchoffo, M.; Fai, L. C. [Mesoscopic and Multilayer Structures Laboratory, Physics Department, University of Dschang, P.O. Box 417 Dschang (Cameroon); Pisma’k, Yu. M. [Department of Theoretical Physics, Saint Petersburg State University, Saint Petersburg (Russian Federation)
2015-12-15
The problem of a particle with position and time-dependent effective mass in a one-dimensional infinite square well is treated by means of a quantum canonical formalism. The dynamics of a launched wave packet of the system reveals a peculiar revival pattern that is discussed. .
Schmidt, Burkhard; Lorenz, Ulf
2017-04-01
WavePacket is an open-source program package for the numerical simulation of quantum-mechanical dynamics. It can be used to solve time-independent or time-dependent linear Schrödinger and Liouville-von Neumann-equations in one or more dimensions. Also coupled equations can be treated, which allows to simulate molecular quantum dynamics beyond the Born-Oppenheimer approximation. Optionally accounting for the interaction with external electric fields within the semiclassical dipole approximation, WavePacket can be used to simulate experiments involving tailored light pulses in photo-induced physics or chemistry. The graphical capabilities allow visualization of quantum dynamics 'on the fly', including Wigner phase space representations. Being easy to use and highly versatile, WavePacket is well suited for the teaching of quantum mechanics as well as for research projects in atomic, molecular and optical physics or in physical or theoretical chemistry. The present Part I deals with the description of closed quantum systems in terms of Schrödinger equations. The emphasis is on discrete variable representations for spatial discretization as well as various techniques for temporal discretization. The upcoming Part II will focus on open quantum systems and dimension reduction; it also describes the codes for optimal control of quantum dynamics. The present work introduces the MATLAB version of WavePacket 5.2.1 which is hosted at the Sourceforge platform, where extensive Wiki-documentation as well as worked-out demonstration examples can be found.
Efremov, MA; Petropavlovsky, SV; Fedorov, MV; Schleich, WP; Yakovlev, VP
2005-01-01
The formation of two-dimensional nonspreading atomic wave packets produced in the interaction of a beam of two-level atoms with two standing light waves polarised in the same plane is considered. The mechanism providing a dispersionless particle dynamics is the balance of two processes: a rapid deca
Institute of Scientific and Technical Information of China (English)
LI JunQing; LIU Fang; XING YongZhong; ZUO Wei
2002-01-01
The quantum correspondence of the very peculiar phenomenon of classical chaos-the exponential instability of motion can be characterized by the initially exponential growth rate of the total uncertainty measurement of the propagating quantum wave packet. Our calculation indicates that quantitatively the growth rate is approximately twice the classical maximum Lyapunov exponent of the system.
Ruetzel, Stefan; Diekmann, Meike; Nuernberger, Patrick; Walter, Christof; Engels, Bernd; Brixner, Tobias
2014-06-01
Upon ultraviolet excitation, photochromic spiropyran compounds can be converted by a ring-opening reaction into merocyanine molecules, which in turn can form several isomers differing by cis and trans configurations in the methine bridge. Whereas the spiropyran-merocyanine conversion reaction of the nitro-substituted indolinobenzopyran 6-nitro-1',3',3'-trimethylspiro[2H-1-benzopyran-2,2'-indoline] (6-nitro BIPS) has been studied extensively in theory and experiments, little is known about photoisomerization among the merocyanine isomers. In this article, we employ femtosecond transient absorption spectroscopy with variable excitation wavelengths to investigate the excited-state dynamics of the merocyanine in acetonitrile at room temperature, where exclusively the trans-trans-cis (TTC) and trans-trans-trans (TTT) isomers contribute. No photochemical ring-closure pathways exist for the two isomers. Instead, we found that (18±4)% of excited TTC isomers undergo an ultrafast excited-state cis→trans photoisomerization to TTT within 200 fs, while the excited-state lifetime of TTC molecules that do not isomerize is 35 ps. No photoisomerization was detected for the TTT isomer, which relaxes to the ground state with a lifetime of roughly 160 ps. Moreover, signal oscillations at 170 cm-1 and 360 cm-1 were observed, which can be ascribed to excited-state wave-packet dynamics occurring in the course of the TTC→TTT isomerization. The results of high-level time-dependent density functional theory in conjunction with polarizable continuum models are presented in the subsequent article [C. Walter, S. Ruetzel, M. Diekmann, P. Nuernberger, T. Brixner, and B. Engels, J. Chem. Phys. 140, 224311 (2014)].
Enhancement of the Signal-to-Noise Ratio in Sonic Logging Waveforms by Seismic Interferometry
Aldawood, Ali
2012-04-01
Sonic logs are essential tools for reliably identifying interval velocities which, in turn, are used in many seismic processes. One problem that arises, while logging, is irregularities due to washout zones along the borehole surfaces that scatters the transmitted energy and hence weakens the signal recorded at the receivers. To alleviate this problem, I have extended the theory of super-virtual refraction interferometry to enhance the signal-to-noise ratio (SNR) sonic waveforms. Tests on synthetic and real data show noticeable signal-to-noise ratio (SNR) enhancements of refracted P-wave arrivals in the sonic waveforms. The theory of super-virtual interferometric stacking is composed of two redatuming steps followed by a stacking procedure. The first redatuming procedure is of correlation type, where traces are correlated together to get virtual traces with the sources datumed to the refractor. The second datuming step is of convolution type, where traces are convolved together to dedatum the sources back to their original positions. The stacking procedure following each step enhances the signal to noise ratio of the refracted P-wave first arrivals. Datuming with correlation and convolution of traces introduces severe artifacts denoted as correlation artifacts in super-virtual data. To overcome this problem, I replace the datuming with correlation step by datuming with deconvolution. Although the former datuming method is more robust, the latter one reduces the artifacts significantly. Moreover, deconvolution can be a noise amplifier which is why a regularization term is utilized, rendering the datuming with deconvolution more stable. Tests of datuming with deconvolution instead of correlation with synthetic and real data examples show significant reduction of these artifacts. This is especially true when compared with the conventional way of applying the super-virtual refraction interferometry method.
DEFF Research Database (Denmark)
Leth, Henriette Astrup; Madsen, Lars Bojer; Mølmer, Klaus
2010-01-01
Theoretical calculations on dissociative double ionization of H2 and D2 in short intense laser pulses using the Monte Carlo wave packet technique are presented for several different field intensities, wavelengths, and pulse durations. We find convincing agreement between theory and experimental...... results for the kinetic energy release spectra of the nuclei. Besides the correctly predicted spectra the Monte Carlo wave packet method offers insight into the nuclear dynamics during the pulse and makes it possible to address the origin of different structures observed in the spectra. Three......-photon resonances in the singly ionized molecule and charge-resonance-enhanced ionization are shown to be the main processes responsible for the observed nuclear energy distributions....
Xie, Xinhua; Kartashov, Daniil; Zhang, Li; Baltuška, Andrius; Kitzler, Markus
2016-01-01
We report on the observation of subcycle interferences of electron wave packets released during the strong field ionization of H$_2$ with cycle-shaped two-color laser fields. With a reaction microscope, channel-resolved photoelectron momentum distribution are obtained for different final products originating from single ionization of H$_2$. Our results show that the subcycle interference structures of electron wave packet are very sensitive to the cycle-shape of the two-color laser field. The reason is that the ionization time within an optical cycle is determined by the cycle-shape of the laser field. The subcycle interference structures can be further used to get the subcycle dynamics of molecules during strong field interaction.
Energy Technology Data Exchange (ETDEWEB)
Mahapatra, Susanta; Ritschel, Thomas
2003-04-15
We report theoretical investigations on the second photoelectron band of chlorine dioxide molecule by ab initio quantum dynamical methods. This band exhibits a highly complex structure and represents a composite portrait of five excited energetically close-lying electronic states of ClO{sub 2}{sup +}. Much of this complexity is likely to be arising due to strong vibronic interactions among these electronic states - which we address and examine herein. The near equilibrium MRCI potential energy surfaces (PESs) of these five cationic states reported by Peterson and Werner [J. Chem. Phys. 99 (1993) 302] for the C{sub 2v} configuration, are extended for the C{sub s} geometry assuming a harmonic vibration along the asymmetric stretching mode. The strength of the vibronic coupling parameters of the Hamiltonian are calculated by ab initio CASSCF-MRCI method and conical intersections of the PESs are established. The diabatic Hamiltonian matrix is constructed within a linear vibronic coupling scheme and the resulting PESs are employed in the nuclear dynamical simulations, carried out with the aid of a time-dependent wave packet approach. Companion calculations are performed for transitions to the uncoupled electronic states in order to reveal explicitly the impact of the nonadiabatic coupling on the photoelectron dynamics. The theoretical findings are in good accord with the experimental observations. The femtosecond nonradiative decay dynamics of ClO{sub 2}{sup +} excited electronic states mediated by conical intersections is also examined and discussed.
Semiclassical wave packet study of anomalous isotope effect in ozone formation.
Vetoshkin, Evgeny; Babikov, Dmitri
2007-10-21
We applied the semiclassical initial value representation method to calculate energies, lifetimes, and wave functions of scattering resonances in a two-dimensional potential for O+O2 collision. Such scattering states represent the metastable O3* species and play a central role in the process of ozone formation. Autocorrelation functions for scattering states were computed and then analyzed using the Prony method, which permits one to extract accurate energies and widths of the resonances. We found that the results of the semiclassical wave packet propagation agree well with fully quantum results. The focus was on the 16O16O18O isotopomer and the anomalous isotope effect associated with formation of this molecule, either through the 16O16O+18O or the 16O+16O18O channels. An interesting correlation between the local vibration mode character of the metastable states and their lifetimes was observed and explained. New insight is obtained into the mechanism by which the long-lived resonances in the delta zero-point energy part of spectrum produce the anomalously large isotope effect.
Trojan Wave Packets in the Quantum Cavity within the Extended Jaynes-Cummings Model
Kalinski, Matt
2016-05-01
Some time ago we have developed the theory of the Trojan Wave Packets (TWP) in the classical strong Circularly Polarized electromagnetic field in terms of the Mathieu generating functions. We have discovered that by the proper partitioning of the Coulomb spectrum i.e. by considering the deviation from the circularity and the vertical tilt of the undressed states as the new quantum numbers we can reduce the problem to the problem of several non-interacting quantum pendula for the Stark-Zeeman field dressed states. The TWP in the infinite physical space however turned out to be weakly unstable due to the spontaneous emission. Here we develop the theory in which the TWP is truly eternal when the electromagnetic interactions are considered quantum and the field is confined by the perfect quantum cavity boundary conditions. First we extend the Jaynes-Cummings (JC) model from the two to the infinite number of levels interacting with the one or two perfectly resonant quantum modes of the electromagnetic field. Similarly the model of JC and our previous pendular model the dressed electron-field eigenstates are constructed within the weakly interacting manifolds. Superpositions of those states are possible with the quantum electron density moving on the circular trajectories.
Wächtler, Maria; Guthmuller, Julien; Kupfer, Stephan; Maiuri, Margherita; Brida, Daniele; Popp, Jürgen; Rau, Sven; Cerullo, Giulio; Dietzek, Benjamin
2015-05-18
The hydrogen-evolving photocatalyst [(tbbpy)2 Ru(tpphz)Pd(Cl)2 ](2+) (tbbpy=4,4'-di-tert-butyl-2,2'-bipyridine, tpphz=tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine) shows excitation-wavelength-dependent catalytic activity, which has been correlated to the localization of the initial excitation within the coordination sphere. In this contribution the excitation-wavelength dependence of the early excited-state relaxation and the occurrence of vibrational coherences are investigated by sub-20 fs transient absorption spectroscopy and DFT/TDDFT calculations. The comparison with the mononuclear precursor [(tbbpy)2 Ru(tpphz)](2+) highlights the influence of the catalytic center on these ultrafast processes. Only in the presence of the second metal center, does the excitation of a (1) MLCT state localized on the central part of the tpphz bridge lead to coherent wave-packet motion in the excited state. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Kroh, Tim; Ahlrichs, Andreas; Sprenger, Benjamin; Benson, Oliver
2017-09-01
Future quantum networks require a hybrid platform of dissimilar quantum systems. Within the platform, joint quantum states have to be mediated either by single photons, photon pairs or entangled photon pairs. The photon wavelength has to lie within the telecommunication band to enable long-distance fibre transmission. In addition, the temporal shape of the photons needs to be tailored to efficiently match the involved quantum systems. Altogether, this requires the efficient coherent wavelength-conversion of arbitrarily shaped single-photon wave packets. Here, we demonstrate the heralded temporal filtering of single photons as well as the synchronisation of state manipulation and detection as key elements in a typical experiment, besides of delaying a photon in a long fibre. All three are realised by utilising commercial telecommunication fibre-optical components which will permit the transition of quantum networks from the lab to real-world applications. The combination of these renders a temporally filtering single-photon storage in a fast switchable fibre loop possible.
Zauleck, Julius P P; Thallmair, Sebastian; Loipersberger, Matthias; de Vivie-Riedle, Regina
2016-12-13
The curse of dimensionality still remains as the central challenge of molecular quantum dynamical calculations. Either compromises on the accuracy of the potential landscape have to be made or methods must be used that reduce the dimensionality of the configuration space of molecular systems to a low dimensional one. For dynamic approaches such as grid-based wave packet dynamics that are confined to a small number of degrees of freedom this dimensionality reduction can become a major part of the overall problem. A common strategy to reduce the configuration space is by selection of a set of internal coordinates using chemical intuition. We devised two methods that increase the degree of automation of the dimensionality reduction as well as replace chemical intuition by more quantifiable criteria. Both methods reduce the dimensionality linearly and use the intrinsic reaction coordinate as guidance. The first one solely relies on the intrinsic reaction coordinate (IRC), whereas the second one uses semiclassical trajectories to identify the important degrees of freedom.
Energy Technology Data Exchange (ETDEWEB)
Sindona, A. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy) and Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy)]. E-mail: sindona@fis.unical.it; Riccardi, P. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy); Maletta, S. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Rudi, S.A. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy); Falcone, G. [Dipartimento di Fisica, Universita della Calabria, Via P. Bucci 31C, 87036 Rende (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Gruppo collegato di Cosenza, Via P. Bucci 31C, 87036 Rende (Italy)
2007-05-15
Secondary emission of Ag{sup -} and Au{sup -} particles, following the sputtering of clean Ag(1 0 0) and Au(1 0 0) targets, respectively, is studied with a Crank-Nicholson wave-packet propagation method. A one-electron pseudo-potential is used to describe the plane metal surface, with a projected band gap, the ejected ion, whose charge state is investigated, and its nearest-neighbor substrate ion, put in motion by the collision cascade generated by the primary ion beam. Time-dependent Schroedinger equation is solved backwards in time to determine the evolution of the affinity orbital of the negative particles from an instant when they are unperturbed, at distances of the order of {approx}10{sup 2} a.u. from the surface, to the instant of ejection. The probability that a band electron will be eventually detected in affinity state of the ejected particle is, thus, calculated and compared with the result of another method based on the spectral decomposition of the one-electron Hamiltonian.
Characterization of a quantum phase transition in Dirac systems by means of the wave-packet dynamics
Directory of Open Access Journals (Sweden)
E. Romera
2012-12-01
Full Text Available We study the signatures of phase transitions in the time evolution of wave-packets by analyzing two simple model systems: a graphene quantum dot model in a magnetic field and a Dirac oscillator in a magnetic field. We have characterized the phase transitions using the autocorrelation function. Our work also reveals that the description in terms of Shannon entropy of the autocorrelation function is a clear phase transition indicator.
Vetoshkin, Evgeny; Babikov, Dmitri
2007-09-28
For the first time Feshbach-type resonances important in recombination reactions are characterized using the semiclassical wave packet method. This approximation allows us to determine the energies, lifetimes, and wave functions of the resonances and also to observe a very interesting correlation between them. Most important is that this approach permits description of a quantum delta-zero-point energy effect in recombination reactions and reproduces the anomalous rates of ozone formation.
National Oceanic and Atmospheric Administration, Department of Commerce — This feature class contains internal wave packets extracted from SAR imagery that were binned in 30x30 second latitude/longitude polygon grid cells. Statistics were...
Beggi, Andrea; Bordone, Paolo; Buscemi, Fabrizio; Bertoni, Andrea
2015-12-01
We compute the exact single-particle time-resolved dynamics of electronic Mach-Zehnder interferometers based on Landau edge-states transport, and assess the effect of the spatial localization of carriers on the interference pattern. The exact carrier dynamics is obtained by solving numerically the time-dependent Schrödinger equation with a suitable 2D potential profile reproducing the interferometer design. An external magnetic field, driving the system to the quantum Hall regime with filling factor one, is included. The injected carriers are represented by a superposition of edge states, and their interference pattern—controlled via magnetic field and/or area variation—reproduces the one of (Ji et al 2003 Nature 422 415). By tuning the system towards different regimes, we find two additional features in the transmission spectra, both related to carrier localization, namely a damping of the Aharonov-Bohm oscillations with increasing difference in the arms length, and an increased mean transmission that we trace to the energy-dependent transmittance of quantum point contacts. Finally, we present an analytical model, also accounting for the finite spatial dispersion of the carriers, able to reproduce the above effects.
Energy Technology Data Exchange (ETDEWEB)
Balakin, A. A., E-mail: balakin.alexey@yandex.ru; Mironov, V. A.; Skobelev, S. A., E-mail: sk.sa1981@gmail.com [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)
2017-01-15
The self-action of two-dimensional and three-dimensional Bessel wave packets in a system of coupled light guides is considered using the discrete nonlinear Schrödinger equation. The features of the self-action of such wave fields are related to their initial strong spatial inhomogeneity. The numerical simulation shows that for the field amplitude exceeding a critical value, the development of an instability typical of a medium with the cubic nonlinearity is observed. Various regimes are studied: the self-channeling of a wave beam in one light guide at powers not strongly exceeding a critical value, the formation of the “kaleidoscopic” picture of a wave packet during the propagation of higher-power radiation along a stratified medium, the formation of light bullets during competition between self-focusing and modulation instabilities in the case of three-dimensional wave packets, etc. In the problem of laser pulse shortening, the situation is considered when the wave-field stratification in the transverse direction dominates. This process is accompanied by the self-compression of laser pulses in well enough separated light guides. The efficiency of conversion of the initial Bessel field distribution to two flying parallel light bullets is about 50%.
Prodhan, Suryoday
2016-01-01
Singlet fission is a potential pathway for significant enhancement of efficiency in organic solar cells. In this article, we have studied singlet fission in a pair of polyene molecules employing exact many-body wave packet dynamics. The individual molecules are treated within Hubbard and Pariser-Parr-Pople (PPP) models and the interaction between them involves transfer terms, intersite electron repulsions and site charge-bond charge repulsion terms. Initial wave packet is constructed from excited singlet state of one molecule and ground state of the other. Time development of this wave packet under the influence of intermolecular interactions is followed within the Schr\\"{o}dinger picture by an efficient predictor-corrector scheme. In unsubstituted Hubbard and PPP chains, $2{}^1A$ excited singlet state leads to significant fission yield while the $1{}^1B$ state gives negligible fission yield. On substitution by donor-acceptor groups of moderate strength, singlet state derived from $1{}^1B$ state also gives si...
Prodhan, Suryoday; Ramasesha, S.
2017-08-01
Singlet fission (SF) is a potential pathway for significant enhancement of efficiency in organic solar cells (OSC). In this paper, we study singlet fission in a pair of polyene molecules in two different stacking arrangements employing exact many-body wave packet dynamics. In the noninteracting model, the SF yield is absent. The individual molecules are treated within Hubbard and Pariser-Parr-Pople (PPP) models and the interaction between them involves transfer terms, intersite electron repulsions, and site-charge-bond-charge repulsion terms. Initial wave packet is constructed from excited singlet state of one molecule and ground state of the other. Time development of this wave packet under the influence of intermolecular interactions is followed within the Schrödinger picture by an efficient predictor-corrector scheme. In unsubstituted Hubbard and PPP chains, 2 1A excited singlet state leads to significant SF yield while the 1 1B state gives negligible fission yield. On substitution by donor-acceptor groups of moderate strength, the lowest excited state will have sufficient 2 1A character and hence results in significant SF yield. Because of rapid internal conversion, the nature of the lowest excited singlet will determine the SF contribution to OSC efficiency. Furthermore, we find the fission yield depends considerably on the stacking arrangement of the polyene molecules.
Thejappa, G.; MacDowall, R. J.; Bergamo, M.
2012-01-01
The four wave interaction process, known as the oscillating two stream instability (OTSI) is considered as one of the mechanisms responsible for stabilizing the electron beams associated with solar type III radio bursts. It has been reported that (1) an intense localized Langmuir wave packet associated with a type III burst contains the spectral characteristics of the OTSI: (a) a resonant peak at the local electron plasma frequency, f(sub pe), (b) a Stokes peak at a frequency slightly lower than f(sub pe), (c) anti-Stokes peak at a frequency slightly higher than f(sub pe), and (d) a low frequency enhancement below a few hundred Hz, (2) the frequencies and wave numbers of these spectral components satisfy the resonance conditions of the OTSI, and (3) the peak intensity of the wave packet is well above the thresholds for the OTSI as well as spatial collapse of envelope solitons. Here, for the first time, applying the trispectral analysis on this wave packet, we show that the tricoherence, which measures the degree of coherent four-wave coupling amongst the observed spectral components exhibits a peak. This provides an additional evidence for the OTSI and related spatial collapse of Langmuir envelope solitons in type III burst sources.
Afraimovich, E. L.; Edemsky, I. K.; Voeykov, S. V.; Yasukevich, Y. V.; Zhivetiev, I. V.
2009-04-01
The great variety of solar terminator (ST) -linked phenomena in the atmosphere gave rise to a num¬ber of studies on the analysis of ionosphere parameter variations obtained by different ionosphere sounding methods. Main part of experimental data was obtained using methods for analyzing the spectrum of ionosphere parameter variations in separate local points. To identify ST-generated wave disturbances it is necessary to measure the dynamic and spectral characteristics of the wave disturbances and to compare it with spatial-temporal characteristics of ST. Using TEC measurements from the dense network of GPS sites GEONET (Japan), we have obtained the first GPS-TEC image of the space structure of medium-scale traveling wave packets (MS TWP) excited by the solar terminator. We use two known forms of the 2D GPS-TEC image for our presentation of the space structure of ST-generated MS TWP: 1) - the diagram "distance-time"; 2) - the 2D-space distribution of the values of filtered TEC series dI (λ, φ, t) on the latitude φ and longitude λ for each 30-sec TEC counts. We found that the time period and wave-length of ST-generated wave packets are about 10-20 min and 200-300 km, respectively. Dynamic images analysis of dI (λ, φ, t) gives precise estimation of velocity and azimuth of TWP wave front propagation. We use the method of determining velocity of traveling ionosphere disturbances (SADM-GPS), which take into account the relative moving of subionosphere points. We found that the velocity of the TWP phase front, traveling along GEONET sites, varies in accordance with the velocity of the ST line displacement. The space image of MS TWP manifests itself in pronounced anisotropy and high coherence over a long distance of about 2000 km. The TWP wave front extends along the ST line with the angular shift of about 20°. The hypothesis on the connection between the TWP generation and the solar terminator can be tested in the terminator local time (TLT) system: d
Abdilghanie, Ammar M.; Diamessis, Peter J.
2012-01-01
Numerical simulations of internal gravity wave (IGW) dynamics typically rely on wave velocity and density fields which are either generated through forcing terms in the governing equations or are explicitly introduced as initial conditions. Both approaches are based on the associated solution to the inviscid linear internal wave equations and, thus, assume weak-amplitude, space-filling waves. Using spectral multidomain-based numerical simulations of the two-dimensional Navier-Stokes equations and focusing on the forcing-driven approach, this study examines the generation and subsequent evolution of large-amplitude IGW packets which are strongly localized in the vertical in a linearly stratified fluid. When the vertical envelope of the forcing terms varies relatively rapid when compared to the vertical wavelength, the associated large vertical gradients in the Reynolds stress field drive a nonpropagating negative horizontal mean flow component in the source region. The highly nonlinear interaction of this mean current with the propagating IGW packet leads to amplification of the wave, a significant distortion of its rear flank, and a substantial decay of its amplitude. Scaling arguments show that the mean flow is enhanced with a stronger degree of localization of the forcing, larger degree of hydrostaticity, and increasing wave packet steepness. Horizontal localization results in a pronounced reduction in mean flow strength mainly on account of the reduced vertical gradient of the wave Reynolds stress. Finally, two techniques are proposed toward the efficient containment of the mean flow at minimal computational cost. The findings of this study are of particular value in overcoming challenges in the design of robust computational process studies of IGW packet (or continuously forced wave train) interactions with a sloping boundary, critical layer, or caustic, where large wave amplitudes are required for any instabilities to develop. In addition, the detailed
Energy Technology Data Exchange (ETDEWEB)
Gray, S.K.
1994-03-01
Vibrational predissociation of XI{sub 2} and X{sub 2}I{sub 2} van der Waals complexes, with X = He and Ne, is studied with wave packets. Three-dimensional calculations are carried out on the three-atom systems. Suitable X{center_dot}{center_dot}I potential interactions are determined, and product distributions are predicted. Reduced dimension models of X{sub 2}I{sub 2}(v{prime}) {yields} 2X + I{sub 2}(v < v{prime}) are investigated. Comparison is made with available experimental results. Mechanistic issues, including the role of intramolecular vibrational relaxation resonances, are addressed.
Time-dependent wave packet approach to the pulse delay effect upon RbI photoelectron spectrum
Institute of Scientific and Technical Information of China (English)
LIU Chunhua; MENG Qingtian; ZHANG Qinggang
2006-01-01
The time-resolved photoelectron spectrum (TRPES) of Rbl molecule is simulated using the time-dependent wave-packet method. Both the normal three-photon ionization process and auto-ionization process are involved in the simulation. The calculated results show that the change of delay time will influence the shape of the photoelectron spectrum (PES), and the influence is substantially due to the existence of the crossing between excited states and the strong laser field which will change the position of relevant curves.
Kreisbeck, C.; Kramer, T.; Molina, R. A.
2017-04-01
We have performed time-dependent wave packet simulations of realistic Aharonov-Bohm (AB) devices with a quantum dot embedded in one of the arms of the interferometer. The AB ring can function as a measurement device for the intrinsic transmission phase through the quantum dot, however, care has to be taken in analyzing the influence of scattering processes in the junctions of the interferometer arms. We consider a harmonic quantum dot and show how the Darwin–Fock spectrum emerges as a unique pattern in the interference fringes of the AB oscillations.
Energy Technology Data Exchange (ETDEWEB)
Zhao, Bin [Center for Theoretical and Computational Chemistry, and State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Sun, Zhigang, E-mail: zsun@dicp.ac.cn, E-mail: hguo@unm.edu [Center for Theoretical and Computational Chemistry, and State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Guo, Hua, E-mail: zsun@dicp.ac.cn, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States)
2014-06-21
A recently proposed transition-state wave packet method [R. Welsch, F. Huarte-Larrañaga, and U. Manthe, J. Chem. Phys. 136, 064117 (2012)] provides an efficient and intuitive framework to study reactive quantum scattering at the state-to-state level. It propagates a few transition-state wave packets, defined by the eigenfunctions of the low-rank thermal flux operator located near the transition state, into the asymptotic regions of the reactant and product arrangement channels separately using the corresponding Jacobi coordinates. The entire S-matrix can then be assembled from the corresponding flux-flux cross-correlation functions for all arrangement channels. Since the transition-state wave packets can be defined in a relatively small region, its transformation into either the reactant or product Jacobi coordinates is accurate and efficient. Furthermore, the grid/basis for the propagation, including the maximum helicity quantum number K, is much smaller than that required in conventional wave packet treatments of state-to-state reactive scattering. This approach is implemented for atom-diatom reactions using a time-dependent wave packet method and applied to the H + D{sub 2} reaction with all partial waves. Excellent agreement with benchmark integral and differential cross sections is achieved.
Zhao, Bin; Sun, Zhigang; Guo, Hua
2014-06-01
A recently proposed transition-state wave packet method [R. Welsch, F. Huarte-Larrañaga, and U. Manthe, J. Chem. Phys. 136, 064117 (2012)] provides an efficient and intuitive framework to study reactive quantum scattering at the state-to-state level. It propagates a few transition-state wave packets, defined by the eigenfunctions of the low-rank thermal flux operator located near the transition state, into the asymptotic regions of the reactant and product arrangement channels separately using the corresponding Jacobi coordinates. The entire S-matrix can then be assembled from the corresponding flux-flux cross-correlation functions for all arrangement channels. Since the transition-state wave packets can be defined in a relatively small region, its transformation into either the reactant or product Jacobi coordinates is accurate and efficient. Furthermore, the grid/basis for the propagation, including the maximum helicity quantum number K, is much smaller than that required in conventional wave packet treatments of state-to-state reactive scattering. This approach is implemented for atom-diatom reactions using a time-dependent wave packet method and applied to the H + D2 reaction with all partial waves. Excellent agreement with benchmark integral and differential cross sections is achieved.
Knappenberger, Kenneth L; Lerch, Eliza-Beth W; Wen, Patrick; Leone, Stephen R
2007-09-28
A two-color (3+1(')) pump-probe scheme is employed to investigate Rydberg wave packet dynamics in carbon disulfide (CS(2) (*)). The state superpositions are created within the 4f and 5p Rydberg manifolds by three photons of the 400 nm pump pulse, and their temporal evolution is monitored with femtosecond time-resolved photoelectron spectroscopy using an 800 nm ionizing probe pulse. The coherent behavior of the non-stationary superpositions are observed through wavepacket revivals upon ionization to either the upper (12) or lower (32) spin-orbit components of CS(2) (+). The results show clearly that the composition of the wavepacket can be efficiently controlled by the power density of the excitation pulse over a range from 500 GWcm(2) to 10 TWcm(2). The results are consistent with the anticipated ac-Stark shift for 400 nm light and demonstrate an effective method for population control in molecular systems. Moreover, it is shown that Rydberg wavepackets can be formed in CS(2) with excitation power densities up to 10 TWcm(2) without significant fragmentation. The exponential 1e population decay (T(1)) of specific excited Rydberg states are recovered by analysis of the coherent part of the signal. The dissociation lifetimes of these states are typically 1.5 ps. However, a region exhibiting a more rapid decay ( approximately 800 fs) is observed for states residing in the energy range of 74 450-74 550 cm(-1), suggestive of an enhanced surface crossing in this region.
Gerberding, Oliver; Kullmann, Joachim; Tröbs, Michael; Bykov, Ioury; Barke, Simon; Brause, Nils Christopher; Delgado, Juan José Esteban; Schwarze, Thomas S; Reiche, Jens; Danzmann, Karsten; Rasmussen, Torben; Hansen, Torben Vendt; Engaard, Anders; Pedersen, Søren Møller; Jennrich, Oliver; Suess, Martin; Sodnik, Zoran; Heinzel, Gerhard
2015-01-01
Precision phase readout of optical beat note signals is one of the core techniques required for intersatellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts, with a precision in the order of $\\mu \\textrm{rad}/\\sqrt{\\textrm{Hz}}$ at frequencies between $0.1\\,\\textrm{mHz}$ and $1\\,\\textrm{Hz}$. In this paper, we present phase readout systems, so-called phasemeters, that are able to achieve such precisions and we discuss various means that have been employed to reduce noise in the analogue circuit domain and during digitisation. We also discuss the influence of some non-linear noise sources in the analogue domain of such phasemeters. And finally, we present the performance that was achieved during testing of the elegant breadboard model of the LISA phasemeter, that was developed in the scope of an ESA technology development activity.
Energy Technology Data Exchange (ETDEWEB)
Sanz, A.S., E-mail: asanz@iff.csic.es [Instituto de Física Fundamental (IFF-CSIC), Serrano 123, 28006 Madrid (Spain); Martínez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Peñate-Rodríguez, H.C.; Rojas-Lorenzo, G. [Instituto Superior de Tecnologías y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Quinta de Los Molinos, Plaza, La Habana 10600 (Cuba); Miret-Artés, S. [Instituto de Física Fundamental (IFF-CSIC), Serrano 123, 28006 Madrid (Spain)
2014-08-15
Classical viscid media are quite common in our everyday life. However, we are not used to find such media in quantum mechanics, and much less to analyze their effects on the dynamics of quantum systems. In this regard, the Caldirola–Kanai time-dependent Hamiltonian constitutes an appealing model, accounting for friction without including environmental fluctuations (as it happens, for example, with quantum Brownian motion). Here, a Bohmian analysis of the associated friction dynamics is provided in order to understand how a hypothetical, purely quantum viscid medium would act on a wave packet from a (quantum) hydrodynamic viewpoint. To this purpose, a series of paradigmatic contexts have been chosen, such as the free particle, the motion under the action of a linear potential, the harmonic oscillator, or the superposition of two coherent wave packets. Apart from their analyticity, these examples illustrate interesting emerging behaviors, such as localization by “quantum freezing” or a particular type of quantum–classical correspondence. The reliability of the results analytically determined has been checked by means of numerical simulations, which has served to investigate other problems lacking of such analyticity (e.g., the coherent superpositions). - Highlights: • A dissipative Bohmian approach is developed within the Caldirola–Kanai model. • Some simple yet physically insightful systems are then studied analytically. • Dissipation leads to spatial localization in free-force regimes. • Under the action of linear forces, dissipation leads to uniform motion. • In harmonic potentials, the system decays unavoidable to the well minimum.
Malakar, Y.; Kaderiya, B.; Zohrabi, M.; Pearson, W. L.; Ziaee, F.; Kananka Raju, P.; Ben-Itzhak, I.; Rolles, D.; Rudenko, A.
2016-05-01
Light-driven vibrational wave packets play an important role in molecular imaging and coherent control applications. Here we present the results of a pump-probe experiment characterizing laser-induced vibrational wave packets in both, neutral and ionic states of CH3 I (iodomethane), one of the prototypical polyatomic systems. Measuring yields and kinetic energies of all ionic fragments as a function of the time delay between two 25 fs, 800 nm pump and probe pulses, we map vibrational motion of the molecule, and identify the states involved by channel-resolved Fourier spectroscopy. In the Coulomb explosion channels we observe features with ~ 130 fs periodicity resulting from C-I symmetric stretch (ν3 mode) of the electronically excited cationic state. However the Fourier transform of the low-energy I+ ion yield produced by the dissociative ionization of CH3 I reveals the signatures of the same vibrational mode in the ground electronic states of both, neutral and cation, reflected in 65-70 fs oscillations. We observe the degeneration of the oscillatory structures from the cationic states within ~ 2 ps and discuss most likely reasons for this behavior. Supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U. S. DOE. K. R. P. and W. L. P. supported by NSF Award No. IIA-143049.
Misra, A P
2010-01-01
We consider the nonlinear propagation of electrostatic wave packets in an ultra-relativistic (UR) degenerate dense electron-ion plasma, whose dynamics is governed by the nonlocal two-dimensional nonlinear Schroedinger-like equations. The coupled set of equations are then used to study the modulational instability (MI) of a uniform wave train to an infinitesimal perturbation of multi-dimensional form. The condition for the MI is obtained, and it is shown that the nondimensional parameter, $\\beta\\propto\\lambda_C n_0^{1/3}$ (where $\\lambda_C$ is the reduced Compton wavelength and $n_0$ is the particle number density), associated with the UR pressure of degenerate electrons, shifts the stable (unstable) regions at $n_{0}\\sim10^{30}$ cm$^{-3}$ to unstable (stable) ones at higher densities, i.e. $n_{0}\\gtrsim7\\times10^{33}$. It is also found that higher the values of $n_{0}$, the lower is the growth rate of MI with cut-offs at lower wave numbers of modulation. Furthermore, the dynamical evolution of the wave packet...
Goussev, Arseni; Dorfman, J. Robert
2006-01-01
We consider the time evolution of a wave packet representing a quantum particle moving in a geometrically open billiard that consists of a number of fixed hard-disk or hard-sphere scatterers. Using the technique of multiple collision expansions we provide a first-principle analytical calculation of the time-dependent autocorrelation function for the wave packet in the high-energy diffraction regime, in which the particle's de Broglie wave length, while being small compared to the size of the ...
Konkin, D. A.; Litvinov, R. V.; Parfenova, E. S.; Rakhim, R. A. A.; Stukach, O. V.
2016-11-01
We consider the frequency dependence of propagation constants (phase dispersion) and of the spatial distribution of the electromagnetic field (shape dispersion) of guided optical TE modes in a thin left-handed film. It is shown that the spatiotemporal transformation of narrow-band intramode wave packets with the spectrum adjacent to the frequency of the zero group velocity is caused by the dispersion of both types. The propagation velocity of the power carried by such wave packets is significantly lower than the group velocity of light in a bulk left-handed metamaterial.
