Two-dimensional attosecond electron wave-packet interferometry.
Xie, Xinhua
2015-05-01
We propose a two-dimensional interferometry based on the electron wave-packet interference by using a cycle-shaped orthogonally polarized two-color laser field. With such a method, the subcycle and intercycle interferences can be disentangled into different directions in the measured photoelectron momentum spectra. The Coulomb influence can be minimized and the overlapping of interference fringes with the complicated low-energy structures can be avoided as well. The contributions of the excitation effect and the long-range Coulomb potential can be traced in the Fourier domain of the photoelectron distribution. Because of these advantages, precise information on valence electron dynamics of atoms or molecules with attosecond temporal resolution and additional spatial information with angstrom resolution can be obtained with the two-dimensional electron wave-packet interferometry.
Wave packet dynamics in periodically kicked nonlinear systems
NASA Astrophysics Data System (ADS)
Yu, Yan; Gao, Yi; Tong, Peiqing
2017-08-01
We investigate the dynamics of a wave packet in a periodically kicked nonlinear Aubry-André (AA) model when the initial state is localized at a single lattice site. We found that, beside the nonlinearity strength β and the strength (phase) of the quasiperiodic potential λ (θ), the kicking period T can also influence the dynamical evolution of the wave packet. Especially when T,β \\ll 1, the periodically kicked nonlinear AA model can be reduced to a static nonlinear AA model with a rescaled nonlinearity strength β /T.
Nonlinear Evolution of Alfvenic Wave Packets
NASA Technical Reports Server (NTRS)
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.
NASA Astrophysics Data System (ADS)
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.
Strongly nonlinear evolution of low-frequency wave packets in a dispersive plasma
NASA Technical Reports Server (NTRS)
Vasquez, Bernard J.
1993-01-01
The evolution of strongly nonlinear, strongly modulated wave packets is investigated in a dispersive plasma using a hybrid numerical code. These wave packets have amplitudes exceeding the strength of the external magnetic field, along which they propagate. Alfven (left helicity) wave packets show strong steepening for p < 1, while fast (fight heIicity) wave packets hardly steepen for any beta. Substantial regions of opposite helicity form on the leading side of steepened Alfven wave packets. This behavior differs qualitatively from that exhibited by the solutions to the derivative nonlinear Schrodinger (DNLS) equation.
Nonlinear electron motion in a coherent whistler wave packet
Khazanov, George; Tel'nikhin, Alexander; Kronberg, Tatiana
2008-07-15
Map equations are derived, with which nonlinear electron motion in a coherent whistler wave packet is investigated. All solutions of these equations belong to a certain strange attractor and describe chaotic motion with the stable means. The class of solutions determined the intermittent dynamics as the control parameter of the wave-particle system increases above the appropriate critical value is found. An application of the results to the problem of the stability of Earth's radiation belts is considered. It is shown that the efficient acceleration processes take place for relativistic electrons of a few MeV.
Cina, Jeffrey A
2008-01-01
This article summarizes theoretical studies of molecular state determination by wave-packet interferometry (WPI) and recounts some recent experimental applications of molecular WPI. Calculations predict that two-color nonlinear WPI data can be used to reconstruct a rovibronic target wave packet evolving under an incompletely characterized nuclear Hamiltonian. This can be accomplished by the isolation via phase cycling or wave-vector matching of an exhaustive collection of overlaps between the unknown target and the members of a family of reference wave packets whose form is known by construction. This review highlights recent experiments employing WPI to gain amplitude-level information about the photoexcited-state dynamics of small molecules in the gas phase and in rare-gas crystals. I briefly describe a new semiclassical theory for condensed-phase WPI and other coherence-spectroscopy measurements, such as time-resolved coherent anti-Stokes Raman scattering, and mention our initial studies of nonlinear WPI from electronic energy-transfer complexes.
NASA Astrophysics Data System (ADS)
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.
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.
Nonlinear Wave-Packet Dynamics in a Disordered Medium
Schwiete, G.; Finkel'stein, A. M.
2010-03-12
We develop an effective theory of pulse propagation in a nonlinear and disordered medium in two dimensions. The theory is formulated in terms of a nonlinear diffusion equation. Despite its apparent simplicity this equation describes novel phenomena which we refer to as 'locked explosion' and diffusive collapse. The equation can be applied to such distinct physical systems as laser beams propagating in disordered photonic crystals or Bose-Einstein condensates expanding in a disordered environment.
Das, Kunal K.
2011-09-15
We propose a way to simulate mesoscopic transport processes with counterpropagating wave packets of ultracold atoms in quasi-one-dimensional (1D) waveguides and show quantitative agreement with analytical results. The method allows the study of a broad range of transport processes at the level of individual modes, not possible in electronic systems. Typically suppressed effects of quantum coherence become manifest, along with the effects of tunable interactions, which can be used to develop a simpler type of sensitive atom interferometer.
Wave-packet rectification in nonlinear electronic systems: A tunable Aharonov-Bohm diode
Li, Yunyun; Zhou, Jun; 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 Schrödinger 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. PMID:24691462
Wave-packet rectification in nonlinear electronic systems: a tunable Aharonov-Bohm diode.
Li, Yunyun; Zhou, Jun; Marchesoni, Fabio; Li, Baowen
2014-04-02
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 Schrödinger 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.
Wave-packet rectification in nonlinear electronic systems: A tunable Aharonov-Bohm diode
NASA Astrophysics Data System (ADS)
Li, Yunyun; Zhou, Jun; Marchesoni, Fabio; Li, Baowen
2014-04-01
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 Schrödinger 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.
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.
NASA Astrophysics Data System (ADS)
Grimshaw, Roger; da Silva, Jose C. B.; Magalhaes, Jorge M.
2017-08-01
The large-amplitude internal solitary waves commonly observed in the coastal ocean can propagate for long distances for long times, so that it may be necessary to take account of the effects of the Earth's background rotation. In this case an appropriate model wave evolution equation is the Ostrovsky equation, whose typical solutions indicate that internal solitary waves will evolve into envelope wave packets. Unlike the more usual Korteweg-de Vries solutions which are typically rank-ordered wave packets, these are centred with the largest waves in the middle. This qualitative feature, together with certain key quantitative parameters such as the envelope carrier wavenumber and speed, can be sought in oceanic observations. Hence we have examined many SAR images of internal solitary waves with the general aim of finding features indicating that rotational effects have become significant. From these we report in detail on six typical cases of which four give indications of rotational effects. In addition we use a two-layer fluid model to estimate how the rotational parameters depend on the background stratification and topography.
NASA Astrophysics Data System (ADS)
Reddy, D. V.; Raymer, M. G.; McKinstrie, C. J.
2015-01-01
All classical and quantum technologies that encode in and retrieve information from optical fields rely on the ability to selectively manipulate orthogonal field modes of light. Such manipulation can be achieved with high selectivity for polarization modes and transverse-spatial modes. For the time-frequency degree of freedom, this could efficiently be achieved for a limited choice of approximately orthogonal modes, i.e., nonoverlapping bins in time or frequency. We recently proposed a method that surmounts the selectivity barrier for sorting arbitrary orthogonal temporal modes [Opt. Lett. 39, 2924 (2014)., 10.1364/OL.39.002924] using cascaded interferometric quantum frequency conversion in nonlinear optical media. We call this method temporal-mode interferometry, as it has a close resemblance to the well-known separated-fields atomic interferometry method introduced by Ramsey. The method has important implications for quantum memories, quantum dense coding, quantum teleportation, and quantum key distribution. Here we explore the inner workings of the method in detail, and extend it to multiple stages with a concurrent asymptotic convergence of temporal-mode selectivity to unity. We also complete our analysis of pump-chirp compensation to counter pump-induced nonlinear phase modulation in four-wave mixing implementations.
Nonlinear propagation of a wave packet in a hard-walled circular duct
NASA Technical Reports Server (NTRS)
Nayfeh, A. H.
1975-01-01
The method of multiple scales is used to derive a nonlinear Schroedinger equation for the temporal and spatial modulation of the amplitudes and the phases of waves propagating in a hard-walled circular duct. This equation is used to show that monochromatic waves are stable and to determine the amplitude dependance of the cutoff frequencies.
Nonlinear propagation of a wave packet in a hard-walled circular duct
NASA Technical Reports Server (NTRS)
Nayfeh, A. H.
1974-01-01
The method of multiple scales is used to derive a nonlinear Schroedinger equation for the temporal and spatial modulation of the amplitudes and the phases of waves propagating in a hard-walled circular duct. This equation is used to show that monochromatic waves are stable and to determine the amplitude dependance of the cut off frequencies.
Exploring Divisibility and Summability of 'Photon' Wave Packets in Nonlinear Optical Phenomena
NASA Technical Reports Server (NTRS)
Prasad, Narasimha; Roychoudhuri, Chandrasekhar
2009-01-01
Formulations for second and higher harmonic frequency up and down conversions, as well as multi photon processes directly assume summability and divisibility of photons. Quantum mechanical (QM) interpretations are completely congruent with these assumptions. However, for linear optical phenomena (interference, diffraction, refraction, material dispersion, spectral dispersion, etc.), we have a profound dichotomy. Most optical engineers innovate and analyze all optical instruments by propagating pure classical electromagnetic (EM) fields using Maxwell s equations and gives only lip-service to the concept "indivisible light quanta". Further, irrespective of linearity or nonlinearity of the phenomena, the final results are always registered through some photo-electric or photo-chemical effects. This is mathematically well modeled by a quadratic action (energy absorption) relation. Since QM does not preclude divisibility or summability of photons in nonlinear & multi-photon effects, it cannot have any foundational reason against these same possibilities in linear optical phenomena. It implies that we must carefully revisit the fundamental roots behind all light-matter interaction processes and understand the common origin of "graininess" and "discreteness" of light energy.
Controlled Splitting of an Atomic Wave Packet
Zhang, M.; Zhang, P.; Chapman, M. S.; You, L.
2006-08-18
We propose a simple scheme capable of adiabatically splitting an atomic wave packet using two independent translating traps. Implemented with optical dipole traps, our scheme allows a high degree of flexibility for atom interferometry arrangements and highlights its potential as an efficient and high fidelity atom optical beam splitter.
NASA Astrophysics Data System (ADS)
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.
Particlelike wave packets in complex scattering systems
NASA Astrophysics Data System (ADS)
Gérardin, Benoît; Laurent, Jérôme; Ambichl, Philipp; Prada, Claire; Rotter, Stefan; Aubry, Alexandre
2016-07-01
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. From the direct experimental access to the time-delay matrix of these systems, we demonstrate the existence of particlelike wave packets that remain focused in time and space throughout their complex trajectory. Due to their limited dispersion, their selective excitation will be crucially relevant for all applications involving selective wave focusing and efficient information transfer through complex media.
Segregation of helicity in inertial wave packets
NASA Astrophysics Data System (ADS)
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.
Two-point coherence of wave packets in turbulent jets
NASA Astrophysics Data System (ADS)
Jaunet, V.; Jordan, P.; Cavalieri, A. V. G.
2017-02-01
An experiment has been performed in order to provide support for wave-packet jet-noise modeling efforts. Recent work has shown that the nonlinear effects responsible for the two-point coherence of wave packets must be correctly accounted for if accurate sound prediction is to be achieved for subsonic turbulent jets. We therefore consider the same Mach 0.4 turbulent jet studied by Cavalieri et al. [Cavalieri et al., J. Fluid Mech. 730, 559 (2013), 10.1017/jfm.2013.346], but this time using two independent but synchronized, time-resolved stereo particle-image velocimetry systems. Each system can be moved independently, allowing simultaneous measurement of velocity in two, axially separated, crossflow planes, enabling eduction of the two-point coherence of wave packets. This and the associated length scales and phase speeds are studied and compared with those of the energy-containing turbulent eddies. The study illustrates how the two-point behavior of wave packets is fundamentally different from that of the more usually studied bulk two-point behavior, suggesting that sound-source modeling efforts should be reconsidered in the framework of wave packets. The study furthermore identifies two families of two-point-coherence behavior, respectively upstream and downstream of the end of the potential core, regions where linear theory is, respectively, successful and unsuccessful in predicting the axial evolution of wave-packets fluctuation energy.
NASA Astrophysics Data System (ADS)
Colas, David; Laussy, Fabrice P.
2016-01-01
We study the propagation of noninteracting polariton wave packets. We show how two qualitatively different concepts of mass that arise from the peculiar polariton dispersion lead to a new type of particlelike object from noninteracting fields—much like self-accelerating beams—shaped by the Rabi coupling out of Gaussian initial states. A divergence and change of sign of the diffusive mass results in a "mass wall" on which polariton wave packets bounce back. Together with the Rabi dynamics, this yields propagation of ultrafast subpackets and ordering of a spacetime crystal.
Controlling plasmonic wave packets in silver nanowires.
Cao, L.; Nome, R.; Montgomery, J. M.; Gray, S. K.; Scherer, N. F.
2010-09-01
Three-dimensional finite-difference time-domain simulations were performed to explore the excitation of surface plasmon resonances in long silver (Ag) nanowires. In particular, we show that it is possible to generate plasmonic wave packets that can propagate along the nanowire by exciting superpositions of surface plasmon resonances. By using an appropriately chirped pulse, it is possible to transiently achieve localization of the excitation at the distal end of the nanowire. Such designed coherent superpositions will allow realizing spatiotemporal control of plasmonic excitations for enhancing nonlinear responses in plasmonic 'circuits'.
Dynamics of quantum wave packets
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
NASA Astrophysics Data System (ADS)
Eckstein, Michał; Miller, Tomasz
2017-03-01
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 Hamiltonian impels a causal evolution of probabilities, even in the presence of interactions, the relativistic-Schrödinger model is acausal. We quantify the causality breakdown in the latter model and argue that, in contrast to the popular viewpoint, it is not related to the localization properties of the states.
Second Harmonic Generation of Nanoscale Phonon Wave Packets.
Bojahr, A; Gohlke, M; Leitenberger, W; Pudell, J; Reinhardt, M; von Reppert, A; Roessle, M; Sander, M; Gaal, P; Bargheer, M
2015-11-06
Phonons are often regarded as delocalized quasiparticles with certain energy and momentum. The anharmonic interaction of phonons determines macroscopic properties of the solid, such as thermal expansion or thermal conductivity, and a detailed understanding becomes increasingly important for functional nanostructures. Although phonon-phonon scattering processes depicted in simple wave-vector diagrams are the basis of theories describing these macroscopic phenomena, experiments directly accessing these coupling channels are scarce. We synthesize monochromatic acoustic phonon wave packets with only a few cycles to introduce nonlinear phononics as the acoustic counterpart to nonlinear optics. Control of the wave vector, bandwidth, and consequently spatial extent of the phonon wave packets allows us to observe nonlinear phonon interaction, in particular, second harmonic generation, in real time by wave-vector-sensitive Brillouin scattering with x-rays and optical photons.
Wave packet systems on local fields
NASA Astrophysics Data System (ADS)
Shah, Firdous A.; Ahmad, Owais
2017-10-01
In this paper, we introduce the notion of wave packet systems on local fields of positive characteristic and derive some characterizations of these systems by means of two basic equations in the Fourier domain. More precisely, we establish a complete characterization of orthogonal wave packet systems in L2(K) which include the corresponding results of wavelet analysis and Gabor theory as the special cases. We shall also provide a sufficient condition of the completeness of wave packet systems on local fields of positive characteristic subject to some mild conditions. The paper concludes with the necessary and sufficient conditions for the wave packet systems to be wave packet Parseval frames for L2(K) .