DEFF Research Database (Denmark)
Marquetand, P.; Materny, A.; Henriksen, Niels Engholm
2004-01-01
We regard the rovibrational wave packet dynamics of NaI in a static electric field after femtosecond excitation to its first electronically excited state. The following quasibound nuclear wave packet motion is accompanied by a bonding situation changing from covalent to ionic. At times when...... the charge separation is present, i.e., when the bond-length is large, a strong dipole moment exists and rotational excitation takes place. Upon bond contraction, the then covalently bound molecule does not experience the external field. This scenario repeats itself periodically. Thus, the vibrational...
Schlesinger, Martin; Stienkemeier, Frank; Strunz, Walter T
2009-01-01
Femtosecond pump-probe spectroscopy has been used to study vibrational dynamics of potassium dimers attached to superfluid helium nanodroplets. Comparing the measured data with theoretical results based on dissipative quantum dynamics we propose that the most important effect of the helium environment is a general damping of the vibrational dynamics as a result of the interaction between dimer and collective degrees of freedom of the helium droplet. The calculations allow us to explain crucial experimental findings that are unobserved in gas-phase measurements. Remarkably, best agreement with experiment is found for a model where we neglect damping once a wave packet moves below a critical velocity. In this way the results provide first direct evidence for the Landau critical velocity in superfluid nanodroplets.
Singh, D; Papini, G; Mobed, Nader; Papini, Giorgio; Singh, Dinesh
2006-01-01
We present the possibility that Dirac and Majorana neutrino wave packets can be distinguished when subject to spin-gravity interaction while propagating through vacuum described by the Lense-Thirring metric. By adopting the techniques of gravitational phase and time-independent perturbation theory following the Brillouin-Wigner method, we generate spin-gravity matrix elements from a perturbation Hamiltonian and show that this distinction is easily reflected in well-defined gravitational corrections to the neutrino oscillation length for a two-flavour system. Explicit examples are presented using the Sun and SN1987A as the gravitational sources for the Lense-Thirring metric. This approach offers the possibility to determine the absolute neutrino masses by this method and identify a theoretical upper bound for the absolute neutrino mass difference, where the distinctions between the Dirac and Majorana cases are evident. We discuss the relevance of this analysis to the upcoming attempts to measure the properties...
Institute of Scientific and Technical Information of China (English)
CHEN Shao-Hao; WANG Feng; LI Jia-Ming
2004-01-01
Introducing a theoretical method to treat time-dependent wave-packet dynamics for atom collisions, we calculate the cross sections of proton impact excitation (2s - 2p) with a Li atom by directly numerically integrating the time-dependent Schrodinger equation on a three-dimensional Cartesian mesh. Our calculated results are in good agreement with the available experimental measurements.
Energy Technology Data Exchange (ETDEWEB)
Segura, J.; Fernandez de Cordoba, P.
1993-01-01
We solve the Schrodinger equation in order to study the time evolution of a wave packet in different situations of physical interest. This work illustrates, with pedagogical aim, some quantum phenomena which shock our classical conception of the universe: propagation in classically forbidden regions, energy quantization. (Author)
Overcoming loss of contrast in atom interferometry due to gravity gradients
Roura, Albert; Schleich, Wolfgang P
2014-01-01
Long-time atom interferometry is instrumental to various high-precision measurements of fundamental physical properties, including tests of the equivalence principle. Due to rotations and gravity gradients, the classical trajectories characterizing the motion of the wave packets for the two branches of the interferometer do not close in phase space, an effect which increases significantly with the interferometer time. The relative displacement between the interfering wave packets in such open interferometers leads to a fringe pattern in the density profile at each exit port and a loss of contrast in the oscillations of the integrated particle number as a function of the phase shift. Paying particular attention to gravity gradients, we present a simple mitigation strategy involving small changes in the timing of the laser pulses which is very easy to implement. A useful representation-free description of the state evolution in an atom interferometer is introduced and employed to analyze the loss of contrast an...
Directory of Open Access Journals (Sweden)
Diaz-Torres Alexis
2015-01-01
Full Text Available Recent progress in a quantitative study of the 12C+12C sub-Coulomb fusion is reported. It is carried out using full-dimensional, time-dependent wave-packet dynamics, a quantum reaction model that has not been much exploited in nuclear physics, unlike in chemical physics. The low-energy collision is described in the rotating center-of-mass frame within a nuclear molecular picture. A collective Hamiltonian drives the time propagation of the wave-packet through the collective potential-energy landscape that is calculated with a realistic two-center shell model. Among other preliminary results, the theoretical sub-Coulomb fusion resonances for 12C+12C seem to correspond well with observations. The method appears to be useful for expanding the cross-section predictions towards stellar energies.
Iihama, S.; Sasaki, Y.; Sugihara, A.; Kamimaki, A.; Ando, Y.; Mizukami, S.
2016-07-01
Coherent spin-wave generation by focused ultrashort laser pulse irradiation was investigated for a permalloy thin film at micrometer scale using an all-optical space- and time-resolved magneto-optical Kerr effect microscope. The spin-wave packet propagating perpendicular to the magnetization direction was clearly observed; however, that propagating parallel to the magnetization direction was not observed. The propagation length, group velocity, center frequency, and packet width of the observed spin-wave packet were evaluated and quantitatively explained in terms of the propagation of a magnetostatic spin wave driven by the ultrafast change of an out-of-plane demagnetization field induced by the focused-pulse laser.
ACCURATE TIME-DEPENDENT WAVE PACKET STUDY OF THE H{sup +}+LiH REACTION AT EARLY UNIVERSE CONDITIONS
Energy Technology Data Exchange (ETDEWEB)
Aslan, E.; Bulut, N. [Department of Physics, Firat University, 23169 Elazig (Turkey); Castillo, J. F.; Banares, L.; Aoiz, F. J. [Departamento de Quimica Fisica I, Facultad de Ciencias Quimicas (Unidad Asociada CSIC), Universidad Complutense de Madrid, 28040 Madrid (Spain); Roncero, O., E-mail: jfernand@quim.ucm.es [Instituto de Fisica Fundamental, CSIC, C/Serrano 123, E-28006 Madrid (Spain)
2012-11-01
The dynamics and kinetics of the H{sup +} + LiH reaction have been studied using a quantum reactive time-dependent wave packet (TDWP) coupled-channel quantum mechanical method on an ab initio potential energy surface at conditions of the early universe. The total reaction probabilities for the H{sup +} + LiH(v = 0, j = 0) {yields} H{sup +} {sub 2} + Li process have been calculated from 5 Multiplication-Sign 10{sup -3} eV up to 1 eV for total angular momenta J from 0 to 110. Using a Langevin model, integral cross sections have been calculated in that range of collision energies and extrapolated for energies below 5 Multiplication-Sign 10{sup -3} eV. The calculated rate constants are found to be nearly independent of temperature in the 10-1000 K interval with a value of Almost-Equal-To 10{sup -9} cm{sup 3} s{sup -1}, which is in good agreement with estimates used in evolutionary models of the early universe lithium chemistry.
Entropy production and wave packet dynamics in the Fock space of closed chaotic many-body systems
Flambaum, V V
2001-01-01
Highly excited many-particle states in quantum systems such as nuclei, atoms, quantum dots, spin systems, quantum computers etc., can be considered as ``chaotic'' superpositions of mean-field basis states (Slater determinants, products of spin or qubit states). This is due to a very high level density of many-body states that are easily mixed by a residual interaction between particles (quasi-particles). For such systems, we have derived simple analytical expressions for the time dependence of energy width of wave packets, as well as for the entropy, number of principal basis components and inverse participation ratio, and tested them in numerical experiments. It is shown that the energy width $\\Delta (t)$ increases linearly and very quickly saturates. The entropy of a system increases quadratically, $S(t) \\sim t^2$ at small times, and after, can grow linearly, $S(t) \\sim t$, before the saturation. Correspondingly, the number of principal components determined by the entropy, $N_{pc} \\sim exp{(S(t))}$, or by ...
Toyota, Koudai
2016-10-01
The method of the envelope Hamiltonian [K. Toyota, U. Saalmann, and J. M. Rost, New J. Phys. 17, 073005 (2015), 10.1088/1367-2630/17/7/073005] is applied to further study a detachment dynamics of a model negative ion in one dimension in the high-frequency regime. This method is based on the Floquet approach, but the time dependency of an envelope function is explicitly kept for arbitrary pulse durations. Therefore, it is capable of describing not only a photon absorption or emission, but also a nonadiabatic transition which is induced by the time-varying envelope of the pulse. It was shown that the envelope Hamiltonian accurately retrieves the results obtained by the time-dependent Schrödinger equation, and the underlying physics were well understood by the adiabatic approximation based on the envelope Hamiltonian. In this paper, we explore two more aspects of the detachment dynamics, which were not considered in our previous work. First, we determine the features of both a spatial and temporal interference of photoelectron wave packets in a photon-absorption process. We conclude that both of the interference mechanisms are universal in ionization dynamics in the high-frequency regime. Second, we extract a pulse duration which maximizes a yield of the nonadiabatic transition as a function of a pulse duration. It is shown that it becomes maximum when the pulse duration is comparable to a time scale of an electron.
Wasilewski, W; Wasilewski, Wojciech
2005-01-01
We analyze quantum entanglement of Stokes light and atomic electronic polarization excited during single-pass, linear-regime, stimulated Raman scattering in terms of optical wave-packet modes and atomic-ensemble spatial modes. The output of this process is confirmed to be decomposable into multiple discrete, bosonic mode pairs, each pair undergoing independent evolution into a two-mode squeezed state. For this we extend the Bloch-Messiah reduction theorem, previously known for discrete linear systems (S. L. Braunstein, Phys. Rev. A, vol. 71, 055801 (2005)). We present typical mode functions in the case of one-dimensional scattering in an atomic vapor. We find that in the absence of dispersion, one mode pair dominates the process, leading to a simple interpretation of entanglement in this continuous-variable system. However, many mode pairs are excited in the presence of dispersion-induced temporal walkoff of the Stokes, as witnessed by the photon-count statistics. We also consider the readout of the stored at...
DEFF Research Database (Denmark)
Engel, Volker; Henriksen, Niels Engholm
2000-01-01
We consider femtosecond excitation of a molecule to a dissociative electronic state. The quantum dynamics is recorded via delayed excitation to a higher electronic state and measurement of the total fluorescence from this state detected as a function of delay time. It is shown that the signal can...
Directory of Open Access Journals (Sweden)
C. L. Fern
2007-02-01
Full Text Available The wave packets of atmospheric gravity waves were numerically generated, with a given characteristic wave period, horizontal wave length and projection mean wind along the horizontal wave vector. Their projection phase and group velocities along the oblique radar beam (vpr and vgr, with different zenith angle θ and azimuth angle φ, were analyzed by the method of phase- and group-velocity tracing. The results were consistent with the theoretical calculations derived by the dispersion relation, reconfirming the accuracy of the method of analysis. The RTI plot of the numerical wave packets were similar to the striation patterns of the QP echoes from the FAI irregularity region. We propose that the striation range rate of the QP echo is equal to the radial phase velocity vpr, and the slope of the energy line across the neighboring striations is equal to the radial group velocity vgr of the wave packet; the horizontal distance between two neighboring striations is equal to the characteristic wave period τ. Then, one can inversely calculate all the properties of the gravity wave responsible for the appearance of the QP echoes. We found that the possibility of some QP echoes being generated by the gravity waves originated from lower altitudes cannot be ruled out.
Goussev, Arseni; Dorfman, J R
2006-07-01
We consider the time evolution of a wave packet representing a quantum particle moving in a geometrically open billiard that consists of a number of fixed hard-disk or hard-sphere scatterers. Using the technique of multiple collision expansions we provide a first-principle analytical calculation of the time-dependent autocorrelation function for the wave packet in the high-energy diffraction regime, in which the particle's de Broglie wavelength, while being small compared to the size of the scatterers, is large enough to prevent the formation of geometric shadow over distances of the order of the particle's free flight path. The hard-disk or hard-sphere scattering system must be sufficiently dilute in order for this high-energy diffraction regime to be achievable. Apart from the overall exponential decay, the autocorrelation function exhibits a generally complicated sequence of relatively strong peaks corresponding to partial revivals of the wave packet. Both the exponential decay (or escape) rate and the revival peak structure are predominantly determined by the underlying classical dynamics. A relation between the escape rate, and the Lyapunov exponents and Kolmogorov-Sinai entropy of the counterpart classical system, previously known for hard-disk billiards, is strengthened by generalization to three spatial dimensions. The results of the quantum mechanical calculation of the time-dependent autocorrelation function agree with predictions of the semiclassical periodic orbit theory.
DEFF Research Database (Denmark)
Gerberding, Oliver; Diekmann, Christian; Kullmann, Joachim
2015-01-01
Precision phase readout of optical beat note signals is one of the core techniques required for inter-satellite laser interferometry. Future space based gravitational wave detectors like eLISA require such a readout over a wide range of MHz frequencies, due to orbit induced Doppler shifts......, with a precision in the order of µ rad/root Hz at frequencies between 0.1 mHz and 1 Hz. In this paper, we present phase readout systems, so-called phasemeters, that are able to achieve such precisions and we discuss various means that have been employed to reduce noise in the analogue circuit domain and during...... digitisation. We also discuss the influence of some non-linear noise sources in the analogue domain of such phasemeters. And finally, we present the performance that was achieved during testing of the elegant breadboard model of the LISA phasemeter, which was developed in the scope of a European Space Agency...
Study on the time-dependent wave packet of IBr molecule%IBr分子含时波包的理论探究
Institute of Scientific and Technical Information of China (English)
赵起; 刘瑞琼; 刘玉芳
2011-01-01
The simulation of time-resolved photoelectron spectra for Ibr molecule is studied mainly. The time-dependent quantum wave packet method is employed to calculate and analyze the photoelectron spectra of different delay times. The common characteristic of bimodal system and the phenomenon of more peaks are interpreted in reason using the theory of wave-packet and light-induced potentials. The reason why the peak decreases monotonically as the increases of delay-time is that the wave packet on the potential energy surface of A3 Ⅱ1 for dissociation make the oscillating of wave packet on the A3 Ⅱ1 curve to decrease. By analyzing the results further, we can conclude that the propagation of wave-packet is a decreasing process of energy. In addition, the competition between different ionization channels in the process of transition also have a certain impact on the energy spectrum.%本文主要对IBr分子的飞秒含时光电子能谱进行了模拟计算.运用含时量子波包方法,对不同延迟时间的光电子能谱进行模拟计算与理论分析.应用波包和光诱导势理论,对光电子能谱共同的两峰系特征及多峰现象给予合理解释.光电子能谱的峰值随延迟时间的增加而递减现象,是由于波包在A3Ⅱ1势能面上因分子解离发散,使整个波包在势能曲线上的振荡递减造成的.研究表明:波包的传播是一个能量减弱的过程；跃迁过程中不同电离通道之间的竞争,也对能谱存在一定的影响.
Ono, Junichi; Ando, Koji
2012-11-01
A semiquantal (SQ) molecular dynamics (MD) simulation method based on an extended Hamiltonian formulation has been developed using multi-dimensional thawed gaussian wave packets (WPs), and applied to an analysis of hydrogen-bond (H-bond) dynamics in liquid water. A set of Hamilton's equations of motion in an extended phase space, which includes variance-covariance matrix elements as auxiliary coordinates representing anisotropic delocalization of the WPs, is derived from the time-dependent variational principle. The present theory allows us to perform real-time and real-space SQMD simulations and analyze nuclear quantum effects on dynamics in large molecular systems in terms of anisotropic fluctuations of the WPs. Introducing the Liouville operator formalism in the extended phase space, we have also developed an explicit symplectic algorithm for the numerical integration, which can provide greater stability in the long-time SQMD simulations. The application of the present theory to H-bond dynamics in liquid water is carried out under a single-particle approximation in which the variance-covariance matrix and the corresponding canonically conjugate matrix are reduced to block-diagonal structures by neglecting the interparticle correlations. As a result, it is found that the anisotropy of the WPs is indispensable for reproducing the disordered H-bond network compared to the classical counterpart with the use of the potential model providing competing quantum effects between intra- and intermolecular zero-point fluctuations. In addition, the significant WP delocalization along the out-of-plane direction of the jumping hydrogen atom associated with the concerted breaking and forming of H-bonds has been detected in the H-bond exchange mechanism. The relevance of the dynamical WP broadening to the relaxation of H-bond number fluctuations has also been discussed. The present SQ method provides the novel framework for investigating nuclear quantum dynamics in the many
Heisenberg's wave packet reconsidered
Grabbe, J. Orlin
2005-01-01
This note shows that Heisenberg's choice for a wave function in his original paper on the uncertainty principle is simply a renormalized characteristic function of a stable distribution with certain restrictions on the parameters. Relaxing Heisenberg's restrictions leads to a more general formulation of the uncertainty principle. This reformulation shows quantum uncertainty can exist at a macroscopic level. These modifications also give rise to a new form of Schrodinger's wave equation as the...
Energy Technology Data Exchange (ETDEWEB)
Sacks, R.A.; Robinson, J.E.
1980-02-15
The time-dependent Schroedinger equation is integrated numerically to obtain the time evolution of an initially Gaussian packet in the presence of Eckart, truncated quadratic, and untruncated quadratic potentials. Potential and packet parameters are chosen with hydrogen interstitials in transition metals in mind and are varied over significant ranges. Use of the smooth, bounded Eckart potential eliminates the pronounced structure and the anomalous spreading reported previously for other potentials. An interesting transient feature of the scattered packet is found and discussed in terms of the Wigner time delay. Packet transmission coefficients are discussed, and a quasiclassical approximation is found to agree closely with the exact results.
Tan, Rui Shan; Yan, Wei; Lin, Shi Ying
2017-01-01
A computational study for the title reaction is carried out employing recent ab initio potential energy surface. J = 0 reaction probability is obtained using both quasiclassical trajectory (QCT) and wave packet methods. The total and state resolved integral as well as differential cross sections are also obtained by means of QCT method. Dynamics of the title reaction shows qualitative similarity with its isotopic counterpart, the H + CaCl reaction, but quantitatively, reactivity is significantly enhanced in the title reaction. In addition, the effect of initial rotational state excitation on H + CaCl reaction is investigated.
Doncheski, M. A.; Robinett, R. W.
2001-10-01
We discuss the time development of Gaussian wave packet solutions of the "quantum bouncer" (a quantum mechanical particle subject to a uniform downward force, above an impermeable flat surface). We focus on the evaluation and visualization of the expectation values and uncertainties of position and momentum variables during a single quasi-classical period as well as during the long-term collapsed phase and several revivals. This approach complements existing analytic and numerical analyses of this system, as well as being useful for comparison with similar results for the harmonic oscillator and infinite well cases.
Doncheski, M A
2001-01-01
We discuss the time development of Gaussian wave packet solutions of the quantum bouncer' (a quantum mechanical particle subject to a uniform downward force, above an impermeable flat surface). We focus on the evaluation and visualization of the expectation values and uncertainties of position and momentum variables during a single quasi-classical period as well as during the long term collapsed phase and several revivals. This approach complements existing analytic and numerical analyses of this system, as well as being useful for comparison with similar results for the harmonic oscillator and infinite well cases.
A Practical Theorem on Using Interferometry to Measure the Global 21-cm Signal
Venumadhav, Tejaswi; Chang, Tzu-Ching; Doré, Olivier; Hirata, Christopher M.
2016-08-01
The sky-averaged, or global, background of redshifted 21 cm radiation is expected to be a rich source of information on cosmological reheating and reionization. However, measuring the signal is technically challenging: one must extract a small, frequency-dependent signal from under much brighter spectrally smooth foregrounds. Traditional approaches to study the global signal have used single antennas, which require one to calibrate out the frequency-dependent structure in the overall system gain (due to internal reflections, for example) as well as remove the noise bias from auto-correlating a single amplifier output. This has motivated proposals to measure the signal using cross-correlations in interferometric setups, where additional calibration techniques are available. In this paper we focus on the general principles driving the sensitivity of the interferometric setups to the global signal. We prove that this sensitivity is directly related to two characteristics of the setup: the cross-talk between readout channels (i.e., the signal picked up at one antenna when the other one is driven) and the correlated noise due to thermal fluctuations of lossy elements (e.g., absorbers or the ground) radiating into both channels. Thus in an interferometric setup, one cannot suppress cross-talk and correlated thermal noise without reducing sensitivity to the global signal by the same factor—instead, the challenge is to characterize these effects and their frequency dependence. We illustrate our general theorem by explicit calculations within toy setups consisting of two short-dipole antennas in free space and above a perfectly reflecting ground surface, as well as two well-separated identical lossless antennas arranged to achieve zero cross-talk.
A practical theorem on using interferometry to measure the global 21-cm signal
Venumadhav, Tejaswi; Doré, Olivier; Hirata, Christopher M
2015-01-01
The sky-averaged, or global, background of redshifted 21-cm radiation is expected to be a rich source of information on the history of re-heating and re-ionization of the intergalactic medium. However, measuring the signal is technically challenging: one must extract the small, frequency-dependent signal from under the much brighter spectrally smooth foregrounds. Traditional approaches to study the global signal have used single-antenna systems, where one must calibrate out frequency-dependent structure in the overall system gain (due e.g. to internal reflections) as well as remove the noise bias from auto-correlating a single amplifier output. This has motivated several proposals to measure the global background using interferometric setups, where the signal appears in cross-correlation and where additional calibration techniques are available. In this paper, we focus on the general principles that drive the sensitivity of any interferometric setup to the global signal. In particular, we prove that this sens...
Low noise amplication of an optically carried microwave signal: application to atom interferometry
Lévèque, Thomas; Chaibi, Walid; Landragin, Arnaud
2010-01-01
In this paper, we report a new scheme to amplify a microwave signal carried on a laser light at $\\lambda$=852nm. The amplification is done via a semiconductor tapered amplifier and this scheme is used to drive stimulated Raman transitions in an atom interferometer. Sideband generation in the amplifier, due to self-phase and amplitude modulation, is investigated and characterized. We also demonstrate that the amplifier does not induce any significant phase-noise on the beating signal. Finally, the degradation of the performances of the interferometer due to the amplification process is shown to be negligible.
Low noise amplification of an optically carried microwave signal: application to atom interferometry
Lévèque, T.; Gauguet, A.; Chaibi, W.; Landragin, A.
2010-12-01
In this paper, we report a new scheme to amplify a microwave signal carried on a laser light at λ=852 nm. The amplification is done via a semiconductor tapered amplifier and this scheme is used to drive stimulated Raman transitions in an atom interferometer. Sideband generation in the amplifier, due to self-phase and amplitude modulation, is investigated and characterized. We also demonstrate that the amplifier does not induce any significant phase-noise on the beating signal. Finally, the degradation of the performances of the interferometer due to the amplification process is shown to be negligible.
Energy Technology Data Exchange (ETDEWEB)
Koner, Debasish; Panda, Aditya N., E-mail: adi07@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Barrios, Lizandra; González-Lezana, Tomás, E-mail: t.gonzalez.lezana@csic.es [Instituto de Física Fundamental, C.S.I.C., Serrano 123, Madrid 28006 (Spain)
2014-09-21
A real wave packet based time-dependent method and a statistical quantum method have been used to study the He + NeH{sup +} (v, j) reaction with the reactant in various ro-vibrational states, on a recently calculated ab initio ground state potential energy surface. Both the wave packet and statistical quantum calculations were carried out within the centrifugal sudden approximation as well as using the exact Hamiltonian. Quantum reaction probabilities exhibit dense oscillatory pattern for smaller total angular momentum values, which is a signature of resonances in a complex forming mechanism for the title reaction. Significant differences, found between exact and approximate quantum reaction cross sections, highlight the importance of inclusion of Coriolis coupling in the calculations. Statistical results are in fairly good agreement with the exact quantum results, for ground ro-vibrational states of the reactant. Vibrational excitation greatly enhances the reaction cross sections, whereas rotational excitation has relatively small effect on the reaction. The nature of the reaction cross section curves is dependent on the initial vibrational state of the reactant and is typical of a late barrier type potential energy profile.
Energy Technology Data Exchange (ETDEWEB)
Jakob, B.
2006-10-10
In this work the wave packet molecular dynamics (WPMD) is presented and applied to dense hydrogen. In the WPMD method the electrons are described by a slater determinant of periodic Gaussian wave packets. Each single particle wave function can parametrised through 8 coordinates which can be interpreted as the position and momentum, the width and its conjugate momentum. The equation of motion for these coordinates can be derived from a time depended variational principle. Properties of the equilibrium can be ascertained by a Monte Carlo simulation. With the now completely implemented antisymmetrisation the simulation yields a fundamental different behavior for dense hydrogen compare to earlier simplified models. The results show a phase transition to metallic hydrogen with a higher density than in the molecular phase. This behavior has e.g. a large implication to the physics of giant planets. This work describes the used model and explains in particular the calculation of the energy and forces. The periodicity of the wave function leads to a description in the Fourier space. The antisymmetrisation is done by Matrix operations. Moreover the numerical implementation is described in detail to allow the further development of the code. The results provided in this work show the equation of state in the temperature range 300K - 50000K an density 10{sup 23}-10{sup 24} cm{sup -3}, according a pressure 1 GPa-1000 GPa. In a phase diagram the phase transition to metallic hydrogen can be red off. The electrical conductivity of both phases is destined. (orig.)
Institute of Scientific and Technical Information of China (English)
陈召杭; 王德华; 程绍昊
2015-01-01
Using the combination of the time-dependent perturbation theory and the closed-orbit theory, we put forward a calculation formula for the autocorrelation function of H ion in a gradient electric field, and then calculate and analyze the autocorrelation function of the system. Especially, we discuss the effect of laser pulse width, electric field strength and the electric field gradient on the autocorrelation function of H ion in a gradient electric field. It is demonstrated that when the laser pulse width is very narrow, far less than the period of the detached electron, the quantum wave packet revival phenomenon is significant. A series of sharp reviving peaks appear in the autocorrelation function, which are caused by the interference between the returning electron wave packets travelling along the closed orbit and the outgoing electron wave packets. However, with the increase of laser pulse width, the quantum wave packet revival phenomenon becomes weakened. When the difference between the pulse width and the period of the closed orbit is not very large, the reviving peaks in the autocorrelation function become widely spread gradually and the oscillatory structures get flattened. This correspondence will vanish finally due to the interference between the adjacent peaks. In addition, our study also suggests that the background electric field strength and the electric field gradient in the gradient electric field can also have significant effects on the autocorrelation function. With the increase of background electric field strength and electric field gradient, the period of the detached electron’s closed orbit gets shorter, the number of the revival peaks in the autocorrelation function is increased gradually, and the quantum wave packet revival phenomenon will be enhanced. Therefore, we can control the autocorrelation function of the hydrogen negative ion by changing the laser pulse width and the external electric field strength. Our results will provide some
Yuan, T.; Heale, C. J.; Snively, J. B.; Cai, X.; Pautet, P.-D.; Fish, C.; Zhao, Y.; Taylor, M. J.; Pendleton, W. R.; Wickwar, V.; Mitchell, N. J.
2016-01-01
Gravity wave packets excited by a source of finite duration and size possess a broad frequency and wave number spectrum and thus span a range of temporal and spatial scales. Observing at a single location relatively close to the source, the wave components with higher frequency and larger vertical wavelength dominate at earlier times and at higher altitudes, while the lower frequency components, with shorter vertical wavelength, dominate during the latter part of the propagation. Utilizing observations from the Na lidar at Utah State University and the nearby Mesospheric Temperature Mapper at Bear Lake Observatory (41.9°N, 111.4°W), we investigate a unique case of vertical dispersion for a spectrally broad gravity wave packet in the mesopause region over Logan, Utah (41.7°N, 111.8°W), that occurred on 2 September 2011, to study the waves' evolution as it propagates upward. The lidar-observed temperature perturbation was dominated by close to a 1 h modulation at 100 km during the early hours but gradually evolved into a 1.5 h modulation during the second half of the night. The vertical wavelength also decreased simultaneously, while the vertical group and phase velocities of the packet apparently slowed, as it was approaching a critical level during the second half of the night. A two-dimensional numerical model is used to simulate the observed gravity wave processes, finding that the location of the lidar relative to the source can strongly influence which portion of the spectrum can be observed at a particular location relative to a source.
Feld, R.; Slob, E. C.; Thorbecke, J.
2015-12-01
Creating virtual sources at locations where physical receivers have measured a response is known as seismic interferometry. A much appreciated benefit of interferometry is its independence of the actual source locations. The use of ambient noise as actual source is therefore not uncommon in this field. Ambient noise can be commercial noise, like for example mobile phone signals. For GPR this can be useful in cases where it is not possible to place a source, for instance when it is prohibited by laws and regulations. A mono-static GPR antenna can measure ambient noise. Interferometry by auto-correlation (AC) places a virtual source on this antenna's position, without actually transmitting anything. This can be used for pavement damage inspection. Earlier work showed very promising results with 2D numerical models of damaged pavement. 1D and 2D heterogeneities were compared, both modelled in a 2D pavement world. In a 1D heterogeneous model energy leaks away to the sides, whereas in a 2D heterogeneous model rays can reflect and therefore still add to the signal reconstruction (see illustration). In the first case the amount of stationary points is strictly limited, while in the other case the amount of stationary points is very large. We extend these models to a 3D world and optimise an experimental configuration. The illustration originates from the journal article under submission 'Non-destructive pavement damage inspection by mono-static GPR without transmitting anything' by R. Feld, E.C. Slob, and J.W. Thorbecke. (a) 2D heterogeneous pavement model with three irregular-shaped misalignments between the base and subbase layer (marked by arrows). Mono-antenna B-scan positions are shown schematically. (b) Ideal output: a real source at the receiver's position. The difference w.r.t. the trace found in the middle is shown. (c) AC output: a virtual source at the receiver's position. There is a clear overlap with the ideal output.
两种扩展Harper模型的波包动力学%Wave packet dynamics of two extended Harper models
Institute of Scientific and Technical Information of China (English)
张振俊; 于淼; 巩龙龚; 童培庆
2011-01-01
We study the wave packet dynamics of two extended Harper models by using the second moment M2（t）and probability distribution Wn（t） numerically. The dynamical behaviors of two extended Harper models in all phases, on all phase boundary lines, and at the bicritical points are studied. For the first extended Harper model, we find that the wave packet is of ballistic diffusion in two metal phases, localized in the insulator phase, and of anomalous diffusion on the phase boundary lines and at the bicritical point. We also find the dynamical behavior on the boundary line of the metal-metal phase transition is the same as that on the metal-insulator phase transition. The spreading at the bicritical point is different from that on the phase boundary lines. For the second extended Harper model, we find that the wave packet is of ballistic diffusion in the metal phase, localized in the insulator phase, and of anomalous diffusion in the critical phase, on the phase boundary lines, and at the bicritical point. We also find the dynamical behavior on the boundary line of the critical-metal phase transition is similar to that at the bicritical point and the critical-insulator phase transition, but different from that of the metal-insulator phase transition.%本文通过二次矩M2（t）和概率分布Wn（t）数值地研究了两种扩展Harper模型的波包动力学,得到了这两种模型中各个相、各条临界线以及三相点的波包扩散情况.对于第一种扩展Harper模型,发现两个金属相中波包是弹道扩散的,在绝缘体相中波包不扩散,而在三相点以及各条临界线上波包是反常扩散的.同时,发现金属相—金属相转变的临界线上的波包动力学行为与金属相—绝缘体相转变的临界线上的相同,但三相点的动力学行为与各临界线上的不同;对于第二种扩展Harper模型,发现金属相中波包是弹道扩散的,在绝缘体相中波包不扩散,而在临界相、三相点、
Chen, Cao; Chu, Xinzhao
2017-09-01
Waves in the atmosphere and ocean are inherently intermittent, with amplitudes, frequencies, or wavelengths varying in time and space. Most waves exhibit wave packet-like properties, propagate at oblique angles, and are often observed in two-dimensional (2-D) datasets. These features make the wavelet transforms, especially the 2-D wavelet approach, more appealing than the traditional windowed Fourier analysis, because the former allows adaptive time-frequency window width (i.e., automatically narrowing window size at high frequencies and widening at low frequencies), while the latter uses a fixed envelope function. This study establishes the mathematical formalism of modified 1-D and 2-D Morlet wavelet transforms, ensuring that the power of the wavelet transform in the frequency/wavenumber domain is equivalent to the mean power of its counterpart in the time/space domain. Consequently, the modified wavelet transforms eliminate the bias against high-frequency/small-scale waves in the conventional wavelet methods and many existing codes. Based on the modified 2-D Morlet wavelet transform, we put forward a wave recognition methodology that automatically identifies and extracts 2-D quasi-monochromatic wave packets and then derives their wave properties including wave periods, wavelengths, phase speeds, and time/space spans. A step-by-step demonstration of this methodology is given on analyzing the lidar data taken during 28-30 June 2014 at McMurdo, Antarctica. The newly developed wave recognition methodology is then applied to two more lidar observations in May and July 2014, to analyze the recently discovered persistent gravity waves in Antarctica. The decomposed inertia-gravity wave characteristics are consistent with the conclusion in Chen et al. (2016a) that the 3-10 h waves are persistent and dominant, and exhibit lifetimes of multiple days. They have vertical wavelengths of 20-30 km, vertical phase speeds of 0.5-2 m/s, and horizontal wavelengths up to several
Iterative supervirtual refraction interferometry
Al-Hagan, Ola
2014-05-02
In refraction tomography, the low signal-to-noise ratio (S/N) can be a major obstacle in picking the first-break arrivals at the far-offset receivers. To increase the S/N, we evaluated iterative supervirtual refraction interferometry (ISVI), which is an extension of the supervirtual refraction interferometry method. In this method, supervirtual traces are computed and then iteratively reused to generate supervirtual traces with a higher S/N. Our empirical results with both synthetic and field data revealed that ISVI can significantly boost up the S/N of far-offset traces. The drawback is that using refraction events from more than one refractor can introduce unacceptable artifacts into the final traveltime versus offset curve. This problem can be avoided by careful windowing of refraction events.
Institute of Scientific and Technical Information of China (English)
高洁; 房丽敏; 李华刚; 麦志杰
2012-01-01
Dispersion relation of 1-D photonic crystal is deduced by the method of transfer matrix, with coordinate transformation of arbitrary Fourier exponent of electromagnetic wave packet which is obliquely incident. By analyzing the dispersion relation, it is easy to find the difference between the first band gap under obliquely incident wave packet and that of plane wave, respectively. Meanwhile, the former gap is located in the latter one, for the former one is narrower than the latter one in width. Characteristic of band gap is obtained under obliquely incident wave packet, by comparing the first band gap structure with that of plane wave considering edge position and width of the gap. The condition of approximately substituting plane wave for wave packet to calculate band gap is analyzed, according to related factors such as different incident angle of central wave vector and angle spectrum of wave packet. The results demonstrate that the first band gap structure is closely related to incident angle of central wave vector and angle spectrum of wave packet. With smaller incident angle, the first band gap structure caused by wave packet would become closer to that of plane wave; and with smaller angle spectrum of wave packet, the width and position of the first band gap is closer to those of plane wave.%对波包的任意傅里叶分量进行坐标变换后,利用转移矩阵法推导出波包斜入射情形下一维光子晶体的色散关系表达式,利用色散关系曲线分析得出波包斜入射的第一带隙结构,与以往平面波的第一带隙结构不同,波包的带隙宽度小于平面波的带隙宽度,并且在位置上前者带隙包含在后者内部.比较了一维光子晶体分别在波包入射与平面波入射情形下带隙位置和宽度,分析了波包中心入射角的变化以及波包的角分布范围的变化对带隙结构的影响,得到了一维光子晶体对波包斜入射的带隙结构的基本特征,确定了计算波包带
Ghosh, Sandip; Sahoo, Tapas; Adhikari, Satrajit; Sharma, Rahul; Varandas, António J C
2015-12-17
We implement a coupled three-dimensional (3D) time-dependent wave packet formalism for the 4D reactive scattering problem in hyperspherical coordinates on the accurate double many body expansion (DMBE) potential energy surface (PES) for the ground and first two singlet states (1(1)A', 2(1)A', and 3(1)A') to account for nonadiabatic processes in the D(+) + H2 reaction for both zero and nonzero values of the total angular momentum (J). As the long-range interactions in D(+) + H2 contribute significantly due to nonadiabatic effects, the convergence profiles of reaction probabilities for the reactive noncharge transfer (RNCT), nonreactive charge transfer (NRCT), and reactive charge transfer (RCT) processes are shown for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. The total and state-to-state cross sections are presented as a function of the collision energy for the initial rovibrational state v = 0, j = 0 of the diatom, and the calculated cross sections compared with other theoretical and experimental results.
Demekhin, Philipp V; Cederbaum, Lorenz S
2013-01-01
The time-dependent Schr\\"{o}dinger equation for the hydrogen atom and its interaction with coherent intense high-frequency short laser pulses is solved numerically exactly by employing the code implemented for the multi-configurational time-dependent Hartree-Fock (MCTDHF) method. Thereby, the wavefunction is followed in space and time for times longer than the pulse duration. Results are explicitly shown for 3 and 10 fs pulses. Particular attention is paid to identifying the effect of dynamic interference of photoelectrons emitted with the same kinetic energy at different times during the rising and falling sides of the pulse predicted in [\\emph{Ph.V. Demekhin and L.S. Cederbaum}, Phys. Rev. Lett. \\textbf{108}, 253001 (2012)]. In order to be able to see the dynamic interference pattern in the computed electron spectra, the photoelectron wave packet has to be propagated over long distances. Clearly, complex absorption potentials often employed to compute spectra of emitted particles cannot be used to detect dy...
Indian Academy of Sciences (India)
Farzana Sharmin; Samir Saha; S S Bhattacharyya
2013-06-01
We have theoretically investigated the high harmonic generation (HHG) spectra of H$_{2}^{+}$ and HD+ using a time-dependent wave packet approach for the nuclear motion with pulsed lasers of peak intensities (0) of 3.5 × 1014 and 4.5 × 1014 W/cm2, wavelengths (L) of 800 and 1064 nm, and pulse durations () of 40 and 50 fs, for initial vibrational levels 0 = 0 and 1. We have argued that for these conditions the harmonic generation due to the transitions in the electronic continuum by tunnelling or multiphoton ionization will not be important. Thus, the characteristic features of HHG spectra in our model arise only due to the nuclear motions on the two lowest field-coupled electronic states between which both interelectronic and intraelectronic (due to intrinsic dipole moments, for HD+) radiative transitions can take place. For HD+, the effect of nonadiabatic (NA) interaction between the two lowest Born–Oppenheimer (BO) electronic states has been taken into account and comparison has been made with the HHG spectra of HD+ obtained in the BO approximation. Even harmonics and a second plateau in the HHG spectra of HD+ with the NA interaction and hyper-Raman lines in the spectra of both H$_{2}^{+}$ and HD+ for 0 = 1 have been observed for higher value of 0 or L. Our calculations indicate reasonable efficiencies of harmonic generation even without involving the electronic continuum.
van Harrevelt, Rob; van Hemert, Marc C.
2000-04-01
A complete three-dimensional quantum mechanical description of the photodissociation of water in the B˜ band, starting from its rotational ground state, is presented. In order to include B˜-X˜ vibronic coupling and the B˜-Ã Renner-Teller coupling, diabatic electronic states have been constructed from adiabatic electronic states and matrix elements of the electronic angular momentum operators, following the procedure developed by A. J. Dobbyn and P. J. Knowles [Mol. Phys. 91, 1107 (1997)], using the ab initio results discussed in the preceding paper. The dynamics is studied using wave packet methods, and the evolution of the time-dependent wave function is discussed in detail. Results for the H2O and D2O absorption spectra, OH(A)/OH(X) and OD(A)/OD(X) branching ratios, and rovibrational distributions of the OH and OD fragments are presented and compared with available experimental data. The present theoretical results agree at least qualitatively with the experiments. The calculations show that the absorption spectrum and the product state distributions are strongly influenced by long-lived resonances on the adiabatic B˜ state. It is also shown that molecular rotation plays an important role in the photofragmentation process, due to both the Renner-Teller B˜-X˜ mixing, and the strong effect of out-of-plane molecular rotations (K>0) on the dynamics at near linear HOH and HHO geometries.
Juanes-Marcos, Juan Carlos; Althorpe, Stuart C
2005-05-22
We report quantum wave-packet calculations on the H+H(2) reaction, aimed at resolving the controversy over whether geometric phase (GP) effects can be observed in this reaction. Two sets of calculations are reported of the state-to-state reaction probabilities, and integral and differential cross sections (ICSs and DCSs). One set includes the GP using the vector potential approach of Mead and Truhlar; the other set neglects the phase. We obtain unequivocal agreement with recent results of Kendrick [J. Phys. Chem. A 107, 6739 (2003)], predicting GP effects in the state-to-state reaction probabilities, which cancel exactly on summing the partial waves to yield the ICS. Our results therefore contradict those of Kuppermann and Wu [Chem. Phys. Lett. 349 537 (2001)], which predicted pronounced GP effects in the cross sections. We also agree with Kendrick in predicting that there are no significant GP effects in the full DCS at energies below 1.8 eV, and in the partial (0
Indian Academy of Sciences (India)
Raman Kumar Singh; Manabendra Sarma; Ankit Jain; Satrajit Adhikari; Manoj K Mishra
2007-09-01
Results from application of a new implementation of the time-dependent wave packet (TDWP) approach to the calculation of vibrational excitation cross-sections in resonant e-CO scattering are presented to examine its applicability in the treatment of e-molecule resonances. The results show that the SCF level local complex potential (LCP) in conjunction with the TDWP approach can reproduce experimental features quite satisfactorily.
Bharadwaj, P.
2013-01-10
The theory of supervirtual interferometry is modified so that free-surface related multiple refractions can be used to enhance the signal-to-noise ratio (SNR) of primary refraction events by a factor proportional to√Ns, where Ns is the number of post-critical sources for a specified refraction multiple. We also show that refraction multiples can be transformed into primary refraction events recorded at virtual hydrophones located between the actual hydrophones. Thus, data recorded by a coarse sampling of ocean bottom seismic (OBS) stations can be transformed, in principle, into a virtual survey with P times more OBS stations, where P is the order of the visible free-surface related multiple refractions. The key assumption is that the refraction arrivals are those of head waves, not pure diving waves. The effectiveness of this method is validated with both synthetic OBS data and an OBS data set recorded offshore from Taiwan. Results show the successful reconstruction of far-offset traces out to a source-receiver offset of 120 km. The primary supervirtual traces increase the number of pickable first arrivals from approximately 1600 to more than 3100 for a subset of the OBS data set where the source is only on one side of the recording stations. In addition, the head waves associated with the first-order free-surface refraction multiples allow for the creation of six new common receiver gathers recorded at virtual OBS station located about half way between the actual OBS stations. This doubles the number of OBS stations compared to the original survey and increases the total number of pickable traces from approximately 1600 to more than 6200. In summary, our results with the OBS data demonstrate that refraction interferometry can sometimes more than quadruple the number of usable traces, increase the source-receiver offsets, fill in the receiver line with a denser distribution of OBS stations, and provide more reliable picking of first arrivals. Apotential liability
Fraternale, Federico
2013-01-01
The present thesis deals with the non-modal linear analysis of 3D perturbations in wall flows. In the first part,a solution to the Orr-Sommerfeld and Squire IVP, in the form of orthogonal functions expansion, is researched. The Galerkin method is successfully implemented to numerically compute approximate solutions for bounded flows. The Chandrasekhar functions revealed to ensure a fifth order of accuracy. The focus of the subsequent analysis is on the transient behavior of the perturbation frequency and phase velocity. The results confirm recent observations about a jump in the temporal evolution of the frequency of the wall-normal velocity signal, considered as the end of an Early Transient. After this jump, the wave frequency for Plane Couette flow experiences a periodic modulation about the asymptotic value, which is motivated and investigated in detail. A new result is the presence of a second frequency jump for the wall-normal vorticity. This fact, together with the possibility for different values of t...
Wu, Hui; Duan, Zhi-Xin; Yin, Shu-Hui; Zhao, Guang-Jiu
2016-09-01
The quantum dynamics calculations of the H + HS (v = 0, j = 0) reaction on the 3A' and 3A″ potential energy surfaces (PESs) are performed using the reactant coordinate based time-dependent wave packet method. State-averaged and state-resolved results for both channels of the title reaction are presented in the 0.02-1.0 eV collision energy range and compared with those carried out with quasi-classical trajectory (QCT) method. Total integral cross sections (ICSs) for both channels are in excellent agreement with previous quantum mechanical (QM)-Coriolis coupling results while poorly agree with the QCT ICSs of the exchange channel, particularly near the threshold energy region. The product rotational distributions show that for the abstraction channel, the agreement between our QM and the QCT results improves with increasing collision energy. For the exchange channel, our calculations predict colder rotational distributions as compared to those obtained by QCT calculations. Although the QM total differential cross sections (DCSs) are in qualitatively good agreement with the QCT results, the two sets of the state-to-state DCSs with several peaks exhibit great divergences. The origin of the divergences are traced by analyzing the QM DCS for the H + HS (v = 0, j = 0) → H2 (v' = 0, j' = 0) + S reaction on the 3A″ PES at Ec = 1.0 eV. It is discovered that several groups of J partial waves are involved in the reaction and the shape of the DCS is greatly altered by quantum interferences between them.
Rivero Santamaría, Alejandro; Dayou, Fabrice; Rubayo-Soneira, Jesus; Monnerville, Maurice
2017-02-15
The dynamics of the Si((3)P) + OH(X(2)Π) → SiO(X(1)Σ(+)) + H((2)S) reaction is investigated by means of the time-dependent wave packet (TDWP) approach using an ab initio potential energy surface recently developed by Dayou et al. ( J. Chem. Phys. 2013 , 139 , 204305 ) for the ground X(2)A' electronic state. Total reaction probabilities have been calculated for the first 15 rotational states j = 0-14 of OH(v=0,j) at a total angular momentum J = 0 up to a collision energy of 1 eV. Integral cross sections and state-selected rate constants for the temperature range 10-500 K were obtained within the J-shifting approximation. The reaction probabilities display highly oscillatory structures indicating the contribution of long-lived quasibound states supported by the deep SiOH/HSiO wells. The cross sections behave with collision energies as expected for a barrierless reaction and are slightly sensitive to the initial rotational excitation of OH. The thermal rate constants show a marked temperature dependence below 200 K with a maximum value around 15 K. The TDWP results globally agree with the results of earlier quasi-classical trajectory (QCT) calculations carried out by Rivero-Santamaria et al. ( Chem. Phys. Lett. 2014 , 610-611 , 335 - 340 ) with the same potential energy surface. In particular, the thermal rate constants display a similar temperature dependence, with TDWP values smaller than the QCT ones over the whole temperature range.
The Sagnac effect: 20 years of development in matter-wave interferometry
Barrett, Brynle; Dutta, Indranil; Meunier, Matthieu; Canuel, Benjamin; Gauguet, Alexandre; Bouyer, Philippe; Landragin, Arnaud
2014-01-01
Since the first atom interferometry experiments in 1991, measurements of rotation through the Sagnac effect in open-area atom interferometers has been studied. These studies have demonstrated very high sensitivity which can compete with state-of-the-art optical Sagnac interferometers. Since the early 2000s, these developments have been motivated by possible applications in inertial guidance and geophysics. Most matter-wave interferometers that have been investigated since then are based on two-photon Raman transitions for the manipulation of atomic wave packets. Results from the two most studied configurations, a space-domain interferometer with atomic beams and a time-domain interferometer with cold atoms, are presented and compared. Finally, the latest generation of cold atom interferometers and their preliminary results are presented.
Roura, Albert
2015-01-01
Atom interferometry tests of universality of free fall based on the differential measurement of two different atomic species provide a useful complement to those based on macroscopic masses. However, when striving for the highest possible sensitivities, gravity gradients pose a serious challenge. Indeed, the relative initial position and velocity for the two species need to be controlled with extremely high accuracy, which can be rather demanding in practice and whose verification may require rather long integration times. Furthermore, in highly sensitive configurations gravity gradients lead to a drastic loss of contrast. These difficulties can be mitigated by employing wave packets with narrower position and momentum widths, but this is ultimately limited by Heisenberg's uncertainty principle. We present a novel scheme that simultaneously overcomes the loss of contrast and the initial co-location problem. In doing so, it circumvents the fundamental limitations due to Heisenberg's uncertainty principle and e...
Wave Packets can Factorize Numbers
Mack, H; Haug, F; Freyberger, M; Schleich, W P; Mack, Holger; Bienert, Marc; Haug, Florian; Freyberger, Matthias; Schleich, Wolfgang P.
2002-01-01
We draw attention to various aspects of number theory emerging in the time evolution of elementary quantum systems with quadratic phases. Such model systems can be realized in actual experiments. Our analysis paves the way to a new, promising and effective method to factorize numbers.
Resonant mode for gravitational wave detectors based on atom interferometry
Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.; Rajendran, Surjeet
2016-11-01
We describe an atom interferometric gravitational wave detector design that can operate in a resonant mode for increased sensitivity. By oscillating the positions of the atomic wave packets, this resonant detection mode allows for coherently enhanced, narrow-band sensitivity at target frequencies. The proposed detector is flexible and can be rapidly switched between broadband and narrow-band detection modes. For instance, a binary discovered in broadband mode can subsequently be studied further as the inspiral evolves by using a tailored narrow-band detector response. In addition to functioning like a lock-in amplifier for astrophysical events, the enhanced sensitivity of the resonant approach also opens up the possibility of searching for important cosmological signals, including the stochastic gravitational wave background produced by inflation. We give an example of detector parameters which would allow detection of inflationary gravitational waves down to ΩGW˜10-14 for a two-satellite space-based detector.
Interferometry with Bose-Einstein Condensates in Microgravity
Müntinga, H; Krutzik, M; Wenzlawski, A; Arnold, S; Becker, D; Bongs, K; Dittus, H; Duncker, H; Gaaloul, N; Gherasim, C; Giese, E; Grzeschik, C; Hänsch, T W; Hellmig, O; Herr, W; Herrmann, S; Kajari, E; Kleinert, S; Lämmerzahl, C; Lewoczko-Adamczyk, W; Malcolm, J; Meyer, N; Nolte, R; Peters, A; Popp, M; Reichel, J; Roura, A; Rudolph, J; Schiemangk, M; Schneider, M; Seidel, S T; Sengstock, K; Tamma, V; Valenzuela, T; Vogel, A; Walser, R; Wendrich, T; Windpassinger, P; Zeller, W; van Zoest, T; Ertmer, W; Schleich, W P; Rasel, E M
2013-01-01
Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Due to their unique coherence properties, Bose-Einstein condensates are ideal sources for an atom interferometer in extended free fall. In this paper we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far-field of a double-slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.
Institute of Scientific and Technical Information of China (English)
关大任; 赵显; 邓从豪; John Z.H.Zhang
1997-01-01
Three-dimensional quantum mechanical calculations for vibrational predissociation of HeI2(B) van der Waals molecules are presented using the time-dependent wave packet technique within the golden rule approxima tion.The total and partial decay widths,lifetimes,rates and their dependence on initial vibrational states were obtained for HeI2 at low initial vibrational excited levels.Our calculations show that the calculated tota decay widths,lifetimes and rates agree well with those extrapolated from experimental data available The predicted total decay widths as a function of initial vibrational states exhibit highly nonlinear behavior.The very short propagation time (less.than 1 ps) required in the golden rule wave packet calculation is determined by the duration time of the final state inter-action between the fragments on the vibrationally deexcited adiabatic potential surface.The final state interaction between the fragments is shown to play an important role in determining the final rotational distri
Unbalanced Michelson's interferometer as a fiber optic distributed sensor of external signals
Chojnacki, M.; Szustakowski, Mieczyslaw; Zyczkowski, Marek
2001-08-01
The subject of this work is a novel fiber optic distributed sensor system. The system uses a technique called multiplexed reflectometric interferometry to measure dynamic strain in a network of single mode optical fiber sensors. The sensor is constructed on unbalanced fiber optic Michelson's interferometer is activated by series of double pulse. The time interval between those pulses depends on the length of the section of sensor. Acousto-optical modulator acts as an optical frequency shifter. A change in a frequency of electrical pulses exciting the modulator result in a frequency shift in each generated wave packet.
Yao, Cui-Xia; Zhang, Pei-Yu
2014-07-10
The dynamics of the Ne + D2(+) (v0 = 0-2, j0 = 0) → NeD(+) + D reaction has been investigated in detail by using an accurate time-dependent wave-packet method on the ground 1(2)A' potential energy surface. Comparisons between the Coriolis coupling results and the centrifugal-sudden ones reveal that Coriolis coupling effect can influence reaction dynamics of the NeD2(+) system. Integral cross sections have been evaluated for the Ne + D2(+) reaction and its isotopic variant Ne + H2(+), and a considerable intermolecular isotopic effect has been found. Also obvious is the great enhancement of the reactivity due to the reagent vibrational excitation. Besides, a comparison with previous theoretical results is also presented and discussed.
Energy Technology Data Exchange (ETDEWEB)
Mouret, L
2002-11-01
The thesis concerns the development and implementation of numerical methods for solving the time-dependent Schroedinger equation. We first considered the case of electron-hydrogen scattering. The originality of our method is the use of a non-uniform radial grid defined by a Schwarz interpolation based on a Coulomb reference function. This grid allows many hydrogen bound states and associated matrix elements of various operators to be reproduced to machine accuracy. The wave function is propagated in time using a Split-Operator method. The efficiency of our method allows the wave function to be propagated out to large distances for all partial waves. We obtain excitation and ionization cross sections in excellent agreement with the best experimental and theoretical data. We subsequently adapted the method and the program package to study reactive atom-dihydrogen scattering. The wave packet is described using product Jacobi coordinates on a regular grid of radial coordinates combined with a basis of Legendre polynomials for the angular part (partial wave S). The wave function is analysed using a time-to-energy Fourier transform, which provides results over the energy range covered by the initial wave packet in one calculation. The method was first tested on the quasi-direct (F,H2) reaction and then applied to the indirect (C(1D),H2)reaction. The state-to-state reaction probabilities are in good agreement with those obtained by a time-independent approach. In particular, the strongly resonant structure of the (C(1D),H2) reaction probabilities is well reproduced. (author)
Synthetic Aperture Radar Interferometry
Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.
1998-01-01
Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.
Optical Intensity Interferometry through Atmospheric Turbulence
Tan, Peng Kian; Kurtsiefer, Christian
2015-01-01
Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using orbital platforms outside the atmosphere. One of the promises of optical intensity interferometry is its independence from atmospherically induced phase fluctuations. By performing narrowband spectral filtering on sunlight and conducting temporal intensity interferometry using actively quenched avalanche photon detectors (APDs), the Solar $g^{(2)}(\\tau)$ signature was directly measured. We observe an averaged photon bunching signal of $g^{(2)}(\\tau) = 1.693 \\pm 0.003$ from the Sun, consistently throughout the day despite fluctuating weather conditions, cloud cover and elevation angle. This demonstrates the robustness of the intensity interferometry technique against atmospheric turbulence and opto-mechanical instabilities, and the feasibility to implement measurement scheme...
Optical intensity interferometry through atmospheric turbulence
Tan, P. K.; Chan, A. H.; Kurtsiefer, C.
2016-04-01
Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using orbital platforms outside the atmosphere. One of the promises of optical intensity interferometry is its independence from atmospherically induced phase fluctuations. By performing narrow-band spectral filtering on sunlight and conducting temporal intensity interferometry using actively quenched avalanche photodiodes, the Solar g(2)(τ) signature was directly measured. We observe an averaged photon bunching signal of g(2)(τ) = 1.693 ± 0.003 from the Sun, consistently throughout the day despite fluctuating weather conditions, cloud cover and elevation angle. This demonstrates the robustness of the intensity interferometry technique against atmospheric turbulence and opto-mechanical instabilities, and the feasibility to implement measurement schemes with both large baselines and long integration times.
Progress in electron- and ion-interferometry
Energy Technology Data Exchange (ETDEWEB)
Hasselbach, Franz [Institut fuer Angewandte Physik der Universitaet Tuebingen, Auf der Morgenstelle 10, D-72076 Tuebingen (Germany)], E-mail: franz.hasselbach@uni-tuebingen.de
2010-01-15
. In the context of holography, methods have been developed to record holograms without modulation of the biprism fringes by waves diffracted at the edges of the biprism filament. This simplifies the reconstruction of holograms and the evaluation of interferograms (taken, e.g. to extract a spectrum by Fourier analysis of the fringe system) significantly. A major section is devoted to the influence of electromagnetic and gravito-inertial potentials and fields on the quantum mechanical phase of matter waves: the Aharonov-Bohm effect, the inertial Aharonov-Bohm effect and its realization, the Sagnac effect and Sagnac experiments with atoms, superfluid helium, Bose-Einstein condensates, electrons and ions and their potential as rotation sensors are discussed. Moellenstedt and Wohland discovered in a crossed beam analyzer (Wien filter) an optical element for charged particles that shifts wave packets longitudinally that transverse a Wien filter on laterally separated paths. This new optical element rendered it possible to measure coherence lengths and the spectrum of charged particle waves by visibility- and Fourier-spectroscopy, to perform a 'Welcher Weg' experiment, to re-establish seemingly lost longitudinal coherence in an interferometer for charged particles and to realize a decoherence free quantum eraser. A precision test of decoherence according to a proposal from Anglin and Zurek and biprism interferences with helium atoms close the section on first-order coherence experiments. The topics of the last section are Hanbury Brown-Twiss correlations and an antibuching experiment of free electrons.
Lu, Ruifeng; Wang, Yunhui; Deng, Kaiming
2013-07-30
The quantum mechanics (QM) and quasiclassical trajectory (QCT) calculations have been carried out for the title reaction with the ground minimal allowed rotational state of CH (j = 1) on the 1 (1)A' potential energy surface. For the reaction probability at total angular momentum J = 0, a similar trend of the QM and QCT calculations is observed, and the QM results are larger than the latter almost in the whole considered energy range (0.1-1.5 eV). The QCT integral cross sections are larger than the QM results with centrifugal sudden approximation, while smaller than those from QM method including Coriolis coupling for collision energies bigger than 0.25 eV. The quantum wave-packet computations show that the Coriolis coupling effects get more and more pronounced with increasing of J. In addition to the scalar properties, the stereodynamical properties, such as the average rotational alignment factor , the angular distributions P(θr ), P(ϕr ), P(θr ,ϕr ), and the polarization-dependent generalized differential cross sections have been explored in detail by QCT approach.
Institute of Scientific and Technical Information of China (English)
Shuang-jiang Lv; Pei-yu Zhang; Guo-zhong He
2012-01-01
A new potential energy surface is presented for the triplet state 3A' of the chemical reaction S(3P)+H2 from a set of accurate ab initio data.The single point energies are computed using highly correlated complete active space self-consistent-field and multi-reference configuration interaction wave functions with a basis set of aug-cc-pV5Z.We have fitted the full set of energy values using many-body expansion method with an Aguado-Paniagua function.Based on the new potential energy surface,we carry out the time-dependent wave packet scattering calculations over the collision energy range of 0.8-2.2 eV.Both the centrifugalsudden approximation and Coriolis Coupling cross sections are obtained.In addition,the total reaction probabilities are calculated for the reactant H2 initially in the vibrational states v=0-3 (j=0).It is found that initial vibrational excitation enhances the title reaction.
Wu, Hui; Liang, Dongyue; Zhang, Pei-Yu
2015-05-01
The state-to-state quantum dynamics of the abstraction channel of S(3P) + H2(v = 0, j = 0) reaction is studied on the potential energy surface (PES) constructed by Lv et al. (2012), utilizing the product Jacobi coordinate based time-dependent wave packet method. Reaction probabilities and total integral cross section (ICS) agree well with previous results (Lv et al., 2012) for collision energies ranging from 0.8 to 1.4 eV. Results show that total differential cross sections (DCSs) for small collision energies have backward structures, whereas those for large collision energies are sideways peaked. Although the summed-over-all-final-state DCS for single collision energy is smoothly varied, the DCS of the product HS of a selected final state shows strong oscillations. For the selected final state, the opacity function derived by reaction probability multiplied by (2J + 1), shows that different mechanisms relevant to several sets of J partial waves lead to the maxima in the differential cross section in the collision process.
Yuan, Jiuchuang; Cheng, Dahai; Sun, Zhigang; Chen, Maodu
2014-11-01
The time-dependent quantum wave packet (TDWP) and quasiclassical trajectory calculations (QCT) are carried out for the Au(2S) + H2(X1∑+g) → AuH(X1∑+g) + H(2S) reaction on a global potential energy surface. The reaction probabilities at a series of J values, integral cross sections (ICSs) and differential cross sections of the title reaction are calculated by the TDWP method. For reaction probabilities, there are a mass of sharp oscillations at low collision energy, which can be attributed to resonances supported by the potential well. Due to the endothermicity of the title reaction, the total ICS shows a threshold about 1.53 eV. In order to further investigate the reactive mechanism, the lifetime of complex is calculated by QCT method. At the low collision energy, most intermediate complexes are long lived, which implies that the reaction is governed by indirect reactive mechanism. With the collision energy increasing, the direct reactive mechanism occupies the dominant position. Due to the change of the reactive mechanism, the angular distribution shifts toward the forward direction with collision energy increasing. The isotopic variant, Au + D2→AuD + D reaction, is also calculated by TDWP method. The calculated reaction probabilities and ICSs show that the isotope effect reduces the reactivity.
Energy Technology Data Exchange (ETDEWEB)
Wu, Hui [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, University of Chinese Academy of Sciences, Dalian 116023 (China); Liang, Dongyue [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Zhang, Pei-Yu, E-mail: pyzhang@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, University of Chinese Academy of Sciences, Dalian 116023 (China)
2015-05-12
Highlights: • The reaction probabilities, characteristic ICS and DCS are presented. • The features of ICS and DCS are explained. • Different mechanisms relevant to several sets of J partial waves lead to the maxima in the DCS in the collision process. - Abstract: The state-to-state quantum dynamics of the abstraction channel of S({sup 3}P) + H{sub 2}(v = 0, j = 0) reaction is studied on the potential energy surface (PES) constructed by Lv et al. (2012), utilizing the product Jacobi coordinate based time-dependent wave packet method. Reaction probabilities and total integral cross section (ICS) agree well with previous results (Lv et al., 2012) for collision energies ranging from 0.8 to 1.4 eV. Results show that total differential cross sections (DCSs) for small collision energies have backward structures, whereas those for large collision energies are sideways peaked. Although the summed-over-all-final-state DCS for single collision energy is smoothly varied, the DCS of the product HS of a selected final state shows strong oscillations. For the selected final state, the opacity function derived by reaction probability multiplied by (2J + 1), shows that different mechanisms relevant to several sets of J partial waves lead to the maxima in the differential cross section in the collision process.
HBT Interferometry: Historical Perspective
Padula, S S
2004-01-01
I review the history of HBT interferometry, since its discovery in the mid 50's, up to the recent developments and results from BNL/RHIC experiments. I focus the discussion on the contributions to the subject given by members of our Brazilian group.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Zhaojun; Zhang, Dong H., E-mail: zhangdh@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)
2014-10-14
Seven-dimensional time-dependent wave packet calculations have been carried out for the title reaction to obtain reaction probabilities and cross sections for CHD{sub 3} in J{sub 0} = 1, 2 rotationally excited initial states with k{sub 0} = 0 − J{sub 0} (the projection of CHD{sub 3} rotational angular momentum on its C{sub 3} axis). Under the centrifugal sudden (CS) approximation, the initial states with the projection of the total angular momentum on the body fixed axis (K{sub 0}) equal to k{sub 0} are found to be much more reactive, indicating strong dependence of reactivity on the orientation of the reagent CHD{sub 3} with respect to the relative velocity between the reagents H and CHD{sub 3}. However, at the coupled-channel (CC) level this dependence becomes much weak although in general the K{sub 0} specified cross sections for the K{sub 0} = k{sub 0} initial states remain primary to the overall cross sections, implying the Coriolis coupling is important to the dynamics of the reaction. The calculated CS and CC integral cross sections obtained after K{sub 0} averaging for the J{sub 0} = 1, 2 initial states with all different k{sub 0} are essentially identical to the corresponding CS and CC results for the J{sub 0} = 0 initial state, meaning that the initial rotational excitation of CHD{sub 3} up to J{sub 0} = 2, regardless of its initial k{sub 0}, does not have any effect on the total cross sections for the title reaction, and the errors introduced by the CS approximation on integral cross sections for the rotationally excited J{sub 0} = 1, 2 initial states are the same as those for the J{sub 0} = 0 initial state.
Geometric Time Delay Interferometry
Vallisneri, Michele
2005-01-01
The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be launched after 2012, will achieve its optimal sensitivity using Time Delay Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise overwhelming laser noise in the inter-spacecraft phase measurements. The TDI observables of the Michelson and Sagnac types have been interpreted physically as the virtual measurements of a synthesized interferometer. In this paper, I present Geometric TDI, a new an...
Gravitational wave detection using atom interferometry
Hogan, Jason
2016-05-01
The advent of gravitational wave astronomy promises to provide a new window into the universe. Low frequency gravitational waves below 10 Hz are expected to offer rich science opportunities both in astrophysics and cosmology, complementary to signals in LIGO's band. Detector designs based on atom interferometry have a number of advantages over traditional approaches in this band, including the possibility of substantially reduced antenna baseline length in space and high isolation from seismic noise for a terrestrial detector. In particular, atom interferometry based on the clock transition in group II atoms offers tantalizing new possibilities. Such a design is expected to be highly immune to laser frequency noise because the signal arises strictly from the light propagation time between two ensembles of atoms. This would allow for a gravitational wave detector with a single linear baseline, potentially offering advantages in cost and design flexibility. In support of these proposals, recent progress in long baseline atom interferometry in a 10-meter drop tower has enabled observation of matter wave interference with atomic wavepacket separations exceeding 50 cm and interferometer durations of more than 2 seconds. This approach can provide ground-based proof-of-concept demonstrations of many of the technical requirements of both terrestrial and satellite gravitational wave detectors.
Towards the Intensity Interferometry Stellar Imaging System
Daniel, M; Dravins, D; Kieda, D; Le Bohec, S; Núñez, P; Ribak, E
2009-01-01
The imminent availability of large arrays of large light collectors deployed to exploit atmospheric Cherenkov radiation for gamma-ray astronomy at more than 100GeV, motivates the growing interest in application of intensity interferometry in astronomy. Indeed, planned arrays numbering up to one hundred telescopes will offer close to 5,000 baselines, ranging from less than 50m to more than 1000m. Recent and continuing signal processing technology developments reinforce this interest. Revisiting Stellar Intensity Interferometry for imaging is well motivated scientifically. It will fill the short wavelength (B/V bands) and high angular resolution (< 0.1mas) gap left open by amplitude interferometers. It would also constitute a first and important step toward exploiting quantum optics for astronomical observations, thus leading the way for future observatories. In this paper we outline science cases, technical approaches and schedule for an intensity interferometer to be constructed and operated in the visible...
Nonlinear Evolution of Alfvenic Wave Packets
Buti, B.; Jayanti, V.; Vinas, A. F.; Ghosh, S.; Goldstein, M. L.; Roberts, D. A.; Lakhina, G. S.; Tsurutani, B. T.
1998-01-01
Alfven waves are a ubiquitous feature of the solar wind. One approach to studying the evolution of such waves has been to study exact solutions to approximate evolution equations. Here we compare soliton solutions of the Derivative Nonlinear Schrodinger evolution equation (DNLS) to solutions of the compressible MHD equations.
Wave-packet dynamics in quantum wells
DEFF Research Database (Denmark)
Kuznetsov, A. V.; Sanders, G. D.; Stanton, C. J.
1995-01-01
It has been recently recognized that in bulk semiconductors the displacement current caused by ultrafast optical generation of ''polarized pairs'' in the applied de field is an important mechanism of charge transport in addition to the usual transport current. In quantum-well systems, this polari......It has been recently recognized that in bulk semiconductors the displacement current caused by ultrafast optical generation of ''polarized pairs'' in the applied de field is an important mechanism of charge transport in addition to the usual transport current. In quantum-well systems......, this polarized pair creation is thought to be the only source of photocurrent at the early stages of photoexcitation since the bulk like transport current is inhibited by the barriers. In this work we perform a full quantum-mechanical analysis of ultrafast optical excitation in a de-biased quantum well. We take...... larger than the well width (for long pulses and/or narrow wells), we recover the polarized pairs behavior of the photocurrent. For shorter pulses, when the coherence length becomes comparable to the well width, the photocurrent exhibits quantum beats. Finally, for very short pulses (around 10 fs) we find...
NONLINEAR APPROXIMATION WITH GENERAL WAVE PACKETS
Institute of Scientific and Technical Information of China (English)
L. Borup; M. Nielsen
2005-01-01
We study nonlinear approximation in the Triebel-Lizorkin spaces with dictionaries formed by dilating and translating one single function g. A general Jackson inequality is derived for best m-term approximation with such dictionaries. In some special cases where g has a special structure, a complete characterization of the approximation spaces is derived.
Nonlinear approximation with general wave packets
DEFF Research Database (Denmark)
Borup, Lasse; Nielsen, Morten
2005-01-01
We study nonlinear approximation in the Triebel-Lizorkin spaces with dictionaries formed by dilating and translating one single function g. A general Jackson inequality is derived for best m-term approximation with such dictionaries. In some special cases where g has a special structure, a complete...... characterization of the approximation spaces is derived....
White Light Heterodyne Interferometry SNR
2015-04-09
for Research and Engineering under Air Force Contract FA8721-05-C-0002. Approved for public release; distribution is unlimited. White Light ...White Light Heterodyne Interferometry SNR J.B. Ashcom Group 91...public release; distribution is unlimited. ii ABSTRACT White light heterodyne interferometry is a powerful technique for obtaining high-angular
Antihydrogen Experiment Gravity Interferometry Spectroscopy
Tietje, I C; Trezzi, D; Dassa, L; Rienacker, B; Khalidova, O; Ferrari, G; Krasnicky, D; Perini, D; Cerchiari, G; Belov, A; Boscolo, I; Sacerdoti, M G; Ferragut, R O; Nedelec, P; Testera, G; Hinterberger, A; Al-qaradawi, I; Malbrunot, C L S; Brusa, R S; Prelz, F; Manuzio, G; Riccardi, C; Fontana, A; Genova, P; Haider, S; Haug, F; Turbabin, A; Castelli, F; Lagomarsino, V E; Doser, M; Penasa, L; Gninenko, S; Cataneo, F; Zenoni, A; Cabaret, L; Comparat, D P; Zmeskal, J; Scampoli, P; Nesteruk, K P; Dudarev, A; Kellerbauer, A G; Mariazzi, S; Fesel, J V; Carraro, C; Zavatarelli, S M
The AEGIS experiment (Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy) has the aim of carrying out the first measurement of the gravitational interaction of antimatter to a precision of 1%, by applying techniques from atomic physics, laser spectroscopy and interferometry to a beam of antihydrogen atoms. A further goal of the experiment is to carry out spectroscopy of the antihydrogen atoms in flight.
Hariharan, P
1992-01-01
This book is for those who have some knowledge of optics, but little or no previous experience in interferometry. Accordingly, the carefully designed presentation helps readers easily find and assimilate the interferometric techniques they need for precision measurements. Mathematics is held to a minimum, and the topics covered are also summarized in capsule overviews at the beginning and end of each chapter. Each chapter also contains a set of worked problems that give a feel for numbers.The first five chapters present a clear tutorial review of fundamentals. Chapters six and seven discus
Holographic interferometry for security and forensic applications
Ambadiyil, Sajan; R. C., Sreelekshmi; Mahadevan Pillai, V. P.; Prabhu, Radhakrishna
2016-10-01
Security holograms having unique 3D images are one of the tools for enhancing the security for product and personnel authentication and anti-counterfeiting. Apart from the high technology that is required, the uniqueness of a 3D object presents a significant additional threshold for the counterfeiting of such security holograms. But, due to the development of 3D printing technology, the hurdles are disabled and allow the chances of counterfeiting. In order to overcome this, holographic interferometry is effectively utilized and the object is recorded twice before and after the state of random object change. At the time of reconstruction, two signal waves generated simultaneously interfere each other, resulting in a fringe modulation. This fringe modulation in 3D image hologram with respect to the random object change is exploited to generate a rigid and unique anticounterfeit feature. Though holographic interferometry techniques are being widely used for the non-destructive evaluation, the applicability of this technology for the security and forensic activity is less exploited. This paper describes our efforts to introduce holographic interferometry in 3D image holograms for security and forensic applications.
GPS radio interferometry of travelling ionospheric disturbances
Afraimovich, E. L.; Palamartchouk, K. S.; Perevalova, N. P.