NASA Astrophysics Data System (ADS)
Chapman, Craig Thomas
We explore the reconstruction of B-state vibrational wave packets in I2 from simulated two-color nonlinear wave packet interferometry data. As a simplification of earlier proposals, we make use of different vibrational energy ranges in the B-state---rather than different electronic potential surfaces---for the short-pulse preparation and propagation of both target and reference wave packets. Numerical results from noisy interferograms indicate that experimental reconstruction should be possible with high fidelity (>0.99). Time-resolved coherent nonlinear optical experiments on small molecules in low-temperature host crystals are exposing valuable information on quantum mechanical dynamics in condensed media. We make use of generic features of these systems to frame two simple, comprehensive theories that will enable the efficient calculation of their ultrafast spectroscopic signals and support their interpretation in terms of the underlying chemical dynamics. Both treatments rely on the identification of normal coordinates to unambiguously partition the well-structured guest-host complex into a system and a bath and expand the overall wave function as a sum of product states between fully anharmonic vibrational basis states for the system and approximate Gaussian wave packets for the bath degrees of freedom. The theories exploit the fact that ultrafast experiments typically drive large-amplitude motion in a few intramolecular degrees of freedom of higher frequency than the crystal phonons, while these intramolecular vibrations indirectly induce smaller-amplitude---but still perhaps coherent---motion among the lattice modes. The equations of motion for the time-dependent parameters of the bath wave packets are fairly compact in a fixed vibrational basis/Gaussian bath (FVB/GB) approach. An alternative adiabatic vibrational basis/Gaussian bath (AVB/GB) treatment leads to more complicated equations of motion involving adiabatic and nonadiabatic vector potentials
Wave packet critical layers in stratified shear flows
NASA Astrophysics Data System (ADS)
Maslowe, S. A.
1996-01-01
In the inviscid theory of shear flow stability, the eigenvalue problem for a neutral or weakly amplified mode revolves around possible discontinuities in the eigenfunction as the singular critical point is crossed. Extensions of the linear normal mode approach to include nonlinearity and/or wave packets lead to amplitude evolution equations whose coefficients generally involve singular integrals. In the past, viscosity, nonlinearity or time dependence has been introduced in a critical layer centered upon the singular point to resolve these integrals. The form of the amplitude evolution equation is greatly influenced by which choice is made. In this paper, a new approach is proposed in which wave packet effects are dominant in the critical layer, and it is argued that in many applications this is the appropriate choice. The theory is applied here to two-dimensional wave propagation in stratified shear flows.
Acoustic emissions from convected wave packets
NASA Astrophysics Data System (ADS)
Obrist, Dominik
2011-02-01
Localized acoustic sources can often be modeled by wave packets. It has been recognized for a long time that the particular structure of these wave packet sources has a strong influence on the character of the acoustic emission to the far field. In the present work, we study the acoustic emission patterns with respect to the phase velocity, group velocity, size, and aspect ratio of the wave packet sources. To this end, the acoustic problem is formulated on the basis of Lighthill's acoustic analogy and then recast to the geometrical problem of conic sections. This leads to the notion of elliptic (subsonic), parabolic (sonic), and hyperbolic (supersonic) acoustic emission patterns. The resulting geometric theory for acoustic emissions from wave packets includes phenomena such as Mach waves, bi- and superdirectivity, Doppler shift, and silent directions.
Cherenkov Radiation Control via Self-accelerating Wave-packets.
Hu, Yi; Li, Zhili; Wetzel, Benjamin; Morandotti, Roberto; Chen, Zhigang; Xu, Jingjun
2017-08-18
Cherenkov radiation is a ubiquitous phenomenon in nature. It describes electromagnetic radiation from a charged particle moving in a medium with a uniform velocity larger than the phase velocity of light in the same medium. Such a picture is typically adopted in the investigation of traditional Cherenkov radiation as well as its counterparts in different branches of physics, including nonlinear optics, spintronics and plasmonics. In these cases, the radiation emitted spreads along a "cone", making it impractical for most applications. Here, we employ a self-accelerating optical pump wave-packet to demonstrate controlled shaping of one type of generalized Cherenkov radiation - dispersive waves in optical fibers. We show that, by tuning the parameters of the wave-packet, the emitted waves can be judiciously compressed and focused at desired locations, paving the way to such control in any physical system.
Dynamics of Attosecond Electron Wave Packets
NASA Astrophysics Data System (ADS)
Mauritsson, Johan
2005-05-01
We present results from some of the first experimental studies of attosecond electron wave packets created via the absorption of ultrashort extreme ultraviolet (XUV) light pulses [1]. The pulses, made via high harmonic generation, form an attosecond pulse train (APT) whose properties we can manipulate by a combination of spatial and spectral filtering. For instance, we show that on-target attosecond pulses of 170 as duration, which is close to the single cycle limit, can be produced [2]. The electron wave packets created when such an APT is used to ionize an atom are different from the tunneling wave packets familiar from strong field ionization. We show how to measure the dynamics of these wave packets in a strong infrared (IR) field, where the absorption of energy above the ionization threshold is found to depend strongly on the APT-IR delay [3]. We also demonstrate that altering the properties of the initial electron wave packet by manipulating the APT changes the subsequent continuum electron dynamics. Finally, we show how the phase of a longer, femtosecond electron wave packet can be modulated by a moderately strong IR pulse with duration comparable to or shorter than that of the electron wave packet. This experiment reveals how the normal ponderomotive shift of an XUV ionization event is modified when the IR pulse is shorter than the XUV pulse.[1] The experiments were done at Lund Institute of Technology, Sweden.[2] R. López-Martens, et al., Phys. Rev. Lett. 94, 033001 (2005)[3] P. Johnsson, et al., submitted to Phys. Rev. Lett.
Atomic Electron Wave Packet Interference and Control
NASA Astrophysics Data System (ADS)
Noel, Michael W.
We have used a train of picosecond laser pulses to excite an atomic electron into a coherent superposition of radially localized wave packets. Such superpositions were used in three separate experiments to study interference and control of atomic electron wave packets. The first experiment is an analog of Young's double -slit interferometer using an atomic electron instead of light. The superposition for this experiment consists of two wave packets coherently excited on opposite sides of a common Kepler orbit, which mimic the pair of slits used in Young's experiment. The two wave packets propagate and spread until they completely overlap, then a third laser pulse probes the resulting fringe pattern. The relative phase of the two wave packet can be varied so that the interference produces a single localized electron wave packet on one side of the orbit or the other. In the second experiment we study the same superposition of two separated wave packets, but this time in an analogy to Schrodinger's coherent superposition of live and dead cat. State selective field ionization is used to verify that only every other atomic level is populated in the cat state, and a Ramsey fringe measurement is used to demonstrate the coherence of the superposition. In the third experiment we have made use of the interference studied in the first two in an effort to control the radial distribution of the electron. This is done by controlling the quantum state distribution that is excited with a train of laser pulses. We have developed this control theory for the weak field case to show the simple and unique solutions that result. We have also demonstrated this type of control by showing how the state distribution can be modified for the simple case of a train of three pulses.
Trajectory description of the quantum-classical transition for wave packet interference
NASA Astrophysics Data System (ADS)
Chou, Chia-Chun
2016-08-01
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.
Trajectory description of the quantum–classical transition for wave packet interference
Chou, Chia-Chun
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.
Ray Curvature and Refraction of Wave Packets.
1978-09-01
1!~~~~~ _ ‘ AD AOM 302 FLORIDA STATE UNIV TALLAHASSEE DEPT OF OCEANOGRAPHY FIG B/3 RAY CURVATURE AND REFRACTION OF WAVE PACKETS. (U) SEP 78 .J E...BREEDING N00014—77—C—0329 UNCLASSIFIED TR JE6 3 NL _ _ _ rwii__ _ ~iU ir!I I -~~ RAYOJR\\1L~[UREAND REFRACI ION OF WAVE F1~\\CKET~S ~y J. Ernest Breeding...01 29 014 -~ Technical Report No. JEB-3 Department of Oceanography • Florida State University RAY CURVATURE AND REFRACTION OF WAVE PACKETS b O G • J
Squeezed Wave Packets in Quantum Cosmology
NASA Astrophysics Data System (ADS)
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.
Test particle simulation study of whistler wave packets observed near Comet Giacobini-Zinner
NASA Technical Reports Server (NTRS)
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.
Qualitative dynamics of wave packets in turbulent jets
NASA Astrophysics Data System (ADS)
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.
Steering attosecond electron wave packets with light.
Kienberger, R; Hentschel, M; Uiberacker, M; Spielmann, Ch; Kitzler, M; Scrinzi, A; Wieland, M; Westerwalbesloh, Th; Kleineberg, U; Heinzmann, U; Drescher, M; Krausz, F
2002-08-16
Photoelectrons excited by extreme ultraviolet or x-ray photons in the presence of a strong laser field generally suffer a spread of their energies due to the absorption and emission of laser photons. We demonstrate that if the emitted electron wave packet is temporally confined to a small fraction of the oscillation period of the interacting light wave, its energy spectrum can be up- or downshifted by many times the laser photon energy without substantial broadening. The light wave can accelerate or decelerate the electron's drift velocity, i.e., steer the electron wave packet like a classical particle. This capability strictly relies on a sub-femtosecond duration of the ionizing x-ray pulse and on its timing to the phase of the light wave with a similar accuracy, offering a simple and potentially single-shot diagnostic tool for attosecond pump-probe spectroscopy.
Energy and Information Transfer Via Coherent Exciton Wave Packets
NASA Astrophysics Data System (ADS)
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
Relativistic Electron Wave Packets Carrying Angular Momentum
NASA Astrophysics Data System (ADS)
Bialynicki-Birula, Iwo; Bialynicka-Birula, Zofia
2017-03-01
There are important differences between the nonrelativistic and relativistic description of electron beams. In the relativistic case the orbital angular momentum quantum number cannot be used to specify the wave functions and the structure of vortex lines in these two descriptions is completely different. We introduce analytic solutions of the Dirac equation in the form of exponential wave packets and we argue that they properly describe relativistic electron beams carrying angular momentum.
Creating and Transporting Trojan Wave Packets
NASA Astrophysics Data System (ADS)
Wyker, B.; Ye, S.; Dunning, F. B.; Yoshida, S.; Reinhold, C. O.; Burgdörfer, J.
2012-01-01
Nondispersive localized Trojan wave packets with ni˜305 moving in near-circular Bohr-like orbits are created and transported to localized near-circular Trojan states of higher n, nf˜600, by driving with a linearly polarized sinusoidal electric field whose period is slowly increased. The protocol is remarkably efficient with over 80% of the initial atoms being transferred to the higher n states, a result confirmed by classical trajectory Monte Carlo simulations.
Relativistic Electron Wave Packets Carrying Angular Momentum.
Bialynicki-Birula, Iwo; Bialynicka-Birula, Zofia
2017-03-17
There are important differences between the nonrelativistic and relativistic description of electron beams. In the relativistic case the orbital angular momentum quantum number cannot be used to specify the wave functions and the structure of vortex lines in these two descriptions is completely different. We introduce analytic solutions of the Dirac equation in the form of exponential wave packets and we argue that they properly describe relativistic electron beams carrying angular momentum.
Teleportation of nonclassical wave packets of light.
Lee, Noriyuki; Benichi, Hugo; Takeno, Yuishi; Takeda, Shuntaro; Webb, James; Huntington, Elanor; Furusawa, Akira
2011-04-15
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 nonclassicality 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
NASA Astrophysics Data System (ADS)
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.
Testing nonlinear vacuum electrodynamics with Michelson interferometry
NASA Astrophysics Data System (ADS)
Schellstede, Gerold O.; Perlick, Volker; Lämmerzahl, Claus
2015-07-01
We discuss the theoretical foundations for testing nonlinear vacuum electrodynamics with Michelson interferometry. Apart from some nondegeneracy conditions to be imposed, our discussion applies to all nonlinear electrodynamical theories of the Plebański class, i.e., to all Lagrangians that depend only on the two Lorentz-invariant scalars quadratic in the field strength. The main idea of the experiment proposed here is to use the fact that, according to nonlinear electrodynamics, the phase velocity of light should depend on the strength and on the direction of an electromagnetic background field. There are two possible experimental setups for testing this prediction with Michelson interferometry. The first possibility is to apply a strong electromagnetic field to the beam in one arm of the interferometer and to compare the situation where the field is switched on with the situation where it is switched off. The second possibility is to place the whole interferometer in a strong electromagnetic field and to rotate it. If an electromagnetic field is placed in one arm, the interferometer could have the size of a gravitational wave detector, i.e., an arm length of several hundred meters. If the whole interferometer is placed in an electromagnetic field, one would have to do the experiment with a tabletop interferometer. As an alternative to a traditional Michelson interferometer, one could use a pair of optical resonators that are not bigger than a few centimeters. Then the whole apparatus would be placed in the background field and one would either compare the situation where the field is switched on with the situation where it is switched off or one would rotate the apparatus with the field kept switched on. We derive the theoretical foundations for these types of experiments, in the context of an unspecified nonlinear electrodynamics of the Plebański class, and we discuss their feasibility. A null result of the experiment would place bounds on the parameters of the
Beresh, Steven Jay; Casper, Katya M.; Schneider, Steven P.
2010-12-01
The development of turbulent spots in a hypersonic boundary layer was studied on the nozzle wall of the Boeing/AFOSR Mach-6 Quiet Tunnel. Under quiet flow conditions, the nozzle wall boundary layer remains laminar and grows very thick over the long nozzle length. This allows the development of large turbulent spots that can be readily measured with pressure transducers. Measurements of naturally occurring wave packets and developing turbulent spots were made. The peak frequencies of these natural wave packets were in agreement with second-mode computations. For a controlled study, the breakdown of disturbances created by spark and glow perturbations were studied at similar freestream conditions. The spark perturbations were the most effective at creating large wave packets that broke down into turbulent spots. The flow disturbances created by the controlled perturbations were analyzed to obtain amplitude criteria for nonlinearity and breakdown as well as the convection velocities of the turbulent spots. Disturbances first grew into linear instability waves and then quickly became nonlinear. Throughout the nonlinear growth of the wave packets, large harmonics are visible in the power spectra. As breakdown begins, the peak amplitudes of the instability waves and harmonics decrease into the rising broad-band frequencies. Instability waves are still visible on either side of the growing turbulent spots during this breakdown process.
Square-integrability of multivariate metaplectic wave-packet representations
NASA Astrophysics Data System (ADS)
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) .
Classical Hamiltonian structures in wave packet dynamics
NASA Astrophysics Data System (ADS)
Gray, Stephen K.; Verosky, John M.
1994-04-01
The general, N state matrix representation of the time-dependent Schrödinger equation is equivalent to an N degree of freedom classical Hamiltonian system. We describe how classical mechanical methods and ideas can be applied towards understanding and modeling exact quantum dynamics. Two applications are presented. First, we illustrate how qualitative insights may be gained by treating the two state problem with a time-dependent coupling. In the case of periodic coupling, Poincaré surfaces of section are used to view the quantum dynamics, and features such as the Floquet modes take on interesting interpretations. The second application illustrates computational implications by showing how Liouville's theorem, or more generally the symplectic nature of classical Hamiltonian dynamics, provides a new perspective for carrying out numerical wave packet propagation. We show how certain simple and explicit symplectic integrators can be used to numerically propagate wave packets. The approach is illustrated with an application to the problem of a diatomic molecule interacting with a laser, although it and related approaches may be useful for describing a variety of problems.