1998-01-01
This paper presents some results investigating the new possibilities of radio interferometry of Travelling Ionospheric Disturbances (TIDs) that are based on exploiting standard measurements of transionospheric radio signal characteristics and coordinate-time measurements using dual-frequency multichannel receivers of the Global Positioning System (GPS). A Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry (SADM-GPS) is proposed for determining the characteristics of the TIDs dynamics by measuring variations of GPS phase derivatives with respect to time and spatial coordinates. These data are used to calculate corresponding values of the velocity vector, in view of a correction for satellite motions based on the current information available regarding the angular coordinates of the satellites. Subsequently, velocity and direction distributions are constructed and analyzed to verify the hypothesis of whether there is a predominant displacement. If it exists, then the pattern can be considered to be travelling, and the mean travel velocity can be determined from the velocity distribution. Through a computer simulation it was shown that multi-satellite GPS radio interferometry in conjunction with the SADM-GPS algorithm allows the detection and measurement of the velocity vector of TIDs in virtually the entire azimuthal range of possible TID propagation directions. The use of the proposed method is exemplified by an investigation of TIDs during the solar eclipse of 9 March 1997, using the GPS-radio interferometer GPSINT at Irkutsk.
Interferometry and synthesis in radio astronomy
Thompson, A Richard; Swenson Jr , George W
2017-01-01
This book is open access under a CC BY-NC 4.0 license. The third edition of this indispensable book in radio interferometry provides extensive updates to the second edition, including results and technical advances from the past decade; discussion of arrays that now span the full range of the radio part of the electromagnetic spectrum observable from the ground, 10 MHz to 1 THz; an analysis of factors that affect array speed; and an expanded discussion of digital signal-processing techniques and of scintillation phenomena and the effects of atmospheric water vapor on image distortion, among many other topics. With its comprehensiveness and detailed exposition of all aspects of the theory and practice of radio interferometry and synthesis imaging, this book has established itself as a standard reference in the field. It begins with an overview of the basic principles of radio astronomy, a short history of the development of radio interferometry, and an elementary discussion of the operation of an interferomete...
Directory of Open Access Journals (Sweden)
Massimo Tinto
2014-08-01
Full Text Available Equal-arm detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers, the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called time-delay interferometry (TDI. This article provides an overview of the theory, mathematical foundations, and experimental aspects associated with the implementation of TDI. Although emphasis on the application of TDI to the Laser Interferometer Space Antenna (LISA mission appears throughout this article, TDI can be incorporated into the design of any future space-based mission aiming to search for gravitational waves via interferometric measurements. We have purposely left out all theoretical aspects that data analysts will need to account for when analyzing the TDI data combinations.
Compressed sensing imaging techniques for radio interferometry
Wiaux, Y; Puy, G; Scaife, A M M; Vandergheynst, P
2009-01-01
Radio interferometry probes astrophysical signals through incomplete and noisy Fourier measurements. The theory of compressed sensing demonstrates that such measurements may actually suffice for accurate reconstruction of sparse or compressible signals. We propose new generic imaging techniques based on convex optimization for global minimization problems defined in this context. The versatility of the framework notably allows introduction of specific prior information on the signals, which offers the possibility of significant improvements of reconstruction relative to the standard local matching pursuit algorithm CLEAN used in radio astronomy. We illustrate the potential of the approach by studying reconstruction performances on simulations of two different kinds of signals observed with very generic interferometric configurations. The first kind is an intensity field of compact astrophysical objects. The second kind is the imprint of cosmic strings in the temperature field of the cosmic microwave backgroun...
Atom Interferometry in a Warm Vapor
Biedermann, G W; Rakholia, A V; Jau, Y -Y; Wheeler, D R; Sterk, J D; Burns, G R
2016-01-01
We demonstrate matterwave interference in a warm vapor of rubidium atoms. Established approaches to light pulse atom interferometry rely on laser cooling to concentrate a large ensemble of atoms into a velocity class resonant with the atom optical light pulse. In our experiment, we show that clear interference signals may be obtained without laser cooling. This effect relies on the Doppler selectivity of the atom interferometer resonance. This interferometer may be configured to measure accelerations, and we demonstrate that multiple interferometers may be operated simultaneously by addressing multiple velocity classes.
Absolute small-angle measurement based on optical feedback interferometry
Institute of Scientific and Technical Information of China (English)
Jingang Zhong; Xianhua Zhang; Zhixiang Ju
2008-01-01
We present a simple but effective method for small-angle measurement based on optical feedback inter-ferometry (or laser self-mixing interferometry). The absolute zero angle can be defined at the biggest fringe amplitude point, so this method can also achieve absolute angle measurement. In order to verify the method, we construct an angle measurement system. The Fourier-transform method is used to analysis the interference signal. Rotation angles are experimentally measured with a resolution of 10-6 rad and a measurement range of approximately from -0.0007 to +0.0007 rad.
Theory of supervirtual refraction interferometry
Bharadwaj, Pawan
2012-01-01
Inverting for the subsurface velocity distribution by refraction traveltime tomography is a well-accepted imaging method by both the exploration and earthquake seismology communities. A significant drawback, however, is that the recorded traces become noisier with increasing offset from the source position, and so accurate picking of traveltimes in far-offset traces is often prevented. To enhance the signal-to-noise ratio (SNR) of the far-offset traces, we present the theory of supervirtual refraction interferometry where the SNR of far-offset head-wave arrivals can be theoretically increased by a factor proportional to; here, N is the number of receiver or source positions associated with the recording and generation of the head-wave arrival. There are two steps to this methodology: correlation and summation of the data to generate traces with virtual head-wave arrivals, followed by the convolution of the data with the virtual traces to create traces with supervirtual head-wave arrivals. This method is valid for any medium that generates head-wave arrivals recorded by the geophones. Results with both synthetic traces and field data demonstrate the feasibility of this method. There are at least four significant benefits of supervirtual interferometry: (1) an enhanced SNR of far-offset traces so the first-arrival traveltimes of the noisy far-offset traces can be more reliably picked to extend the useful aperture of the data, (2) the SNR of head waves in a trace that arrive later than the first arrival can be enhanced for accurate traveltime picking and subsequent inversion by later-arrival traveltime tomography, (3) common receiver-pair gathers can be analysed to detect the presence of diving waves in the first arrivals, which can be used to assess the nature of the refracting boundary, and (4) the source statics term is eliminated in the correlation operations so that the timing of the virtual traces is independent of the source excitation time. This suggests the
Bandwidth in bolometric interferometry
Charlassier, R; Hamilton, J -Ch; Kaplan, J; Malu, S
2009-01-01
Bolometric Interferometry is a technology currently under development that will be first dedicated to the detection of B-mode polarization fluctuations in the Cosmic Microwave Background. A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers in order to be competitive with imaging experiments. A crucial concern is that interferometers are presumed to be importantly affected by a spoiling effect known as bandwidth smearing. In this paper, we investigate how the bandwidth modifies the work principle of a bolometric interferometer and how it affects its sensitivity to the CMB angular power spectra. We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. Using an angular power spectrum estimator ...
Decoherence Free Neutron Interferometry
Pushin, Dmitry A; Cory, David G
2016-01-01
Perfect single-crystal neutron interferometers are adversely sensitive to environmental disturbances, particularly mechanical vibrations. The sensitivity to vibrations results from the slow velocity of thermal neutrons and the long measurement time that are encountered in a typical experiment. Consequently, to achieve a good interference solutions for reducing vibration other than those normally used in optical experiments must be explored. Here we introduce a geometry for a neutron interferometer that is less sensitive to low-frequency vibrations. This design may be compared with both dynamical decoupling methods and decoherence-free subspaces that are described in quantum information processing. By removing the need for bulky vibration isolation setups, this design will make it easier to adopt neutron interferometry to a wide range of applications and increase its sensitivity.
Practical optical interferometry imaging at visible and infrared wavelengths
Buscher, David F
2015-01-01
Optical interferometry is a powerful technique to make images on angular scales hundreds of times smaller than is possible with the largest telescopes. This concise guide provides an introduction to the technique for graduate students and researchers who want to make interferometric observations and acts as a reference for technologists building new instruments. Starting from the principles of interference, the author covers the core concepts of interferometry, showing how the effects of the Earth's atmosphere can be overcome using closure phase, and the complete process of making an observation, from planning to image reconstruction. This rigorous approach emphasizes the use of rules-of-thumb for important parameters such as the signal-to-noise ratios, requirements for sampling the Fourier plane and predicting image quality. The handbook is supported by web resources, including the Python source code used to make many of the graphs, as well as an interferometry simulation framework, available at www.cambridg...
Phase Referencing in Optical Interferometry
Mercedes E. Filho; Garcia, Paulo; Duvert, Gilles; Duchene, Gaspard; Thiebaut, Eric; Young, John; Absil, Olivier; Berger, Jean-Phillipe; Beckert, Thomas; Hoenig, Sebastian; Schertl, Dieter; Weigelt, Gerd; Testi, Leonardo; Tatuli, Eric; Borkowski, Virginie
2008-01-01
One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce...
Extreme ultraviolet interferometry
Energy Technology Data Exchange (ETDEWEB)
Goldberg, Kenneth A. [Univ. of California, Berkeley, CA (United States). Dept. of Physics
1997-12-01
EUV lithography is a promising and viable candidate for circuit fabrication with 0.1-micron critical dimension and smaller. In order to achieve diffraction-limited performance, all-reflective multilayer-coated lithographic imaging systems operating near 13-nm wavelength and 0.1 NA have system wavefront tolerances of 0.27 nm, or 0.02 waves RMS. Owing to the highly-sensitive resonant reflective properties of multilayer mirrors and extraordinarily tight tolerances set forth for their fabrication, EUV optical systems require at-wavelength EUV interferometry for final alignment and qualification. This dissertation discusses the development and successful implementation of high-accuracy EUV interferometric techniques. Proof-of-principle experiments with a prototype EUV point-diffraction interferometer for the measurement of Fresnel zoneplate lenses first demonstrated sub-wavelength EUV interferometric capability. These experiments spurred the development of the superior phase-shifting point-diffraction interferometer (PS/PDI), which has been implemented for the testing of an all-reflective lithographic-quality EUV optical system. Both systems rely on pinhole diffraction to produce spherical reference wavefronts in a common-path geometry. Extensive experiments demonstrate EUV wavefront-measuring precision beyond 0.02 waves RMS. EUV imaging experiments provide verification of the high-accuracy of the point-diffraction principle, and demonstrate the utility of the measurements in successfully predicting imaging performance. Complementary to the experimental research, several areas of theoretical investigation related to the novel PS/PDI system are presented. First-principles electromagnetic field simulations of pinhole diffraction are conducted to ascertain the upper limits of measurement accuracy and to guide selection of the pinhole diameter. Investigations of the relative merits of different PS/PDI configurations accompany a general study of the most significant sources
Landau-Zener-Stueckelberg interferometry
Energy Technology Data Exchange (ETDEWEB)
Shevchenko, S.N., E-mail: sshevchenko@ilt.kharkov.u [B.Verkin Institute for Low Temperature Physics and Engineering, Kharkov (Ukraine); RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Ashhab, S.; Nori, Franco [RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Department of Physics, The University of Michigan, Ann Arbor, MI (United States)
2010-07-15
A transition between energy levels at an avoided crossing is known as a Landau-Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stueckelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau-Zener-Stueckelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory.
Coherent Anti-Stokes Raman Scattering Heterodyne Interferometry
Bredfeldt, J S; Vinegoni, C; Hambir, S; Boppart, S A
2003-01-01
A new interferometric technique is demonstrated for measuring Coherent Anti-Stokes Raman Scattering (CARS) signals. Two forward-directed CARS signals are generated, one in each arm of an interferometer. The deterministic nature of the CARS process allows for these two signals, when spatially and temporally overlapped, to interfere with one another. Heterodyne detection can therefore be employed to increase the sensitivity in CARS signal detection. In addition, nonlinear CARS interferometry will facilitate the use of this spectroscopic technique for molecular contrast in Optical Coherence Tomography (OCT).
100-Picometer Interferometry for EUVL
Energy Technology Data Exchange (ETDEWEB)
Sommargren, G E; Phillion, D W; Johnson, M A; Nguyen, N O; Barty, A; Snell, F J; Dillon, D R; Bradsher, L S
2002-03-18
Future extreme ultraviolet lithography (EWL) steppers will, in all likelihood, have six-mirror projection cameras. To operate at the diffraction limit over an acceptable depth of focus each aspheric mirror will have to be fabricated with an absolute figure accuracy approaching 100 pm rms. We are currently developing visible light interferometry to meet this need based on modifications of our present phase shifting diffraction interferometry (PSDI) methodology where we achieved an absolute accuracy of 250pm. The basic PSDI approach has been further simplified, using lensless imaging based on computational diffractive back-propagation, to eliminate auxiliary optics that typically limit measurement accuracy. Small remaining error sources, related to geometric positioning, CCD camera pixel spacing and laser wavelength, have been modeled and measured. Using these results we have estimated the total system error for measuring off-axis aspheric EUVL mirrors with this new approach to interferometry.
Phase Referencing in Optical Interferometry
Filho, Mercedes E; Duvert, Gilles; Duchene, Gaspard; Thiebaut, Eric; Young, John; Absil, Olivier; Berger, Jean-Phillipe; Beckert, Thomas; Hoenig, Sebastian; Schertl, Dieter; Weigelt, Gerd; Testi, Leonardo; Tatuli, Eric; Borkowski, Virginie; de Becker, Michael; Surdej, Jean; Aringer, Bernard; Hron, Joseph; Lebzelter, Thomas; Chiavassa, Andrea; Corradi, Romano; Harries, Tim
2008-01-01
One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce images. Such techniques allow only to achieve modest dynamic ranges. However, with high contrast objects, for faint targets or when structure detail is needed, phase referencing techniques as used in radio interferometry, should theoretically achieve higher dynamic ranges for the same number of telescopes. Our approach is not to provide evidence either for or against the hypothesis that phase referenced imaging gives better dynamic range than closure phase imaging. Instead we wish to explore the potential of this techniq...
Bandwidth in bolometric interferometry
Charlassier, R.; Bunn, E. F.; Hamilton, J.-Ch.; Kaplan, J.; Malu, S.
2010-05-01
Context. Bolometric interferometry is a promising new technology with potential applications to the detection of B-mode polarization fluctuations of the cosmic microwave background (CMB). A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers to be competitive with imaging experiments. A crucial concern is that interferometers are assumed to be significantly affected by a spoiling effect known as bandwidth smearing. Aims: We investigate how the bandwidth modifies the work principle of a bolometric interferometer and affects its sensitivity to the CMB angular power spectra. Methods: We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. If the phase shifters produce shifts that are constant with respect to frequency, the instrument works like its monochromatic version (the modulation matrix is not modified), while if they vary (linearly or otherwise) with respect to frequency, one has to perform a special reconstruction scheme, which allows the visibilities to be reconstructed in frequency subbands. Using an angular power spectrum estimator that accounts for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation is performed that confirms the analytical results. Results: We conclude that (i) broadband bolometric interferometers allow broadband visibilities to be reconstructed regardless of the type of phase shifters used and (ii) for dedicated B-mode bolometric interferometers, the sensitivity loss caused by bandwidth smearing is quite acceptable, even for wideband instruments (a factor of 2 loss for a typical 20% bandwidth experiment).
Techniques in Broadband Interferometry
Energy Technology Data Exchange (ETDEWEB)
Erskine, D J
2004-01-04
This is a compilation of my patents issued from 1997 to 2002, generally describing interferometer techniques that modify the coherence properties of broad-bandwidth light and other waves, with applications to Doppler velocimetry, range finding, imaging and spectroscopy. Patents are tedious to read in their original form. In an effort to improve their readability I have embedded the Figures throughout the manuscript, put the Figure captions underneath the Figures, and added section headings. Otherwise I have resisted the temptation to modify the words, though I found many places which could use healthy editing. There may be minor differences with the official versions issued by the US Patent and Trademark Office, particularly in the claims sections. In my shock physics work I measured the velocities of targets impacted by flyer plates by illuminating them with laser light and analyzing the reflected light with an interferometer. Small wavelength changes caused by the target motion (Doppler effect) were converted into fringe shifts by the interferometer. Lasers having long coherence lengths were required for the illumination. While lasers are certainly bright sources, and their collimated beams are convenient to work with, they are expensive. Particularly if one needs to illuminate a wide surface area, then large amounts of power are needed. Orders of magnitude more power per dollar can be obtained from a simple flashlamp, or for that matter, a 50 cent light bulb. Yet these inexpensive sources cannot practically be used for Doppler velocimetry because their coherence length is extremely short, i.e. their bandwidth is much too wide. Hence the motivation for patents 1 & 2 is a method (White Light Velocimetry) for allowing use of these powerful but incoherent lamps for interferometry. The coherence of the illumination is modified by passing it through a preparatory interferometer.
Phase estimation in optical interferometry
Rastogi, Pramod
2014-01-01
Phase Estimation in Optical Interferometry covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding the phase estimation methods in use today. The first four chapters focus on phase retrieval from image transforms using a single frame. The next several chapters examine the local environment of a fringe pattern, give a broad picture of the phase estimation approach based on local polynomial phase modeling, cover temporal high-resolution phase evaluation methods, and pre
Virtual Reference Interferometry: Theory & Experiment
Galle, Michael Anthony
This thesis introduces the idea that a simulated interferogram can be used as a reference for an interferometer. This new concept represents a paradigm shift from the conventional thinking, where a reference is the phase of a wavefront that traverses a known path. The simulated interferogram used as a reference is called a virtual reference. This thesis develops the theory of virtual reference interferometry and uses it for the characterization of chromatic dispersion in short length (virtual reference combines the advantages of these techniques so that it is both accurate and easy to operate. Chromatic dispersion measurements based on virtual reference interferometry have similar accuracy as the best conventional measurement techniques due to the ability to measure first and second order dispersion directly from the interference pattern. Unique capabilities of virtual reference interferometry are demonstrated, followed by a derivation of the operational constraints and system parameters. The technique is also applied to the characterization of few-mode fibers, a hot topic in telecommunications research where mode division multiplexing promises to expand network bandwidth. Also introduced is the theory of dispersive virtual reference interferometry, which can be used to overcome the bandwidth limitations associated with the measurement of near-zero dispersion-length optical components via compression of the interference pattern. Additionally, a method for utilizing the virtual reference interferometer in a low-coherence setup is introduced, enabling characterization in new wavelength ranges and further reducing the cost of characterization.
New Methods in Moire Interferometry
Czarnek, Robert
Experimental observations and measurements are the essential source of information necessary for correct development of mathematical models of real materials. Moire interferometry offers high sensitivity in full-field measurements of the in-plane displacements on the surface of the specimen. The (+OR-)45(DEGREES) method of moire interferometry increases the efficiency of a three-beam interferometer making its use outside of an optical laboratory more practical. Analysis of the (+OR-)45(DEGREES) method is provided. A concept of the vector representation of the fringe gradient is introduced and used in the analysis. Although existing systems require coherent light, the proposed system can use a relatively broad spectral bandwidth. Features that are related to the vibration sensitivity of such an instrument are investigated analytically. The basic concepts of an achromatic moire interferometry system are developed. Attachment of the critical elements of the system to the specimen solves the problem of relative rigid body motions, including vibrations, between the specimen and the virtual reference grating. Application of a laser diode light source reduces size, weight and cost of the interferometer making moire interferometry more practical for most materials testing laboratories. Laboratory tests confirmed the developed methods. This work enhances the probability of successful construction of a portable moire interferometer for measurements outside of the optical laboratory, in a mechanical testing or field environment.
AIPY: Astronomical Interferometry in PYthon
Parsons, Aaron
2016-09-01
AIPY collects together tools for radio astronomical interferometry. In addition to pure-python phasing, calibration, imaging, and deconvolution code, this package includes interfaces to MIRIAD (ascl:1106.007) and HEALPix (ascl:1107.018), and math/fitting routines from SciPy.
Special topics in infrared interferometry. [Michelson interferometer development
Hanel, R. A.
1985-01-01
Topics in IR interferometry related to the development of a Michelson interferometer are treated. The selection and reading of the signal from the detector to the analog to digital converter is explained. The requirements for the Michelson interferometer advance speed are deduced. The effects of intensity modulation on the interferogram are discussed. Wavelength and intensity calibration of the interferometer are explained. Noise sources (Nyquist or Johnson noise, phonon noise), definitions of measuring methods of noise, and noise measurements are presented.
Time-domain Ramsey interferometry with interacting Rydberg atoms
Sommer, Christian; Pupillo, Guido; Takei, Nobuyuki; Takeda, Shuntaro; Tanaka, Akira; Ohmori, Kenji; Genes, Claudiu
2016-11-01
We theoretically investigate the dynamics of a gas of strongly interacting Rydberg atoms subject to a time-domain Ramsey interferometry protocol. The many-body dynamics is governed by an Ising-type Hamiltonian with long-range interactions of tunable strength. We analyze and model the contrast degradation and phase accumulation of the Ramsey signal and identify scaling laws for varying interrogation times, ensemble densities, and ensemble dimensionalities.
Radio sources - Very, Very Long Baseline Interferometry
Roberts, D. H.
1983-03-01
With resolution of a thousandth of an arcsecond, the radio technique of Very Long Baseline Interferometry (VLBI) provides astronomers with their highest-resolution view of the universe. Data taken with widely-separated antennas are combined, with the help of atomic clocks, to form a Michelson interferometer whose size may be as great as the earth's diameter. Extraordinary phenomena, from the birth of stars as signaled by the brilliant flashes of powerful interstellar masers to the 'faster-than-light' expansion of the cores of distant quasars, are being explored with this technique. However, earth-bound VLBI suffers from several restrictions due to the location of the component antennas at fixed places on the earth's surface. The use of one or more antennas in space in concert with ground-based equipment will greatly expand the technical and scientific capabilities of VLBI, leading to a more complete and even higher resolution view of cosmic phenomena.
Interferometry with Photon-Subtracted Thermal Light
Rafsanjani, Seyed Mohammad Hashemi; Magana-Loaiza, Omar S; Gard, Bryan T; Birrittella, Richard; Koltenbah, B E; Parazzoli, C G; Capron, Barbara A; Gerry, Christopher C; Dowling, Jonathan P; Boyd, Robert W
2016-01-01
We propose and implement a quantum procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a weak light beam possessing thermal statistics in passing through an interferometer. Our procedure entails subtracting exactly one (which can be generalized to m) photons from the light field exiting an interferometer containing a phase-shifting element in one of its arms. As a consequence of the process of photon subtraction, and somewhat surprisingly, the mean photon number and signal-to-noise ratio of the resulting light field are thereby increased, leading to enhanced interferometry. This method can be used to increase measurement sensitivity in a variety of practical applications, including that of forming the image of an object illuminated only by weak thermal light.
Pulsed-Source Interferometry in Acoustic Imaging
Shcheglov, Kirill; Gutierrez, Roman; Tang, Tony K.
2003-01-01
A combination of pulsed-source interferometry and acoustic diffraction has been proposed for use in imaging subsurface microscopic defects and other features in such diverse objects as integrated-circuit chips, specimens of materials, and mechanical parts. A specimen to be inspected by this technique would be mounted with its bottom side in contact with an acoustic transducer driven by a continuous-wave acoustic signal at a suitable frequency, which could be as low as a megahertz or as high as a few hundred gigahertz. The top side of the specimen would be coupled to an object that would have a flat (when not vibrating) top surface and that would serve as the acoustical analog of an optical medium (in effect, an acoustical "optic").
Electro-optic dual-comb interferometry over 40-nm bandwidth
Duran, Vicente; Torres-Company, Victor
2016-01-01
Dual-comb interferometry is a measurement technique that uses two laser frequency combs to retrieve complex spectra in a line-by-line basis. This technique can be implemented with electro-optic frequency combs, offering intrinsic mutual coherence, high acquisition speed and flexible repetition-rate operation. A challenge with the operation of this kind of frequency comb in dual-comb interferometry is its limited optical bandwidth. Here, we use coherent spectral broadening and demonstrate electro-optic dual-comb interferometry over the entire telecommunications C band (200 lines covering ~ 40 nm, measured within 10 microseconds at 100 signal-to-noise ratio per spectral line). These results offer new prospects for electro-optic dual-comb interferometry as a suitable technology for high-speed broadband metrology, for example in optical coherence tomography or coherent Raman microscopy.
Frequency-scanning interferometry for dynamic absolute distance measurement using Kalman filter.
Tao, Long; Liu, Zhigang; Zhang, Weibo; Zhou, Yangli
2014-12-15
We propose a frequency-scanning interferometry using the Kalman filtering technique for dynamic absolute distance measurement. Frequency-scanning interferometry only uses a single tunable laser driven by a triangle waveform signal for forward and backward optical frequency scanning. The absolute distance and moving speed of a target can be estimated by the present input measurement of frequency-scanning interferometry and the previously calculated state based on the Kalman filter algorithm. This method not only compensates for movement errors in conventional frequency-scanning interferometry, but also achieves high-precision and low-complexity dynamic measurements. Experimental results of dynamic measurements under static state, vibration and one-dimensional movement are presented.
Ghetti, R; Colonna, N; Helgesson, J; Avdeichikov, [No Value; Golubev, P; Jakobsson, B; Tagliente, G; Brandenburg, S; Kravchuk, VL; Wilschut, HW; Kopecky, S; Anderson, EW; Nadel-Turonski, P; Westerberg, L; Bellini, [No Value; Sperduto, ML; Sutera, C
2004-01-01
We present the details of an experiment on light particle interferometry. In particular, we focus on a time-of-flight technique which uses a cyclotron RF signal as a start and a liquid scintillator time signal as a stop, to measure neutron energy in the range of En approximate to 1.8-150 MeV. This d
A demonstrator for bolometric interferometry
Ghribi, Adnan; Galli, Silvia; Piat, Michel; Breelle, Eric; Hamilton, Jean-Christophe; Spinelli, Sebastiano; Gervasi, Massimo; Zannoni, Mario
2009-01-01
Bolometric Interferometry (BI) is one of the most promising techniques for precise measurements of the Cosmic Microwave Background polarization. In this paper, we present the results of DIBO (Demonstrateur d'Interferometrie Bolometrique), a single-baseline demonstrator operating at 90 GHz, built to proof the validity of the BI concept applied to a millimeter-wave interferometer. This instrument has been characterized in the laboratory with a detector at room temperature and with a 4 K bolometer. This allowed us to measure interference patterns in a clean way, both (1) rotating the source and (2) varying with time the phase shift among the two interferometer's arms. Detailed modelisation has also been performed and validated with measurements.
Generalized interferometry - I: theory for interstation correlations
Fichtner, Andreas; Stehly, Laurent; Ermert, Laura; Boehm, Christian
2017-02-01
Earth structure. Not making any restrictive assumptions on the nature of the wavefield sources, our theory can be applied to earthquake and ambient noise data, either separately or combined. This allows us (i) to locate earthquakes using interstation correlations and without knowledge of the origin time, (ii) to unify the earthquake-based two-station method and noise correlations without the need to exclude either of the two data types, and (iii) to eliminate the requirement to remove earthquake signals from noise recordings prior to the computation of correlation functions. In addition to the basic theory for acoustic wavefields, we present numerical examples for 2-D media, an extension to the most general viscoelastic case, and a method for the design of optimal processing schemes that eliminate the forward modelling error completely. This work is intended to provide a comprehensive theoretical foundation of full-waveform interferometry by correlation, and to suggest improvements to current passive monitoring methods.
Holographic interferometry in construction analysis
Energy Technology Data Exchange (ETDEWEB)
Hartikainen, T.
1995-12-31
In this work techniques for visualizing phase and opaque objects by ruby laser interferometry are introduced. A leakage flow as a phase object is studied by holographic interferometry and the intensity distribution of the interferograms presenting the leakage flow are computer-simulated. A qualitative and quantitative analysis of the leakage flow is made. The analysis is based on the experimental and theoretical results presented in this work. The holographic setup and the double pass method for visualizing leakage flow are explained. A vibrating iron plate is the opaque object. Transient impact waves are generated by a pistol bullet on the iron plate and visualized by holographic interferometry. An apparatus with the capability of detecting and calculating the delays necessary for laser triggering is introduced. A time series of interferograms presenting elastic wave formation in an iron plate is shown. A computer-simulation of the intensity distributions of these interferograms is made. An analysis based on the computer-simulation and the experimental data of the transient elastic wave is carried out and the results are presented. (author)
Non-linear Kalman filters for calibration in radio interferometry
Tasse, Cyril
2014-01-01
We present a new calibration scheme based on a non-linear version of Kalman filter that aims at estimating the physical terms appearing in the Radio Interferometry Measurement Equation (RIME). We enrich the filter's structure with a tunable data representation model, together with an augmented measurement model for regularization. We show using simulations that it can properly estimate the physical effects appearing in the RIME. We found that this approach is particularly useful in the most extreme cases such as when ionospheric and clock effects are simultaneously present. Combined with the ability to provide prior knowledge on the expected structure of the physical instrumental effects (expected physical state and dynamics), we obtain a fairly cheap algorithm that we believe to be robust, especially in low signal-to-noise regime. Potentially the use of filters and other similar methods can represent an improvement for calibration in radio interferometry, under the condition that the effects corrupting visib...
Stellar Intensity Interferometry: Prospects for sub-milliarcsecond optical imaging
Dravins, Dainis; Jensen, Hannes; Nuñez, Paul D
2012-01-01
Using kilometric arrays of air Cherenkov telescopes, intensity interferometry may increase the spatial resolution in optical astronomy by an order of magnitude, enabling images of rapidly rotating stars with structures in their circumstellar disks and winds, or mapping out patterns of nonradial pulsations across stellar surfaces. Intensity interferometry (pioneered by Hanbury Brown and Twiss) connects telescopes only electronically, and is practically insensitive to atmospheric turbulence and optical imperfections, permitting observations over long baselines and through large airmasses, also at short optical wavelengths. The required large telescopes with very fast detectors are becoming available as arrays of air Cherenkov telescopes, distributed over a few square km. Digital signal handling enables very many baselines to be synthesized, while stars are tracked with electronic time delays, thus synthesizing an optical interferometer in software. Simulated observations indicate limiting magnitudes around m(v)...
Homodyne digital interferometry for a sensitive fiber frequency reference.
Ngo, Silvie; McRae, Terry G; Gray, Malcolm B; Shaddock, Daniel A
2014-07-28
Digitally enhanced homodyne interferometry enables robust interferometric sensitivity to be achieved in an optically simple configuration by shifting optical complexity into the digital signal processing regime. We use digitally enhanced homodyne interferometry in a simple, all-fiber Michelson interferometer to achieve a frequency reference stability of better than 20 Hz/√Hz from 10 mHz to 1 Hz, satisfying, for the first time in an all fiber system, the stability requirements for the Gravity Recovery and Climate Experiment Follow On mission. In addition, we have demonstrated stability that satisfies the future mission objectives at frequencies down to 1 mHz. This frequency domain stability translates into a fractional Allan deviation of 3.3 × 10(-17) for an integration time of 55 seconds.
Noise Characterization of Supercontinuum Sources for Low Coherence Interferometry Applications
Brown, William J.; Kim, Sanghoon; Wax, Adam
2015-01-01
We examine the noise properties of supercontinuum light sources when used in low coherence interferometry applications. The first application is a multiple-scattering low-coherence interferometry (ms2/LCI) system where high power and long image acquisition times are required to image deep into tissue. For this system we compare the noise characteristics of two supercontinuum sources from different suppliers. Both sources have long term drift that limits the amount of time over which signal averaging is advantageous for reducing noise. The second application is a high resolution optical coherence tomography system where broadband light is needed for high axial resolution. For this system we compare the noise performance of the two supercontinuum sources and a light source based on four superluminescent diodes (SLDs) using imaging contrast as a comparative metric. We find that the NKT SuperK has superior noise performance compared to the Fianium SC-450-4 but neither meets the performance of the SLDs. PMID:25606759
Integrated optics for astronomical interferometry; 1, Concept and astronomical applications
Malbet, M; Schanen-Duport, J P; Berger, J P; Rousselet-Perraut, K; Benech, P
1999-01-01
We propose a new instrumental concept for long-baseline optical single-mode interferometry using integrated optics which were developed for telecommunication. Visible and infrared multi-aperture interferometry requires many optical functions (spatial filtering, beam combination, photometric calibration, polarization control) to detect astronomical signals at very high angular resolution. Since the 80's, integrated optics on planar substrate have become available for telecommunication applications with multiple optical functions like power dividing, coupling, multiplexing, etc. We present the concept of an optical / infrared interferometric instrument based on this new technology. The main advantage is to provide an interferometric combination unit on a single optical chip. Integrated optics are compact, provide stability, low sensitivity to external constrains like temperature, pressure or mechanical stresses, no optical alignment except for coupling, simplicity and intrinsic polarization control. The integra...
Background-Free Nonlinear Microspectroscopy with Vibrational Molecular Interferometry
Garbacik, Erik T.; Korterik, Jeroen P.; Otto, Cees; Mukamel, Shaul; Herek, Jennifer L.; Offerhaus, Herman L.
2013-01-01
We demonstrate a method for performing nonlinear microspectroscopy that provides an intuitive and unified description of the various signal contributions, and allows the direct extraction of the vibrational response. Three optical fields create a pair of Stokes Raman pathways that interfere in the same vibrational state. Frequency modulating one of the fields leads to amplitude modulations on all of the fields. This vibrational molecular interferometry technique allows imaging at high speed free of nonresonant background, and is able to distinguish between electronic and vibrational contributions to the total signal. PMID:22243075
Intracavity interferometry using synchronously pumped OPO
Zavadilová, Alena; Vyhlídal, David; Kubeček, Václav; Šulc, Jan; Navrátil, Petr
2016-12-01
The concept of system for intracavity interferometry based on the beat note detection in subharmonic synchronously intracavity pumped optical parametrical oscillator (OPO) is presented. The system consisted of SESAM-modelocked, picosecond, diode pumped Nd:YVO4 laser, operating at wavelength 1.06 μm and tunable linear intracavity pumped OPO based on MgO:PPLN crystal, widely tunable in 1.5 μm able to deliver two independent trains of picosecond pulses. The optical length of the OPO cavity was set to be exactly twice the pumping cavity length. In this configuration the OPO produces signal pulses with the same repetition frequency as the pump laser but the signal consists of two completely independent pulse trains. For purpose of pump probe measurements the setup signal with half repetition rate and scalable amplitude was derived from the OPO signal using RF signal divider, electropotical modulator and fiber amplifier. The impact of one pump beam on the sample is detected by one probing OPO train, the other OPO train is used as a reference. The beat note measured using the intracavity interferometer is proportional to phase modulation caused by the pump beam. The bandwidth of observed beat-note was less than 1 Hz (FWHM), it corresponds to a phase shift measurement error of less than 1.5 × 10-7 rad without any active stabilization. Such compact low-cost system could be used for ultra-sensitive phase-difference measurements (e.g. nonlinear refractive index measurement) for wide range of material especially in spectral range important for telecom applications.
Passive seismic interferometry by multidimensional deconvolution
Wapenaar, C.P.A.; Van der Neut, J.R.; Ruigrok, E.N.
2008-01-01
We introduce seismic interferometry of passive data by multidimensional deconvolution (MDD) as an alternative to the crosscorrelation method. Interferometry by MDD has the potential to correct for the effects of source irregularity, assuming the first arrival can be separated from the full response.
Progress in Interferometry for LISA at JPL
Spero, Robert; de Vine, Glenn; Dickson, Jeffrey; Klipstein, William; Ozawa, Tetsuo; McKenzie, Kirk; Shaddock, Daniel; Robison, David; Sutton, Andrew; Ware, Brent
2011-01-01
Recent advances at JPL in experimentation and design for LISA interferometry include the demonstration of Time Delay Interferometry using electronically separated end stations, a new arm-locking design with improved gain and stability, and progress in flight readiness of digital and analog electronics for phase measurements.
Progress in interferometry for LISA at JPL
Energy Technology Data Exchange (ETDEWEB)
Spero, Robert; Bachman, Brian; De Vine, Glenn; Dickson, Jeffrey; Klipstein, William; Ozawa, Tetsuo; McKenzie, Kirk; Shaddock, Daniel; Robison, David; Ware, Brent [Jet Propulsion Laboratory (JPL), California Institute of Technology, 4800 Oak Grove Drive Pasadena, CA 91109 (United States); Sutton, Andrew, E-mail: robert.spero@jpl.nasa.gov [Centre for Gravitational Physics, The Australian National University, ACT 0200 (Australia)
2011-05-07
Recent advances at JPL in experimentation and design for LISA interferometry include the demonstration of time delay interferometry using electronically separated end stations, a new arm-locking design with improved gain and stability, and progress in flight readiness of digital and analog electronics for phase measurements.
A system for airborne SAR interferometry
DEFF Research Database (Denmark)
Madsen, Søren Nørvang; Skou, Niels; Granholm, Johan
1996-01-01
Interferometric synthetic aperture radar (INSAR) systems have already demonstrated that elevation maps can be generated rapidly with single pass airborne across-track interferometry systems (XTT), and satellite repeat track interferometry (RTT) techniques have been used to map both elevation and ...
CURIE: Cubesat Radio Interferometry Experiment
Sundkvist, D. J.; Saint-Hilaire, P.; Bain, H. M.; Bale, S. D.; Bonnell, J. W.; Hurford, G. J.; Maruca, B.; Martinez Oliveros, J. C.; Pulupa, M.
2016-12-01
The CUbesat Radio Interferometry Experiment (CURIE) is a proposed two-element radio interferometer, based on proven and developed digital radio receivers and designed to fit within a Cubesat platform. CURIE will launch as a 6U Cubesat and then separate into two 3U Cubesats once in orbit. CURIE measures radio waves from 0.1-19MHz, which must be measured from space, as those frequencies fall below the cutoff imposed by Earth's ionosphere. The principal science objective for CURIE is to use radio interferometry to study radio burst emissions from solar eruptive events such as flares and coronal mass ejections (CMEs) in the inner heliosphere, providing observations important for our understanding of the heliospheric space weather environment. The influence of space weather can be felt at Earth and other planets, as radiation levels increase and lead to auroral activity and geomagnetic effects. CURIE will be able to determine the location and size of radio burst source regions and then to track their movement outward from the Sun. In addition to the primary objective CURIE will measure the gradients of the local ionospheric density and electron temperature on the spatial scale of a few kilometers, as well as create an improved map of the radio sky at these unexplored frequencies. A space based radio interferometry observatory has long been envisioned, in orbit around the Earth or the Moon, or on the far side of the Moon. Beyond its important science objectives, CURIE will prove that the concept of a dedicated space-based interferometer can be realized by using relatively cheap Cubesats. CURIE will therefore not only provide new important science results but also serve as a pathfinder in the development of new space-based radio observation techniques for helio- and astro-physics.
Radar interferometry persistent scatterer technique
Kampes, Bert M
2006-01-01
Only book on Permanent Scatterer technique of radar interferometryExplains the Permanent Scatterer technique in detail, possible pitfalls, and details a newly developed stochastic model and estimator algorithm to cope with possible problems for the application of the PS techniqueThe use of Permanent Scatterer allows very precise measurements of the displacement of hundreds of points per square kilometerDescribes the only technique currently able to perform displacement measurements in the past, utilizing the ERS satellite data archive using data acquired from 1992-prese
Golographic interferometry of physical processes
Ostrovskaya, G. V.
2016-06-01
This paper is devoted to the contribution of Yuri Ostrovsky to holographic interferometry, one of the fundamental scientific and practical applications of holography. The title of this paper is the same as the title of his doctoral thesis that he defended in 1974, and, as it seems to me, reflects most of the specific features of the majority of his scientific publications, viz., an inseparable link of the methods developed by him with the results obtained with the help of these methods in a wide range of investigations of physical processes and phenomena.
Vibration analysis using moire interferometry
Asundi, A.; Cheung, M. T.
The present use of moire interferometry for low amplitude vibration and analysis demonstrates the possibility of obtaining out-of-plane displacement contours whose sensitivity is comparable to that of holographic methods. A major advantage of the present system, is the obviation of prior knowledge of resonant frequencies, as called for in time-average holography. The experimental apparatus employed encompasses a laser beam, a parabolic mirror, a high frequency (600 line/mm) grating, and a camera, in addition to the test model.
An Interferometry Imaging Beauty Contest
Lawson, Peter R.; Cotton, William D.; Hummel, Christian A.; Monnier, John D.; Zhaod, Ming; Young, John S.; Thorsteinsson, Hrobjartur; Meimon, Serge C.; Mugnier, Laurent; LeBesnerais, Guy; Thiebaut, Eric; Tuthill, Peter G.; Hani, Christopher A.; Pauls, Thomas; DuvertI, Gilles; Garcia, Paulo; Kuchner, Marc
2004-01-01
We present a formal comparison of the performance of algorithms used for synthesis imaging with optical/infrared long-baseline interferometers. Six different algorithms are evaluated based on their performance with simulated test data. Each set of test data is formated in the interferometry Data Exchange Standard and is designed to simulate a specific problem relevant to long-baseline imaging. The data are calibrated power spectra and bispectra measured with a ctitious array, intended to be typical of existing imaging interferometers. The strengths and limitations of each algorithm are discussed.
Bibliography of spatial interferometry in optical astronomy
Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude
1990-01-01
The Bibliography of Spatial Interferometry in Optical Astronomy is a guide to the published literature in applications of spatial interferometry techniques to astronomical observations, theory and instrumentation at visible and infrared wavelengths. The key words spatial and optical define the scope of this discipline, distinguishing it from spatial interferometry at radio wavelengths, interferometry in the frequency domain applied to spectroscopy, or more general electro-optics theoretical and laboratory research. The main bibliography is a listing of all technical articles published in the international scientific literature and presented at the major international meetings and workshops attended by the spatial interferometry community. Section B summarizes publications dealing with the basic theoretical concepts and algorithms proposed and applied to optical spatial interferometry and imaging through a turbulent atmosphere. The section on experimental techniques is divided into twelve categories, representing the most clearly identified major areas of experimental research work. Section D, Observations, identifies publications dealing specifically with observations of astronomical sources, in which optical spatial interferometry techniques have been applied.
High sensitivity moiré interferometry with compact achromatic interferometry
Czarnek, Robert
Experimental observations and measurements are the sources of information essential for correct development of mathematical models of real structural materials. Moiré interferometry offers high sensitivity in full-field measurements of in-plane displacements on the surface of a specimen. Although it is a powerful method in experimental stress analysis, it has some shortcomings. One is that existing systems require highly coherent light. The only sufficient source of light for this application is a long cavity laser, which is relatively expensive and at best cumbersome. Another shortcoming is that measurements must be performed in a vibration-free environment, such as that found on a holographic table. These requirements limit the use of existing moiré interferometers to a holographic laboratory. In this paper a modified concept of compensation is presented, which permits the use of a chromatic source of light in a compact moiré system. The compensator provides order in the angles of incident light for each separate wavelength, so that the virtual reference grating created by each wavelength in a continuous spectrum is identical in frequency and spatial position. The result is a virtual reference grating that behaves exactly like that created in coherent light. With this development the use of a laser diode, which is a non-coherent light source of tiny dimensions, becomes practical. The special configuration of the optics that create the virtual grating allows its synchronization with the specimen grating and leads to an interferometer design that is relatively insensitive to the vibrations found in a mechanical testing laboratory. Sensitivity to relative motion is analyzed theoretically. This development provides the oppurtunity to apply moiré interferometry to solid mechanics problems that cannot be studied in an optics laboratory. Experimental verification of the optical concepts is provided. A compact moiré interferometer based on the presented idea was
Auriac, A.; Spaans, K.H.; Sigmundsson, F.; Hooper, A.; Schmidt, P.; Lund, B.
2013-01-01
A broad uplift occurs in Iceland in response to the retreat of ice caps, which began circa 1890. Until now, this deformation signal has been measured primarily using GPS at points some distance away from the ice caps. Here, for the first time we use satellite radar interferometry (interferometric sy
CSIR Research Space (South Africa)
Veldman, CS
2003-01-01
Full Text Available An implementation of the sine-approximation method of ISO 16063-11 (primary vibration calibration by laser interferometry) is described. The quadrature interference signals are generated using an interferometer as described in method 3 of ISO 16063...
Influence of the Coriolis force in atom interferometry.
Lan, Shau-Yu; Kuan, Pei-Chen; Estey, Brian; Haslinger, Philipp; Müller, Holger
2012-03-01
In a light-pulse atom interferometer, we use a tip-tilt mirror to remove the influence of the Coriolis force from Earth's rotation and to characterize configuration space wave packets. For interferometers with a large momentum transfer and large pulse separation time, we improve the contrast by up to 350% and suppress systematic effects. We also reach what is to our knowledge the largest space-time area enclosed in any atom interferometer to date. We discuss implications for future high-performance instruments.
Phase shift in atom interferometry due to spacetime curvature
Asenbaum, Peter; Kovachy, Tim; Brown, Daniel D; Hogan, Jason M; Kasevich, Mark A
2016-01-01
We present a single-source dual atom interferometer and utilize it as a gradiometer for precise gravitational measurements. The macroscopic separation between interfering atomic wave packets (as large as 16 cm) reveals the interplay of recoil effects and gravitational curvature from a nearby Pb source mass. The gradiometer baseline is set by the laser wavelength and pulse timings, which can be measured to high precision. Using a long drift time and large momentum transfer atom optics, the gradiometer reaches a resolution of $3 \\times 10^{-9}$ s$^{-2}$ per shot and measures a 1 rad phase shift induced by the source mass.
Linear approximation for measurement errors in phase shifting interferometry
van Wingerden, Johannes; Frankena, Hans J.; Smorenburg, Cornelis
1991-07-01
This paper shows how measurement errors in phase shifting interferometry (PSI) can be described to a high degree of accuracy in a linear approximation. System error sources considered here are light source instability, imperfect reference phase shifting, mechanical vibrations, nonlinearity of the detector, and quantization of the detector signal. The measurement inaccuracies resulting from these errors are calculated in linear approximation for several formulas commonly used for PSI. The results are presented in tables for easy calculation of the measurement error magnitudes for known system errors. In addition, this paper discusses the measurement error reduction which can be achieved by choosing an appropriate phase calculation formula.
Optical Frequency-Modulated Continuous-Wave (FMCW) Interferometry
Zheng, Jesse
2005-01-01
This book introduces the optical frequency-modulated continuous-wave (FMCW) interferometry - a new field of optics that is derived from radar. The study of optical FMCW interference not only updates our knowledge about the nature of light, but also creates an advanced technology for precision measurements. The principles, applications and signal processing of optical FMCW interference are systematically discussed. This book is intended for scientists and engineers in both academia and industry. It is especially suited to professionals who are working in the field of measurement instruments.
Bounding the Higgs boson width through interferometry.
Dixon, Lance J; Li, Ye
2013-09-13
We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg→γγ. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum.
3D super-virtual refraction interferometry
Lu, Kai
2014-08-05
Super-virtual refraction interferometry enhances the signal-to-noise ratio of far-offset refractions. However, when applied to 3D cases, traditional 2D SVI suffers because the stationary positions of the source-receiver pairs might be any place along the recording plane, not just along a receiver line. Moreover, the effect of enhancing the SNR can be limited because of the limitations in the number of survey lines, irregular line geometries, and azimuthal range of arrivals. We have developed a 3D SVI method to overcome these problems. By integrating along the source or receiver lines, the cross-correlation or the convolution result of a trace pair with the source or receiver at the stationary position can be calculated without the requirement of knowing the stationary locations. In addition, the amplitudes of the cross-correlation and convolution results are largely strengthened by integration, which is helpful to further enhance the SNR. In this paper, both synthetic and field data examples are presented, demonstrating that the super-virtual refractions generated by our method have accurate traveltimes and much improved SNR.
Binary Cepheids from optical interferometry
Gallenne, A; Mérand, A; Monnier, J D; Pietrzyński, J Breitfelder G; Gieren, W
2013-01-01
Classical Cepheid stars have been considered since more than a century as reliable tools to estimate distances in the universe thanks to their Period-Luminosity (P-L) relationship. Moreover, they are also powerful astrophysical laboratories, providing fundamental clues for studying the pulsation and evolution of intermediate-mass stars. When in binary systems, we can investigate the age and evolution of the Cepheid, estimate the mass and distance, and constrain theoretical models. However, most of the companions are located too close to the Cepheid (1-40 mas) to be spatially resolved with a 10-meter class telescope. The only way to spatially resolve such systems is to use long-baseline interferometry. Recently, we have started a unique and long-term interferometric program that aims at detecting and characterizing physical parameters of the Cepheid companions, with as main objectives the determination of accurate masses and geometric distances.
Parasitic interference in nulling interferometry
Matter, Alexis; Danchi, William C; Lopez, Bruno; Absil, Olivier
2013-01-01
Nulling interferometry aims to detect faint objects close to bright stars. Its principle is to produce a destructive interference along the line-of-sight so that the stellar flux is rejected, while the flux of the off-axis source can be transmitted. In practice, various instrumental perturbations can degrade the nulling performance. Any imperfection in phase, amplitude, or polarization produces a spurious flux that leaks to the interferometer output and corrupts the transmitted off-axis flux. One of these instrumental pertubations is the crosstalk phenomenon, which occurs because of multiple parasitic reflections inside transmitting optics, and/or diffraction effects related to beam propagation along finite size optics. It can include a crosstalk of a beam with itself, and a mutual crosstalk between different beams. This can create a parasitic interference pattern, which degrades the intrinsic transmission map - or intensity response - of the interferometer. In this context, we describe how this instrumental ...
Moire interferometry with increased sensitivity
Han, Bongtae; Post, Daniel
The basic sensitivity of moire interferometry was increased beyond the previously conceived theoretical limit. This was accomplished by creating the virtual reference grating inside a refractive medium instead of air, thus shortening the wavelength of light. A very compact four-beam moire interferometer in a refractive medium was developed for microscopic viewing, which produced a basic sensitivity of 208 nm per fringe order, corresponding to moire with 4800 lines per mm. Its configuration made it inherently stable and relatively insensitive to environmental disturbances. An optical microscope was employed as the image recording system to obtain high spatial resolution. The method was demonstrated for deformation of a thick graphite/epoxy composite at the 0/90 deg ply interface.
Fundamental physics research and neutron interferometry
Energy Technology Data Exchange (ETDEWEB)
Ioffe, A. [Hahn-Meitner-Institut Berlin GmbH (Germany)
1996-08-01
The possibility of the use of an extremely sensitive neutron interferometry technique for the study of electromagnetic structure of the neutron and the parity non-conservative effects in neutron spin rotation is discussed. (author)
Novel Polarimetric SAR Interferometry Algorithms Project
National Aeronautics and Space Administration — Polarimetric radar interferometry (PolInSAR) is a new SAR imaging mode that is rapidly becoming an important technique for bare earth topographic mapping, tree...
Some applications of holographic interferometry in biomechanics
Ebbeni, Jean P. L.
1992-03-01
Holographic interferometry is well adapted for the determination of 2D strain fields in osseous structures. The knowledge of those strain fields is important for the understanding of structure behavior such as arthrosis.
Novel Polarimetric SAR Interferometry Algorithms Project
National Aeronautics and Space Administration — Polarimetric SAR interferometry (PolInSAR) is a recently developed synthetic aperture radar (SAR) imaging mode that combines the capabilities of radar polarimetry...
High-contrast Nulling Interferometry Techniques Project
National Aeronautics and Space Administration — "We are developing rotating-baseline nulling-interferometry techniques and algorithms on the single-aperture Hale and Keck telescopes at near-infrared wavelengths,...
Terahertz Detection Based on Spectral-Domain Interferometry Using Mach-Zehnder Interferometer
Ibrahim, Akram; Sharma, Gargi; Singh, Kanwarpal; Ozaki, Tsuneyuki
2016-09-01
We demonstrate the use of a Mach-Zehnder interferometer (MZI) to improve the performance of terahertz electric field measurements based on spectral-domain interferometry. The interferometer is introduced into the probe beam line to improve the temporal overlap between the two probe pulses. The probe pulse in the sample arm of the interferometer passes through the detection crystal and overlaps with the terahertz pulse, while the probe pulse in the reference arm does not. We measure the phase change between spectral components of these two pulses using spectral-domain interferometry. Using this new technique, we enable an unlimited temporal scanning window without the loss in the signal-to-noise ratio, thus overcoming the major limitation of conventional spectral-domain interferometry techniques for terahertz electric field detection.
Chong, Wee Keat; Li, Xiang; Soh, Yeng Chai
2013-07-01
Unlike a conventional white light source that emits a continuous and broad spectrum of light, the dual wavelength white light emitting diode (LED) generates white light by mixing blue and yellow lights, so there are two distinct peaks in its intensity spectrum. Prior works had shown that the spectral property of the dual wavelength white LED can affect the vertical scanning interferometry negatively if the spectral effects are not compensated. In this paper, we shall examine this issue by modeling the spectral property and variation of the dual wavelength white LED, followed by investigating its effects on the interference signal of vertical scanning interferometry. Instead of compensating the spectral effects of the dual wavelength white LED, we harness its spectral property to improve the performance of a phase-based height reconstruction algorithm in vertical scanning interferometry.
Nanoscale optical interferometry with incoherent light
Dongfang Li,; Jing Feng; Domenico Pacifici
2016-01-01
Optical interferometry has empowered an impressive variety of biosensing and medical imaging techniques. A widely held assumption is that devices based on optical interferometry require coherent light to generate a precise optical signature in response to an analyte. Here we disprove that assumption. By directly embedding light emitters into subwavelength cavities of plasmonic interferometers, we demonstrate coherent generation of surface plasmons even when light with extremely low degrees of...
Fringe formation in dual-hologram interferometry
Burner, A. W.
1990-01-01
Reference-fringe formation in nondiffuse dual-hologram interferometry is described by combining a first-order geometrical hologram treatment with interference fringes generated by two point sources. The first-order imaging relationships can be used to describe reference-fringe patterns for the geometry of the dual-hologram interferometry. The process can be completed without adjusting the two holograms when the reconstructing wavelength is less than the exposing wavelength, and the process is found to facilitate basic intereferometer adjustments.
Super-virtual refraction interferometry: Theory
Bharadwaj, Pawan
2011-01-01
Inverting for the subsurface velocity distribution by refraction traveltime tomography is a well-accepted imaging method by both the exploration and earthquake seismology communities. A significant drawback, however, is that the recorded traces become noisier with increasing offset from the source position, and so prevents accurate picking of traveltimes in far-offset traces. To enhance the signal-to-noise ratio of the far-offset traces, we present the theory of super-virtual refraction interferometry where the signal-to-noise ratio (SNR) of far-offset head-wave arrivals can be theoretically increased by a factor proportional to N; here, N is the number of receiver and source positions associated with the recording and generation of the head-wave arrival. There are two steps to this methodology: correlation and summation of the data to generate traces with virtual head-wave arrivals, followed by the convolution of the data with the virtual traces to create traces with super-virtual head-wave arrivals. This method is valid for any medium that generates head-wave arrivals. There are at least three significant benefits to this methodology: 1). enhanced SNR of far-offset traces so the first-arrival traveltimes of the noisy far-offset traces can be more reliably picked to extend the useful aperture of data, 2). the SNR of head waves in a trace that arrive after the first arrival can be enhanced for accurate traveltime picking and subsequent inversion by traveltime tomography, and 3). common receiver-pair gathers can be analyzed to detect the presence of diving waves in the first arrivals, which can be used to assess the nature of the refracting boundary. © 2011 Society of Exploration Geophysicists.
Energy Technology Data Exchange (ETDEWEB)
Mitryk, Shawn J; Wand, Vinzenz; Mueller, Guido, E-mail: smitryk@phys.ufl.ed, E-mail: mueller@phys.ufl.ed [Department of Physics, University of Florida, PO Box 118440, Gainesville, FL 32611-8440 (United States)
2010-04-21
Laser Interferometer Space Antenna (LISA) is a cooperative NASA/ESA mission proposed to directly measure gravitational waves (GW) in the frequency range from 30 muHz to 1 Hz with an optimal strain sensitivity of 10{sup -21}/sq root(Hz) at 3 mHz. LISA will utilize a modified Michelson interferometer to measure length changes of 40 pm/sq root(Hz) between drag-free proof masses located on three separate spacecraft (SC) separated by a distance of 5 Gm. The University of Florida has developed a hardware-in-the-loop simulator of the LISA constellation to verify the laser noise cancellation technique known as time-delay interferometry (TDI). We replicate the frequency stabilization of the laser on the local SC and the phase-locking of the lasers on the far SC. The laser photodetector beatnotes are electronically delayed, Doppler shifted and applied with a mock GW signal to simulate the laser link between the SC. The beatnotes are also measured with a LISA-like phasemeter and the data are used to extract the laser phase and residual phase-lock loop noise in post-processing through TDI. This uncovers the GW modulation signal buried under the laser noise. The results are then compared to the requirements defined by the LISA science collaboration.
Lui, H S; Taimre, T; Bertling, K; Lim, Y L; Dean, P; Khanna, S P; Lachab, M; Valavanis, A; Indjin, D; Linfield, E H; Davies, A G; Rakić, A D
2014-05-01
We propose a terahertz (THz)-frequency synthetic aperture radar imaging technique based on self-mixing (SM) interferometry, using a quantum cascade laser. A signal processing method is employed which extracts and exploits the radar-related information contained in the SM signals, enabling the creation of THz images with improved spatial resolution. We demonstrate this by imaging a standard resolution test target, achieving resolution beyond the diffraction limit.
Spherical grating based x-ray Talbot interferometry
Energy Technology Data Exchange (ETDEWEB)
Cong, Wenxiang, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Xi, Yan, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu; Wang, Ge, E-mail: congw@rpi.edu, E-mail: xiy2@rpi.edu, E-mail: wangg6@rpi.edu [Biomedical Imaging Center, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)
2015-11-15
Purpose: Grating interferometry is a state-of-the-art x-ray imaging approach, which can acquire information on x-ray attenuation, phase shift, and small-angle scattering simultaneously. Phase-contrast imaging and dark-field imaging are very sensitive to microstructural variation and offers superior contrast resolution for biological soft tissues. However, a common x-ray tube is a point-like source. As a result, the popular planar grating imaging configuration seriously restricts the flux of photons and decreases the visibility of signals, yielding a limited field of view. The purpose of this study is to extend the planar x-ray grating imaging theory and methods to a spherical grating scheme for a wider range of preclinical and clinical applications. Methods: A spherical grating matches the wave front of a point x-ray source very well, allowing the perpendicular incidence of x-rays on the grating to achieve a higher visibility over a larger field of view than the planer grating counterpart. A theoretical analysis of the Talbot effect for spherical grating imaging is proposed to establish a basic foundation for x-ray spherical gratings interferometry. An efficient method of spherical grating imaging is also presented to extract attenuation, differential phase, and dark-field images in the x-ray spherical grating interferometer. Results: Talbot self-imaging with spherical gratings is analyzed based on the Rayleigh–Sommerfeld diffraction formula, featuring a periodic angular distribution in a polar coordinate system. The Talbot distance is derived to reveal the Talbot self-imaging pattern. Numerical simulation results show the self-imaging phenomenon of a spherical grating interferometer, which is in agreement with the theoretical prediction. Conclusions: X-ray Talbot interferometry with spherical gratings has a significant practical promise. Relative to planar grating imaging, spherical grating based x-ray Talbot interferometry has a larger field of view and
Neutron interferometry with cold stage
Mineeva, Taisiya; Arif, M.; Huber, M. G.; Shahi, C. B.; Clark, C. W.; Cory, D. G.; Nsofini, J.; Sarenac, D.; Pushin, D. A.
Neutron interferometry (NI) is amongst the most precise methods for characterizing neutron interactions by measuring the relative difference between two neutron paths, one of which contains a sample-of-interest. Because neutrons carry magnetic moment and are deeply penetrating, they are excellent probes to investigate properties of magnetic materials. The advantage of NI is its unique sensitivity which allows to directly measure magnetic and structural transitions in materials. Up to now NI has been sparingly used in material research due to its sensitivity to environmental noise. However, recent successes in implementing Quantum Error Correction principles lead to an improved NI design making it robust against mechanical vibrations. Following these advances, a new user facility at the National Institute for Standards and Technology was built to study condensed matter applications, biology and quantum physics. Incorporating cold sample stage inside NI is the first of its kind experiment which can be carried out on large range of temperatures down to 4K. Upon successful realization, it will open new frontiers to characterize magnetic domains, phase transitions and spin properties in a variety of materials such as, for example, iron-based superconductors and spintronic materials. Supported in part by CERC, CIFAR, NSERC and CREATE.
Parsimonious Refraction Interferometry and Tomography
Hanafy, Sherif
2017-02-04
We present parsimonious refraction interferometry and tomography where a densely populated refraction data set can be obtained from two reciprocal and several infill shot gathers. The assumptions are that the refraction arrivals are head waves, and a pair of reciprocal shot gathers and several infill shot gathers are recorded over the line of interest. Refraction traveltimes from these shot gathers are picked and spawned into O(N2) virtual refraction traveltimes generated by N virtual sources, where N is the number of geophones in the 2D survey. The virtual traveltimes can be inverted to give the velocity tomogram. This enormous increase in the number of traveltime picks and associated rays, compared to the many fewer traveltimes from the reciprocal and infill shot gathers, allows for increased model resolution and a better condition number with the system of normal equations. A significant benefit is that the parsimonious survey and the associated traveltime picking is far less time consuming than that for a standard refraction survey with a dense distribution of sources.
High-resolution wind profiling using combined spatial and frequency domain interferometry
Palmer, R. D.; Huang, X.; Fukao, S.; Yamamoto, M.; Nakamura, T.
1995-11-01
A novel approach to wind profiling is presented which is based on the hybrid use of spatial interferometry (SI) and frequency domain interferometry (FDI). Many algorithms exist that can be used to determine the wind field using SI. However, the imaging Doppler interferometry (IDI) technique is somewhat unique in that the wind field within the radar beam is angularly "imaged" using the Doppler sorting effect. The spatial locations of scatterers are determined by assuming a wind field across the beam and Fourier analyzing signals to sort Doppler velocities. Pulsed radar systems are limited in range resolution by the length of the transmitted pulse, and wind estimates are obtained for a discrete set of altitudes determined by sampling the continuous stream of signals. Frequency domain interferometry (FDI) can be used to determine the radial location of scattering layers within the resolution volume. Thus the combined use of FDI and IDI can provide the radial and angular location of particular scattering points. Using the Doppler sorting idea, a new wind profiling technique is presented which uses FDI to increase the altitude resolution of wind estimates obtained from IDI. Experimental data that illustrate the implementation of the algorithm are presented from the Middle and Upper (MU) Atmosphere radar.
Laser Interferometry for Harsh Environment MEMS Sensors
Nieva, Patricia
2008-03-01
Silicon-based MEMS technology has enabled the fabrication of a broad range of sensor and actuator systems that are having a great impact in areas that benefit from miniaturization and increased functionality. The main advantage of Si-based MEMS technologies is their possibility of integration with microelectronics thus allowing the economical production of smart microsystems. In the automotive industry for example, there is a need for inexpensive smart MEMS sensors for engine control applications. For instance, smart MEMS sensors capable of operating ``in cylinder'', where temperatures are around 400 C, could continuously monitor the combustion quality of the cylinders of automotive engines thus leading to reduced emissions and improved fuel economy. However, when the environment temperature is too high (>180 C), conventional Si-based microelectronics suffer from severe performance degradation, thus making smart Si-based MEMS impractical. Hence, further development, in terms of new MEMS materials and/or new technologies, is needed especially where high temperature capability is crucial to realizing improved electronic control. Remote sensing through optical signal detection has major advantages for safe signal transmission in harsh environments. It is highly resistant to electromagnetic interference (EMI) and radio frequency interference (RFI) and at the same time, it eliminates the necessity of on-board electronics, which has been one of the main obstacles in the development of smart MEMS sensors for high temperature applications. An economical way to deal with higher temperatures and other aggressive environmental conditions is to build MEMS sensors out of robust materials (e.g. Silicon nitride, SiC) and integrate them with optical signal detection techniques to form MOEMS. In this paper, we review recent trends for the use of laser interferometry for MEMS sensors in the context of using them for high temperature applications. Technological challenges faced in
Phase extraction in dynamic speckle interferometry: proposal of a road map
Directory of Open Access Journals (Sweden)
Jacquot P.
2010-06-01
Full Text Available Of all the two-beam interference patterns, the ones obtained in speckle interferometry (SI are the most difficult to be phase-demodulated. Many solutions exist in classical smooth-wave interferometry and alike techniques, both in static and dynamic regimes. In SI, the three constituents of the signals – the background, the modulation and the phase – are all basically random variables. There is no way to make a prediction of the evolution of these variables outside the small size of the correlation volumes – the volumes defined by the average speckle grain. To some extent, the classical methods can be adapted to SI. Here, we prefer to develop a series of new processing tools tailored to the specificities of the dynamic SI signals: the cooperative use of the empirical mode decomposition (EMD, the Hilbert transform (HT, and the three dimensional piecewise processing (3DPP for recovering efficiently the phase of these signals.
Recurrence properties of quantum observables in wave packet dynamics
Sudheesh, C; Balakrishnan, V
2009-01-01
We investigate the recurrence properties of the time series of quantum mechanical expectation values, in terms of two representative models for a single-mode radiation field interacting with a nonlinear medium. From recurrence-time distributions, return maps and recurrence plots, we conclude that the dynamics of appropriate observables pertaining to the field can vary from quasiperiodicity to hyperbolicity, depending on the extent of the nonlinearity and of the departure from coherence of the initial state of the field. We establish that, in a simple bipartite model in which the field is effectively an open quantum system, a decaying exponential recurrence-time distribution, characteristic of a hyperbolic dynamical system, is associated with chaotic temporal evolution as characterized by a positive Liapunov exponent.
Quantum electrodynamics of one-photon wave packets
Stobińska, M; Leuchs, G
2010-01-01
In this contribution we investigate quantum electrodynamical many-mode aspects by exploring the simplest possible situation in this context, namely the interaction of a single atom, modeled by a simple two-level system, with many-mode one-photon quantum states of the electromagnetic field. In particular, we concentrate on the question how the engineering of electromagnetic field modes influences the atom-field interaction. An interesting problem in this context is the engineering of ideal one-photon multi-mode quantum states which may excite a single atom perfectly [M. Stobi\\'nska, G. Alber, and G. Leuchs, EPL {\\bf 86}, 14007 (2009)]. For purposes of quantum information processing such one-photon multi-mode states are particularly well suited for transmitting quantum information and for storing it in a material memory again.
Dynamical phase diagram of Gaussian wave packets in optical lattices
Hennig, H.; Neff, T.; Fleischmann, R.
2016-03-01
We study the dynamics of self-trapping in Bose-Einstein condensates (BECs) loaded in deep optical lattices with Gaussian initial conditions, when the dynamics is well described by the discrete nonlinear Schrödinger equation (DNLSE). In the literature an approximate dynamical phase diagram based on a variational approach was introduced to distinguish different dynamical regimes: diffusion, self-trapping, and moving breathers. However, we find that the actual DNLSE dynamics shows a completely different diagram than the variational prediction. We calculate numerically a detailed dynamical phase diagram accurately describing the different dynamical regimes. It exhibits a complex structure that can readily be tested in current experiments in BECs in optical lattices and in optical waveguide arrays. Moreover, we derive an explicit theoretical estimate for the transition to self-trapping in excellent agreement with our numerical findings, which may be a valuable guide as well for future studies on a quantum dynamical phase diagram based on the Bose-Hubbard Hamiltonian.
Momentum mapping of continuum electron wave packet interference
Yang, Weifeng; Lin, Cheng; Xu, Jingwen; Sheng, Zhihao; Song, Xiaohong; Hu, Shilin; Chen, Jing
2016-01-01
We analyze the two-dimensional photoelectrons momentum distribution of Ar atom ionized by midinfrared laser pulses and mainly concentrate on the energy range below 2Up. By using a generalized quantum trajectory Monte Carlo (GQTMC) simulation and comparing with the numerical solution of time-dependent Schrodinger equation (TDSE), we show that in the deep tunneling regime, the rescattered electron trajectories plays unimportant role and the interplay between the intracycle and inter-cycle results in a ring-like interference pattern. The ring-like interference pattern will mask the holographic interference structure in the low longitudinal momentum region. When the nonadiabatic tunneling contributes significantly to ionization, i.e., the Keldysh parameter 1, the contribution of the rescattered electron trajectories become large, thus holographic interference pattern can be clearly observed. Our results help paving the way for gaining physical insight into ultrafast electron dynamic process with attosecond tempor...
Modulated Wave Packets in DNA and Impact of Viscosity
Institute of Scientific and Technical Information of China (English)
Conrad Bertrand Tabi; Alidou Mohamadou; Timoleon Crepin Kofan(e)
2009-01-01
We study the nonlinear dynamics of a DNA molecular system at physiological temperature in a viscous media by using the Peyrard-Bishop model.The nonlinear dynamics of the above system is shown to be governed by the discrete complex Ginzburg-Landau equation.In the non-viscous limit,the equation reduces to the nonlinear Schrodinger equation.Modulational instability criteria are derived for both the cases.On the basis of these criteria,numerical simulations are made,which confirm the analytical predictions.The planar wave solution used as the initial condition makes localized oscillations of base pairs and causes energy localization.The results also show that the viscosity of the solvent in the surrounding damps out the amplitude of wave patterns.
Quantum teleportation of nonclassical wave packets: An effective multimode theory
Energy Technology Data Exchange (ETDEWEB)
Benichi, Hugo; Takeda, Shuntaro; Lee, Noriyuki; Furusawa, Akira [Department of Applied Physics, University of Tokyo, Tokyo (Japan)
2011-07-15
We develop a simple and efficient theoretical model to understand the quantum properties of broadband continuous variable quantum teleportation. We show that, if stated properly, the problem of multimode teleportation can be simplified to teleportation of a single effective mode that describes the input state temporal characteristic. Using that model, we show how the finite bandwidth of squeezing and external noise in the classical channel affect the output teleported quantum field. We choose an approach that is especially relevant for the case of non-Gaussian nonclassical quantum states and we finally back-test our model with recent experimental results.
The Lindley paradox in optical interferometry
Energy Technology Data Exchange (ETDEWEB)
Mauri, Camillo [Quantum Technology Lab, Dipartimento di Fisica, Università degli Studi di Milano, I-20133 Milano (Italy); Paris, Matteo G.A., E-mail: matteo.paris@fisica.unimi.it [Quantum Technology Lab, Dipartimento di Fisica, Università degli Studi di Milano, I-20133 Milano (Italy); CNISM, Unità Milano Statale, I-20133 Milano (Italy); INFN, Sezione di Milano, I-20133 Milano (Italy)
2016-02-05
The so-called Lindley paradox is a counterintuitive statistical effect where the Bayesian and frequentist approaches to hypothesis testing give radically different answers, depending on the choice of the prior distribution. In this paper we address the occurrence of the Lindley paradox in optical interferometry and discuss its implications for high-precision measurements. In particular, we focus on phase estimation by Mach–Zehnder interferometers and show how to mitigate the conflict between the two approaches by using suitable priors. - Highlights: • We address the occurence of Lindley paradox in interferometry and discuss its implications for high-precision measurements. • We show how to mitigate the conflict between Bayesian and frequentist approach to interferometry using suitable priors. • Our results apply to calibration of homodyne detectors for quantum tomography.
The Wide Field Imaging Interferometry Testbed
Zhang, X; Leisawitz, D T; Leviton, D B; Martino, A J; Mather, J C; Zhang, Xiaolei; Feinberg, Lee; Leisawitz, Dave; Leviton, Douglas B.; Martino, Anthony J.; Mather, John C.
2001-01-01
We are developing a Wide-Field Imaging Interferometry Testbed (WIIT) in support of design studies for NASA's future space interferometry missions, in particular the SPIRIT and SPECS far-infrared/submillimeter interferometers. WIIT operates at optical wavelengths and uses Michelson beam combination to achieve both wide-field imaging and high-resolution spectroscopy. It will be used chiefly to test the feasibility of using a large-format detector array at the image plane of the sky to obtain wide-field interferometry images through mosaicing techniques. In this setup each detector pixel records interferograms corresponding to averaging a particular pointing range on the sky as the optical path length is scanned and as the baseline separation and orientation is varied. The final image is constructed through spatial and spectral Fourier transforms of the recorded interferograms for each pixel, followed by a mosaic/joint-deconvolution procedure of all the pixels. In this manner the image within the pointing range ...