Collective neutrino oscillations and neutrino wave packets
NASA Astrophysics Data System (ADS)
Akhmedov, Evgeny; Kopp, Joachim; Lindner, Manfred
2017-09-01
Effects of decoherence by wave packet separation on collective neutrino oscillations in dense neutrino gases are considered. We estimate the length of the wave packets of neutrinos produced in core collapse supernovae and the expected neutrino coherence length, and then proceed to consider the decoherence effects within the density matrix formalism of neutrino flavour transitions. First, we demonstrate that for neutrino oscillations in vacuum the decoherence effects are described by a damping term in the equation of motion of the density matrix of a neutrino as a whole (as contrasted to that of the fixed-momentum components of the neutrino density matrix). Next, we consider neutrino oscillations in ordinary matter and dense neutrino backgrounds, both in the adiabatic and non-adiabatic regimes. In the latter case we study two specific models of adiabaticity violation—one with short-term and another with extended non-adiabaticity. It is demonstrated that, while in the adiabatic case a damping term is present in the equation of motion of the neutrino density matrix (just like in the vacuum oscillation case), no such term in general appears in the non-adiabatic regime.
Do Free Quantum-Mechanical Wave Packets Always Spread?
ERIC Educational Resources Information Center
Klein, James R.
1980-01-01
The spreading or shrinking of free three-dimensional quantum-mechanical wave packets is addressed. A seeming paradox concerning the time evolution operator and nonspreading wave packets is discussed, and the necessity of taking into account the appropriate mathematical structure of quantum mechanics is emphasized. Teaching implications are given.…
Do Free Quantum-Mechanical Wave Packets Always Spread?
ERIC Educational Resources Information Center
Klein, James R.
1980-01-01
The spreading or shrinking of free three-dimensional quantum-mechanical wave packets is addressed. A seeming paradox concerning the time evolution operator and nonspreading wave packets is discussed, and the necessity of taking into account the appropriate mathematical structure of quantum mechanics is emphasized. Teaching implications are given.…
Spatial control of recollision wave packets with attosecond precision.
Kitzler, Markus; Lezius, Matthias
2005-12-16
We propose orthogonally polarized two-color laser pulses to steer tunneling electrons with attosecond precision around the ion core. We numerically demonstrate that the angles of birth and recollision, the recollision energy, and the temporal structure of the recolliding wave packet can be controlled without stabilization of the carrier-envelope phase of the laser, and that the wave packet's properties can be described by classical relations for a point charge. This establishes unique mapping between parameters of the laser field and attributes of the recolliding wave packet. The method is capable of probing ionic wave packet dynamics with attosecond resolution from an adjustable direction and might be used as an alternative to aligning molecules. Shaping the properties of the recollision wave packet by controlling the laser field may also provide new routes for improvement of attosecond pulse generation via high harmonic radiation.
A singular vortex Rossby wave packet within a rapidly rotating vortex
NASA Astrophysics Data System (ADS)
Caillol, Philippe
2017-04-01
This paper describes the quasi-steady régime attained by a rapidly rotating vortex after a wave packet has interacted with it. We consider singular, nonlinear, helical, and shear asymmetric modes within a linearly stable, columnar, axisymmetric, and dry vortex in the f-plane. The normal modes enter resonance with the vortex at a certain radius rc, where the phase angular speed is equal to the rotation frequency. The related singularity in the modal equation at rc strongly modifies the flow in the 3D helical critical layer, the region where the wave/vortex interaction occurs. This interaction induces a secondary mean flow of higher amplitude than the wave packet and that diffuses at either side of the critical layer inside two spiral diffusion boundary layers. We derive the leading-order equations of the system of nonlinear coupled partial differential equations that govern the slowly evolving amplitudes of the wave packet and induced mean flow a long time after this interaction started. We show that the critical layer imposes its proper scalings and evolution equations; in particular, two slow times are involved, the faster being secular. This system leads to a more complex dynamics with respect to the previous studies on wave packets where this coupling was omitted and where, for instance, a nonlinear Schrödinger equation was derived [D. J. Benney and S. A. Maslowe, "The evolution in space and time of nonlinear waves in parallel shear flows," Stud. Appl. Math. 54, 181 (1975)]. Matched asymptotic expansion method lets appear that the neutral modes are distorted. The main outcome is that a stronger wave/vortex interaction takes place when a wave packet is considered with respect to the case of a single mode. Numerical simulations of the leading-order inviscid Burgers-like equations of the derived system show that the wave packet rapidly breaks and that the vortex, after intensifying in the transition stage, is substantially weakened before the breaking onset. This
Realization of localized Bohr-like wave packets.
Mestayer, J J; Wyker, B; Lancaster, J C; Dunning, F B; Reinhold, C O; Yoshida, S; Burgdörfer, J
2008-06-20
We demonstrate a protocol to create localized wave packets in very-high-n Rydberg states which travel in nearly circular orbits around the nucleus. Although these wave packets slowly dephase and eventually lose their localization, their motion can be monitored over several orbital periods. These wave packets represent the closest analog yet achieved to the original Bohr model of the hydrogen atom, i.e., an electron in a circular classical orbit around the nucleus. The possible extension of the approach to create "planetary atoms" in highly correlated stable multiply excited states is discussed.
Wave-packet formation at the zero-dispersion point in the Gardner-Ostrovsky equation
NASA Astrophysics Data System (ADS)
Whitfield, A. J.; Johnson, E. R.
2015-05-01
The long-time effect of weak rotation on an internal solitary wave is the decay into inertia-gravity waves and the eventual emergence of a coherent, steadily propagating, nonlinear wave packet. There is currently no entirely satisfactory explanation as to why these wave packets form. Here the initial value problem is considered within the context of the Gardner-Ostrovsky, or rotation-modified extended Korteweg-de Vries, equation. The linear Gardner-Ostrovsky equation has maximum group velocity at a critical wave number, often called the zero-dispersion point. It is found here that a nonlinear splitting of the wave-number spectrum at the zero-dispersion point, where energy is shifted into the modulationally unstable regime of the Gardner-Ostrovsky equation, is responsible for the wave-packet formation. Numerical comparisons of the decay of a solitary wave in the Gardner-Ostrovsky equation and a derived nonlinear Schrödinger equation at the zero-dispersion point are used to confirm the spectral splitting.
Wave-packet formation at the zero-dispersion point in the Gardner-Ostrovsky equation.
Whitfield, A J; Johnson, E R
2015-05-01
The long-time effect of weak rotation on an internal solitary wave is the decay into inertia-gravity waves and the eventual emergence of a coherent, steadily propagating, nonlinear wave packet. There is currently no entirely satisfactory explanation as to why these wave packets form. Here the initial value problem is considered within the context of the Gardner-Ostrovsky, or rotation-modified extended Korteweg-de Vries, equation. The linear Gardner-Ostrovsky equation has maximum group velocity at a critical wave number, often called the zero-dispersion point. It is found here that a nonlinear splitting of the wave-number spectrum at the zero-dispersion point, where energy is shifted into the modulationally unstable regime of the Gardner-Ostrovsky equation, is responsible for the wave-packet formation. Numerical comparisons of the decay of a solitary wave in the Gardner-Ostrovsky equation and a derived nonlinear Schrödinger equation at the zero-dispersion point are used to confirm the spectral splitting.
Scattering of wave packets with phases
NASA Astrophysics Data System (ADS)
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.
Engineering and manipulating exciton wave packets
NASA Astrophysics Data System (ADS)
Zang, Xiaoning; Montangero, Simone; Carr, Lincoln D.; Lusk, Mark T.
2017-05-01
When a semiconductor absorbs light, the resulting electron-hole superposition amounts to a uncontrolled quantum ripple that eventually degenerates into diffusion. If the conformation of these excitonic superpositions could be engineered, though, they would constitute a new means of transporting information and energy. We show that properly designed laser pulses can be used to create such excitonic wave packets. They can be formed with a prescribed speed, direction, and spectral make-up that allows them to be selectively passed, rejected, or even dissociated using superlattices. Their coherence also provides a handle for manipulation using active, external controls. Energy and information can be conveniently processed and subsequently removed at a distant site by reversing the original procedure to produce a stimulated emission. The ability to create, manage, and remove structured excitons comprises the foundation for optoexcitonic circuits with application to a wide range of quantum information, energy, and light-flow technologies. The paradigm is demonstrated using both tight-binding and time-domain density functional theory simulations.
Theory of discrete wave packets in the solar wind.
NASA Technical Reports Server (NTRS)
Wu, C. S.
1972-01-01
Discrete wave packets were observed by Ogo 5 and earlier satellites. These waves were believed to be in the whistler mode. Since their group velocities were found to be smaller than the solar-wind speed, these waves could not have been generated in the bow shock and could not have propagated upstream later. The present theory discusses a mechanism similar to that of the echo phenomenon in plasma physics discovered in recent years. The present theory enables us to explain (a) why the wave packets were associated with the bow shock, (b) why the wave packets were characterized by coherent oscillations, and (c) why the wave packets had group velocities smaller than the solar wind and yet could still occur in the solar wind. In short, our theory is able to interpret all the essential features deduced from the observational data.
Analytic approach to the wave packet formalism in oscillation phenomena
Bernardini, A.E.; Leo, S. de
2004-09-01
We introduce an approximation scheme to perform an analytic study of the oscillation phenomena in a pedagogical and comprehensive way. By using Gaussian wave packets, we show that the oscillation is bounded by a time-dependent vanishing function which characterizes the slippage between the mass-eigenstate wave packets. We also demonstrate that the wave packet spreading represents a secondary effect which plays a significant role only in the nonrelativistic limit. In our analysis, we note the presence of a new time-dependent phase and calculate how this additional term modifies the oscillating character of the flavor conversion formula. Finally, by considering box and sine wave packets we study how the choice of different functions to describe the particle localization changes the oscillation probability.
Theory for low-frequency modulated Langmuir wave packets
NASA Technical Reports Server (NTRS)
Cairns, Iver H.; Robinson, P. A.
1992-01-01
Langmuir wave packets with low frequency modulations (or beats) observed in the Jovian foreshock are argued to be direct evidence for the Langmuir wave decay L yields L-prime + S. In this decay, 'pump' Langmuir waves L, driven by an electron beam, produce backscattered product Langmuir waves L-prime and ion sound waves S. The L and L-prime waves beat at the frequency and wavevector of the S waves, thereby modulating the wave packets. Beam speeds calculated using the modulated Jovian wave packets (1) are reasonable, at 4-10 times the electron thermal speed, (2) are consistent with theoretical limits on the decay process, and (3) decrease with increasing foreshock depth, as expected theoretically. These results strongly support the theory. The modulation depth of some wave packets suggests saturation by the decay L yields L-prime + S. Applications to modulated Langmuir packets in the Venusian and terrestrial foreshocks and in a type III radio source are proposed.
Direct observation of an attosecond electron wave packet in a nitrogen molecule
Okino, Tomoya; Furukawa, Yusuke; Nabekawa, Yasuo; Miyabe, Shungo; Amani Eilanlou, A.; Takahashi, Eiji J.; Yamanouchi, Kaoru; Midorikawa, Katsumi
2015-01-01
Capturing electron motion in a molecule is the basis of understanding or steering chemical reactions. Nonlinear Fourier transform spectroscopy using an attosecond-pump/attosecond-probe technique is used to observe an attosecond electron wave packet in a nitrogen molecule in real time. The 500-as electronic motion between two bound electronic states in a nitrogen molecule is captured by measuring the fragment ions with the same kinetic energy generated in sequential two-photon dissociative ionization processes. The temporal evolution of electronic coherence originating from various electronic states is visualized via the fragment ions appearing after irradiation of the probe pulse. This observation of an attosecond molecular electron wave packet is a critical step in understanding coupled nuclear and electron motion in polyatomic and biological molecules to explore attochemistry. PMID:26601262
Sinusoidal nonlinearity in wavelength-sweeping interferometry
Perret, Luc; Pfeiffer, Pierre
2007-11-20
We report the influence of the nonlinearities in the wavelength-sweeping speed on the resulting interferometric signals in an absolute distance interferometer. The sweeping signal is launched in the reference and target interferometers from an external cavity laser source. The experimental results demonstrate a good resolution in spite of the presence of nonlinearities in the wavelength sweep. These nonlinearities can be modeled by a sum of sinusoids. A simulation is then implemented to analyze the influence of their parameters. It shows that a sinusoidal nonlinearity is robust enough to give a good final measurement uncertainty through a Fourier transform technique. It can be concluded that an optimal value of frequency and amplitude exists in the case of a sinusoidal nonlinearity.
Spectra of KeV Protons Related to Ion-Cyclotron Wave Packets
NASA Technical Reports Server (NTRS)
Khazanov, G. V.; Sibeck, D. G.; Tel'Nikhin, A. A.; Kronberg, T. K.
2017-01-01
We use the Fokker-Planck-Kolmogorov equation to study the statistical aspects of stochastic dynamics of the radiation belt (RB) protons driven by nonlinear electromagnetic ion-cyclotron (EMIC) wave packets. We obtain the spectra of keV protons scattered by these waves that showsteeping near the gyroresonance, the signature of resonant wave-particle interaction that cannot be described by a simple power law. The most likely mechanism for proton precipitation events in RBs is shown to be nonlinear wave-particle interaction, namely, the scattering of RB protons into the loss cone by EMIC waves.
Coda wave interferometry for estimating nonlinear behavior in seismic velocity.
Snieder, Roel; Grêt, Alexandre; Douma, Huub; Scales, John
2002-03-22
In coda wave interferometry, one records multiply scattered waves at a limited number of receivers to infer changes in the medium over time. With this technique, we have determined the nonlinear dependence of the seismic velocity in granite on temperature and the associated acoustic emissions. This technique can be used in warning mode, to detect the presence of temporal changes in the medium, or in diagnostic mode, where the temporal change in the medium is quantified.
NASA Astrophysics Data System (ADS)
Casper, Katya M.
During atmospheric reentry, hypersonic vehicles are subjected to high levels of boundary-layer pressure fluctuations that cause vibration of internal components. Current models are not adequate to predict these fluctuations. A more physics-based approach can be obtained by using a turbulent-spot model of transition. In order to gain a better understanding of the pressure-fluctuation field and the growth of turbulent spots in a hypersonic boundary layer, the development of disturbances was studied on the nozzle wall of the Boeing/AFOSR Mach-6 Quiet Tunnel. Under quiet flow conditions, the nozzle wall boundary layer remains laminar and grows very thick over the long nozzle length. This allows the development of large disturbances that can be well-resolved with high-frequency pressure transducers. For a controlled study, disturbances were created by pulsed glow perturbations and studied at various freestream conditions. Both the centerline and the spanwise distribution of pressure fluctuations were measured as boundary-layer disturbances grew from linear instability wave packets into turbulent spots. A disturbance first grows into a linear instability wave packet and then quickly becomes nonlinear. At this point, the wave packet is still concentrated near the disturbance centerline, but weaker disturbances are seen spreading from the center. Throughout the nonlinear growth of the wave packets, large harmonics are visible in the power spectra. Breakdown to turbulence begins in the core of the wave packets where the wave amplitudes are largest. As breakdown begins, the peak amplitudes of the instability waves and harmonics decrease into the rising broadband frequencies. Second-mode waves are still evident in front of and behind the breakdown point and can be seen propagating in the spanwise direction at a spreading angle. The turbulent core grows downstream, resulting in a turbulent spot with a typical arrowhead shape. However, the spot is not merely a localized patch
Accelerating Airy–Gauss–Kummer localized wave packets
Zhong, Wei-Ping; Belić, Milivoj; Zhang, Yiqi; Huang, Tingwen
2014-01-15
A general approach to generating three-dimensional nondiffracting spatiotemporal solutions of the linear Schrödinger equation with an Airy-beam time-dependence is reported. A class of accelerating optical pulses with the structure of Airy–Gauss–Kummer vortex beams is obtained. Our results demonstrate that the optical field contributions to the Airy–Gauss–Kummer accelerating optical wave packets of the cylindrical symmetry can be characterized by the radial and angular mode numbers. -- Highlights: •A general solution of 3D linear Schrödinger equation with an Airy time-dependence is reported. •We find that the Airy–Kummer spatiotemporal wave packets can carry infinite energy. •A class of the accelerating spatiotemporal optical pulses with special structures was found. •The spatiotemporal wave packets retain their energy features over several Rayleigh lengths.