Demonstration of X-ray talbot interferometry
Momose, A; Kawamoto, S; Hamaishi, Y; Takai, K; Suzuki, Y
2003-01-01
First Talbot interferometry in the hard X-ray region was demonstrated using a pair of transmission gratings made by forming gold stripes on glass plates. By aligning the gratings on the optical axis of X-rays with a separation that caused the Talbot effect by the first grating, moire fringes were produced inclining one grating slightly against the other around the optical axis. A phase object placed in front of the first grating was detected by moire-fringe bending. Using the technique of phase-shifting interferometry, the differential phase corresponding to the phase object could also be measured. This result suggests that X-ray Talbot interferometry is a novel and simple method for phase-sensitive X-ray radiography. (author)
An Adaptive Iterated Nonlocal Interferometry Filtering Method
Directory of Open Access Journals (Sweden)
Lin Xue
2014-04-01
Full Text Available Interferometry filtering is one of the key steps in obtain high-precision Digital Elevation Model (DEM and Digital Orthophoto Map (DOM. In the case of low-correlation or complicated topography, traditional phase filtering methods fail in balancing noise elimination and phase preservation, which leads to inaccurate interferometric phase. This paper proposed an adaptive iterated nonlocal interferometry filtering method to deal with the problem. Based on the thought of nonlocal filtering, the proposed method filters the image with utilization of the image redundancy information. The smoothing parameter of the method is adaptive to the interferometry, and automatic iteration, in which the window size is adjusted, is applied to improve the filtering precision. Validity of the proposed method is verified by simulated and real data. Comparison with existed methods is given at the same time.
Fast and accurate line scanner based on white light interferometry
Lambelet, Patrick; Moosburger, Rudolf
2013-04-01
White-light interferometry is a highly accurate technology for 3D measurements. The principle is widely utilized in surface metrology instruments but rarely adopted for in-line inspection systems. The main challenges for rolling out inspection systems based on white-light interferometry to the production floor are its sensitivity to environmental vibrations and relatively long measurement times: a large quantity of data needs to be acquired and processed in order to obtain a single topographic measurement. Heliotis developed a smart-pixel CMOS camera (lock-in camera) which is specially suited for white-light interferometry. The demodulation of the interference signal is treated at the level of the pixel which typically reduces the acquisition data by one orders of magnitude. Along with the high bandwidth of the dedicated lock-in camera, vertical scan-speeds of more than 40mm/s are reachable. The high scan speed allows for the realization of inspection systems that are rugged against external vibrations as present on the production floor. For many industrial applications such as the inspection of wafer-bumps, surface of mechanical parts and solar-panel, large areas need to be measured. In this case either the instrument or the sample are displaced laterally and several measurements are stitched together. The cycle time of such a system is mostly limited by the stepping time for multiple lateral displacements. A line-scanner based on white light interferometry would eliminate most of the stepping time while maintaining robustness and accuracy. A. Olszak proposed a simple geometry to realize such a lateral scanning interferometer. We demonstrate that such inclined interferometers can benefit significantly from the fast in-pixel demodulation capabilities of the lock-in camera. One drawback of an inclined observation perspective is that its application is limited to objects with scattering surfaces. We therefore propose an alternate geometry where the incident light is
Multi-link laser interferometry architecture for interspacecraft displacement metrology
Francis, Samuel P.; Lam, Timothy T.-Y.; McClelland, David E.; Shaddock, Daniel A.
2017-09-01
Targeting a future Gravity Recovery and Climate Experiment (GRACE) mission, we present a new laser interferometry architecture that can be used to recover the displacement between two spacecraft from multiple interspacecraft measurements. We show it is possible to recover the displacement between the spacecraft centers of mass in post-processing by forming linear combinations of multiple, spatially offset, interspacecraft measurements. By canceling measurement error due to angular misalignment of the spacecraft, we remove the need for precise placement or alignment of the interferometer, potentially simplifying spacecraft integration. To realize this multi-link architecture, we propose an all-fiber interferometer, removing the need for any ultrastable optical components such as the GRACE Follow-On mission's triple mirror assembly. Using digitally enhanced heterodyne interferometry, the number of links is readily scalable, adding redundancy to our measurement. We present the concept, an example multi-link implementation and the signal processing required to recover the center of mass displacement from multiple link measurements. Finally, in a simulation, we analyze the limiting noise sources in a 9 link interferometer and ultimately show we can recover the 80nm/√{Hz} displacement sensitivity required by the GRACE Follow-On laser ranging interferometer.
Synthetic aperture radar and interferometry development at Sandia National Laboratories
Energy Technology Data Exchange (ETDEWEB)
NONE
1993-04-01
Environmental monitoring, earth-resource mapping, and military systems require broad-area imaging at high resolutions. Many times the imagery must be acquired in inclement weather or during night as well as day. Synthetic aperture radar (SAR) provides such a capability. SAR systems take advantage of the long-range propagation characteristics of radar signals and the complex information processing capability of modern digital electronics to provide high resolution imagery. SAR complements photographic and other optical imaging capabilities because of the minimum constrains on time-of-day and atmospheric conditions and because of the unique responses of terrain and cultural targets to radar frequencies. Interferometry is a method for generating a three-dimensional image of terrain. The height projection is obtained by acquiring two SAR images from two slightly differing locations. It is different from the common method of stereoscopic imaging for topography. The latter relies on differing geometric projections for triangulation to define the surface geometry whereas interferometry relies on differences in radar propagation times between the two SAR locations. This paper presents the capabilities of SAR, explains how SAR works, describes a few SAR applications, provides an overview of SAR development at Sandia, and briefly describes the motion compensation subsystem.
Precision measurements with atom interferometry
Schubert, Christian; Abend, Sven; Schlippert, Dennis; Ertmer, Wolfgang; Rasel, Ernst M.
2017-04-01
Interferometry with matter waves enables precise measurements of rotations, accelerations, and differential accelerations [1-5]. This is exploited for determining fundamental constants [2], in fundamental science as e.g. testing the universality of free fall [3], and is applied for gravimetry [4], and gravity gradiometry [2,5]. At the Institut für Quantenoptik in Hannover, different approaches are pursued. A large scale device is designed and currently being set up to investigate the gain in precision for gravimetry, gradiometry, and fundamental tests on large baselines [6]. For field applications, a compact and transportable device is being developed. Its key feature is an atom chip source providing a collimated high flux of atoms which is expected to mitigate systematic uncertainties [7,8]. The atom chip technology and miniaturization benefits from microgravity experiments in the drop tower in Bremen and sounding rocket experiments [8,9] which act as pathfinders for space borne operation [10]. This contribution will report about our recent results. The presented work is supported by the CRC 1227 DQ-mat, the CRC 1128 geo-Q, the RTG 1729, the QUEST-LFS, and by the German Space Agency (DLR) with funds provided by the Federal Ministry of Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under Grant No. DLR 50WM1552-1557. [1] P. Berg et al., Phys. Rev. Lett., 114, 063002, 2015; I. Dutta et al., Phys. Rev. Lett., 116, 183003, 2016. [2] J. B. Fixler et al., Science 315, 74 (2007); G. Rosi et al., Nature 510, 518, 2014. [3] D. Schlippert et al., Phys. Rev. Lett., 112, 203002, 2014. [4] A. Peters et al., Nature 400, 849, 1999; A. Louchet-Chauvet et al., New J. Phys. 13, 065026, 2011; C. Freier et al., J. of Phys.: Conf. Series 723, 012050, 2016. [5] J. M. McGuirk et al., Phys. Rev. A 65, 033608, 2002; P. Asenbaum et al., arXiv:1610.03832. [6] J. Hartwig et al., New J. Phys. 17, 035011, 2015. [7] H. Ahlers et al., Phys. Rev. Lett. 116, 173601
Monitoring civil infrastructure using satellite radar interferometry
Chang, L.
2015-01-01
Satellite radar interferometry (InSAR) is a precise and efficient technique to monitor deformation on Earth with millimeter precision. Most InSAR applications focus on geophysical phenomena, such as earthquakes, volcanoes, or subsidence. Monitoring civil infrastructure with InSAR is relatively new,
Airborne Repeat Pass Interferometry for Deformation Measurements
Groot, J.; Otten, M.; Halsema, E. van
2000-01-01
In ground engineering the need for deformation measurements is urgent. SAR interferometry can be used to measure small (sub-wavelength) deformations. An experiment to investigate this for dike deformations was set up, using the C-band SAR system PHARUS (PHased ARray Universal SAR). This paper descri
Astronomical Optical Interferometry. I. Methods and Instrumentation
Directory of Open Access Journals (Sweden)
Jankov, S.
2010-12-01
Full Text Available Previous decade has seen an achievement of large interferometricprojects including 8-10m telescopes and 100m class baselines. Modern computerand control technology has enabled the interferometric combination of lightfrom separate telescopes also in the visible and infrared regimes. Imagingwith milli-arcsecond (mas resolution and astrometry with micro-arcsecond($mu$as precision have thus become reality. Here, I review the methods andinstrumentation corresponding to the current state in the field ofastronomical optical interferometry. First, this review summarizes thedevelopment from the pioneering works of Fizeau and Michelson. Next, thefundamental observables are described, followed by the discussion of the basicdesign principles of modern interferometers. The basic interferometrictechniques such as speckle and aperture masking interferometry, aperture synthesisand nulling interferometry are disscused as well. Using the experience ofpast and existing facilities to illustrate important points, I considerparticularly the new generation of large interferometers that has beenrecently commissioned (most notably, the CHARA, Keck, VLT and LBTInterferometers. Finally, I discuss the longer-term future of opticalinterferometry, including the possibilities of new large-scale ground-based projects and prospects for space interferometry.
Basic radio interferometry for future lunar missions
Aminaei, Amin; Klein Wolt, Marc; Chen, Linjie; Bronzwaer, Thomas; Pourshaghaghi, Hamid Reza; Bentum, Mark J.; Falcke, Heino
2014-01-01
In light of presently considered lunar missions, we investigate the feasibility of the basic radio interferometry (RIF) for lunar missions. We discuss the deployment of two-element radio interferometer on the Moon surface. With the first antenna element is envisaged to be placed on the lunar lander,
Constraining symmetron fields with atom interferometry
Burrage, Clare; Stevenson, James; Thrussell, Ben
2016-01-01
We apply the new constraints from atom-interferometry searches for screening mechanisms to the symmetron model, finding that these experiments exclude a previously unexplored region of parameter space. We discuss the possibility of networks of domain walls forming in the vacuum chamber, and how this could be used to discriminate between models of screening.
Linear response, multi-order grating interferometry using a reversal shearing imaging system.
Tao, Zhang; Tan, Jiubin; Cui, Jiwen
2015-10-01
Linear response, multi-order grating interferometry is proposed to measure grating displacement. The system, a combination of a reversal shearing interferometer and an imaging system, enables calculating multi-order, integrated intensity signals with a linear waveform response. A theoretical multi-order model for the linear response signal analysis is presented with a Fourier series expansion. The results of the experiment, which prove the validity of the theoretical model, indicate a linear response to displacement with a linearity of 98.7% and a resolution of 10 nm. We conclude that the proposed method enables the development of a new class of potent linear response grating interferometry for displacement metrology.
Optimal Arrays for Compressed Sensing in Snapshot-Mode Radio Interferometry
Fannjiang, Clara
2015-01-01
Radio interferometry has always faced the problem of incomplete sampling of the Fourier plane. A possible remedy can be found in the promising new theory of compressed sensing (CS), which allows for the accurate recovery of sparse signals from sub-Nyquist sampling given certain measurement conditions. We provide an introductory assessment of optimal arrays for CS in snapshot-mode radio interferometry, using orthogonal matching pursuit (OMP), a widely used CS recovery algorithm similar in some respects to CLEAN. We focus on centrally condensed (specifically, Gaussian) arrays versus uniform arrays, and the principle of randomization versus deterministic arrays such as the VLA. The theory of CS is grounded in $a)$ sparse representation of signals and $b)$ measurement matrices of low coherence. We calculate a related quantity, mutual coherence (MC), as a theoretical indicator of arrays' suitability for OMP based on the recovery error bounds in (Donoho et al. 2006). OMP reconstructions of both point and extended o...
Jacquin, Olivier; Glastre, Wilfried; Hugon, Olivier; De Chatellus, Hugues Guillet
2012-01-01
Using a Nd:YVO4 microchip laser with a relaxation frequency in the megahertz range, we have experimentally compared a heterodyne interferometer based on a Michelson configuration with an autodyne interferometer based on the laser optical feedback imaging (LOFI) method regarding their signal to noise ratios. In the heterodyne configuration, the beating between the reference beam and the signal beam is realized outside the laser cavity while in the autodyne configuration, the wave beating takes place inside the laser cavity and the relaxation oscillations of the laser intensity then play an important part. For a given laser output power, object under investigation and detection noise level, we have determined the amplification gain of the LOFI interferometer compared to the heterodyne interferometer. LOFI interferometry is demonstrated to show higher performances than heterodyne interferometry for a wide range of laser power and detection level of noise. The experimental results are in good agreement with the t...
Fluctuations of spacetime and holographic noise in atomic interferometry
Göklü, Ertan
2009-01-01
Space--time can be understood as some kind of space--time foam of fluctuating bubbles or loops which are expected to be an outcome of a theory of quantum gravity. One recently discussed model for this kind of space--time fluctuations is the holographic principle which allows to deduce the structure of these fluctuations. We review and discuss two scenarios which rely on the holographic principle leading to holographic noise. One scenario leads to fluctuations of the space--time metric affecting the dynamics of quantum systems: (i) an apparent violation of the equivalence principle, (ii) a modification of the spreading of wave packets, and (iii) a loss of quantum coherence. All these effects can be tested with cold atoms. These tests would supplement measurements of a so called ``mystery noise'' at the gravitational wave detector GEO600 which was recently speculated to have its origin in holographic noise.
Sensitivity of atom interferometry to ultralight scalar field dark matter
Geraci, Andrew A
2016-01-01
We discuss the use of atom interferometry as a tool to search for Dark Matter (DM) composed of ultra-light scalar fields. Previous work on ultra-light DM detection using accelerometers has considered the possibility of equivalence principle violating effects whereby gradients in the dark matter field can directly produce relative accelerations between media of differing composition. In atom interferometers, we find that time-varying phase signals from oscillatory, or dilaton-like, DM can also arise due to changes in the atom rest mass that can occur between light-pulses throughout the interferometer sequence as well as changes in the earth's gravitational field. We estimate that several orders of magnitude of unexplored phase space for light DM fields can be probed with our proposed method.
Quantum nonlocality in weak-thermal-light interferometry
Tsang, Mankei
2011-01-01
In astronomy, interferometry of light collected by separate telescopes is often performed by physically interfering the optical paths in the form of the classic Young's double-slit experiment. Optical loss along the paths severely hampers the efficiency of this so-called direct detection method, limiting the maximum baseline between the telescopes and thus the achievable resolution. This problem motivates the fundamental question of whether one can achieve a comparable signal-to-noise performance by separate optical measurements at the two telescopes before combining the measurement results. Using quantum mechanics and estimation theory, here I show that any such spatially local measurement scheme, such as heterodyne or homodyne detection, is fundamentally inferior to coherently nonlocal measurements, such as direct detection, for estimating the mutual coherence of bipartite thermal light when the average photon flux is low. This surprising result can be regarded as a dual of Einstein-Podolsky-Rosen entanglem...
Ionospheric effects on repeat-pass SAR interferometry
Feng, Jian; Zhen, Weimin; Wu, Zhensen
2017-10-01
InSAR measurements can be significantly affected by the atmosphere when the radar signal propagates through the atmosphere since it varies with space and time. Great efforts have been made in recent years to better understand the properties of the tropospheric effects and to develop methods for mitigating these effects. By using the basic principles of InSAR, the quantitative analysis of ionospheric delay effects on topography and surface deformation have been introduced for the first time. The measurement errors can be related to the vertical ionospheric total electron content (vTEC). By using the ionospheric observations, the effects of temporal ionospheric variations on InSAR have been analyzed. The results indicate that the ionospheric variations with time, season, solar cycle and geomagnetic activities can compromise the effectiveness of InSAR for both the measurement of topography and surface determination. The repeat-pass SAR interferometry errors induced by ionosphere should be corrected by actual measurements.
Super-virtual refraction interferometry: an engineering field data example
Hanafy, Sherif M.
2012-10-01
The theory of super-virtual refraction interferometry (SVI) was recently developed to enhance the signal-to-noise ratio (SNR) of far-offset traces in refraction surveys. This enhancement of the SNR is proportional to √N and can be as high as N if an iterative procedure is used. Here N is the number of post-critical shot positions that coincides with the receiver locations. We now demonstrate the SNR enhancement of super-virtual refraction traces for one engineering-scale synthetic data and two field seismic data sets. The field data are collected over a normal fault in Saudi Arabia. Results show that both the SNR of the super-virtual data set and the number of reliable first-arrival traveltime picks are significantly increased. © 2012 European Association of Geoscientists & Engineers.
Adapting a Cryogenic Sapphire Oscillator for Very Long Baseline Interferometry
Doeleman, Sheperd; Rogers, Alan; Hartnett, John; Tobar, Michael; Nand, Nitin; 10.1086/660156
2011-01-01
Extension of very long baseline interferometry (VLBI) to observing wavelengths shorter than 1.3mm provides exceptional angular resolution (~20 micro arcsec) and access to new spectral regimes for the study of astrophysical phenomena. To maintain phase coherence across a global VLBI array at these wavelengths requires that ultrastable frequency references be used for the heterodyne receivers at all participating telescopes. Hydrogen masers have traditionally been used as VLBI references, but atmospheric turbulence typically limits (sub) millimeter VLBI coherence times to ~1-30 s. Cryogenic Sapphire Oscillators (CSO) have better stability than Hydrogen masers on these time scale and are potential alternatives to masers as VLBI references. Here, We describe the design, implementation and tests of a system to produce a 10 MHz VLBI frequency standard from the microwave (11.2 GHz) output of a CSO. To improve long-term stability of the new reference, the CSO was locked to the timing signal from the Global Positionin...
All-Sky Interferometry with Spherical Harmonic Transit Telescopes
Shaw, J Richard; Pen, Ue-Li; Stebbins, Albert; Sitwell, Michael
2014-01-01
In this paper we describe the spherical harmonic transit telescope, a novel formalism for the analysis of transit radio telescopes. This all-sky approach bypasses the curved sky complications of traditional interferometry and so is particularly well suited to the analysis of wide-field radio interferometers. It enables compact and computationally efficient representations of the data and its statistics that allow new ways of approaching important problems like map-making and foreground removal. In particular, we show how it enables the use of the Karhunen-Loeve transform as a highly effective foreground filter, suppressing realistic foreground residuals for our fiducial example by at least a factor twenty below the 21cm signal even in highly contaminated regions of the sky. This is despite the presence of the angle-frequency mode mixing inherent in real-world instruments with frequency-dependent beams. We show, using Fisher forecasting, that foreground cleaning has little effect on power spectrum constraints ...
Sensitivity of Atom Interferometry to Ultralight Scalar Field Dark Matter.
Geraci, Andrew A; Derevianko, Andrei
2016-12-23
We discuss the use of atom interferometry as a tool to search for dark matter (DM) composed of virialized ultralight fields (VULFs). Previous work on VULF DM detection using accelerometers has considered the possibility of equivalence-principle-violating effects whereby gradients in the dark matter field can directly produce relative accelerations between media of differing composition. In atom interferometers, we find that time-varying phase signals induced by coherent oscillations of DM fields can also arise due to changes in the atom rest mass that can occur between light pulses throughout the interferometer sequence as well as changes in Earth's gravitational field. We estimate that several orders of magnitude of unexplored phase space for VULF DM couplings can be probed due to these new effects.
Heterodyne Angle Deviation Interferometry in Vibration and Bubble Measurements
Directory of Open Access Journals (Sweden)
Ming-Hung Chiu
2016-07-01
Full Text Available We proposed heterodyne angle deviation interferometry (HADI for angle deviation measurements. The phase shift of an angular sensor (which can be a metal film or a surface plasmon resonance (SPR prism is proportional to the deviation angle of the test beam. The method has been demonstrated in bubble and speaker’s vibration measurements in this paper. In the speaker’s vibration measurement, the voltage from the phase channel of a lock-in amplifier includes the vibration level and frequency. In bubble measurement, we can count the number of bubbles passing through the cross section of the laser beam and measure the bubble size from the phase pulse signal.
Self-mixing interferometry: a novel yardstick for mechanical metrology
Donati, Silvano
2016-11-01
A novel configuration of interferometry, SMI (self-mixing interferometry), is described in this paper. SMI is attractive because it doesn't require any optical part external to the laser and can be employed in a variety of measurements - indeed it is sometimes indicated as the "interferometer for measuring without an interferometer". On processing the phase carried by the optical field upon propagation to the target under test, a number of applications have been developed, including traditional measurements related to metrology and mechanical engineering - like displacement, distance, small-amplitude vibrations, attitude angles, velocity, as well as new measurements, like mechanical stress-strain hysterisis and microstructure/MEMS electro-mechanical response. In another field, sensing of motility finds direct application in a variety of biophysical measurements, like blood pulsation, respiratory sounds, chest acoustical impedance, and blood velocity profile. And, we may also look at the amplitude of the returning signal in a SMI, and we can measure weak optical echoes - for return loss and isolation factor measurements, CD readout and scroll sensing, and THz-wave detection. Last, the fine details of the SMI waveform reveal physical parameters of the laser like the laser linewidth, coherence length, and alpha factor. Worth to be noted, SMI is also a coherent detection scheme, and measurement close to the quantum limit of received field with minimum detectable displacements of 100 pm/√Hz are currently achieved upon operation on diffusive targets, whereas in detection mode returning signal can be sensed down to attenuations of -80dB.
Radio interferometry and satellite tracking
Kawase, Seiichiro
2012-01-01
Worldwide growth of space communications has caused a rapid increase in the number of satellites operating in geostationary orbits, causing overcrowded orbits. This practical resource is designed to help professionals overcome this problem. This timely book provides a solid understanding of the use of radio interferometers for tracking and monitoring satellites in overcrowded environments. Practitioners learn the fundamentals of radio interferometer hardware, including antennas, receiving equipment, signal processing and phase detection, and measurement accuracies. This in-depth volume describ
Kinetic titration series with biolayer interferometry.
Frenzel, Daniel; Willbold, Dieter
2014-01-01
Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1-42). Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i) circumvents problems in data evaluation caused by unavoidable sensor differences, ii) saves resources and iii) increases throughput if screening a multitude of different analyte/ligand combinations.
Kinetic titration series with biolayer interferometry.
Directory of Open Access Journals (Sweden)
Daniel Frenzel
Full Text Available Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1-42. Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i circumvents problems in data evaluation caused by unavoidable sensor differences, ii saves resources and iii increases throughput if screening a multitude of different analyte/ligand combinations.
Freeform metrology using subaperture stitching interferometry
Supranowitz, Chris; Lormeau, Jean-Pierre; Maloney, Chris; Murphy, Paul; Dumas, Paul
2016-11-01
As applications for freeform optics continue to grow, the need for high-precision metrology is becoming more of a necessity. Currently, coordinate measuring machines (CMM) that implement touch probes or optical probes can measure the widest ranges of shapes of freeform optics, but these measurement solutions often lack sufficient lateral resolution and accuracy. Subaperture stitching interferometry (SSI™) extends traditional Fizeau interferometry to provide accurate, high-resolution measurements of flats, spheres, and aspheres, and development is currently on-going to enable measurements of freeform surfaces. We will present recent freeform metrology results, including repeatability and cross-test data. We will also present MRF® polishing results where the stitched data was used as the input "hitmap" to the deterministic polishing process.
Nanoscale optical interferometry with incoherent light
Li, Dongfang; Feng, Jing; Pacifici, Domenico
2016-01-01
Optical interferometry has empowered an impressive variety of biosensing and medical imaging techniques. A widely held assumption is that devices based on optical interferometry require coherent light to generate a precise optical signature in response to an analyte. Here we disprove that assumption. By directly embedding light emitters into subwavelength cavities of plasmonic interferometers, we demonstrate coherent generation of surface plasmons even when light with extremely low degrees of spatial and temporal coherence is employed. This surprising finding enables novel sensor designs with cheaper and smaller light sources, and consequently increases accessibility to a variety of analytes, such as biomarkers in physiological fluids, or even airborne nanoparticles. Furthermore, these nanosensors can now be arranged along open detection surfaces, and in dense arrays, accelerating the rate of parallel target screening used in drug discovery, among other high volume and high sensitivity applications. PMID:26880171
Joint Multi-baseline SAR Interferometry
Directory of Open Access Journals (Sweden)
S. Tebaldini
2005-12-01
Full Text Available We propose a technique to provide interferometry by combining multiple images of the same area. This technique differs from the multi-baseline approach in literature as (a it exploits all the images simultaneously, (b it performs a spectral shift preprocessing to remove most of the decorrelation, and (c it exploits distributed targets. The technique is mainly intended for DEM generation at centimetric accuracy, as well as for differential interferometry. The problem is framed in the contest of single-input multiple-output (SIMO channel estimation via the cross-relations (CR technique and the resulting algorithm provides significant improvements with respect to conventional approaches based either on independent analysis of single interferograms or multi-baselines phase analysis of single pixels of current literature, for those targets that are correlated in all the images, like for long-term coherent areas, or for acquisitions taken with a short revisit time (as those gathered with future satellite constellations.
A system for airborne SAR interferometry
DEFF Research Database (Denmark)
Madsen, Søren Nørvang; Skou, Niels; Granholm, Johan
1996-01-01
Interferometric synthetic aperture radar (INSAR) systems have already demonstrated that elevation maps can be generated rapidly with single pass airborne across-track interferometry systems (XTT), and satellite repeat track interferometry (RTT) techniques have been used to map both elevation...... and perturbations of the surface of the Earth. The Danish Center for Remote Sensing (DCRS) has experimented with airborne INSAR since 1993. Multiple track data are collected in a special mode in which the radar directly steers the aircraft which allows for very precise control of the flight path. Such data sets...... have been acquired at both L- and C-band. During 1994/95 the system was further modified to add the capability to perform single pass interferometric data acquisitions at C-band. This paper will discuss: (1) the general principles of INSAR systems and their application to topographic mapping and (2...
Time-average dynamic speckle interferometry
Vladimirov, A. P.
2014-05-01
For the study of microscopic processes occurring at structural level in solids and thin biological objects, a method of dynamic speckle interferometry successfully applied. However, the method has disadvantages. The purpose of the report is to acquaint colleagues with the method of averaging in time in dynamic speckle - interferometry of microscopic processes, allowing eliminating shortcomings. The main idea of the method is the choice the averaging time, which exceeds the characteristic time correlation (relaxation) the most rapid process. The method theory for a thin phase and the reflecting object is given. The results of the experiment on the high-cycle fatigue of steel and experiment to estimate the biological activity of a monolayer of cells, cultivated on a transparent substrate is given. It is shown that the method allows real-time visualize the accumulation of fatigue damages and reliably estimate the activity of cells with viruses and without viruses.
A New Neutron Interferometry Facility at NCNR
Shahi, Chandra; Wietfeldt, Fred; Huber, Michael; Pushin, Dmitry; Arif, Muhammad
2013-10-01
A neutron interferometer splits an incoming neutron beam into two coherent partial beams, which travel on different paths and then recombine to form an interference pattern. This pattern is used to precisely determine the phase shift of a sample in one of the paths, thus the neutron interaction potential in the sample can be measured with high precision. A new neutron interferometry setup (NIOFa) has been constructed at the NIST Center for Neutron Research (NCNR). This new facility is mainly focused on spin based interferometry, which will expand its applications in both quantum computation and material research. New spin-control mechanisms are being tested; including thin-film spin flippers and efficient polarizing double cavity super mirrors. Doubling the neutron's degrees of freedom inside the interferometer promises exciting new quantum mechanical experiments and research capabilities. This work is supported by the National Science Foundation.
Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).
Energy Technology Data Exchange (ETDEWEB)
Abbott, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knox, Hunter Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); James, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Rebekah [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cole, Chris [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-01-01
We present findings from a novel field experiment conducted at Poker Flat Research Range in Fairbanks, Alaska that was designed to monitor changes in active layer thickness in real time. Results are derived primarily from seismic data streaming from seven Nanometric Trillium Posthole seismometers directly buried in the upper section of the permafrost. The data were evaluated using two analysis methods: Horizontal to Vertical Spectral Ratio (HVSR) and ambient noise seismic interferometry. Results from the HVSR conclusively illustrated the method's effectiveness at determining the active layer's thickness with a single station. Investigations with the multi-station method (ambient noise seismic interferometry) are continuing at the University of Florida and have not yet conclusively determined active layer thickness changes. Further work continues with the Bureau of Land Management (BLM) to determine if the ground based measurements can constrain satellite imagery, which provide measurements on a much larger spatial scale.
Optical interferometry for biology and medicine
Nolte, David D
2012-01-01
This book presents the fundamental physics of optical interferometry as applied to biophysical, biological and medical research. Interference is at the core of many types of optical detection and is a powerful probe of cellular and tissue structure in interfererence microscopy and in optical coherence tomography. It is also the root cause of speckle and other imaging artefacts that limit range and resolution. For biosensor applications, the inherent sensitivity of interferometry enables ultrasensitive detection of molecules in biological samples for medical diagnostics. In this book, emphasis is placed on the physics of light scattering, beginning with the molecular origins of refraction as light propagates through matter, and then treating the stochastic nature of random fields that ultimately dominate optical imaging in cells and tissue. The physics of partial coherence plays a central role in the text, with a focus on coherence detection techniques that allow information to be selectively detected out of ...
Fundamental Stellar Properties from Optical Interferometry
van Belle, Gerard T; Boyajian, Tabetha; Harper, Graham; Hummel, Christian; Pedretti, Ettore; Baines, Ellyn; White, Russel; Ravi, Vikram; Ridgway, Steve
2010-01-01
High-resolution observations by visible and near-infrared interferometers of both single stars and binaries have made significant contributions to the foundations that underpin many aspects of our knowledge of stellar structure and evolution for cool stars. The CS16 splinter on this topic reviewed contributions of optical interferometry to date, examined highlights of current research, and identified areas for contributions with new observational constraints in the near future.
Lateral shear interferometry with holo shear lens
Joenathan, C.; Mohanty, R. K.; Sirohi, R. S.
1984-12-01
A simple method for obtaining lateral shear using holo shear lenses (HSL) has been discussed. This simple device which produces lateral shears in the orthogonal directions has been used for lens testing. The holo shear lens is placed at or near the focus of the lens to be tested. It has also been shown that HSL can be used in speckle shear interferometry as it performs both the functions of shearing and imaging.
Measuring Close Binary Stars with Speckle Interferometry
2014-09-01
telescope has access to an adaptive optics system, and those telescopes utilize a prior method developed in 1970 by Antoine Labeyrie [2]. This method...23019+4220. a) b) c) 3. SPECKLE INTERFEROMETRY In 1970, Antoine Labeyrie [2] developed a technique to detect double stars that are closer than the...resulting in a simple product of cosine squared with no additive constant . The effects of a non- zero additive constant will become apparent in section 5
Large momentum beamsplitting in atom interferometry
Institute of Scientific and Technical Information of China (English)
G; D; McDonald; P; M; anju; P; B; Wigley; P; J; Everitt; WEI; Chunhua; M; A; Sooriyabandara; M; Boozarjmehr; A; Kordbacheh; C; Quinlivan; C; N; Kuhn; J; E; Debs; K; S; Hardman; N; P; Robins
2015-01-01
Large momentum transfer( LM T) beamsplitting in atom interferometry is review ed,focusing on the use of Bloch Oscillations to achieve high momentum separation w ithout loss of visibility. Phase sensitivity w ith a fringe visibility of 7% is observed in a horizontally guided,acceleration-sensitive atom interferometer w ith a momentum separation of 80k betw een its arms.In addition,a 510 k beamsplitter is demonstrated.
Holographic Interferometry Applications In External Osteosynthesis
Jacquot, P.; Rastogi, P. K.; Pflug, L.
1985-08-01
In order to maintain fragments of fractured bones in a state of immobilization, the use of an external rigid frame has proved to be very advantageous. Confronted by contradictory requirements, the conception of external fixation has, however, been a difficult task. The present paper aims to show, through three examples of varied bearings, the interest of holographic interferometry in external osteosynthesis. The first example deals with the mechanical behavior of a key element of the fixation device the ball joint submitted to realistic loads. The last two examples compare two models of ball joints as to their characteristics of rigidity and of resistance to slipping. Whereas in the former case holographic interferometry primarily fulfills the function of a prelude to the modelization work, in the latter cases it serves to formulate an engineering diagnostic. The findings relate to the remarkable elastic behavior of the ball joint, to the effectiveness of a lightened bowl design, and to the fact that cousin models may behave quite differently as to their resistance to slipping rotations of the bar. In comparison with other experimental methods, holographic interferometry appears to be very competitive and result-oriented and, as such, is expected to multiply applications in similar evaluation tasks.
Baker, John; Thorpe, Ira
2012-01-01
Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.
X-ray grating interferometry at photon energies over 180 keV
Energy Technology Data Exchange (ETDEWEB)
Ruiz-Yaniz, M., E-mail: maite.ruiz-yaniz@esrf.fr [European Synchrotron Radiation Facility, 71 Rue des Martyrs, 38000 Grenoble (France); Lehrstuhl für Biomedizinische Physik, Physik-Department and Institut für Medizintechnik, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany); Koch, F.; Meyer, P.; Kunka, D.; Mohr, J. [Institute of Microstructure Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Zanette, I. [Lehrstuhl für Biomedizinische Physik, Physik-Department and Institut für Medizintechnik, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Rack, A. [European Synchrotron Radiation Facility, 71 Rue des Martyrs, 38000 Grenoble (France); Hipp, A. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Plank Strasse 1, 21502 Geesthacht (Germany); Pfeiffer, F. [Lehrstuhl für Biomedizinische Physik, Physik-Department and Institut für Medizintechnik, Technische Universität München, James-Franck-Str. 1, 85748 Garching (Germany); Institut für diagnostische und interventionelle Radiologie, Klinikum rechts der Isar, Technische Universität München, 81675 München (Germany)
2015-04-13
We report on the implementation and characterization of grating interferometry operating at an x-ray energy of 183 keV. With the possibility to use this technique at high x-ray energies, bigger specimens could be studied in a quantitative way. Also, imaging strongly absorbing specimens will benefit from the advantages of the phase and dark-field signals provided by grating interferometry. However, especially at these high photon energies the performance of the absorption grating becomes a key point on the quality of the system, because the grating lines need to keep their small width of a couple of micrometers and exhibit a greater height of hundreds of micrometers. The performance of high aspect ratio absorption gratings fabricated with different techniques is discussed. Further, a dark-field image of an alkaline multicell battery highlights the potential of high energy x-ray grating based imaging.
Crest Factor Reduction in MC-CDMA Employing Carrier Interferometry Codes
Directory of Open Access Journals (Sweden)
Natarajan Balasubramaniam
2004-01-01
Full Text Available This paper addresses signal compactness issues in MC-CDMA employing carrier interferometry codes using the measure of crest factor (CF. Carrier interferometry codes, applied to N -carrier MC-CDMA systems, enable 2N users to simultaneously share the system bandwidth with minimal degradation in performance (relative to the N -orthogonal-user case. First, for a fully loaded ( K=N and K=2N users MC-CDMA system with practical values of N , it is shown that the CF in downlink transmission demonstrates desirable properties of low mean and low variance. The downlink CF degrades when the number of users in the system decreases. Next, the high CF observed in the uplink is characterized and the poor CF in a partially loaded downlink as well as uplink is effectively combated using Schroeder's analytical CF reduction techniques.
Signal Processing in Cold Atom Interferometry-Based INS
2014-03-27
uninterrupted tracking of at least four GPS satellites [1]. Large buildings, canyons and indoor environments still pose problems for users attempting to...it is commonly referred to as the Angle Random Walk (ARW) specification because the gyro drift introduces a zero-mean random walk error in the angle...uncertainty brought about by integrating the accelerometer’s output over one hour. The accelerometer drift introduces a zero-mean random walk error in the
pSIN: A scalable, Parallel algorithm for Seismic INterferometry of large-N ambient-noise data
Chen, Po; Taylor, Nicholas J.; Dueker, Ken G.; Keifer, Ian S.; Wilson, Andra K.; McGuffy, Casey L.; Novitsky, Christopher G.; Spears, Alec J.; Holbrook, W. Steven
2016-08-01
Seismic interferometry is a technique for extracting deterministic signals (i.e., ambient-noise Green's functions) from recordings of ambient-noise wavefields through cross-correlation and other related signal processing techniques. The extracted ambient-noise Green's functions can be used in ambient-noise tomography for constructing seismic structure models of the Earth's interior. The amount of calculations involved in the seismic interferometry procedure can be significant, especially for ambient-noise datasets collected by large seismic sensor arrays (i.e., "large-N" data). We present an efficient parallel algorithm, named pSIN (Parallel Seismic INterferometry), for solving seismic interferometry problems on conventional distributed-memory computer clusters. The design of the algorithm is based on a two-dimensional partition of the ambient-noise data recorded by a seismic sensor array. We pay special attention to the balance of the computational load, inter-process communication overhead and memory usage across all MPI processes and we minimize the total number of I/O operations. We have tested the algorithm using a real ambient-noise dataset and obtained a significant amount of savings in processing time. Scaling tests have shown excellent strong scalability from 80 cores to over 2000 cores.