Semiclassical dynamics of electron wave packet states with phase vortices.
Bliokh, Konstantin Yu; Bliokh, Yury P; Savel'ev, Sergey; Nori, Franco
2007-11-09
We consider semiclassical higher-order wave packet solutions of the Schrödinger equation with phase vortices. The vortex line is aligned with the propagation direction, and the wave packet carries a well-defined orbital angular momentum (OAM) variant Planck's over 2pil (l is the vortex strength) along its main linear momentum. The probability current coils around the momentum in such OAM states of electrons. In an electric field, these states evolve like massless particles with spin l. The magnetic-monopole Berry curvature appears in momentum space, which results in a spin-orbit-type interaction and a Berry/Magnus transverse force acting on the wave packet. This brings about the OAM Hall effect. In a magnetic field, there is a Zeeman interaction, which, can lead to more complicated dynamics.
Propagation velocity of Alfven wave packets in a dissipative plasma
Amagishi, Y.; Nakagawa, H. ); Tanaka, M. )
1994-09-01
We have experimentally studied the behavior of Alfven wave packets in a dissipative plasma due to ion--neutral-atom collisions. It is urged that the central frequency of the packet is observed to gradually decrease with traveling distance in the absorption range of frequencies because of a differential damping among the Fourier components, and that the measured average velocity of its peak amplitude is not accounted for by the conventional group velocity, but by the prediction derived by Tanaka, Fujiwara, and Ikegami [Phys. Rev. A 34, 4851 (1986)]. Furthermore, when the initial central frequency is close to the critical frequency in the anomalous dispersion, the wave packet apparently collapses when traveling along the magnetic field; however, we have found that it is decomposed into another two wave packets with the central frequencies being higher or lower than the critical frequency.
Flavor and chiral oscillations with Dirac wave packets
Bernardini, A.E.; Leo, S. de
2005-04-01
We report about recent results on Dirac wave packets in the treatment of neutrino flavor oscillation where the initial localization of a spinor state implies an interference between positive and negative energy components of mass-eigenstate wave packets. A satisfactory description of fermionic particles requires the use of the Dirac equation as evolution equation for the mass eigenstates. In this context, a new flavor conversion formula can be obtained when the effects of chiral oscillation are taken into account. Our study leads to the conclusion that the fermionic nature of the particles, where chiral oscillations and the interference between positive and negative frequency components of mass-eigenstate wave packets are implicitly assumed, modifies the standard oscillation probability. Nevertheless, for ultrarelativistic particles and sharply peaked momentum distributions, we can analytically demonstrate that these modifications introduce correction factors proportional to m{sub 1,2}{sup 2}/p{sub 0}{sup 2} which are practically undetectable by any experimental analysis.
Attosecond Electron Wave Packet Dynamics in Strong Laser Fields
Johnsson, P.; Remetter, T.; Varju, K.; L'Huillier, A.; Lopez-Martens, R.; Valentin, C.; Balcou, Ph.; Kazamias, S.; Mauritsson, J.; Gaarde, M. B.; Schafer, K. J.; Mairesse, Y.; Wabnitz, H.; Salieres, P.
2005-07-01
We use a train of sub-200 attosecond extreme ultraviolet (XUV) pulses with energies just above the ionization threshold in argon to create a train of temporally localized electron wave packets. We study the energy transfer from a strong infrared (IR) laser field to the ionized electrons as a function of the delay between the XUV and IR fields. When the wave packets are born at the zero crossings of the IR field, a significant amount of energy ({approx}20 eV) is transferred from the field to the electrons. This results in dramatically enhanced above-threshold ionization in conditions where the IR field alone does not induce any significant ionization. Because both the energy and duration of the wave packets can be varied independently of the IR laser, they are valuable tools for studying and controlling strong-field processes.
Semiclassical Dynamics of Electron Wave Packet States with Phase Vortices
Bliokh, Konstantin Yu.; Bliokh, Yury P.; Savel'ev, Sergey; Nori, Franco
2007-11-09
We consider semiclassical higher-order wave packet solutions of the Schroedinger equation with phase vortices. The vortex line is aligned with the propagation direction, and the wave packet carries a well-defined orbital angular momentum (OAM) ({Dirac_h}/2{pi})l (l is the vortex strength) along its main linear momentum. The probability current coils around the momentum in such OAM states of electrons. In an electric field, these states evolve like massless particles with spin l. The magnetic-monopole Berry curvature appears in momentum space, which results in a spin-orbit-type interaction and a Berry/Magnus transverse force acting on the wave packet. This brings about the OAM Hall effect. In a magnetic field, there is a Zeeman interaction, which, can lead to more complicated dynamics.
Optimal control of wave-packets: a semiclassical approach
NASA Astrophysics Data System (ADS)
Darío Guerrero, Rubén; Arango, Carlos A.; Reyes, Andrés
2014-02-01
We studied the optimal quantum control of a molecular rotor in tilted laser fields using the time-sliced Herman-Kluk propagator for the evaluation of the optimal pulse and the light-dipole interaction as the control mechanism. The proposed methodology was used to study the effects of an optimal pulse on the evolution of a wave-packet in a double-well potential and in the effective potential of a molecular rotor in a collinear tilted fields setup. The amplitude and frequency of the control pulse were obtained in such a way that the transition probability between two rotational wave-packets was maximised.
Zeno dynamics in wave-packet diffraction spreading
Porras, Miguel A.; Luis, Alfredo; Gonzalo, Isabel; Sanz, Angel S.
2011-11-15
We analyze a simple and feasible practical scheme displaying Zeno, anti-Zeno, and inverse-Zeno effects in the observation of wave-packet spreading caused by free evolution. The scheme is valid both in spatial diffraction of classical optical waves and in time diffraction of a quantum wave packet. In the optical realization, diffraction spreading is observed by placing slits between a light source and a light-power detector. We show that the occurrence of Zeno or anti-Zeno effects depends just on the frequency of observations between the source and detector. These effects are seen to be related to the diffraction mode theory in Fabry-Perot resonators.
Gabor Wave Packet Method to Solve Plasma Wave Equations
A. Pletzer; C.K. Phillips; D.N. Smithe
2003-06-18
A numerical method for solving plasma wave equations arising in the context of mode conversion between the fast magnetosonic and the slow (e.g ion Bernstein) wave is presented. The numerical algorithm relies on the expansion of the solution in Gaussian wave packets known as Gabor functions, which have good resolution properties in both real and Fourier space. The wave packets are ideally suited to capture both the large and small wavelength features that characterize mode conversion problems. The accuracy of the scheme is compared with a standard finite element approach.
Symmetry and conservation laws in semiclassical wave packet dynamics
Ohsawa, Tomoki
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.
Fourier optics and time evolution of de Broglie wave packets
NASA Astrophysics Data System (ADS)
Dillon, G.
2012-06-01
It is shown that, under the conditions of validity of the Fresnel approximation, diffraction and interference for a monochromatic wave traveling in the z-direction may be described in terms of the spreading in time of the transverse ( x, y wave packet. The time required for the evolved wave packet to yield identical patterns as given by standard optics corresponds to the time for the quantum to cross the optical apparatus. This point of view may provide interesting cues in wave mechanics and quantum physics education.
Electron acceleration by Landau resonance with whistler mode wave packets
NASA Technical Reports Server (NTRS)
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.
Electron acceleration by Landau resonance with whistler mode wave packets
NASA Technical Reports Server (NTRS)
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.
Symmetry and conservation laws in semiclassical wave packet dynamics
NASA Astrophysics Data System (ADS)
Ohsawa, Tomoki
2015-03-01
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.
Wave-packet dynamics of Bogoliubov quasiparticles: Quantum metric effects
NASA Astrophysics Data System (ADS)
Liang, Long; Peotta, Sebastiano; Harju, Ari; Törmä, Päivi
2017-08-01
We study the dynamics of the Bogoliubov wave packet in superconductors and calculate the supercurrent carried by the wave packet. We discover an anomalous contribution to the supercurrent, related to the quantum metric of the Bloch wave function. This anomalous contribution is most important for flat or quasiflat bands, as exemplified by the attractive Hubbard models on the Creutz ladder and sawtooth lattice. Our theoretical framework is general and can be used to study a wide variety of phenomena, such as spin transport and exciton transport.
Short-time Chebyshev wave packet method for molecular photoionization
NASA Astrophysics Data System (ADS)
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.
NASA Astrophysics Data System (ADS)
Dolcini, Fabrizio; Iotti, Rita Claudia; Montorsi, Arianna; Rossi, Fausto
2016-10-01
We show that, when a spatially localized electric pulse is applied at the edge of a quantum spin Hall system, electron wave packets of the helical states can be photoexcited by purely intrabranch electrical transitions, without invoking the bulk states or the magnetic Zeeman coupling. In particular, as long as the electric pulse remains applied, the photoexcited densities lose their character of right and left movers, whereas after the ending of the pulse they propagate in opposite directions without dispersion, i.e., maintaining their space profile unaltered. Notably we find that, while the momentum distribution of the photoexcited wave packets depends on the temperature T and the chemical potential μ of the initial equilibrium state and displays a nonlinear behavior on the amplitude of the applied pulse, in the mesoscopic regime the space profile of the wave packets is independent of T and μ . Instead, it depends purely on the applied electric pulse, in a linear manner, as a signature of the chiral anomaly characterizing massless Dirac electrons. We also discuss how the photoexcited wave packets can be tailored with the electric pulse parameters, for both low and finite frequencies.
Perfect wave-packet splitting and reconstruction in a one-dimensional lattice
NASA Astrophysics Data System (ADS)
Banchi, Leonardo; Compagno, Enrico; Bose, Sougato
2015-05-01
Particle delocalization is a common feature of quantum random walks in arbitrary lattices. However, in the typical scenario a particle spreads over multiple sites and its evolution is not directly useful for controlled quantum interferometry, as may be required for technological applications. In this paper we devise a strategy to perfectly split the wave packet of an incoming particle into two components, each propagating in opposite directions, which reconstruct the shape of the initial wavefunction after a particular time t*. Therefore, a particle in a δ -like initial state becomes exactly delocalized between two distant sites after t*. We find the mathematical conditions to achieve the perfect splitting, which are satisfied by viable example Hamiltonians with static site-dependent interaction strengths. Our results pave the way for the generation of peculiar many-body interference patterns in a many-site atomic chain (such as the Hanbury Brown and Twiss and quantum Talbot effects) as well as for the distribution of entanglement between remote sites. Thus, as for the case of perfect state transfer, the perfect wave-packet splitting can be a new tool for varied applications.
NASA Technical Reports Server (NTRS)
Vasquez, Bernard J.; Cargill, Peter J.
1993-01-01
The evolution of strongly modulated wave packets in a dispersive plasma that propagate parallel to the magnetic field is studied. Modulation effects are shown to reduce significantly (about 30 percent) the rate of spreading from that due to dispersion alone. For fluidlike behavior, nonlinearity has its greatest impact on evolution when the linear sound speed and initial wave packet speeds are well matched, resulting in a strong coupling between the wave magnetic and sonic components. Ion kinetic processes reduce the impact of nonlinearity and cause the rate of spreading to approach that expected from dispersion alone as the ratio of ion and electron temperatures, Ti/Te approaches 4. For Beta equal to or greater than 1 and Ti/Te of about 1, the coupled waveforms correspond qualitatively to kinetic treatments of the derivative nonlinear Schroedinger equation.
Nonlinear interferometry with Bose-Einstein condensates
Tacla, Alexandre B.; Boixo, Sergio; Datta, Animesh; Shaji, Anil; Caves, Carlton M.
2010-11-15
We analyze a proposed experiment [Boixo et al., Phys. Rev. Lett. 101, 040403 (2008)] for achieving sensitivity scaling better than 1/N in a nonlinear Ramsey interferometer that uses a two-mode Bose-Einstein condensate (BEC) of N atoms. We present numerical simulations that confirm the analytical predictions for the effect of the spreading of the BEC ground-state wave function on the ideal 1/N{sup 3/2} scaling. Numerical integration of the coupled, time-dependent, two-mode Gross-Pitaevskii equations allows us to study the several simplifying assumptions made in the initial analytic study of the proposal and to explore when they can be justified. In particular, we find that the two modes share the same spatial wave function for a length of time that is sufficient to run the metrology scheme.
Asymmetric Acoustic Propagation of Wave Packets Via the Self-Demodulation Effect
NASA Astrophysics Data System (ADS)
Devaux, Thibaut; Tournat, Vincent; Richoux, Olivier; Pagneux, Vincent
2015-12-01
This Letter 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 1 06, 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.
Direct Harmonic Linear Navier-Stokes Methods for Efficient Simulation of Wave Packets
NASA Technical Reports Server (NTRS)
Streett, C. L.
1998-01-01
Wave packets produced by localized disturbances play an important role in transition in three-dimensional boundary layers, such as that on a swept wing. Starting with the receptivity process, we show the effects of wave-space energy distribution on the development of packets and other three-dimensional disturbance patterns. Nonlinearity in the receptivity process is specifically addressed, including demonstration of an effect which can enhance receptivity of traveling crossflow disturbances. An efficient spatial numerical simulation method is allowing most of the simulations presented to be carried out on a workstation.
Asymmetric Acoustic Propagation of Wave Packets Via the Self-Demodulation Effect.
Devaux, Thibaut; Tournat, Vincent; Richoux, Olivier; Pagneux, Vincent
2015-12-04
This Letter 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.
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.
Diffraction of Gaussian wave packets by a single slit
NASA Astrophysics Data System (ADS)
Zecca, A.
2011-02-01
A two-dimensional formulation of particle diffraction by a single slit is proposed within Schrödinger QM. The study is done in terms of Gaussian wave packets. A "confinement" assumption is considered together with a previous "truncation" assumption when the wave packet passes the slit. In the limiting situation of entering Gaussian wave packet peaked in the transverse-momentum probability distribution, the diffraction pattern results in an unaltered central maximum with lateral maxima narrower and higher than in the absence of the confinement assumption. For entering wave packets peaked in the transverse position probability distribution, the diffraction pattern consists of a central Gaussian spot with lateral diffraction maxima, not present in the absence of the "confinement" assumption, whose visibility depends on the configuration of the parameters. With a different analysis, a similar effect was obtained also in G. Kalbermann (J. Phys. A: Math. Gen. 35, 4599 (2002)). Its experimental verification seems of interest to discriminate between Schrödinger QM and stochastic electrodynamics with spin.