Jurado, Maria Jose; Teixido, Teresa; Martin, Elena; Segarra, Miguel; Segura, Carlos
2013-04-01
In the frame of the research conducted to develop efficient strategies for investigation of rock properties and fluids ahead of tunnel excavations the seismic interferometry method was applied to analyze the data acquired in boreholes instrumented with geophone strings. The results obtained confirmed that seismic interferometry provided an improved resolution of petrophysical properties to identify heterogeneities and geological structures ahead of the excavation. These features are beyond the resolution of other conventional geophysical methods but can be the cause severe problems in the excavation of tunnels. Geophone strings were used to record different types of seismic noise generated at the tunnel head during excavation with a tunnelling machine and also during the placement of the rings covering the tunnel excavation. In this study we show how tunnel construction activities have been characterized as source of seismic signal and used in our research as the seismic source signal for generating a 3D reflection seismic survey. The data was recorded in vertical water filled borehole with a borehole seismic string at a distance of 60 m from the tunnel trace. A reference pilot signal was obtained from seismograms acquired close the tunnel face excavation in order to obtain best signal-to-noise ratio to be used in the interferometry processing (Poletto et al., 2010). The seismic interferometry method (Claerbout 1968) was successfully applied to image the subsurface geological structure using the seismic wave field generated by tunneling (tunnelling machine and construction activities) recorded with geophone strings. This technique was applied simulating virtual shot records related to the number of receivers in the borehole with the seismic transmitted events, and processing the data as a reflection seismic survey. The pseudo reflective wave field was obtained by cross-correlation of the transmitted wave data. We applied the relationship between the transmission
Polarimetric SAR interferometry applied to land ice: modeling
DEFF Research Database (Denmark)
Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning
2004-01-01
This paper introduces a few simple scattering models intended for the application of polarimetric SAR interfer-ometry to land ice. The principal aim is to eliminate the penetration bias hampering ice sheet elevation maps generated with single-channel SAR interferometry. The polarimetric coherent...
Atom Interferometry for Fundamental Physics and Gravity Measurements in Space
Kohel, James M.
2012-01-01
Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.
Atom Interferometry for Fundamental Physics and Gravity Measurements in Space
Kohel, James M.
2012-01-01
Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.
Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry
Energy Technology Data Exchange (ETDEWEB)
Erskine, D J; Edelstein, J; Lloyd, J; Muirhead, P
2006-05-04
Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. Both regular and high-frequency spectral components can be recovered from the data--the moire component carries additional information that increases the signal to noise for velocimetry and spectroscopy. Here we present simulations and theoretical studies of the photon limited Doppler velocity noise in an EDI. We used a model spectrum of a 1600K temperature star. For several rotational blurring velocities 0, 7.5, 15 and 25 km/s we calculated the dimensionless Doppler quality index (Q) versus wavenumber v. This is the normalized RMS of the derivative of the spectrum and is proportional to the photon-limited Doppler signal to noise ratio.
Enhanced Propagating Surface Plasmon Signal Detection
Energy Technology Data Exchange (ETDEWEB)
Gong, Y.; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.
2016-12-21
Overcoming the dissipative nature of propagating surface plasmons (PSPs) is pre-requisite to realizing functional plasmonic circuitry, in which large bandwidth signals can be manipulated over length scales far-below the diffraction limit of light. To this end, we report on a novel PSP enhanced signal detection technique achieved in an all-metallic substrate. We take advantage of two strategically spatio-temporally separated phase-locked femtosecond laser pulses, incident onto lithographically patterned PSP coupling structures. We follow PSP propagation with joint femtosecond temporal and nanometer spatial resolution in a time-resolved non-linear photoemission electron microscopy scheme. Initially, a PSP signal wave packet is launched from a hole etched into the silver surface from where it propagates through an open trench structure and is decoded through the use of a timed probe pulse. FDTD calculations demonstrate that PSP signal waves may traverse open trenches in excess of 10 microns in diameter, thereby allowing remote detection even through vacuum regions. This arrangement results in a 10X enhancement in photoemission relative to readout from the bare metal surface. The enhancement is attributed to an all-optical homodyne detection technique that mixes signal and reference PSP waves in a non-linear scheme. Larger readout trenches achieve higher readout levels, however reduced transmission through the trench limits the trench size to 6 microns for maximum readout levels. However, the use of an array of trenches increases the maximum enhancement to near 30X. The attainable enhancement factor may be harnessed to achieve extended coherent PSP propagation in ultrafast plasmonic circuitry.
Synchronous two-wavelength temporal interferometry
Zhang, Xiaoqiong; Gao, Zhan; Qin, Jie; Li, Guangyu; Feng, Ziang; Wang, Shengjia
2016-09-01
Interferometry is an optical measuring method with the character of non-destructive, high sensitivity and high accuracy. However, its measurement range is limited by the phase ambiguity. Hence the method with two separate different wavelengths light source is introduced to enlarge the measurement range. As for the two-wavelength interferometry case, phase shifting is the traditional way to acquire the phase map, it needs to repeat the measurement twice, which means the measurement cannot be accomplished in real time. Hence to solve the problem, a temporal sequence interferometry has been used. This method can obtain the desired phase information in real time by using the Fourier transform methods of the interferogram recorded in a sequence while the object is being deformed. But, it is difficult to retrieve the phase information directly due to the multi extreme points in one period of the cosine function. In this paper, an algorithm based on the wavelet ridge analysis is adopted to retrieve the two wavelength phase fluctuation caused by the displacement simultaneously. The preliminary experiment is conducted and the results are compared with theoretical simulations to validate the proposed approach. The laser emits light with two wavelengths 532 nm and 473 nm, two separated interference patterns in time sequence are detected by the CCD camera in the same time. The overlapped interferograms of two colors are analyzed by this algorithm and the corresponding phase information are obtained. The maximum error value between the simulation and theory is 0.03 um and the relative error is 0.33%.
Stitching algorithm for annular subaperture interferometry
Institute of Scientific and Technical Information of China (English)
Xi Hou; Fan Wu; Li Yang; Shibin Wu; Qiang Chen
2006-01-01
@@ Annular subaperture interferometry (ASI) has been developed for low cost and flexible test of rotationally symmetric aspheric surfaces, in which accurately combining the subaperture measurement data corrupted by misalignments and noise into a complete surface figure is the key problem. By introducing the Zernike annular polynomials which are orthogonal over annulus, a method that eliminates the coupling problem in the earlier algorithm based on Zernike circle polynomials is proposed. Vector-matrix notation is used to simplify the description and calculations. The performance of this reduction method is evaluated by numerical simulation. The results prove this method with high precision and good anti-noise capability.
Atomic Interferometry Test of Dark Energy
Brax, Philippe
2016-01-01
Atomic interferometry can be used to probe dark energy models coupled to matter. We consider the constraints coming from recent experimental results on models generalising the inverse power law chameleons such as $f(R)$ gravity in the large curvature regime, the environmentally dependent dilaton and symmetrons. Using the tomographic description of these models, we find that only symmetrons with masses smaller than the dark energy scale can be efficiently tested. In this regime, the resulting constraints complement the bounds from the E\\"otwash experiment and exclude small values of the symmetron self-coupling.
Frequency scanning interferometry for CLIC component fiducialisation
Kamugasa, Solomon William; Mainaud Durand, Helene; CERN. Geneva. ATS Department
2016-01-01
We present a strategy for the fiducialisation of CLIC’s Main Beam Quadrupole (MBQ) magnets using Frequency Scanning Interferometry (FSI). We have developed complementary device for a commercial FSI system to enable coordinate determination via multilateration. Using spherical high index glass retroreflectors with a wide acceptance angle, we optimise the geometry of measurement stations with respect to fiducials -- thus improving the precision of coordinates. We demonstrate through simulations that the 10 μm uncertainty required in the vertical and lateral axes for the fiducialisation of the MBQ can be attained using FSI multilateration.
Probing Dark Energy with Atom Interferometry
Burrage, Clare; Hinds, E A
2015-01-01
Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Here we show that individual atoms are too small to screen the chameleon field inside a large high-vacuum chamber, and therefore can detect the field with high sensitivity. We derive new limits on the chameleon parameters from existing experiments, and show that most of the remaining chameleon parameter space is readily accessible using atom interferometry.
Report on ''European Radio Interferometry School 2015''
Laing, R.; Richards, A.
2016-03-01
The sixth European Interferometry School (ERIS2015) was held at ESO for the first time. As usual the school was aimed at graduate students and early-career postdocs, but this year the emphasis was on enhanced wide-bandwidth interferometers covering metre to submillimetre wavebands. More than 100 participants attended ERIS2015. The topics of the school are briefly described here. They covered a wide range, from an introduction to radio interferometric techniques through packages for data reduction and analysis to hands-on workshop sessions and proposal writing.
Neutron interferometry constrains dark energy chameleon fields
Directory of Open Access Journals (Sweden)
H. Lemmel
2015-04-01
Full Text Available We present phase shift measurements for neutron matter waves in vacuum and in low pressure Helium using a method originally developed for neutron scattering length measurements in neutron interferometry. We search for phase shifts associated with a coupling to scalar fields. We set stringent limits for a scalar chameleon field, a prominent quintessence dark energy candidate. We find that the coupling constant β is less than 1.9×107 for n=1 at 95% confidence level, where n is an input parameter of the self-interaction of the chameleon field φ inversely proportional to φn.
Moire interferometry for vibration analysis of plates
Asundi, A.; Cheung, M. T.
1987-12-01
Moire interferometry is used to locate nodal regions and measure vibration amplitudes of sinusoidally vibrating square plates. The high sensitivity afforded by this technique makes possible the study of plate vibrations at high frequencies and low amplitudes. The initial pattern is modulated by the zero-order Bessel function representing the vibratory motion. The fringe (or fringes) with best contrast indicate the nodal regions, while the higher order fringes, describing loci of points vibrating with the same amplitude, have decreasing contrast which is improved by spatial filtering.
Brombin, M; Boboc, A; Murari, A; Zilli, E; Giudicotti, L
2009-06-01
A systematic comparison between the line integrated electron density derived from interferometry and polarimetry at JET has been carried out. For the first time the reliability of the measurements of the Cotton-Mouton effect has been analyzed for a wide range of main plasma parameters and the possibility to evaluate the electron density directly from polarimetric data has been studied. The purpose of this work is to recover the interferometric data with the density derived from the measured Cotton-Mouton effect, when the fringe jump phenomena occur. The results show that the difference between the line integrated electron density from interferometry and polarimetry is with one fringe (1.143 x 10(19) m(-2)) for more than 90% of the cases. It is possible to consider polarimetry as a satisfactory alternative method to interferometry to measure the electron density and it could be used to recover interferometric signal when a fringe jumps occurs, preventing difficulties for the real-time control of many experiments at the JET machine.
Attosecond dynamics through a Fano resonance: Monitoring the birth of a photoelectron
Gruson, V.; Barreau, L.; Jiménez-Galan, Á.; Risoud, F.; Caillat, J.; Maquet, A.; Carré, B.; Lepetit, F.; Hergott, J.-F.; Ruchon, T.; Argenti, L.; Taïeb, R.; Martín, F.; Salières, P.
2016-11-01
The dynamics of quantum systems are encoded in the amplitude and phase of wave packets. However, the rapidity of electron dynamics on the attosecond scale has precluded the complete characterization of electron wave packets in the time domain. Using spectrally resolved electron interferometry, we were able to measure the amplitude and phase of a photoelectron wave packet created through a Fano autoionizing resonance in helium. In our setup, replicas obtained by two-photon transitions interfere with reference wave packets that are formed through smooth continua, allowing the full temporal reconstruction, purely from experimental data, of the resonant wave packet released in the continuum. In turn, this resolves the buildup of the autoionizing resonance on an attosecond time scale. Our results, in excellent agreement with ab initio time-dependent calculations, raise prospects for detailed investigations of ultrafast photoemission dynamics governed by electron correlation, as well as coherent control over structured electron wave packets.
Fast sub-electron detectors review for interferometry
Feautrier, Philippe; Gach, Jean-Luc; Bério, Philippe
2016-08-01
New disruptive technologies are now emerging for detectors dedicated to interferometry. The detectors needed for this kind of applications need antonymic characteristics: the detector noise must be very low, especially when the signal is dispersed but at the same time must also sample the fast temporal characteristics of the signal. This paper describes the new fast low noise technologies that have been recently developed for interferometry and adaptive optics. The first technology is the Avalanche PhotoDiode (APD) infrared arrays made of HgCdTe. In this paper are presented the two programs that have been developed in that field: the Selex Saphira 320x256 [1] and the 320x255 RAPID detectors developed by Sofradir/CEA LETI in France [2], [3], [4]. Status of these two programs and future developments are presented. Sub-electron noise can now be achieved in the infrared using this technology. The exceptional characteristics of HgCdTe APDs are due to a nearly exclusive impaction ionization of the electrons, and this is why these devices have been called "electrons avalanche photodiodes" or e-APDs. These characteristics have inspired a large effort in developing focal plan arrays using HgCdTe APDs for low photon number applications such as active imaging in gated mode (2D) and/or with direct time of flight detection (3D imaging) and, more recently, passive imaging for infrared wave front correction and fringe tracking in astronomical observations. In addition, a commercial camera solution called C-RED, based on Selex Saphira and commercialized by First Light Imaging [5], is presented here. Some groups are also working with instruments in the visible. In that case, another disruptive technology is showing outstanding performances: the Electron Multiplying CCDs (EMCCD) developed mainly by e2v technologies in UK. The OCAM2 camera, commercialized by First Light Imaging [5], uses the 240x240 EMMCD from e2v and is successfully implemented on the VEGA instrument on the CHARA
Astronomical optical interferometry, II: Astrophysical results
Directory of Open Access Journals (Sweden)
Jankov S.
2011-01-01
Full Text Available Optical interferometry is entering a new age with several ground- based long-baseline observatories now making observations of unprecedented spatial resolution. Based on a great leap forward in the quality and quantity of interferometric data, the astrophysical applications are not limited anymore to classical subjects, such as determination of fundamental properties of stars; namely, their effective temperatures, radii, luminosities and masses, but the present rapid development in this field allowed to move to a situation where optical interferometry is a general tool in studies of many astrophysical phenomena. Particularly, the advent of long-baseline interferometers making use of very large pupils has opened the way to faint objects science and first results on extragalactic objects have made it a reality. The first decade of XXI century is also remarkable for aperture synthesis in the visual and near-infrared wavelength regimes, which provided image reconstructions from stellar surfaces to Active Galactic Nuclei. Here I review the numerous astrophysical results obtained up to date, except for binary and multiple stars milliarcsecond astrometry, which should be a subject of an independent detailed review, taking into account its importance and expected results at microarcsecond precision level. To the results obtained with currently available interferometers, I associate the adopted instrumental settings in order to provide a guide for potential users concerning the appropriate instruments which can be used to obtain the desired astrophysical information.
Multiple phase estimation in digital holographic interferometry using product cubic phase function
Kulkarni, Rishikesh; Rastogi, Pramod
2013-10-01
Digital holographic interferometry (DHI) involves multi-directional illumination of an object to measure the in-plane and out-of plane displacements simultaneously. This results in multiple interference phases which have to be reliably estimated. The paper proposes a method where the interference field is represented as sum of multicomponent quadratic phase signal. Subsequently, product cubic phase function (PCPF) is used to estimate the quadratic coefficients. Using these coefficients multiple interference phases are estimated. The applicability of this method in DHI is demonstrated with simulation results.
Atomic Bloch-Zener oscillations and Stückelberg interferometry in optical lattices.
Kling, Sebastian; Salger, Tobias; Grossert, Christopher; Weitz, Martin
2010-11-19
We report on experiments investigating quantum transport and band interferometry of an atomic Bose-Einstein condensate in an optical lattice with a two-band miniband structure, realized with a Fourier-synthesized optical lattice potential. Bloch-Zener oscillations, the coherent superposition of Bloch oscillations and Landau-Zener tunneling between the two bands, are observed. When the relative phase between paths in different bands is varied, an interference signal is observed, demonstrating the coherence of the dynamics in the miniband system. Measured fringe patterns of this Stückelberg interferometer allow us to interferometrically map out the band structure of the optical lattice over the full Brillouin zone.
Wavelength Sweep Interferometry for Measuring the Refractive Index and Physical Thickness
Institute of Scientific and Technical Information of China (English)
SONG Guiju; WANG Xiangzhao; FANG Zujie
2001-01-01
A method combining wavelength sweep interferometry with the Fourior transform technique to perform the separate measurements of the physical thickness and the refractive index is proposed. By converting the optical path difference of the interferometer to the beat frequency of the interference signal we realize the depth scanning without mechanical moving parts. The effect of specimen dispersion is avoided by using a narrow tuning laser diode. For demonstrating this method we measure the physical thickness and the refractive index of an x-cut LiNbO3, BK9 and BK7 glass, and the results consist with the reported values.
Free Nano-Object Ramsey Interferometry for Large Quantum Superpositions
Wan, C.; Scala, M.; Morley, G. W.; Rahman, ATM. A.; Ulbricht, H.; Bateman, J.; Barker, P. F.; Bose, S.; Kim, M. S.
2016-09-01
We propose an interferometric scheme based on an untrapped nano-object subjected to gravity. The motion of the center of mass (c.m.) of the free object is coupled to its internal spin system magnetically, and a free flight scheme is developed based on coherent spin control. The wave packet of the test object, under a spin-dependent force, may then be delocalized to a macroscopic scale. A gravity induced dynamical phase (accrued solely on the spin state, and measured through a Ramsey scheme) is used to reveal the above spatially delocalized superposition of the spin-nano-object composite system that arises during our scheme. We find a remarkable immunity to the motional noise in the c.m. (initially in a thermal state with moderate cooling), and also a dynamical decoupling nature of the scheme itself. Together they secure a high visibility of the resulting Ramsey fringes. The mass independence of our scheme makes it viable for a nano-object selected from an ensemble with a high mass variability. Given these advantages, a quantum superposition with a 100 nm spatial separation for a massive object of 1 09 amu is achievable experimentally, providing a route to test postulated modifications of quantum theory such as continuous spontaneous localization.
All-sky interferometry with spherical harmonic transit telescopes
Energy Technology Data Exchange (ETDEWEB)
Shaw, J. Richard; Pen, Ue-Li [Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Sigurdson, Kris; Sitwell, Michael [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1 (Canada); Stebbins, Albert, E-mail: jrs65@cita.utoronto.ca [Theoretical Astrophysics Group, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)
2014-02-01
In this paper, we describe the spherical harmonic transit telescope through the use of a novel formalism for the analysis of transit radio telescopes. This all-sky approach bypasses the curved-sky complications of traditional interferometry and so is particularly well-suited to the analysis of wide-field radio interferometers. It enables compact and computationally efficient representations of the data and its statistics, which allow new ways of approaching important problems like map-making and foreground removal. In particular, we show how it enables the use of the Karhunen-Loève transform as a highly effective foreground filter, suppressing realistic foreground residuals for our fiducial example by at least a factor 20 below the 21 cm signal, even in highly contaminated regions of the sky. This is despite the presence of the mode-mixing inherent in real-world instruments with frequency-dependent beams. We show, using Fisher forecasting, that foreground cleaning has little effect on power spectrum constraints compared to hypothetical foreground-free measurements. Beyond providing a natural real-world data analysis framework for 21 cm telescopes now under construction and future experiments, this formalism allows accurate power spectrum forecasts to be made that include the interplay of design constraints and realistic experimental systematics with 21st century 21 cm science.
Enhancing core-diffracted arrivals by supervirtual interferometry
Bharadwaj, P.
2013-12-03
A supervirtual interferometry (SVI) method is presented that can enhance the signal-to-noise ratio (SNR) of core diffracted waveforms by as much as O( √ N), where N is the number of inline receivers that record the core-mantle boundary (CMB) diffractions from more than one event. Here, the events are chosen to be approximately inline with the receivers along the same great circle. Results with synthetic and teleseismic data recorded by USArray stations demonstrate that formerly unusable records with low SNR can be transformed to high SNR records with clearly visible CMB diffractions. Another benefit is that SVI allows for the recording of a virtual earthquake at stations not deployed during the time of the earthquake. This means that portable arrays such as USArray can extend the aperture of one recorded earthquake from the West coast to the East coast, even though the teleseism might have only been recorded during theWest coast deployment. In summary, SVI applied to teleseismic data can significantly enlarge the catalogue of usable records both in SNR and available aperture for analysing CMB diffractions. A potential drawback of this method is that it generally provides the correct kinematics of CMB diffractions, but does not necessarily preserve correct amplitude information. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.
Development of a Multi-Point Microwave Interferometry (MPMI) Method
Energy Technology Data Exchange (ETDEWEB)
Specht, Paul Elliott [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cooper, Marcia A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jilek, Brook Anton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-09-01
A multi-point microwave interferometer (MPMI) concept was developed for non-invasively tracking a shock, reaction, or detonation front in energetic media. Initially, a single-point, heterodyne microwave interferometry capability was established. The design, construction, and verification of the single-point interferometer provided a knowledge base for the creation of the MPMI concept. The MPMI concept uses an electro-optic (EO) crystal to impart a time-varying phase lag onto a laser at the microwave frequency. Polarization optics converts this phase lag into an amplitude modulation, which is analyzed in a heterodyne interfer- ometer to detect Doppler shifts in the microwave frequency. A version of the MPMI was constructed to experimentally measure the frequency of a microwave source through the EO modulation of a laser. The successful extraction of the microwave frequency proved the underlying physical concept of the MPMI design, and highlighted the challenges associated with the longer microwave wavelength. The frequency measurements made with the current equipment contained too much uncertainty for an accurate velocity measurement. Potential alterations to the current construction are presented to improve the quality of the measured signal and enable multiple accurate velocity measurements.
All-Sky Interferometry with Spherical Harmonic Transit Telescopes
Energy Technology Data Exchange (ETDEWEB)
Shaw, J.Richard [Canadian Inst. Theor. Astrophys.; Sigurdson, Kris [British Columbia U.; Pen, Ue-Li [Canadian Inst. Theor. Astrophys.; Stebbins, Albert [Fermilab; Sitwell, Michael [British Columbia U.
2013-02-01
In this paper we describe the spherical harmonic transit telescope, a novel formalism for the analysis of transit radio telescopes. This all-sky approach bypasses the curved sky complications of traditional interferometry and so is particularly well suited to the analysis of wide-field radio interferometers. It enables compact and computationally efficient representations of the data and its statistics that allow new ways of approaching important problems like map-making and foreground removal. In particular, we show how it enables the use of the Karhunen-Loeve transform as a highly effective foreground filter, suppressing realistic foreground residuals for our fiducial example by at least a factor twenty below the 21cm signal even in highly contaminated regions of the sky. This is despite the presence of the angle-frequency mode mixing inherent in real-world instruments with frequency-dependent beams. We show, using Fisher forecasting, that foreground cleaning has little effect on power spectrum constraints compared to hypothetical foreground-free measurements. Beyond providing a natural real-world data analysis framework for 21cm telescopes now under construction and future experiments, this formalism allows accurate power spectrum forecasts to be made that include the interplay of design constraints and realistic experimental systematics with twenty-first century 21cm science.
Phase-wrapping ambiguity in along-track interferometry
Deming, Ross; Ilin, Roman; Best, Matthew
2013-05-01
In a previous SPIE paper we described several variations of along-track interferometry (ATI), which can be used for moving target detection and geo-location in clutter. ATI produces a phase map in range/Doppler coordinates by combining radar data from several receive channels separated fore-and-aft (along-track) on the sensor platform. In principle, the radial velocity of a moving target can be estimated from the ATI phase of the pixels in the target signature footprint. Once the radial velocity is known, the target azimuth follows directly. Unfortunately, the ATI phase is wrapped, i.e., it repeats in the interval [-π, π], and therefore the mapping from ATI phase to target azimuth is non-unique. In fact, depending on the radar system parameters, each detected target can map to several equally-likely azimuth values. In the present paper we discuss a signal processing method for resolving the phase wrapping ambiguity, in which the radar bandwidth is split into a high and low sub-band in software, and an ATI phase map is generated for each. By subtracting these two phase maps we can generate a coarse, but unambiguous, radial velocity estimate. This coarse estimate is then combined with the fine, but ambiguous estimate to pinpoint the target radial velocity, and therefore its azimuth. Since the coarse estimate is quite sensitive to noise, a rudimentary tracker is used to help smooth out the phase errors. The method is demonstrated on Gotcha 2006 Challenge data.
Fourier domain multispectral multiple scattering low coherence interferometry.
Matthews, Thomas E; Giacomelli, Michael G; Brown, William J; Wax, Adam
2013-12-01
We have implemented multispectral multiple scattering low coherence interferometry (ms2/LCI) with Fourier domain data collection. The ms2/LCI system is designed to localize features with spectroscopic contrast with millimeter resolution up to 1 cm deep in scattering samples by using photons that have undergone multiple low-angle (forward) scattering events. Fourier domain detection both increases the data acquisition speed of the system and gives access to rich spectroscopic information, compared to the previous single channel, time-domain implementation. Separate delivery and detection angular apertures reduce collection of the diffuse background signal in order to isolate localized spectral features from deeper in scattering samples than would be possible with traditional spectroscopic optical coherence tomography. Light from a supercontinuum source is used to acquire absorption spectra of chromophores in the visible range within a tissue-like scattering phantom. An intensity modulation and digital lock-in detection scheme is implemented to mitigate relative intensity and spectral noise inherent in supercontinuum sources. The technical parameters of the system and comparative analysis are presented.
Fundamental aspects of resolution and precision in vertical scanning white-light interferometry
Lehmann, Peter; Tereschenko, Stanislav; Xie, Weichang
2016-06-01
We discuss the height and lateral resolution that can be achieved in vertical scanning white-light interferometry (SWLI). With respect to interferometric height resolution, phase-shifting interferometry (PSI) is assumed to provide the highest accuracy. However, if the noise dependence of SWLI phase evaluation and PSI algorithms is considered, SWLI measurements can be shown to be more precise. With respect to lateral resolution, the determination of the coherence peak position of SWLI signals seems to lead to better results compared to phase based-interferometric measurements. This can be attributed to the well-known batwing effect. Since batwing is a nonlinear effect applying nonlinear filters, e.g. a median filter, it reduces them significantly. If filtering is applied prior to the fringe order determination and phase evaluation, the number of artefacts known as ghost steps can be eliminated without changing the modulus of the phase. Finally, we discuss the dependence of measured height values on surface slope. We show that in interference microscopy there are additional limitations which are more rigid compared to the maximum surface slope angle resulting from the numerical aperture of the objective lens. As a consequence, the measurement precision breaks down at slope changes of steeper flanks even if the modulation depth of the interference signals is still good enough for signal analysis.
Externally Dispersed Interferometry for Precision Radial Velocimetry
Energy Technology Data Exchange (ETDEWEB)
Erskine, D J; Muterspaugh, M W; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E
2007-03-27
Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.
Self-calibrating common-path interferometry.
Porras-Aguilar, Rosario; Falaggis, Konstantinos; Ramirez-San-Juan, Julio C; Ramos-Garcia, Ruben
2015-02-09
A quantitative phase measuring technique is presented that estimates the object phase from a series of phase shifted interferograms that are obtained in a common-path configuration with unknown phase shifts. The derived random phase shifting algorithm for common-path interferometers is based on the Generalized Phase Contrast theory [pl. Opt.40(2), 268 (2001)10.1063/1.1404846], which accounts for the particular image formation and includes effects that are not present in two-beam interferometry. It is shown experimentally that this technique can be used within common-path configurations employing nonlinear liquid crystal materials as self-induced phase filters for quantitative phase imaging without the need of phase shift calibrations. The advantages of such liquid crystal elements compared to spatial light modulator based solutions are given by the cost-effectiveness, self-alignment, and the generation of diminutive dimensions of the phase filter size, giving unique performance advantages.
Endoscopic low coherence interferometry in upper airways
Delacrétaz, Yves; Boss, Daniel; Lang, Florian; Depeursinge, Christian
2009-07-01
We introduce Endoscopic Low Coherence Interferometry to obtain topology of upper airways through commonly used rigid endoscopes. Quantitative dimensioning of upper airways pathologies is crucial to provide maximum health recovery chances, for example in order to choose the correct stent to treat endoluminal obstructing pathologies. Our device is fully compatible with procedures used in day-to-day examinations and can potentially be brought to bedside. Besides this, the approach described here can be almost straightforwardly adapted to other endoscopy-related field of interest, such as gastroscopy and arthroscopy. The principle of the method is first exposed, then filtering procedure used to extract the depth information is described. Finally, demonstration of the method ability to operate on biological samples is assessed through measurements on ex-vivo pork bronchi.
Chameleon Dark Energy and Atom Interferometry
Elder, Benjamin; Haslinger, Philipp; Jaffe, Matt; Müller, Holger; Hamilton, Paul
2016-01-01
Atom interferometry experiments are searching for evidence of chameleon scalar fields with ever-increasing precision. As experiments become more precise, so too must theoretical predictions. Previous work has made numerous approximations to simplify the calculation, which in general requires solving a 3-dimensional nonlinear partial differential equation (PDE). In this paper, we introduce a new technique for calculating the chameleonic force, using a numerical relaxation scheme on a uniform grid. This technique is more general than previous work, which assumed spherical symmetry to reduce the PDE to a 1-dimensional ordinary differential equation (ODE). We examine the effects of approximations made in previous efforts on this subject, and calculate the chameleonic force in a set-up that closely mimics the recent experiment of Hamilton et al. Specifically, we simulate the vacuum chamber as a cylinder with dimensions matching those of the experiment, taking into account the backreaction of the source mass, its o...
Frequency Scanned Interferometry for ILC Tracker Alignment
Yang, Hai-Jun; Riles, Keith
2011-01-01
In this paper, we report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. High-finesse Fabry-Perot interferometers were used to determine frequency changes during scanning. A dual-laser scanning technique was used to cancel drift errors to improve the absolute distance measurement precision. A new dual-channel FSI demonstration system is also presented which is an interim stage toward practical application of multi-channel distance measurement. Under realistic conditions, a precision of 0.3 microns was achieved for an absolute distance of 0.57 meters. A possible optical alignment system for a silicon tracker is also presented.
Shell deformation studies using holographic interferometry
Parmerter, R. R.
1974-01-01
The buckling of shallow spherical shells under pressure has been the subject of many theoretical and experimental papers. Experimental data above the theoretical buckling load of Huang have given rise to speculation that shallow shell theory may not adequately predict the stability of nonsymmetric modes in higher-rise shells which are normally classified as shallow by the Reissner criterion. This article considers holographic interferometry as a noncontact, high-resolution method of measuring prebuckling deformations. Prebuckling deformations of a lambda = 9, h/b = 0.038 shell are Fourier-analyzed. Buckling is found to occur in an N = 5 mode as predicted by Huang's theory. The N = 4 mode was unusually stable, suggesting that even at this low value of h/b, stabilizing effects may be at work.
Intensity interferometry: Optical imaging with kilometer baselines
Dravins, Dainis
2016-01-01
Optical imaging with microarcsecond resolution will reveal details across and outside stellar surfaces but requires kilometer-scale interferometers, challenging to realize either on the ground or in space. Intensity interferometry, electronically connecting independent telescopes, has a noise budget that relates to the electronic time resolution, circumventing issues of atmospheric turbulence. Extents up to a few km are becoming realistic with arrays of optical air Cherenkov telescopes (primarily erected for gamma-ray studies), enabling an optical equivalent of radio interferometer arrays. Pioneered by Hanbury Brown and Twiss, digital versions of the technique have now been demonstrated, reconstructing diffraction-limited images from laboratory measurements over hundreds of optical baselines. This review outlines the method from its beginnings, describes current experiments, and sketches prospects for future observations.
Externally Dispersed Interferometry for Precision Radial Velocimetry
Erskine, D J; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E
2007-01-01
Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.
Edge effects in composites by moire interferometry
Czarnek, R.; Post, D.; Herakovich, C.
1983-01-01
The very high sensitivity of moire interferometry has permitted the present edge effect experiments to be conducted at a low average stress and strain level, assuring linear and elastic behavior in the composite material samples tested. Sensitivity corresponding to 2450 line/mm moire was achieved with a 0.408 micron/fringe. Simultaneous observations of the specimen face and edge displacement fields showed good fringe definition despite the 1-mm thickness of the specimens and the high gradients, and it is noted that the use of a carrier pattern and optical filtering was effective in even these conditions. Edge effects and dramatic displacement gradients were confirmed in angle-ply composite laminates.
Phase difference enhancement with classical intensity interferometry
Shirai, Tomohiro
2016-12-01
It is demonstrated theoretically and experimentally that, as a novel function of classical intensity interferometry, a phase difference distribution recorded in the form of an interferogram can be enhanced by a factor of 2 on the basis of the classical intensity correlation. Such phase difference enhancement which is also referred to as phase difference amplification is, in general, known to be practically important since it increases sensitivity and accuracy in interferometric measurements. The method proposed in this study prevails over the existing methods in the sense that it can be readily implemented without difficulty in comparison with all other methods so far proposed, although the phase difference enhancement is limited to a factor of 2 in our method and thus so is the improvement of sensitivity and accuracy.
Ultrafast electrooptic dual-comb interferometry
Duran, Vicente; Torres-Company, Victor
2015-01-01
The femtosecond laser frequency comb has enabled the 21st century revolution in optical synthesis and metrology. A particularly compelling technique that relies on the broadband coherence of two laser frequency combs is dual-comb interferometry. This method is rapidly advancing the field of optical spectroscopy and empowering new applications, from nonlinear microscopy to laser ranging. Up to now, most dual-comb interferometers were based on modelocked lasers, whose repetition rates have restricted the measurement speed to ~ kHz. Here we demonstrate a novel dual-comb interferometer that is based on electrooptic frequency comb technology and measures consecutive complex spectra at a record-high refresh rate of 25 MHz. These results pave the way for novel scientific and metrology applications of frequency comb generators beyond the realm of molecular spectroscopy, where the measurement of ultrabroadband waveforms is of paramount relevance.
Real-time color holographic interferometry
Desse, Jean-Michel; Albe, Felix; Tribillon, Jean-Louis
2002-09-01
A new optical technique based on real-time color holographic interferometry has been developed for analyzing unsteady aerodynamic wakes in fluid mechanics or for measuring displacements and deformations in solid mechanics. The technique's feasibility is demonstrated here. It uses three coherent wavelengths produced simultaneously by a cw laser (mixed argon and krypton). Holograms are recorded on single-layer panchromatic silver halide (Slavich PFG 03C) plates. Results show the optical setup can be adjusted to obtain a uniform background color. The interference fringe pattern visualized is large and colored and exhibits a single central white fringe, which makes the zero order of the interferogram easy to identify. An application in a subsonic wind tunnel is presented, in which the unsteady wake past a cylinder is recorded at high rate.
Generalised interferometry - I. Theory for inter-station correlations
Fichtner, Andreas; Stehly, Laurent; Ermert, Laura; Boehm, Christian
2016-11-01
Earth structure. Not making any restrictive assumptions on the nature of the wavefield sources, our theory can be applied to earthquake and ambient noise data, either separately or combined. This allows us (i) to locate earthquakes using inter-station correlations and without knowledge of the origin time, (ii) to unify the earthquake-based two-station method and noise correlations without the need to exclude either of the two data types, and (iii) to eliminate the requirement to remove earthquake signals from noise recordings prior to the computation of correlation functions. In addition to the basic theory for acoustic wavefields, we present numerical examples for 2-D media, an extension to the most general visco-elastic case, and a method for the design of optimal processing schemes that eliminate the forward modelling error completely. This work is intended to provide a comprehensive theoretical foundation of full-waveform interferometry by correlation, and to suggest improvements to current passive monitoring methods.
Direct Measurement of Aerosol Absorption Using Photothermal Interferometry
Sedlacek, A. J.; Lee, J. A.