Wave packet motion in harmonic potential and computer visualization
NASA Technical Reports Server (NTRS)
Tsuru, Hideo; Kobayashi, Takeshi
1993-01-01
Wave packet motions of a single electron in harmonic potentials or a magnetic field are obtained analytically. The phase of the wave function which depends on both time and space is also presented explicitly. The probability density of the electron changes its width and central position periodically. These results are visualized using computer animation techniques.
Resonance-assisted decay of nondispersive wave packets.
Wimberger, Sandro; Schlagheck, Peter; Eltschka, Christopher; Buchleitner, Andreas
2006-07-28
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.
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
Background-free nonlinear microspectroscopy with vibrational molecular interferometry
NASA Astrophysics Data System (ADS)
Garbacik, Erik T.; Korterik, Jeroen P.; Otto, Cees; Mukamel, Shaul; Herek, Jennifer L.; Offerhaus, Herman L.
2012-03-01
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 (VMI) technique allows imaging at high speed free of non-resonant background, and is able to distinguish between electronic and vibrational contributions to the total signal.
Revivals and classical-motion bases of quantum wave packets
NASA Astrophysics Data System (ADS)
Aronstein, David L.
This thesis explores the boundary between classical and quantum mechanics by studying wave packets, coherent superpositions of the stationary states of a quantum system. Such wave packets travel as localized entities along the trajectories predicted by classical mechanics for small windows of time before they spread out and decay away. Our investigations focus on two central issues---the revivals of the shape and classical motion of these wave packets that occur long after their initial decay, and the classical-motion bases that describe the quantum wavefunction in terms of constitutive objects that move classically. We study the infinite square-well potential, a simple model of complete confinement in a one-dimensional interval. The quantum motion seen in this potential is compared with classical models of a particle bouncing between two walls and of a wave traveling along a stretched string with both ends secured. We uncover a remarkable wave-motion basis, with which the wavefunction at any moment in time can be decomposed into a sum of distinct wave propagations of the initial quantum wavefunction in the classical wave equation. These results are extended to the finite square-well potential and we show how the wave-motion basis can be reconciled with the seemingly disparate theory of revivals for highly excited quantum wave packets. We explore the commonalities of the quantum revivals seen in a wide variety of systems by developing a mathematical formalism called phase-difference equations. These equations connect physical models for revivals with the subsequent prediction of revival times in a general way and offer a comprehensive "calculus" for understanding revival phenomena. We apply this calculus to several examples to demonstrate its power and versatility. Using a recently developed semiclassical basis for quantum states, we explore the radial wave packets of the hydrogen atom. Viewed in the semiclassical basis, the revivals of these wave packets are shown
The Interference of the Dynamically Squeezed Vibrational Wave Packets
NASA Technical Reports Server (NTRS)
Vinogradov, An. V.; Janszky, J.; Kobayashi, T.
1996-01-01
An electronic excitation of a molecule by a sequence of two femtosecond phase-locked laser pulses is considered. In this case the interference between the vibrational wave packets induced by each of the subpulses within a single molecule takes place. It is shown that due to the dynamical squeezing effect of a molecular vibrational state the interference of the vibrational wave packets allows one to measure the duration of a femtosecond laser pulse. This can be achieved experimentally by measuring the dependence of the integral fluorescence of the excited molecule on the delay time between the subpulses. The interference can lead to a sharp peak (or to a down-fall) in that dependence, the width of which is equal to the duration of the laser pulse. It is shown that finite temperature of the medium is favorable for such an experiment.
Stochastic acceleration of ions driven by Pc1 wave packets
Khazanov, G. V. Sibeck, D. G.; Tel'nikhin, A. A.; Kronberg, T. K.
2015-07-15
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{sup −4} nT{sup 2}/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.
Stochastic Acceleration of Ions Driven by Pc1 Wave Packets
NASA Technical Reports Server (NTRS)
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.
Stochastic Acceleration of Ions Driven by Pc1 Wave Packets
NASA Technical Reports Server (NTRS)
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.
Wave packet dynamics in the optimal superadiabatic approximation
NASA Astrophysics Data System (ADS)
Betz, V.; Goddard, B. D.; Manthe, U.
2016-06-01
We explain the concept of superadiabatic representations and show how in the context of electronically non-adiabatic transitions 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 potential energy surfaces near the avoided crossing is required for the computation. In particular, this means that no diabatization procedure is necessary, the adiabatic electronic energies 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.
Wave-packet model for excitation by ultrashort pulses
NASA Astrophysics Data System (ADS)
Suominen, Kalle-Antti; Garraway, Barry M.; Stenholm, Stig
1992-03-01
In this paper we discuss the excitation of a localized molecular ground-state wave function by a short laser pulse. With a one-dimensional approach we show when it is possible to excite a considerable fraction of the ground state without too much distortion of the shape of the wave packet. This is of interest in time-resolved molecular experiments where an excited wave packet is often taken as the initial state. We solve the two coupled wave equations numerically and compare results to an analytical approximation based on the Rosen-Zener model. The validity of the approximation and its breakdown is considered in detail. Special attention is paid to the effect of lengthening the pulse duration and the consequences of the accompanying number of Rabi flops occurring in the area theorem. When the approximation breaks down, the wave packet becomes distorted and spread out, but there are still interesting coherence effects due to the interplay between the Rabi flopping and the molecular dynamics; these are displayed and discussed. Finally, the relationship to other works and possible generalizations are presented.
Electronically nonadiabatic wave packet propagation using frozen Gaussian scattering
NASA Astrophysics Data System (ADS)
Kondorskiy, Alexey D.; Nanbu, Shinkoh
2015-09-01
We present an approach, which allows to employ the adiabatic wave packet propagation technique and semiclassical theory to treat the nonadiabatic processes by using trajectory hopping. The approach developed generates a bunch of hopping trajectories and gives all additional information to incorporate the effect of nonadiabatic coupling into the wave packet dynamics. This provides an interface between a general adiabatic frozen Gaussian wave packet propagation method and the trajectory surface hopping technique. The basic idea suggested in [A. D. Kondorskiy and H. Nakamura, J. Chem. Phys. 120, 8937 (2004)] is revisited and complemented in the present work by the elaboration of efficient numerical algorithms. We combine our approach with the adiabatic Herman-Kluk frozen Gaussian approximation. The efficiency and accuracy of the resulting method is demonstrated by applying it to popular benchmark model systems including three Tully's models and 24D model of pyrazine. It is shown that photoabsorption spectrum is successfully reproduced by using a few hundreds of trajectories. We employ the compact finite difference Hessian update scheme to consider feasibility of the ab initio "on-the-fly" simulations. It is found that this technique allows us to obtain the reliable final results using several Hessian matrix calculations per trajectory.
Electronically nonadiabatic wave packet propagation using frozen Gaussian scattering.
Kondorskiy, Alexey D; Nanbu, Shinkoh
2015-09-21
We present an approach, which allows to employ the adiabatic wave packet propagation technique and semiclassical theory to treat the nonadiabatic processes by using trajectory hopping. The approach developed generates a bunch of hopping trajectories and gives all additional information to incorporate the effect of nonadiabatic coupling into the wave packet dynamics. This provides an interface between a general adiabatic frozen Gaussian wave packet propagation method and the trajectory surface hopping technique. The basic idea suggested in [A. D. Kondorskiy and H. Nakamura, J. Chem. Phys. 120, 8937 (2004)] is revisited and complemented in the present work by the elaboration of efficient numerical algorithms. We combine our approach with the adiabatic Herman-Kluk frozen Gaussian approximation. The efficiency and accuracy of the resulting method is demonstrated by applying it to popular benchmark model systems including three Tully's models and 24D model of pyrazine. It is shown that photoabsorption spectrum is successfully reproduced by using a few hundreds of trajectories. We employ the compact finite difference Hessian update scheme to consider feasibility of the ab initio "on-the-fly" simulations. It is found that this technique allows us to obtain the reliable final results using several Hessian matrix calculations per trajectory.
Electronically nonadiabatic wave packet propagation using frozen Gaussian scattering
Kondorskiy, Alexey D.; Nanbu, Shinkoh
2015-09-21
We present an approach, which allows to employ the adiabatic wave packet propagation technique and semiclassical theory to treat the nonadiabatic processes by using trajectory hopping. The approach developed generates a bunch of hopping trajectories and gives all additional information to incorporate the effect of nonadiabatic coupling into the wave packet dynamics. This provides an interface between a general adiabatic frozen Gaussian wave packet propagation method and the trajectory surface hopping technique. The basic idea suggested in [A. D. Kondorskiy and H. Nakamura, J. Chem. Phys. 120, 8937 (2004)] is revisited and complemented in the present work by the elaboration of efficient numerical algorithms. We combine our approach with the adiabatic Herman-Kluk frozen Gaussian approximation. The efficiency and accuracy of the resulting method is demonstrated by applying it to popular benchmark model systems including three Tully’s models and 24D model of pyrazine. It is shown that photoabsorption spectrum is successfully reproduced by using a few hundreds of trajectories. We employ the compact finite difference Hessian update scheme to consider feasibility of the ab initio “on-the-fly” simulations. It is found that this technique allows us to obtain the reliable final results using several Hessian matrix calculations per trajectory.
Generalized Gaussian wave packet dynamics: Integrable and chaotic systems.
Pal, Harinder; Vyas, Manan; Tomsovic, Steven
2016-01-01
The ultimate semiclassical wave packet propagation technique is a complex, time-dependent Wentzel-Kramers-Brillouin method known as generalized Gaussian wave packet dynamics (GGWPD). It requires overcoming many technical difficulties in order to be carried out fully in practice. In its place roughly twenty years ago, linearized wave packet dynamics was generalized to methods that include sets of off-center, real trajectories for both classically integrable and chaotic dynamical systems that completely capture the dynamical transport. The connections between those methods and GGWPD are developed in a way that enables a far more practical implementation of GGWPD. The generally complex saddle-point trajectories at its foundation are found using a multidimensional Newton-Raphson root search method that begins with the set of off-center, real trajectories. This is possible because there is a one-to-one correspondence. The neighboring trajectories associated with each off-center, real trajectory form a path that crosses a unique saddle; there are exceptions that are straightforward to identify. The method is applied to the kicked rotor to demonstrate the accuracy improvement as a function of ℏ that comes with using the saddle-point trajectories.
NASA Astrophysics Data System (ADS)
Balakin, A. A.; Mironov, V. A.; Skobelev, S. A.
2017-01-01
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%.
NASA Astrophysics Data System (ADS)
Pal, Sukla; Bhattacharjee, Jayanta K.
2015-10-01
The propagation of an initially Gaussian wave packet of width Δ0 in Gross-Pitaevskii equation is extensively studied both for attractive and repulsive interactions. It is predicted analytically and verified numerically that for a free particle with attractive interaction, the dynamics of the width is governed by an effective potential which is sensitive to initial conditions. If Δ0 is equal to a corresponding critical width Δc, then the packet will propagate in time with very little change in shape. These are in essence like coherent states. Whereas, if Δ≠Δc, depending on the nature of the effective potential for chosen Δ0 and the interaction strength (|g|), the width of the packet in course of time, either oscillates with bounded width or will spread like a free particle. For a simple harmonic oscillator (SHO) also, we find that for Δ0 smaller than a critical value, there always exists a coupling strength for which the packet simply oscillates about the mean position without changing its shape, once again providing a resemblance to a coherent state. We also consider the Morse potential, which interpolates between the free particle and the oscillator. For large attractive interactions, the two limiting dynamics (free and simple harmonic) are indeed observed but in the intermediate form of the potential where the nonlinear terms dominate in the dynamics, an initial Gaussian wave packet does not retain its shape. For repulsive interaction, the Gaussian packet always changes shape no matter what the system parameters are.
Tracking an electronic wave packet in the vicinity of a conical intersection
NASA Astrophysics Data System (ADS)
Qi, Da-Long; Duan, Hong-Guang; Sun, Zhen-Rong; Miller, R. J. Dwayne; Thorwart, Michael
2017-08-01
This work treats the impact of vibrational coherence on the quantum efficiency of a dissipative electronic wave packet in the vicinity of a conical intersection by monitoring the time-dependent wave packet projection onto the tuning and the coupling mode. The vibrational coherence of the wave packet is tuned by varying the strength of the dissipative vibrational coupling of the tuning and the coupling modes to their thermal baths. We observe that the most coherent wave packet yields a quantum efficiency of 93%, but with a large transfer time constant. The quantum yield is dramatically decreased to 50% for a strongly damped incoherent wave packet, but the associated transfer time of the strongly localized wave packet is short. In addition, we find for the strongly damped wave packet that the transfer occurs via tunneling of the wave packet between the potential energy surfaces before the seam of the conical intersection is reached and a direct passage takes over. Our results provide direct evidence that vibrational coherence of the electronic wave packet is a decisive factor which determines the dynamical behavior of a wave packet in the vicinity of the conical intersection.
Tracking an electronic wave packet in the vicinity of a conical intersection.
Qi, Da-Long; Duan, Hong-Guang; Sun, Zhen-Rong; Miller, R J Dwayne; Thorwart, Michael
2017-08-21
This work treats the impact of vibrational coherence on the quantum efficiency of a dissipative electronic wave packet in the vicinity of a conical intersection by monitoring the time-dependent wave packet projection onto the tuning and the coupling mode. The vibrational coherence of the wave packet is tuned by varying the strength of the dissipative vibrational coupling of the tuning and the coupling modes to their thermal baths. We observe that the most coherent wave packet yields a quantum efficiency of 93%, but with a large transfer time constant. The quantum yield is dramatically decreased to 50% for a strongly damped incoherent wave packet, but the associated transfer time of the strongly localized wave packet is short. In addition, we find for the strongly damped wave packet that the transfer occurs via tunneling of the wave packet between the potential energy surfaces before the seam of the conical intersection is reached and a direct passage takes over. Our results provide direct evidence that vibrational coherence of the electronic wave packet is a decisive factor which determines the dynamical behavior of a wave packet in the vicinity of the conical intersection.
Exponential wave-packet spreading via self-interaction time modulation
NASA Astrophysics Data System (ADS)
Zhao, Wen-Lei; Gong, Jiangbin; Wang, Wen-Ge; Casati, Giulio; Liu, Jie; Fu, Li-Bin
2016-11-01
The time-periodic modulation of the self-interaction of a Bose-Einstein condensate or a nonlinear optics system has been recognized as an exciting tool to explore interesting physics that was previously unavailable. This tool is exploited here to examine the exotic dynamics of a nonlinear system described by the Gross-Pitaevskii equation. We observe three remarkable and closely related dynamical phenomena, exponentially localized profile of wave functions in momentum space with localization length exponentially increasing in time, exponential wave-packet spreading, and exponential sensitivity to initial conditions. A hybrid quantum-classical theory is developed to partly explain these findings. Time-periodic self-interaction modulation is seen to be a robust method to achieve superfast spreading and induce genuine chaos even in the absence of any external potential.
Production and manipulation of wave packets from ultracold atoms in an optical lattice
NASA Astrophysics Data System (ADS)
Pedersen, Poul L.; Gajdacz, Miroslav; Winter, Nils; Hilliard, Andrew J.; Sherson, Jacob F.; Arlt, Jan
2013-08-01
Within the combined potential of an optical lattice and a harmonic magnetic trap, it is possible to form matter wave packets by intensity modulation of the lattice. An analysis of the production and motion of these wave packets provides a detailed understanding of the dynamical evolution of the system. The modulation technique also allows for a controllable transfer (deexcitation) of atoms from such wave packets to a state bound by the lattice. Thus, it acts as a beam splitter for matter waves that can selectively address different bands, enabling the preparation of atoms in localized states. The combination of wave packet creation and deexcitation closely resembles the well-known method of pump-probe spectroscopy. Here, we use the deexcitation for spectroscopy of the anharmonicity of the combined potential. Finally, we demonstrate that lattice modulation can be used to excite matter wave packets to even higher momenta, producing fast wave packets with potential applications in precision measurements.
Semiclassical wave-packets emerging from interaction with an environment
Recchia, Carla; Teta, Alessandro
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.
Semiclassical wave-packets emerging from interaction with an environment
Recchia, Carla; Teta, Alessandro
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.
Modelling of quasi-periodic oscillations with wave packets
NASA Astrophysics Data System (ADS)
Alpar, M. A.; Yilmaz, A.
1997-08-01
Model dispersion relations are introduced to explore power spectra of the normal-branch (NB) and horizontal-branch (HB) quasi-periodic oscillations (QPOs; for reviews see Van der Klis (1989)[ARA&A, 27, 517], (1992) [Proc. of NATO ASI X-Ray Binaries and Recycled Pulsars, eds. E.P.J. Van den Heuvel & S.A. Rappaport, Kluwer, Dordrecht], (1995)[Proc. of NATO ASI The Lives of the Neutron Stars, eds. M.A. Alpar, Ümit Kiziloğlu, & J. van Paradijs, Kluwer, Dordrecht]) of low mass X-ray binaries (LMXBs) in terms of wave packets and to illustrate the presence of frequency bands around the Kepler and beat frequencies. For the NB QPOs wave packets of sound waves in a thick middle disk state, with frequencies determined by the rotation frequency, have wavelengths comparable to the size of the middle disk. For Z-sources on the HB, the wave packets result from disturbances in the inner disk induced by the neutron star magnetic field which rotates at the beat frequency with respect to the inner disk. For both the NB and the HB QPOs, we construct simple model dispersion relations, and show that the QPO peaks in the observed power spectra correspond to reasonable wavelengths and system parameters. The kilohertz QPOs, which were discovered after the original version of this paper was submitted, are also discussed as a possible realization of the Kepler and beat frequency bands. Problems of integrating the kHz and HB QPOs in a disk model are briefly noted. It is tentatively suggested that supersonic and wave propagation regions of the inner disk have complementary functions for the origin of kHz and HB QPOs respectively.
Localization of a matter wave packet in a disordered potential
Piraud, M.; Bouyer, P.; Aspect, A.; Sanchez-Palencia, L.; Lugan, P.
2011-03-15
We theoretically study the Anderson localization of a matter wave packet in a one-dimensional disordered potential. We develop an analytical model which includes the initial phase-space density of the matter wave and the spectral broadening induced by the disorder. Our approach predicts a behavior of the localized density profile significantly more complex than a simple exponential decay. These results are confirmed by large-scale and long-time numerical calculations. They shed new light on recent experiments with ultracold atoms and may impact their analysis.
NASA Astrophysics Data System (ADS)
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.
NASA Technical Reports Server (NTRS)
Hizanidis, Kyriakos
1989-01-01
The relativistic motion of electrons in an intense electromagnetic wave packet propagating obliquely to a uniform magnetic field is analytically studied on the basis of the Fokker-Planck-Kolmogorov (FPK) approach. The wavepacket consists of circularly polarized electron-cyclotron waves. The dynamical system in question is shown to be reducible to one with three degrees of freedom. Within the framework of the Hamiltonian analysis the nonlinear diffusion tensor is derived, and it is shown that this tensor can be separated into zeroth-, first-, and second-order parts with respect to the relative bandwidth. The zeroth-order part describes diffusive acceleration along lines of constant unperturbed Hamiltonian. The second-order part, which corresponds to the longest time scale, describes diffusion across those lines. A possible transport theory is outlined on the basis of this separation of the time scales.
NASA Technical Reports Server (NTRS)
Hizanidis, Kyriakos
1989-01-01
The relativistic motion of electrons in an intense electromagnetic wave packet propagating obliquely to a uniform magnetic field is analytically studied on the basis of the Fokker-Planck-Kolmogorov (FPK) approach. The wavepacket consists of circularly polarized electron-cyclotron waves. The dynamical system in question is shown to be reducible to one with three degrees of freedom. Within the framework of the Hamiltonian analysis the nonlinear diffusion tensor is derived, and it is shown that this tensor can be separated into zeroth-, first-, and second-order parts with respect to the relative bandwidth. The zeroth-order part describes diffusive acceleration along lines of constant unperturbed Hamiltonian. The second-order part, which corresponds to the longest time scale, describes diffusion across those lines. A possible transport theory is outlined on the basis of this separation of the time scales.
Scattering of wave packets on atoms in the Born approximation
NASA Astrophysics Data System (ADS)
Karlovets, D. V.; Kotkin, G. L.; Serbo, V. G.
2015-11-01
It has recently been demonstrated experimentally that 200 -300 keV electrons with the unusual spatial profiles can be produced and even focused to a subnanometer scale—namely, electrons carrying nonzero orbital angular momentum and also the so-called Airy beams. Since the wave functions of such electrons do not represent plane waves, the standard Born formula for scattering of them off a potential field is no longer applicable and, hence, needs modification. In the present paper, we address the generic problem of elastic scattering of a wave packet of a fast nonrelativistic particle off a potential field. We obtain simple and convenient formulas for a number of events and an effective cross section in such a scattering, which represent generalization of the Born formula for a case when finite sizes and spatial inhomogeneity of the initial packet should be taken into account. As a benchmark, we consider two simple models corresponding to scattering of a Gaussian wave packet on a Gaussian potential and on a hydrogen atom, and perform a detailed analysis of the effects brought about by the limited sizes of the incident beam and by the finite impact parameter between the potential center and the packet's axis.
Three-dimensional wave packets in a compressible boundary layer
NASA Astrophysics Data System (ADS)
Forgoston, Eric; Tumin, Anatoli
2006-10-01
A three-dimensional wave packet generated by a local disturbance in a two-dimensional hypersonic boundary layer flow is studied with the aid of the previously solved initial-value problem. The solution to this problem can be expanded in a biorthogonal eigenfunction system as a sum of modes consisting of continuous and discrete spectra of temporal stability theory. A specific disturbance consisting of an initial temperature spot is considered, and the receptivity to this initial temperature spot is computed for both the two-dimensional and three-dimensional cases. Using previous analysis of the discrete and continuous spectrum, the inverse Fourier transform is computed numerically. The two-dimensional inverse Fourier transform is calculated for two discrete modes: Mode F and Mode S. The Mode S result is compared with an asymptotic approximation of the Fourier integral, which is obtained using the Gaussian model as well as the method of steepest descent. It is shown that the method of steepest descent provides an excellent approximation to the more computationally intensive numerical evaluation of the inverse Fourier transform. Additionally, the three-dimensional inverse Fourier transform is found using an asymptotic approximation of the Fourier integral. A main feature of the resulting three-dimensional wave packet is its two-dimensional nature, which arises from an association of Mode S with Mack's second mode.
Non-Hermitian wave packet approximation of Bloch optical equations
Charron, Eric; Sukharev, Maxim
2013-01-14
We introduce a non-Hermitian approximation of Bloch optical equations. This approximation provides a complete description of the excitation, relaxation, and decoherence dynamics of ensembles of coupled quantum systems in weak laser fields, taking into account collective effects and dephasing. In the proposed method, one propagates the wave function of the system instead of a complete density matrix. Relaxation and dephasing are taken into account via automatically adjusted time-dependent gain and decay rates. As an application, we compute the numerical wave packet solution of a time-dependent non-Hermitian Schroedinger equation describing the interaction of electromagnetic radiation with a quantum nano-structure, and compare the calculated transmission, reflection, and absorption spectra with those obtained from the numerical solution of the Liouville-von Neumann equation. It is shown that the proposed wave packet scheme is significantly faster than the propagation of the full density matrix while maintaining small error. We provide the key ingredients for easy-to-use implementation of the proposed scheme and identify the limits and error scaling of this approximation.
Wave analysis of the evolution of a single wave packet in supersonic boundary layer
NASA Astrophysics Data System (ADS)
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.
Simulation on the electronic wave packet cyclotron motion in a Weyl semimetal slab
NASA Astrophysics Data System (ADS)
Yao, Haibo; Zhu, Mingfeng; Jiang, Liwei; Zheng, Yisong
2017-04-01
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.
On the Behavior of Three-dimensional Wave Packets in Viscously Spreading Mixing Layers
NASA Technical Reports Server (NTRS)
Balsa, Thomas F.
1994-01-01
We consider analytically the evolution of a three-dimensional wave packet generated by an impulsive source in a mixing layer. The base flow is assumed to be spreading due to viscous diffusion. The analysis is restricted to small disturbances (linearized theory). A suitable high-frequency ansatz is used to describe the packet; the key elements of this description are a complex phase and a wave action density. It is found that the product of this density and an infinitesimal material volume convecting at the local group velocity is not conserved: there is a continuous interaction between the base flow and the wave action. This interaction is determined by suitable mode-weighted averages of the second and fourth derivatives of the base-flow velocity profile. Although there is some tendency for the dominant wave number in the packet to shift from the most unstable value toward the neutral value, this shift is quite moderate. In practice, wave packets do not become locally neutral in a diverging base flow (as do instability modes), therefore, they are expected to grow more suddenly than pure instability modes and do not develop critical layers. The group velocity is complex; the full significance of this is realized by analytically continuing the equations for the phase and wave action into a complex domain. The implications of this analytic continuation are discussed vis-a-vis the secondary instabilities of the packet: very small scale perturbations on the phase can grow very rapidly initially, but saturate later because most of the energy in these perturbations is convected away by the group velocity. This remark, as well as the one regarding critical layers, has consequences for the nonlinear theories.
NASA Astrophysics Data System (ADS)
V, N. Likhachev; O, I. Shevaleevskii; G, A. Vinogradov
2016-01-01
The wave function temporal evolution on the one-dimensional (1D) lattice is considered in the tight-binding approximation. The lattice consists of N equal sites and one impurity site (donor). The donor differs from other lattice sites by the on-site electron energy E and the intersite coupling C. The moving wave packet is formed from the wave function initially localized on the donor. The exact solution for the wave packet velocity and the shape is derived at different values E and C. The velocity has the maximal possible group velocity v = 2. The wave packet width grows with time ˜ t1/3 and its amplitude decreases ˜ t-1/3. The wave packet reflects multiply from the lattice ends. Analytical expressions for the wave packet front propagation and recurrence are in good agreement with numeric simulations.
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.
Controlled wave-packet manipulation with driven optical lattices
Arlinghaus, Stephan; Holthaus, Martin
2011-12-15
Motivated by recent experimental progress achieved with ultracold atoms in kilohertz-driven optical lattices, we provide a theoretical discussion of mechanisms governing the response of a particle in a cosine lattice potential to strong forcing pulses with smooth envelope. Such pulses effectuate adiabatic motion of a wave packet's momentum distribution on quasienergy surfaces created by spatiotemporal Bloch waves. Deviations from adiabaticity can then be deliberately exploited for exerting coherent control and for reaching target states which may not be accessible by other means. As one particular example, we consider an analog of the {pi} pulses known from optical resonance. We also suggest adapting further techniques previously developed for controlling atomic and molecular dynamics by laser pulses to the coherent control of matter waves in shaken optical lattices.
NASA Astrophysics Data System (ADS)
Afraimovich, E. L.; Perevalova, N. P.; Voyeikov, S. V.
2003-07-01
We identified a specific class of mid-latitude medium-scale traveling ionospheric disturbances (MSTIDs), namely traveling wave packets (TWPs) of total electron content (TEC) disturbances. For the first time, we present the TWP morphology for 105 days 1998-2001. A total number of the TEC series, with a duration of each series of about 2.3h (2h18m), exceeded 700,000. The data were obtained using the technology GLOBDET of global detection of ionospheric disturbances using a global network of GPS receivers, and the technique of GPS interferometry of TIDs, developed at the ISTP SD RAS. It was found that TWPs are observed no more than in 0.1-0.4% of all TEC series, most commonly during the daytime in winter and autumn. TWPs are quasi-periodic oscillations of TEC with a period of around 10-20min, and a time duration of the order of 1h. The TWP amplitudes exceed the amplitudes of ``background'' TEC fluctuations by one order of magnitude, as a minimum. The radius of spatial correlation of TWPs does not exceed 500-600km (3-5 wavelengths). We carried out a detailed analysis of the spatial-temporal properties of TWPs by considering an example of the most conspicuous manifestation of TWPs on October 18, 2001 over California, USA. The velocity and direction of TWP displacement correspond to those of mid-latitude MSTIDs.
Eliminating the dipole phase in attosecond pulse characterization using Rydberg wave packets
NASA Astrophysics Data System (ADS)
Pabst, Stefan; Dahlström, Jan Marcus
2016-07-01
We propose a technique to fully characterize the temporal structure of extreme ultraviolet pulses by ionizing a bound coherent electronic wave packet. The influence of the dipole phase, which is the main obstacle for state-of-the-art pulse characterization schemes, can be eliminated by angle integration of the photoelectron spectrum. We show that in particular, atomic Rydberg wave packets are ideal and that wave packets involving multiple electronic states provide redundant information that can be used to cross-check the consistency of the phase reconstruction.
Formation of ground-state vibrational wave packets in intense ultrashort laser pulses.
Goll, Erich; Wunner, Günter; Saenz, Alejandro
2006-09-08
The formation of coherent vibrational wave packets in the electronic ground state of neutral molecules in intense ultrashort laser pulses and their subsequent detection by means of recently developed pump-probe experiments are discussed. The wave packet formation is due to the pronounced dependence of the strong-field ionization rate on the internuclear distance. This leads to a deformation of the initial wave function due to an internuclear-distance dependent depletion. The phenomenon is demonstrated with a time-dependent wave packet study for molecular hydrogen.
Choi, N. N.; Jiang, T. F.; Morishita, T.; Lee, M.-H.; Lin, C. D.
2010-07-15
We study theoretically the electron wave packet generated by an attosecond pulse train (APT) which is probed with a time-delayed infrared (IR) laser pulse. The APT creates an excited state and a continuum electron wave packet. By ionizing the excited state with an IR, a delayed new continuum electron wave packet is created. The interference of the wave packets from the two paths, as reflected in angle-resolved photoelectron spectra, is analyzed analytically. Using the analytical expressions, we examine the possibility of retrieving information on the electron wave packet generated by the APT.
Riemann {zeta} function from wave-packet dynamics
Mack, R.; Schleich, W. P.; Dahl, J. P.; Moya-Cessa, H.; Strunz, W. T.; Walser, R.
2010-09-15
We show that the time evolution of a thermal phase state of an anharmonic oscillator with logarithmic energy spectrum is intimately connected to the generalized Riemann {zeta} function {zeta}(s,a). Indeed, the autocorrelation function at a time t is determined by {zeta}({sigma}+i{tau},a), where {sigma} 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 display a universal behavior; they take the shape of a logarithm. However, their form close to the origin depends on the value of the Hurwitz parameter a in {zeta}(s,a). In particular, we establish a connection between the value of the potential energy at its minimum, the Hurwitz parameter and the Maslov 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 in appropriately tailored light fields.
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.