2007-12-01
Efforts to bound the contribution of light absorption in aerosol radiative forcing is still very much an active area of research in large part because aerosol extinction is dominated by light scattering. In response to this and other technical issues, the aerosol community has actively pursued the development of new instruments to measure aerosol absorption (e.g., photoacoustic spectroscopy (PAS) and multi-angle absorption photometer (MAAP)). In this poster, we introduce the technique of photothermal interferometry (PTI), which combines the direct measurement capabilities of photothermal spectroscopy (PTS) with high-sensitivity detection of the localized heating brought about by the PT process through interferometry. At its most fundamental level, the PTI technique measures the optical pathlength change that one arm of an interferometer (referred to as the 'probe' arm) experiences relative to the other arm of the interferometer (called the 'reference' arm). When the two arms are recombined at a beamsplitter, an interference pattern is created. If the optical pathlength in one arm of the interferometer changes, a commensurate shift in the interference pattern will take place. For the specific application of measuring light absorption, the heating of air surrounding the light- absorbing aerosol following laser illumination induces the optical pathlength change. This localized heating creates a refractive index gradient causing the probe arm of the interferometer to take a slightly different optical pathlength relative to the unperturbed reference arm. This effect is analogous to solar heating of a road causing mirages. As discussed above, this altered optical pathlength results in a shift in the interference pattern that is then detected as a change in the signal intensity by a single element detector. The current optical arrangement utilizes a folded Jamin interferometer design (Sedlacek, 2006) that provides a platform that is robust with respect to sensitivity
Interferometry using undulator sources (invited, abstract)
Beguiristain, R.; Goldberg, K. A.; Tejnil, E.; Bokor, J.; Medecki, H.; Attwood, D. T.; Jackson, K.
1996-09-01
Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in Soft X-Ray Projection Lithography, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), 18, 1089, and D. Attwood et al., Appl. Opt. 32, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg et al., in Extreme Ultra Lithography, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg et al., Proc. SPIE 2437, to be published, and K. Goldberg et al., J. Vac. Sci. Technol. B 13, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown.
Range Surveillance Using Radio Interferometry and TDOA Techniques Project
National Aeronautics and Space Administration — The proposed innovation will utilize a small network of remote sensors to perform Radio Interferometry (RI) and Time Difference of Arrival (TDOA) techniques to...
Experiments on diffusion in liquids using holographic interferometry
Fenichel, Henry; Frankena, Hans; Groen, Fokke
1984-08-01
An experiment is described which uses the technique of holographic interferometry to study diffusion in liquids. The diffusion process can be recorded on double exposed holograms or it can be observed and recorded in real time using video techniques.
Digital speckle pattern shearing interferometry: Limitations and prospects
DEFF Research Database (Denmark)
Owner-Petersen, Mette
1996-01-01
requires optical processing of double exposed interferograms. Hence the technique is not in real time. This paper explores the possibilities and limitations for real time shearing fringe observation using the electronic speckle pattern interferometry technique. Prospects for quantitative determination...
Depth profilometry via multiplexed optical high-coherence interferometry
National Research Council Canada - National Science Library
Kazemzadeh, Farnoud; Wong, Alexander; Behr, Bradford B; Hajian, Arsen R
2015-01-01
... such as defect detection, corrosion assessment, and dental assessment to name a few. In this study, we investigate the feasibility of depth profilometry using an Multiplexed Optical High-coherence Interferometry MOHI instrument...
Range Surveillance Using Radio Interferometry and TDOA Techniques Project
National Aeronautics and Space Administration — The proposed innovation will utilize a small network of remote sensors (Figure 2.1) to perform Radio Interferometry (RI) and Time Difference of Arrival (TDOA)...
Interferometry by deconvolution of multicomponent multioffset GPR data
Slob, E.C.
2009-01-01
Interferometric techniques are now well known to retrieve data between two receivers by the cross correlation of the data recorded by these receivers. Cross-correlation methods for interferometry rely mostly on the assumption that the medium is loss free and that the sources are all around the receivers. A recently developed method introduced interferometry by deconvolution that is insensitive to loss mechanisms by principle and requires sources only on one side of the receivers. In this pape...
Boerner, Wolfgang-Martin; Yamaguchi, Yoshio
2000-01-01
The development of Radar Polarimetry and Radar Interferometry is advancing rapidly. Whereas with radar polarimetry, the textural fine-structure, target orientation, symmetries and material constituents can be recovered with considerable improvement above that of standard amplitude-only radar; with radar interferometry the spatial(in depth)structure can be explored. In Polarimetric Interferometric Synthetic Aperture Radar(POL-IN-SAR)Imaging, it is possible to recover such co-registered textura...
Merritt, Elizabeth C; Gilmore, Mark A; Thoma, Carsten; Loverich, John; Hsu, Scott C
2012-01-01
A multi-chord fiber-coupled interferometer [Merritt et al., Rev. Sci. Instrum. 83, 033506 (2012)] is being used to make time-resolved density measurements of supersonic argon plasma jets on the Plasma Liner Experiment [Hsu et al., Bull. Amer. Phys. Soc. 56, 307 (2011)]. The long coherence length of the laser (>10 m) allows signal and reference path lengths to be mismatched by many meters without signal degradation, making for a greatly simplified optical layout. Measured interferometry phase shifts are consistent with a partially ionized plasma in which an initially positive phase shift becomes negative when the ionization fraction drops below a certain threshold. In this case, both free electrons and bound electrons in ions and neutral atoms contribute to the index of refraction. This paper illustrates how the interferometry data, aided by numerical modeling, are used to derive total jet density, jet propagation velocity (~15-50 km/s), jet length (~20-100 cm), and 3D expansion.
Frequency domain interferometry mode observations of PMSE using the EISCAT VHF radar
Directory of Open Access Journals (Sweden)
P. B. Chilson
Full Text Available During the summer of 1997 investigations into the nature of polar mesosphere summer echoes (PMSE were conducted using the European incoherent scatter (EISCAT VHF radar in Norway. The radar was operated in a frequency domain interferometry (FDI mode over a period of two weeks to study the frequency coherence of the returned radar signals. The operating frequencies of the radar were 224.0 and 224.6 MHz. We present the first results from the experiment by discussing two 4-h intervals of data collected over two consecutive nights. During the first of the two days an enhancement of the FDI coherence, which indicates the presence of distinct scattering layers, was found to follow the lower boundary of the PMSE. Indeed, it is not unusual to observe that the coherence values are peaked around the heights corresponding to both the lower- and upper-most boundaries of the PMSE layer and sublayers. A Kelvin-Helmholtz mechanism is offered as one possible explanation for the layering structure. Additionally, our analysis using range-time-pseudocolor plots of signal-to-noise ratios, spectrograms of Doppler velocity, and estimates of the positions of individual scattering layers is shown to be consistent with the proposition that upwardly propagating gravity waves can become steepened near the mesopause.
Key words: Ionosphere (polar ionosphere · Meteorology and Atmospheric Dynamics (middle atmosphere dynamics · Radio Science (Interferometry
Time Delay Interferometry with Moving Spacecraft Arrays
Tinto, M; Armstrong, J W; Tinto, Massimo; Estabrook, Frank B.; Armstrong, adn J.W.
2004-01-01
Space-borne interferometric gravitational wave detectors, sensitive in the low-frequency (millihertz) band, will fly in the next decade. In these detectors the spacecraft-to-spacecraft light-travel-times will necessarily be unequal, time-varying, and (due to aberration) have different time delays on up- and down-links. Reduction of data from moving interferometric laser arrays in solar orbit will in fact encounter non-symmetric up- and downlink light time differences that are about 100 times larger than has previously been recognized. The time-delay interferometry (TDI) technique uses knowledge of these delays to cancel the otherwise dominant laser phase noise and yields a variety of data combinations sensitive to gravitational waves. Under the assumption that the (different) up- and downlink time delays are constant, we derive the TDI expressions for those combinations that rely only on four inter-spacecraft phase measurements. We then turn to the general problem that encompasses time-dependence of the light...
Optical interferometry from the lunar surface
Rayman, M. D.; Saunders, R. S.
A preliminary study was conducted to determine the feasibility of a concept for a robust and expandable lunar optical interferometer that would perform new science even with the modest first element. With a phased approach, early steps verify technology for later phases. As elements are added to the observational system, astronomical observations unachievable from the surface of Earth are made possible. The initial experiment is supported by the Lunar Ultraviolet Telescope Experiment (LUTE), a 1-meter-class transit telescope. The first interferometry element, the Lunar Interferometer Technology Experiment (LITE), will perform ultraviolet astrometry and will demonstrate critical interferometer technologies (including optical delay lines and nanometer-level metrology) in the lunar environment. Subsequent elements will add capability, building on the design and performance of both LITE and LUTE. The starlight collectors will be based on the LUTE design but will be capable of being pointed. They will relay the received light to a centrally positioned beam combiner. As more collectors are added, the system will build up from an astrometric interferometer to an imaging interferometer with 100-m-class baselines. Because discrete elements are used, if any one of the collectors fails completely, the system remains functional.
High-Frame-Rate Oil Film Interferometry
White, Jonathan C; Chen, John
2010-01-01
The fluid dynamics video to which this abstract relates contains visualization of the response of a laminar boundary layer to a sudden puff from a small hole. The boundary layer develops on a flat plate in a wind tunnel; the hole is located at a streamwise Reynolds number of 100,000. The visualization of the boundary layer response is accomplished using interferometry of a transparent, thin film of oil placed on the surface immediately downstream of the hole and with its leading edge perpendicular to the direction of flow. Through lubrication theory, it is understood that the rate of change of the spacing of the interference fringes is proportional to the skin friction at any instant. For reference, a small disk-shaped protrusion of the type often used to trip the boundary layer in wind model tunnel testing is also shown. Three cases with different puff strengths are included. Using a high-speed commercial camera, frame rates in excess of 1000/sec have been recorded; the video shown here was taken at 24 frame...
Lorentz symmetry and very long baseline interferometry
Le Poncin-Lafitte, C.; Hees, A.; Lambert, S.
2016-12-01
Lorentz symmetry violations can be described by an effective field theory framework that contains both general relativity and the Standard Model of particle physics called the Standard Model extension (SME). Recently, postfit analysis of Gravity Probe B and binary pulsars led to an upper limit at the 10-4 level on the time-time coefficient s¯T T of the pure-gravity sector of the minimal SME. In this work, we derive the observable of very long baseline interferometry (VLBI) in SME and then implement it into a real data analysis code of geodetic VLBI observations. Analyzing all available observations recorded since 1979, we compare estimates of s¯T T and errors obtained with various analysis schemes, including global estimations over several time spans, and with various Sun elongation cutoff angles, and by analysis of radio source coordinate time series. We obtain a constraint on s¯ T T=(-5 ±8 )×10-5 , directly fitted to the observations and improving by a factor of 5 previous postfit analysis estimates.
Laser Wakefield diagnostic using holographic longitudinal interferometry
Energy Technology Data Exchange (ETDEWEB)
Volfbeyn, P.; Esarey, E.; Leemans, W.P.
1999-03-26
We propose a diagnostic technique for wakefield measurement in plasma channels. A new technique for plasma channel creation, the Ignitor Heater scheme was proposed and experimentally tested in hydrogen and nitrogen previously. It makes use of two laser pulses. The Ignitor, an ultrashort (sub 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used to heat the existing spark via in-verse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has properties of an optical waveguide. This technique allows creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. Laser pulses injected into such plasma channels produce a plasma wake that has a phase velocity close to the speed of light. A discussion of plasma wake measurements, using a Longitudinal Interferometry Wakefield Diagnostic Based on Time Domain Rayleigh Refractometry with Holographic Inversion, will be presented.
Quasar Astrophysics with the Space Interferometry Mission
Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn
2007-01-01
Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.
Extending temporal coherence in speckle interferometry
Crespo Contiñas, J. M.; Moreno de las Cuevas, V.; Gallas Torreira, M.; Calizaya Calizaya, M.
2013-11-01
Electronic Speckle Pattern Interferometry (ESPI) and Shearography (ESPSI) techniques have been used in the field of non-destructive testing for a long time, providing accuracy, and allowing whole field analysis of pure deformation (ESPI) or the gradient of deformation (ESPSI). One of the major weaknesses of this two techniques is linked to speckle de-correlation. When the deformation process produces a displacement greater than a certain proportion of the speckle size, there is a severe loss of coherence which limits the application of these techniques to processes with strong or fast deformations. In order to avoid this limitation, the use of a dynamically updated reference frame is tested in this work. First, in ESPI and ESPSI setups, a metacrylathe bar is used as specimen for testing procedures, and finally a human jaw bone will be used in an ESPSI setup. One basic and regular-shaped object, the bar, and a structurally 3D complex structure, the human jaw bone, with complex elastic properties are the samples to test.
Glaciological Applications of Terrestrial Radar Interferometry
Voytenko, D.; Dixon, T. H.
2014-12-01
Terrestrial Radar Interferometry (TRI) is a relatively new ground-based technique that combines the precision and spatial resolution of InSAR with the temporal resolution of GPS. Although TRI can be applied to a variety of fields including bridge and landslide monitoring, it is ideal for studies of the highly dynamic terminal zones of marine-terminating glaciers. Our TRI instrument is the Gamma Portable Radar Interferometer, which operates at 17.2 GHz (1.74 cm wavelength), has two receiving antennas for DEM generation, and generates amplitude and phase images at minute-scale sampling rates. Here we review preliminary results from Breiðamerkurjökull in Iceland and Helheim and Jakobshavn in Greenland. We show that the high sampling rate of the TRI can be used to observe velocity variations at the glacier terminus associated with calving, and the spatial distribution of tidal forcing. Velocity uncertainties, mainly due to atmospheric effects, are typically less than 0.05 m/d. Additionally, iceberg tracking using the amplitude imagery may provide insight into ocean currents near the terminus when fjord or lagoon conditions permit.
Ball bearing measurement with white light interferometry
Schmit, Joanna; Han, Sen; Novak, Erik
2009-06-01
Requirements on high-performance of ball bearings in terms of the loads they experience and their reliability are increasing as the automotive, aerospace, and power generation industries look to cut costs, reduce emissions, and improve efficiency. Most bearings are evaluated with a stylus profiler or with a bright field scopes or microscopes for form, roughness, and defect classification. Two-dimensional stylus measurements captures only very localized surface profiles unless multiple scans are performed which slow the measurement time unacceptably; this leads to inadequate sampling and sometimes greatly varying results based on location and directionality of the line scan. Bright field microscopes deliver only the lateral information about defects but not their depth, volume or surface roughness. White light interferometry can be very successfully utilized in the measurement of full field form, roughness and defect detection and is gaining adoption. They provide rapid, accurate, three-dimensional imaging compatible with the newly developed ISO 3D surface parameters which are expected to rapidly displace traditional 2D metrics. These surface parameters allow for better characterization of surface structure and better understanding of the production process and bearing and race wear. New 3D filtering techniques allow effective separation of form, waviness, and roughness for highly accurate and repeatable bearing qualification.
Chameleon dark energy and atom interferometry
Elder, Benjamin; Khoury, Justin; Haslinger, Philipp; Jaffe, Matt; Müller, Holger; Hamilton, Paul
2016-08-01
Atom interferometry experiments are searching for evidence of chameleon scalar fields with ever-increasing precision. As experiments become more precise, so too must theoretical predictions. Previous work has made numerous approximations to simplify the calculation, which in general requires solving a three-dimensional nonlinear partial differential equation. This paper calculates the chameleonic force using a numerical relaxation scheme on a uniform grid. This technique is more general than previous work, which assumed spherical symmetry to reduce the partial differential equation to a one-dimensional ordinary differential equation. We examine the effects of approximations made in previous efforts on this subject and calculate the chameleonic force in a setup that closely mimics the recent experiment of Hamilton et al. Specifically, we simulate the vacuum chamber as a cylinder with dimensions matching those of the experiment, taking into account the backreaction of the source mass, its offset from the center, and the effects of the chamber walls. Remarkably, the acceleration on a test atomic particle is found to differ by only 20% from the approximate analytical treatment. These results allow us to place rigorous constraints on the parameter space of chameleon field theories, although ultimately the constraint we find is the same as the one we reported in Hamilton et al. because we had slightly underestimated the size of the vacuum chamber. This computational technique will continue to be useful as experiments become even more precise and will also be a valuable tool in optimizing future searches for chameleon fields and related theories.
General Relativistic Effects in Atom Interferometry
Energy Technology Data Exchange (ETDEWEB)
Dimopoulos, Savas; /Stanford U., Phys. Dept.; Graham, Peter W.; /SLAC /Stanford U., Phys. Dept.; Hogan, Jason M.; Kasevich, Mark A.; /Stanford U., Phys. Dept.
2008-03-17
Atom interferometry is now reaching sufficient precision to motivate laboratory tests of general relativity. We begin by explaining the non-relativistic calculation of the phase shift in an atom interferometer and deriving its range of validity. From this we develop a method for calculating the phase shift in general relativity. This formalism is then used to find the relativistic effects in an atom interferometer in a weak gravitational field for application to laboratory tests of general relativity. The potentially testable relativistic effects include the non-linear three-graviton coupling, the gravity of kinetic energy, and the falling of light. We propose experiments, one currently under construction, that could provide a test of the principle of equivalence to 1 part in 10{sup 15} (300 times better than the present limit), and general relativity at the 10% level, with many potential future improvements. We also consider applications to other metrics including the Lense-Thirring effect, the expansion of the universe, and preferred frame and location effects.
Quasar Astrophysics with the Space Interferometry Mission
Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn
2007-01-01
Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.
An Approach to Persistent Scatterer Interferometry
Directory of Open Access Journals (Sweden)
Núria Devanthéry
2014-07-01
Full Text Available This paper describes a new approach to Persistent Scatterer Interferometry (PSI data processing and analysis, which is implemented in the PSI chain of the Geomatics (PSIG Division of CTTC. This approach includes three main processing blocks. In the first one, a set of correctly unwrapped and temporally ordered phases are derived, which are computed on Persistent Scatterers (PSs that cover homogeneously the area of interest. The key element of this block is given by the so-called Cousin PSs (CPSs, which are PSs characterized by a moderate spatial phase variation that ensures a correct phase unwrapping. This block makes use of flexible tools to check the consistency of phase unwrapping and guarantee a uniform CPS coverage. In the second block, the above phases are used to estimate the atmospheric phase screen. The third block is used to derive the PS deformation velocity and time series. Its key tool is a new 2+1D phase unwrapping algorithm. The procedure offers different tools to globally control the quality of the processing steps. The PSIG procedure has been successfully tested over urban, rural and vegetated areas using X-band PSI data. Its performance is illustrated using 28 TerraSAR-X StripMap images over the metropolitan area of Barcelona.
Laser wavelength comparison by high resolution interferometry.
Layer, H P; Deslattes, R D; Schweitzer, W G
1976-03-01
High resolution interferometry has been used to determine the wavelength ratio between two molecularly stabilized He-Ne lasers, one locked to a methane absorption at 3.39 microm and the other locked to the k peak of (129)I(2) at 633 nm. An optical beat frequency technique gave fractional orders while a microwave sideband method yielded the integer parts. Conventional (third derivative) peak seeking servoes stabilized both laser and cavity lengths. Reproducibility of the electronic control system and optics was a few parts in 10(12), while systematic errors associated with curvature of the cavity mirrors limited the accuracy of the wavelength ratio measurement to 2 parts in 10(10). The measured wavelength ratio of the methane stabilized He-Ne laser at 3.39 microm [P(7) line, nu(3) band] to the (129)I(2) (k peak) stabilized He-Ne laser at 633 nm was 5.359 049 260 6 (0.000 2 ppm). This ratio agrees with that calculated from the (lower accuracy) results of earlier wavelength measurements made relative to the (86)Kr standard. Its higher accuracy thus permits a provisional extension of the frequency scale based on the cesium oscillator into the visible spectrum.
Advancing differential atom interferometry for space applications
Chiow, Sheng-Wey; Williams, Jason; Yu, Nan
2016-05-01
Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. Dual atomic sensors operating in a differential mode further extend AI applicability beyond environmental disturbances. Extraction of the phase difference between dual AIs, however, typically introduces uncertainty and systematic in excess of that warranted by each AI's intrinsic noise characteristics, especially in practical applications and real time measurements. In this presentation, we report our efforts in developing practical schemes for reducing noises and enhancing sensitivities in the differential AI measurement implementations. We will describe an active phase extraction method that eliminates the noise overhead and demonstrates a performance boost of a gravity gradiometer by a factor of 3. We will also describe a new long-baseline approach for differential AI measurements in a laser ranging assisted AI configuration. The approach uses well-developed AIs for local measurements but leverage the mature schemes of space laser interferometry for LISA and GRACE. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a Contract with NASA.
Lorentz symmetry and Very Long Baseline Interferometry
Poncin-Lafitte, C Le; lambert, S
2016-01-01
Lorentz symmetry violations can be described by an effective field theory framework that contains both General Relativity and the Standard Model of particle physics called the Standard-Model extension (SME). Recently, post-fit analysis of Gravity Probe B and binary pulsars lead to an upper limit at the $10^{-4}$ level on the time-time coefficient $\\bar s^{TT}$ of the pure-gravity sector of the minimal SME. In this work, we derive the observable of Very Long Baseline Interferometry (VLBI) in SME and then we implement it into a real data analysis code of geodetic VLBI observations. Analyzing all available observations recorded since 1979, we compare estimates of $\\bar s^{TT}$ and errors obtained with various analysis schemes, including global estimations over several time spans and with various Sun elongation cut-off angles, and with analysis of radio source coordinate time series. We obtain a constraint on $\\bar s^{TT}=(-5\\pm 8)\\times 10^{-5}$, directly fitted to the observations and improving by a factor 5 pr...
Hunziker, J.W.; Slob, E.C.; Wapenaar, C.P.A.
2014-01-01
Interferometry by multidimensional deconvolution for marine Controlled-Source Electromagnetics can suppress the direct field and the airwave in order to increase the detectability of the reservoir. For monitoring, interferometry by multidimensional deconvolution can increase the source repeatability
Liu, H. K.
1976-01-01
The techniques of speckle beam holographic interferometry and speckle photographic interferometry are described. In particular, their practical limitations and their applications to the existing holographic nondestructive test system are discussed.
Forest canopy height estimation using double-frequency repeat pass interferometry
Karamvasis, Kleanthis; Karathanassi, Vassilia
2015-06-01
In recent years, many efforts have been made in order to assess forest stand parameters from remote sensing data, as a mean to estimate the above-ground carbon stock of forests in the context of the Kyoto protocol. Synthetic aperture radar interferometry (InSAR) techniques have gained traction in last decade as a viable technology for vegetation parameter estimation. Many works have shown that forest canopy height, which is a critical parameter for quantifying the terrestrial carbon cycle, can be estimated with InSAR. However, research is still needed to understand further the interaction of SAR signals with forest canopy and to develop an operational method for forestry applications. This work discusses the use of repeat pass interferometry with ALOS PALSAR (L band) HH polarized and COSMO Skymed (X band) HH polarized acquisitions over the Taxiarchis forest (Chalkidiki, Greece), in order to produce accurate digital elevation models (DEMs) and estimate canopy height with interferometric processing. The effect of wavelength-dependent penetration depth into the canopy is known to be strong, and could potentially lead to forest canopy height mapping using dual-wavelength SAR interferometry at X- and L-band. The method is based on scattering phase center separation at different wavelengths. It involves the generation of a terrain elevation model underneath the forest canopy from repeat-pass L-band InSAR data as well as the generation of a canopy surface elevation model from repeat pass X-band InSAR data. The terrain model is then used to remove the terrain component from the repeat pass interferometric X-band elevation model, so as to enable the forest canopy height estimation. The canopy height results were compared to a field survey with 6.9 m root mean square error (RMSE). The effects of vegetation characteristics, SAR incidence angle and view geometry, and terrain slope on the accuracy of the results have also been studied in this work.
MULTI-TEMPORAL SAR INTERFEROMETRY FOR LANDSLIDE MONITORING
Directory of Open Access Journals (Sweden)
R. Dwivedi
2016-06-01
Full Text Available In the past few years, SAR Interferometry specially InSAR and D-InSAR were extensively used for deformation monitoring related applications. Due to temporal and spatial decorrelation in dense vegetated areas, effectiveness of InSAR and D-InSAR observations were always under scrutiny. Multi-temporal InSAR methods are developed in recent times to retrieve the deformation signal from pixels with different scattering characteristics. Presently, two classes of multi-temporal InSAR algorithms are available- Persistent Scatterer (PS and Small Baseline (SB methods. This paper discusses the Stanford Method for Persistent Scatterer (StaMPS based PS-InSAR and the Small Baselines Subset (SBAS techniques to estimate the surface deformation in Tehri dam reservoir region in Uttarkhand, India. Both PS-InSAR and SBAS approaches used sixteen ENVISAT ASAR C-Band images for generating single master and multiple master interferograms stack respectively and their StaMPS processing resulted in time series 1D-Line of Sight (LOS mean velocity maps which are indicative of deformation in terms of movement towards and away from the satellites. From 1D LOS velocity maps, localization of landslide is evident along the reservoir rim area which was also investigated in the previous studies. Both PS-InSAR and SBAS effectively extract measurement pixels in the study region, and the general results provided by both approaches show a similar deformation pattern along the Tehri reservoir region. Further, we conclude that StaMPS based PS-InSAR method performs better in terms of extracting more number of measurement pixels and in the estimation of mean Line of Sight (LOS velocity as compared to SBAS method. It is also proposed to take up a few major landslides area in Uttarakhand for slope stability assessment.
Multi-Temporal SAR Interferometry for Landslide Monitoring
Dwivedi, R.; Narayan, A. B.; Tiwari, A.; Dikshit, O.; Singh, A. K.
2016-06-01
In the past few years, SAR Interferometry specially InSAR and D-InSAR were extensively used for deformation monitoring related applications. Due to temporal and spatial decorrelation in dense vegetated areas, effectiveness of InSAR and D-InSAR observations were always under scrutiny. Multi-temporal InSAR methods are developed in recent times to retrieve the deformation signal from pixels with different scattering characteristics. Presently, two classes of multi-temporal InSAR algorithms are available- Persistent Scatterer (PS) and Small Baseline (SB) methods. This paper discusses the Stanford Method for Persistent Scatterer (StaMPS) based PS-InSAR and the Small Baselines Subset (SBAS) techniques to estimate the surface deformation in Tehri dam reservoir region in Uttarkhand, India. Both PS-InSAR and SBAS approaches used sixteen ENVISAT ASAR C-Band images for generating single master and multiple master interferograms stack respectively and their StaMPS processing resulted in time series 1D-Line of Sight (LOS) mean velocity maps which are indicative of deformation in terms of movement towards and away from the satellites. From 1D LOS velocity maps, localization of landslide is evident along the reservoir rim area which was also investigated in the previous studies. Both PS-InSAR and SBAS effectively extract measurement pixels in the study region, and the general results provided by both approaches show a similar deformation pattern along the Tehri reservoir region. Further, we conclude that StaMPS based PS-InSAR method performs better in terms of extracting more number of measurement pixels and in the estimation of mean Line of Sight (LOS) velocity as compared to SBAS method. It is also proposed to take up a few major landslides area in Uttarakhand for slope stability assessment.
Energy Technology Data Exchange (ETDEWEB)
Ghetti, R. E-mail: roberta.ghetti@nuclear.lu.se; Colonna, N.; Helgesson, J.; Avdeichikov, V.; Golubev, P.; Jakobsson, B.; Tagliente, G.; Brandenburg, S.; Kravchuk, V.L.; Wilschut, H.W.; Kopecky, S.; Anderson, E.W.; Nadel-Turonski, P.; Westerberg, L.; Bellini, V.; Sperduto, M.L.; Sutera, C
2004-01-11
We present the details of an experiment on light particle interferometry. In particular, we focus on a time-of-flight technique which uses a cyclotron RF signal as a start and a liquid scintillator time signal as a stop, to measure neutron energy in the range of E{sub n}{approx}1.8-150 MeV. This dynamic range (up to 300 ns) is much larger than the beam bunch separation (54 ns) of the AGOR cyclotron (KVI). However, the problem of a short burst period is overcome by using the time information obtained from a fast projectile fragment phoswich detector. The complete analysis procedure to extract the final neutron kinetic energy spectra, is discussed.
Measurement of Out-of-plane Dynamic Deformations by Digital Speckle Pattern Interferometry
Directory of Open Access Journals (Sweden)
Rajesh Kurnar
2003-01-01
Full Text Available In this paper, measurement of dynamic deformations in a rectangular plate fixed at one end, using digital speckle pattem interferometry (DSPI, has been prese,nted. To improve the measurement accuracy,a new filtering scheme has been developed. This scheme is based on the combination of average/ median filtering and Symlet wavelet filtering which enhances the signal-to-noise ratio in the speckleinterferogram obtained from the DSPI. Experimental results show that this filtering scheme is quite effective in improving signal-to-noise ratio of the speckle .interferogram. The measurements by DSPIand accelerometer are in good agreement. The DSPI technique can be implemented for measuring the large deformations as well.
Simple digital phase-measuring algorithm for low-noise heterodyne interferometry
Kokuyama, Wataru; Ohta, Akihiro; Hattori, Koichiro
2016-01-01
We present a digital algorithm for measuring the phase difference between two sinusoidal signals that combines the modified fringe-counting method with two-sample zero crossing to enable sequential signal processing. This technique can be applied to a phase meter for measuring dynamic phase differences with high resolution, particularly for heterodyne interferometry. The floor noise obtained from a demonstration with an electrical apparatus is $5\\times10^{-8} \\mathrm{rad/\\sqrt{Hz}}$ at frequencies above approximately 0.1 Hz. In addition, by applying this method to a commercial heterodyne interferometer, the floor-noise level is confirmed to be $7\\times10^{-14} \\mathrm{m/\\sqrt{Hz}}$ from 4 kHz to 1 MHz. We also confirm the validity of the algorithm by comparing its results with those from a standard homodyne interferometer for measuring shock-motion peak acceleration greater than 5000 m/s^2 and a 10 mm stroke.
Digital Double-Pulse Holographic Interferometry for Vibration Analysis
Directory of Open Access Journals (Sweden)
H.J. Tiziani
1996-01-01
Full Text Available Different arrangements for double-pulsed holographic and speckle interferometry for vibration analysis will be described. Experimental results obtained with films (classical holographic interferometry and CCD cameras (digital holographic interferometry as storage materials are presented. In digital holography, two separate holograms of an object under test are recorded within a few microseconds using a CCD camera and are stored in a frame grabber. The phases of the two reconstructed wave fields are calculated from the complex amplitudes. The deformation is obtained from the phase difference. In the case of electronic speckle pattern interferometry (or image plane hologram, the phase can be calculated by using the sinusoid-fitting method. In the case of digital holographic interferometry, the phase is obtained by digital reconstruction of the complex amplitudes of the wave fronts. Using three directions of illumination and one direction of observation, all the information necessary for the reconstruction of the 3-dimensional deformation vector can be recorded at the same time. Applications of the method for measuring rotating objects are discussed where a derotator needs to be used.
Kimura, Tomoki; Taki, Hirofumi; Sakamoto, Takuya; Sato, Toru
2009-07-01
We employed frequency domain interferometry (FDI) for use as a medical acoustic imager to detect multiple targets with high range resolution. The phase of each frequency component of an echo varies with the frequency, and target intervals can be estimated from the phase variance. This processing technique is generally used in radar imaging. When the interference within a range gate is coherent, the cross correlation between the desired signal and the coherent interference signal is nonzero. The Capon method works under the guiding principle that output power minimization cancels the desired signal with a coherent interference signal. Therefore, we utilize frequency averaging to suppress the correlation of the coherent interference. The results of computational simulations using a pseudoecho signal show that the Capon method with adaptive frequency averaging (AFA) provides a higher range resolution than a conventional method. These techniques were experimentally investigated and we confirmed the effectiveness of the proposed method of processing by FDI.
Validation and intercomparison of Persistent Scatterers Interferometry: PSIC4 project results
Raucoules, D.; Bourgine, B.; Michele, M. de; Le Cozannet, G.; Closset, L.; Bremmer, C.; Veldkamp, H.; Tragheim, D.; Bateson, L.; Crosetto, M.; Agudo, M.; Engdahl, M.
2009-01-01
This article presents the main results of the Persistent Scatterer Interferometry Codes Cross Comparison and Certification for long term differential interferometry (PSIC4) project. The project was based on the validation of the PSI (Persistent Scatterer Interferometry) data with respect to levellin
Scanning White light interferometry: calibration and application to roughness assesment
DEFF Research Database (Denmark)
Bariani, Paolo
This report refers to an experimental investigation recently completed. The aim was to gain some knowledge of the application of white light interferometry to surface metrology. The following issues were addressed by the present work: • How a white light interferometry microscope works, what...... similarities and differences compared to laser interferometry can be identified. • What the main error sources are, and how such an instrument should be calibrated. The possibility of using calibration standards developed for other techniques was evaluated. • The technique was then applied to assessment...... of polymer replicated EDM rough topographies. The present method resulted to be not suitable for the purpose. • Based on the matured experience, some conclusions regarding the applicability of the method to some typical surface metrology problems to be investigated at nanometer-scale were drawn This work...
Radio & Optical Interferometry: Basic Observing Techniques and Data Analysis
Monnier, John D
2012-01-01
Astronomers usually need the highest angular resolution possible, but the blurring effect of diffraction imposes a fundamental limit on the image quality from any single telescope. Interferometry allows light collected at widely-separated telescopes to be combined in order to synthesize an aperture much larger than an individual telescope thereby improving angular resolution by orders of magnitude. Radio and millimeter wave astronomers depend on interferometry to achieve image quality on par with conventional visible and infrared telescopes. Interferometers at visible and infrared wavelengths extend angular resolution below the milli-arcsecond level to open up unique research areas in imaging stellar surfaces and circumstellar environments. In this chapter the basic principles of interferometry are reviewed with an emphasis on the common features for radio and optical observing. While many techniques are common to interferometers of all wavelengths, crucial differences are identified that will help new practi...
Resolving microstructures in Z pinches with intensity interferometry
Energy Technology Data Exchange (ETDEWEB)
Apruzese, J. P. [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States); Kroupp, E.; Maron, Y. [Weizmann Institute of Science, Rehovot 76100 (Israel); Giuliani, J. L.; Thornhill, J. W. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States)
2014-03-15
Nearly 60 years ago, Hanbury Brown and Twiss [R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956)] succeeded in measuring the 30 nrad angular diameter of Sirius using a new type of interferometry that exploited the interference of photons independently emitted from different regions of the stellar disk. Its basis was the measurement of intensity correlations as a function of detector spacing, with no beam splitting or preservation of phase information needed. Applied to Z pinches, X pinches, or laser-produced plasmas, this method could potentially provide spatial resolution under one micron. A quantitative analysis based on the work of Purcell [E. M. Purcell, Nature 178, 1449 (1956)] reveals that obtaining adequate statistics from x-ray interferometry of a Z-pinch microstructure would require using the highest-current generators available. However, using visible light interferometry would reduce the needed photon count and could enable its use on sub-MA machines.
Temporal decorrelation model for the bistatic SAR interferometry
Institute of Scientific and Technical Information of China (English)
Qilei Zhang; Wenge Chang
2015-01-01
This paper develops a temporal decorrelation model for the bistatic synthetic aperture radar (BSAR) interferometry. The temporal baseline is one of the important decorrelation sources for the repeat-pass synthetic aperture radar (SAR) interferometry. The study of temporal decorrelation is chal enging, especial y for the bistatic configuration, since temporal decorrelation is related to the data acquisition geometry. To develop an appropriate theoretical model for BSAR interferometry, the existing models for monostatic SAR cases are extended, and the general BSAR geometry con-figuration is involved in the derivation. Therefore, the developed temporal decorrelation model can be seen as a general model. The validity of the theoretical model is supported by Monte Carlo simulations. Furthermore, the impacts of the system parameters and BSAR geometry configurations on the temporal decorrelation model are discussed briefly.
Narrow linewidth single laser source system for onboard atom interferometry
Theron, Fabien; Renon, Geoffrey; Bidel, Yannick; Zahzam, Nassim; Cadoret, Malo; Bresson, Alexandre
2014-01-01
We present an original compact and robust laser system for atom interferometry based on a frequency-doubled telecom laser. Thanks to an original stabilization architecture on a saturated absorption, we obtain a frequency agile laser system allowing fast tuning of the laser frequency over 1 GHz in few ms using only a single laser source. The different laser frequencies used for atom interferometry are created by changing dynamically the frequency of the laser and by creating sidebands using a phase modulator. We take advantage of the maturity of fiber telecom technology to reduce the number of free-space optical components, which are intrinsically less stable, and to make the setup compact, much less sensitive to vibrations and thermal fluctuations. This source provides spectral linewidth below 2.5 kHz required for precision atom interferometry, and particularly for an high performance atomic inertial sensor.