Alfvénic wave packets collision in a kinetic plasma
NASA Astrophysics Data System (ADS)
Pezzi, Oreste; Parashar, Tulasi N.; Servidio, Sergio; Valentini, Francesco; Malara, Francesco; Matthaeus, William H.; Veltri, Pierluigi
2016-04-01
The problem of two colliding and counter-propagating Alfvénic wave packets has been investigated in detail since the late Seventies. In particular Moffatt [1] and Parker [2] showed that, in the framework of the incompressible magnetohydrodynamics (MHD), nonlinear interactions can develop only during the overlapping of the two packets. Here we describe a similar problem in the framework of the kinetic physics. The collision of two quasi-Alfvénic packets has been analyzed by means of MHD, Hall-MHD and kinetic simulations performed with two different hybrid codes: a PIC code [3] and a Vlasov-Maxwell code [4]. Due to the huge computational cost, only a 2D-3V phase space is allowed (two dimensions in the physical space, three dimensions in the velocity space). Preliminary results suggest that, as well as in the MHD case, the most relevant nonlinear effects occur during the overlapping of the two packets. For both the PIC and Vlasov cases, strong temperature anisotropies are present during the evolution of the wave packets. Moreover, due to the absence of numerical noise, Vlasov simulations show that the collision of the counter-propagating solitary waves produces a significant beam in the velocity distribution functions [5], which, instead, cannot be appreciated in PIC simulations. We remark that, beyond the interest of studying a well-known MHD problem in the realm of the kinetic physics, our results allows also to compare different numerical codes. [1] H.K. Moffatt, Field generation in electrically conducting fluids (Cambridge University Press, 1978). [2] E.N. Parker, Cosmical magnetic fields: their origin and their activity (Oxford University Press, 1979). [3] T.N. Parashar, M.A. Shay, P.A. Cassak and W.H. Matthaeus, Physics of Plasmas 16, 032310 (2009). [4] F. Valentini, P. Trávníček, F. Califano, P. Hellinger & A. Mangeney, Journal of Computational Physics 225, 753-770 (2007). [5] J. He, C. Tu, E. Marsch, C.H. Chen, L. Wang, Z. Pei, L. Zhang, C.S. Salem and S
Collisions of two Alfvénic wave packets in a kinetic plasma
NASA Astrophysics Data System (ADS)
Pezzi, O.; Servidio, S.; Valentini, F.; Parashar, T.; Malara, F.; Matthaeus, W. H.; Veltri, P.
2016-12-01
The problem of two colliding and counter-propagating Alfvénic wave packets has been investigated in detail since the late Seventies. In particular Moffatt [1] and Parker [2] showed that, in the framework of the incompressible magnetohydrodynamics (MHD), nonlinear interactions can develop only during the overlapping of the two packets. Here we describe a similar problem in the framework of the kinetic physics. The collision of two quasi-Alfvénic packets has been analyzed by means of MHD, Hall-MHD and kinetic simulations performed with two different hybrid codes: a PIC code [3] and a Vlasov-Maxwell code [4]. Due to the huge computational cost, only a 2D-3V phase space is allowed (two dimensions in the physical space, three dimensions in the velocity space). Preliminary results suggest that, as well as in the MHD case, the most relevant nonlinear effects occur during the overlapping of the two packets. For both the PIC and Vlasov cases, strong temperature anisotropies are present during the evolution of the wave packets. Moreover, due to the absence of numerical noise, Vlasov simulations show that the collision of the counter-propagating solitary waves produces a significant beam in the velocity distribution functions [5], which, instead, cannot be appreciated in PIC simulations. We remark that, beyond the interest of studying a well-known MHD problem in the realm of the kinetic physics, our results allows also to compare different numerical codes. [1] H.K. Moffatt, Field generation in electrically conducting fluids (Cambridge University Press, 1978). [2] E.N. Parker, Cosmical magnetic fields: their origin and their activity (Oxford University Press, 1979). [3] T.N. Parashar, M.A. Shay, P.A. Cassak and W.H. Matthaeus, Physics of Plasmas 16, 032310 (2009). [4] F. Valentini, P. Trávníček, F. Califano, P. Hellinger & A. Mangeney, Journal of Computational Physics 225, 753-770 (2007). [5] J. He, C. Tu, E. Marsch, C.H. Chen, L. Wang, Z. Pei, L. Zhang, C.S. Salem and S
NASA Technical Reports Server (NTRS)
Ridgway, Stephen; Wilson, Robert W.; Begelman, Mitchell C.; Bender, Peter; Burke, Bernard F.; Cornwell, Tim; Drever, Ronald; Dyck, H. Melvin; Johnston, Kenneth J.; Kibblewhite, Edward
1991-01-01
The following recommended programs are reviewed: (1) infrared and optical interferometry (a ground-based and space programs); (2) compensation for the atmosphere with adaptive optics (a program for development and implementation of adaptive optics); and (3) gravitational waves (high frequency gravitational wave sources (LIGO), low frequency gravitational wave sources (LAGOS), a gravitational wave observatory program, laser gravitational wave observatory in space, and technology development during the 1990's). Prospects for international collaboration and related issues are also discussed.
Nonreciprocal emission of spin-wave packet in FeNi film
NASA Astrophysics Data System (ADS)
Sekiguchi, K.; Yamada, K.; Seo, S. M.; Lee, K. J.; Chiba, D.; Kobayashi, K.; Ono, T.
2010-07-01
We report a time-resolved propagating spin wave spectroscopy for Fe19Ni81 film. We show that the amplitude of the spin-wave packet depends on the direction of magnetization and that its phase can be controlled by the polarity of pulsed magnetic field for the excitation. The nonreciprocal emission of spin-wave packet can be utilized for the binary spin-wave input into the spin-wave logic circuit.
Characteristics of Wave Packets in the Upper Troposphere. Part I: Northern Hemisphere Winter.
NASA Astrophysics Data System (ADS)
Chang, Edmund K. M.; Yu, Daniel B.
1999-06-01
Gridded data produced by the ECMWF reanalysis project have been analyzed to document the properties of wave packets in the Northern Hemisphere winter midlatitude upper troposphere. Based on results from earlier investigations, 300-hPa meridional wind variations were chosen for analysis. Wave packet envelopes were also defined by performing complex demodulation on the wind data. The properties of the wave packets are mainly illustrated using time-lagged one-point correlation maps performed both on and wave packet envelopes.The results show that, over most regions in the Northern Hemisphere winter, with the exception of the deep Tropics and near the Aleutian low, medium-scale waves (dominant wavenumber 5-8) exhibit the characteristics of downstream development and occur within wave trains that propagate with eastward group velocities much faster than the phase speeds of individual phases of the waves. Their group velocity is highly correlated with the local time mean 200-400-hPa wind, while the phase speed is well correlated with the 500-700-hPa flow.A wave coherence index has been defined to show the geographical variations in the downstream development tendency of wave propagation. The results show that wave packets are most coherent along a band that extends from North Africa into southern Asia, toward the Pacific storm track, across North America, then over the central North Atlantic back toward North Africa. The maximum coherence occurs over southern Asia. This band can be regarded as the waveguide for upper-tropospheric wave packets in the Northern Hemisphere winter. Over this band, wave packets generally stay coherent significantly longer than individual troughs and ridges. There is also a secondary waveguide across Russia toward the Pacific, acting as a second source of waves that propagate across the Pacific storm track. Away from the primary waveguide, while wave packet coherence is less, the waves still show the characteristics of downstream development.
Observation of Wave Packet Distortion during a Negative-Group-Velocity Transmission
Ye, Dexin; Salamin, Yannick; Huangfu, Jiangtao; Qiao, Shan; Zheng, Guoan; Ran, Lixin
2015-01-01
In Physics, causality is a fundamental postulation arising from the second law of thermodynamics. It states that, the cause of an event precedes its effect. In the context of Electromagnetics, the relativistic causality limits the upper bound of the velocity of information, which is carried by electromagnetic wave packets, to the speed of light in free space (c). In anomalously dispersive media (ADM), it has been shown that, wave packets appear to propagate with a superluminal or even negative group velocity. However, Sommerfeld and Brillouin pointed out that the “front” of such wave packets, known as the initial point of the Sommerfeld precursor, always travels at c. In this work, we investigate the negative-group-velocity transmission of half-sine wave packets. We experimentally observe the wave front and the distortion of modulated wave packets propagating with a negative group velocity in a passive artificial ADM in microwave regime. Different from previous literature on the propagation of superluminal Gaussian packets, strongly distorted sinusoidal packets with non-superluminal wave fronts were observed. This result agrees with Brillouin's assertion, i.e., the severe distortion of seemingly superluminal wave packets makes the definition of group velocity physically meaningless in the anomalously dispersive region. PMID:25631746
Controllable accelerating and decelerating Airy-elegant-Laguerre-Gaussian wave packets in free space
NASA Astrophysics Data System (ADS)
Zhang, Xiaping
2017-05-01
The propagation of three-dimensional controllably accelerating and decelerating Airy-elegant-Laguerre-Gaussian (CAiELG) wave packets in free space is investigated theoretically and numerically by solving the (3+1)D Schrödinger equation in cylindric coordinates. The CAiELG wave packets are constructed with the Airy pulses with the initial velocity in temporal domain and the elegant-Laguerre-Gaussian beams in space domain. Decelerating and accelerating AiELG wave packets are obtained by selecting different initial velocities. The initial velocities can be determined by incident angle and directions. According to the intensity distribution of CAiELG wave packets at the propagating section, two special types of wave packets are accessed: one type is ring shaped with the modulation depth q=1 and another type is necklace shaped with q=0. The direction of the energy flow of CAiELG wave packets is kept away from the center during propagation, and their Poynting vector snapshots at different propagating distances are shown.
NASA Astrophysics Data System (ADS)
Nalegaev, Sergey S.; Belashov, Andrey V.; Petrov, Nikolay V.
2017-07-01
The methodology of Photothermal Interferometry implemented through off-axis digital holography for the nonlinear refractive index measurements of optical media with the thermal mechanism of nonlinearity is presented. An experimental appraisal is done on the example of chlorophyllin 1% solution in ethyl alcohol. It allows us to estimate the effective value of nonlinear refractive index as - 0.65 ·10-3 cm2/W. The comparison of the experimental result with data obtained by means of a reference approach was performed. Possible errors lead to a mismatch between them are highlighted and analyzed.
Annular wave packets at Dirac points in graphene and their probability-density oscillation.
Luo, Ji; Valencia, Daniel; Lu, Junqiang
2011-12-14
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 from the magnetic length, expanding and shrinking ripple-rings form and disappear alternatively in a limited spread, and the wave packet resumes the Gaussian form frequently. The probability thus oscillates persistently between the central peak and the ripple-rings. If the initial Gaussian width is close to the magnetic length, the wave packet retains the Gaussian form and its height and width oscillate with a period determined by the first Landau energy. The wave-packet evolution is determined jointly by the initial state and the magnetic field, through the electronic structure of graphene in a magnetic field. © 2011 American Institute of Physics
NASA Astrophysics Data System (ADS)
Chen, Zhaohang; Wang, Dehua; Cheng, Shaohao
2017-01-01
The electronic wave packet dynamics photodetached from H- ion in a magnetic field near an elastic surface has been studied by using the time-dependent perturbation theory combined with the semiclassical closed orbit theory for the first time. Firstly, we put forward an analytic formula for calculating the autocorrelation function of this system. Then we calculate and analyze the autocorrelation function in great detail. It is demonstrated that the quantum wave packet revival phenomenon is significant when the laser pulse width is far less than the period of the detached electron's closed orbit. As the pulse width is close to the period of the detached electron's closed orbit, the quantum wave packet revival phenomenon becomes weakened. When the laser pulse width is bigger than the period of the closed orbit of the detached electron, the adjacent revival peaks in the autocorrelation function begin to merge and the quantum revival phenomenon disappears. In addition, the magnetic field strength can also affect the autocorrelation function of this system. As the magnetic field strength is relatively small, the quantum wave packet revival phenomenon is weak. With the increase of the magnetic field strength, the number of the reviving peaks in the autocorrelation function becomes increased and the quantum wave packet revival phenomenon becomes significant. Therefore, we can control the quantum wave packet revival in the autocorrelation function of this system by changing the laser pulse width and the external magnetic field strength. This study can guide the future experimental research on the wave packet dynamics of atoms or ions in the external fields or surfaces.
Optical control of molecular dynamics: Molecular cannons, reflectrons, and wave-packet focusers
NASA Astrophysics Data System (ADS)
Krause, Jeffrey L.; Whitnell, Robert M.; Wilson, Kent R.; Yan, YiJing; Mukamel, Shaul
1993-11-01
We consider the control of molecular dynamics using tailored light fields, based on a phase space theory of control [Y. J. Yan et al., J. Phys. Chem. 97, 2320 (1993)]. This theory enables us to calculate, in the weak field (one-photon) limit, the globally optimal light field that produces the best overlap for a given phase space target. We present as an illustrative example the use of quantum control to overcome the natural tendency of quantum wave packets to delocalize on excited state potential energy curves. Three cases are studied: (i) a ``molecular cannon'' in which we focus an outgoing continuum wave packet of I2 in both position and momentum, (ii) a ``reflectron'' in which we focus an incoming bound wave packet of I2, and (iii) the focusing of a bound wave packet of Na2 at a turning point on the excited state potential using multiple light pulses to create a localized wave packet with zero momentum. For each case, we compute the globally optimal light field and also how well the wave packet produced by this light field achieves the desired target. These globally optimal fields are quite simple and robust. While our theory provides the globally optimal light field in the linear, weak field regime, experiment can in reality only provide a restricted universe of possible light fields. We therefore also consider the control of molecular quantum dynamics using light fields restricted to a parametrized functional form which spans a set of fields that can be experimentally realized. We fit the globally optimal electric field with a functional form consisting of a superposition of subpulses with variable parameters of amplitude, center time, center frequency, temporal width, relative phase, and linear and quadratic chirp. The best fit light fields produce excellent quantum control and are within the range of experimental possibility. We discuss relevant experiments such as ultrafast spectroscopy and ultrafast electron and x-ray diffraction which can in principle
Phase-shift migration with wave-packet algorithms
NASA Astrophysics Data System (ADS)
Mosher, Charles C.; Foster, Douglas J.; Wu, Ru-Shan
1996-10-01
Wavelet transforms have a simple representation in the frequency domain (Daubchies, 1992; Veterlli and Herley, 1992; Mosher and Foster, 1995). Since wave propagation also has a simple representation in the frequency domain, frequency domain wavelet transforms provide a useful framework for studying the nature of wave propagation in the wavelet domain. In this paper, we study phase shift extrapolators for 2-dimensional wavefields that have been Fourier transformed over time and wavelet transformed over space. The wavelet transform over the space axis is implemented in the wavenumber-frequency domain by complex multiplication of low and high pass wavenumber filter functions to form wave packet trees. To differentiate this operation from time-frequency wavelet transforms, we refer to the space-wavenumber-frequency transform as the 'beamlet transform.' The interaction of beamlet transform filter banks and phase shift wavefield extrapolators are simple complex multiplications. Wavefield propagation in the beamlet domain is complicated, however, by the digital implementation of decimation and upsampling operators used in orthogonal wavelet transforms. Unlike the filter functions, which can be viewed as diagonal matrix operators, the decimation and upsampling operators have significant off-diagonal terms. Since these operators do not commute with the filter and phase shift operators, the effects of the non-diagonal operators must be accounted for in the application of wave propagation operators. A simple (but unsatisfying) solution would be to apply forward-inverse transforms at each extrapolation step. Beamlet transforms with compact support in the wavenumber domain (Mosher and Foster, 1995) provide an alternate solution. Analysis of phase shift migration in the beamlet domain yields a simple matrix representation defining the interaction of filters, phase operators, and decimation/upsampling. The effects of decimation/upsampling are represented by simple folding
Three-dimensional effects in nonlinear fracture explored with interferometry
NASA Astrophysics Data System (ADS)
Pfaff, Richard D.
The prospects for understanding fracture mechanics in terms of a general material constitutive description are explored. The effort consists of three distinct components.First, optical interferometry, in its various forms (Twyman-Green, diffraction moire, etc.), can potentially be used under a wide range of conditions to very accurately measure the displacement and strain fields associated with the deformation surrounding a cracktip. To broaden the range of fracture problems to which interferometry may be applied, certain of the necessary experimental improvements have been developed:1. High speed camera designs capable of extremely high (> 10(9) frames/second) framing rates with large array sizes, (> 4000 x 4000 pixels per frame) so that the application of optical techniques to solid mechanics may be considered without limitation on the rate of deformation.2. An accurate and adaptable device for dynamic loading of fracture specimens to high load levels utilizing electromagnetic (Lorentz force) loading with ultrahigh (> 2,000,000 Amp/cm(2)) current flux densities.3. Implementation of high sensitivity (2 nm), large range (2 nm x 3,200,000) interferometry achieved with wide field array sizes of 50,000 x 50,000 and 8 bit gray scale (error restricted to 1 bit) for surface deformation measurements on fracture specimens.Second, functional descriptions for certain aspects of the displacement fields associated with fracture specimens are developed. It is found that the fully three-dimensional crack tip field surrounding a through-thickness crack in a plate of elastic-plastic material shows a hierarchical structure of organization and that the primary aspects of the deformation field would seem to have a relatively simple form of expression if the deformation is viewed in a properly normalized form.Third, a comparison is made between interferometrically measured surface displacements for a notched 3-point-bend speciemn of a ductile heat treatment of 4340 steel and a
Three-Dimensional Effects in Nonlinear Fracture Explored with Interferometry
NASA Astrophysics Data System (ADS)
Pfaff, Richard David
The prospects for understanding fracture mechanics in terms of a general material constitutive description are explored. The effort consists of three distinct components. First, optical interferometry, in its various forms (Twyman-Green, diffraction moire, etc.), can potentially be used under a wide range of conditions to very accurately measure the displacement and strain fields associated with the deformation surrounding a cracktip. To broaden the range of fracture problems to which interferometry may be applied, certain of the necessary experimental improvements have been developed: (1) High speed camera designs capable of extremely high (>10^9 frames/second) framing rates with large array sizes, (>4000 x 4000 pixels per frame) so that the application of optical techniques to solid mechanics may be considered without limitation on the rate of deformation. (2) An accurate and adaptable device for dynamic loading of fracture specimens to high load levels utilizing electromagnetic (Lorentz force) loading with ultrahigh (>2,000,000 Amp/cm^2) current flux densities. (3) Implementation of high sensitivity (2 nm), large range (2 nm x 3,200,000) interferometry achieved with wide field array sizes of 50,000 x 50,000 and 8 bit gray scale (error restricted to 1 bit) for surface deformation measurements on fracture specimens. Second, functional descriptions for certain aspects of the displacement fields associated with fracture specimens are developed. It is found that the fully three-dimensional crack tip field surrounding a through-thickness crack in a plate of elastic-plastic material shows a hierarchical structure of organization and that the primary aspects of the deformation field would seem to have a relatively simple form of expression if the deformation is viewed in a properly normalized form. Third, a comparison is made between interferometrically measured surface displacements for a notched 3-point-bend specimen of a ductile heat treatment of 4340 steel and a
Higher order dispersion in the propagation of a gravity wave packet
NASA Technical Reports Server (NTRS)
Yeh, K. C.; Dong, B.
1989-01-01
To the first order of approximation, the complex amplitude of a wave packet in an anisotropic and dispersive medium is convected with the group of velocity. However, a gravity wave is a vector wave. Its wave packet must be formed by superposition of various wave numbers with corresponding frequencies, as is the case for scalar waves, and additionally by superposing many eigenmodes which also depend on the wave number. To represent the vector wave packet self-consistently, it is found that a gradient term must be included in the expansion. For a Guassian wave packet, this gradient term is shown to have important implications on the velocity vector as represented by its hodograph. Numerical results show that the hodograph is influenced by the location of the relative position of interest from the center of a Gaussian pulse. Higher order expansion shows that an initial Gaussian wave packet will retain its Gaussian shape as it propagates, but the pulse will spread in all directions with its major axis undergoing a rotation. Numerical results indicate that these higher order dispersive effects may be marginally observable in the atmosphere.
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.
Periodic nonlinearity resulting from ghost reflections in heterodyne interferometry
NASA Astrophysics Data System (ADS)
Wu, Chien-ming
2003-01-01
Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as frequency mixing, polarization mixing, polarization-frequency mixing, and ghost reflections. The purpose of this paper is to study the periodic nonlinearity resulting from ghost reflections, which has not been investigated before. A generalized scheme of interferometer, which is free of frequency and polarization mixings, is used in the study. This ensures that the residual periodic nonlinearity is from the ghost reflections only. In this paper, a general form of periodic nonlinearity and a model including two kinds of ghost reflections, one with the same frequency and the other with two frequencies, are presented. The model is verified by experimental results.
NASA Astrophysics Data System (ADS)
Meier, Amanda; Adams, Daniel; Squier, Jeff; Durfee, Charles
2010-10-01
Characterization of the nonlinear refractive index of a material is important in order to fully understand the nonlinear propagation of femtosecond laser pulses. The most common method to obtaining the nonlinear refractive index is Z-scan. However, since it averages over pulse duration and beam profile, Z-scan is not reliable when there is time- and intensity-dependence of the nonlinear response. The new method we are exploring to make these nonlinear refractive index measurements is spatially and spectrally resolved interferometry (SSRI). SSRI is a method that can give a simultaneous measurement of the spatial wave-front across the frequency or temporal profile of the pulse. The SSRI method proves better in measuring response at specific y and t, allowing it to measure both delayed response and saturation effects. The ability to make a measurement in both dimensions enables understanding of spatiotemporal dynamics in other experiments as cross-wave polarization and filamentation.
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.
Laser control of electronic transitions of wave packet by using quadratically chirped pulses
Zou Shiyang; Kondorskiy, Alexey; Mil'nikov, Gennady; Nakamura, Hiroki
2005-02-22
An effective scheme is proposed for the laser control of wave packet dynamics. It is demonstrated that by using specially designed quadratically chirped pulses, fast and nearly complete excitation of wave packet can be achieved without significant distortion of its shape. The parameters of the laser pulse can be estimated analytically from the Zhu-Nakamura theory of nonadiabatic transition. If the wave packet is not too narrow or not too broad, then the scheme is expected to be utilizable for multidimensional systems. The scheme is applicable to various processes such as simple electronic excitation, pump-dump, and selective bond breaking, and it is actually numerically demonstrated to work well by taking diatomic and triatomic molecules (LiH, NaK, H{sub 2}O) as examples.
Juxtaposing density matrix and classical path-based wave packet dynamics
Aghtar, Mortaza; Liebers, Jörg; Strümpfer, Johan; Schulten, Klaus; Kleinekathöfer, Ulrich
2012-01-01
In many physical, chemical, and biological systems energy and charge transfer processes are of utmost importance. To determine the influence of the environment on these transport processes, equilibrium molecular dynamics simulations become more and more popular. From these simulations, one usually determines the thermal fluctuations of certain energy gaps, which are then either used to perform ensemble-averaged wave packet simulations, also called Ehrenfest dynamics, or to employ a density matrix approach via spectral densities. These two approaches are analyzed through energy gap fluctuations that are generated to correspond to a predetermined spectral density. Subsequently, density matrix and wave packet simulations are compared through population dynamics and absorption spectra for different parameter regimes. Furthermore, a previously proposed approach to enforce the correct long-time behavior in the wave packet simulations is probed and an improvement is proposed. PMID:22697524
Three-dimensional time-dependent wave-packet calculations of OBrO absorption spectra
NASA Astrophysics Data System (ADS)
Yuan, Kai-Jun; Sun, Zhigang; Cong, Shu-Lin; Lou, Nanquan
2005-08-01
The absorption spectra of the C(A22)←X(B12) transition of the OBrO molecule are calculated using three-dimensional time-dependent wave-packet method in Radau coordinates for a total angular momentum J =0. The wave packet is propagated using the split operator technique associated with fast Fourier transform. Employing the basis functions obtained by one-dimensional Fourier grid Hamiltonian method, the initial wave packet is calculated directly on the three-dimensional Fourier grid. The numerical model is characterized by simplicity and efficiency. The ab initio potential surfaces for the C(A22) and X(B12) states are used in the calculation. The calculated absorption spectra of the C(A22)←X(B12) transition of OBrO molecule agree well with the experimental results.
Scattering of intense laser radiation by a single-electron wave packet
Corson, John P.; Peatross, Justin; Mueller, Carsten; Hatsagortsyan, Karen Z.
2011-11-15
A quantum theoretical description of photoemission by a single laser-driven electron wave packet is presented. Energy-momentum conservation ensures that the partial emissions from individual momentum components of the electron wave packet do not interfere when the driving field is unidirectional. In other words, light scattering by an electron packet is independent of the phases of the pure momentum states comprising the packet; the size of the electron wave packet does not matter. This result holds also in the case of high-intensity multiphoton scattering. Our analysis is first presented in the QED framework. Since QED permits the second-quantized entangled electron-photon final state to be projected onto pure plane-wave states, the Born probability interpretation requires these projections to be first squared and then summed to find an overall probability of a scattering event. The QED treatment indicates how a semiclassical framework can be developed to recover the key features of the correct result.
Scattering of intense laser radiation by a single-electron wave packet
NASA Astrophysics Data System (ADS)
Corson, John P.; Peatross, Justin; Müller, Carsten; Hatsagortsyan, Karen Z.
2011-11-01
A quantum theoretical description of photoemission by a single laser-driven electron wave packet is presented. Energy-momentum conservation ensures that the partial emissions from individual momentum components of the electron wave packet do not interfere when the driving field is unidirectional. In other words, light scattering by an electron packet is independent of the phases of the pure momentum states comprising the packet; the size of the electron wave packet does not matter. This result holds also in the case of high-intensity multiphoton scattering. Our analysis is first presented in the QED framework. Since QED permits the second-quantized entangled electron-photon final state to be projected onto pure plane-wave states, the Born probability interpretation requires these projections to be first squared and then summed to find an overall probability of a scattering event. The QED treatment indicates how a semiclassical framework can be developed to recover the key features of the correct result.
Rovibrational Wave-Packet Dispersion during Femtosecond Laser Filamentation in Air
Odhner, J. H.; Romanov, D. A.; Levis, R. J.
2009-08-14
An impulsive, femtosecond filament-based Raman technique producing high quality Raman spectra over a broad spectral range (1554.7-4155 cm{sup -1}) is presented. The temperature of gas phase molecules can be measured by temporally resolving the dispersion of impulsively excited vibrational wave packets. Application to laser-induced filamentation in air reveals that the initial rovibrational temperature is 300 K for both N{sub 2} and O{sub 2}. The temperature-dependent wave-packet dynamics are interpreted using an analytic anharmonic oscillator model. The wave packets reveal a 1/e dispersion time of 3.9 ps for N{sub 2} and 2.8 ps for O{sub 2}. Pulse self-compression of temporal features to 8 fs within the filament is directly measured by impulsive vibrational excitation of H{sub 2}.
Langoju, Rajesh; Patil, Abhijit; Rastogi, Pramod
2007-11-20
Signal processing methods based on maximum-likelihood theory, discrete chirp Fourier transform, and spectral estimation methods have enabled accurate measurement of phase in phase-shifting interferometry in the presence of nonlinear response of the piezoelectric transducer to the applied voltage. We present the statistical study of these generalized nonlinear phase step estimation methods to identify the best method by deriving the Cramer-Rao bound. We also address important aspects of these methods for implementation in practical applications and compare the performance of the best-identified method with other bench marking algorithms in the presence of harmonics and noise.
NASA Astrophysics Data System (ADS)
Langoju, Rajesh; Patil, Abhijit; Rastogi, Pramod
2007-11-01
Signal processing methods based on maximum-likelihood theory, discrete chirp Fourier transform, and spectral estimation methods have enabled accurate measurement of phase in phase-shifting interferometry in the presence of nonlinear response of the piezoelectric transducer to the applied voltage. We present the statistical study of these generalized nonlinear phase step estimation methods to identify the best method by deriving the Cramér-Rao bound. We also address important aspects of these methods for implementation in practical applications and compare the performance of the best-identified method with other bench marking algorithms in the presence of harmonics and noise.
Strong field dissociative ionization of the D2+: Nuclear wave packet analysis
NASA Astrophysics Data System (ADS)
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.
A Gaussian wave packet phase-space representation of quantum canonical statistics
NASA Astrophysics Data System (ADS)
Coughtrie, David J.; Tew, David P.
2015-07-01
We present a mapping of quantum canonical statistical averages onto a phase-space average over thawed Gaussian wave-packet (GWP) parameters, which is exact for harmonic systems at all temperatures. The mapping invokes an effective potential surface, experienced by the wave packets, and a temperature-dependent phase-space integrand, to correctly transition from the GWP average at low temperature to classical statistics at high temperature. Numerical tests on weakly and strongly anharmonic model systems demonstrate that thermal averages of the system energy and geometric properties are accurate to within 1% of the exact quantum values at all temperatures.
Time delay of wave packets during their tunnelling through a quantum diode
Ivanov, N A; Skalozub, V V
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)
Hydrodynamic analysis of the Schrödinger-Langevin equation for wave packet dynamics
NASA Astrophysics Data System (ADS)
Chou, Chia-Chun
2017-10-01
Frictional effects on the wave packet dynamics of quantum systems are investigated in the framework of the Schrödinger-Langevin equation. The Schrödinger-Langevin equation is directly solved using the split-operator method. Frictional effects impede the propagation and suppress the spreading of the wave packet. Computational results are presented for an Eckart barrier scattering problem, the decay of a metastable state, and the long-time behavior of a decaying quantum system. Significant features of dissipative Bohmian trajectory dynamics are analyzed for these quantum processes.
A Gaussian wave packet phase-space representation of quantum canonical statistics
Coughtrie, David J.; Tew, David P.
2015-07-28
We present a mapping of quantum canonical statistical averages onto a phase-space average over thawed Gaussian wave-packet (GWP) parameters, which is exact for harmonic systems at all temperatures. The mapping invokes an effective potential surface, experienced by the wave packets, and a temperature-dependent phase-space integrand, to correctly transition from the GWP average at low temperature to classical statistics at high temperature. Numerical tests on weakly and strongly anharmonic model systems demonstrate that thermal averages of the system energy and geometric properties are accurate to within 1% of the exact quantum values at all temperatures.
The origin of ultrafast proton transfer: Multidimensional wave packet motion vs. tunneling
NASA Astrophysics Data System (ADS)
Schriever, Christian; Lochbrunner, Stefan; Ofial, Armin R.; Riedle, Eberhard
2011-02-01
We investigate the reaction kinetics of ultrafast excited state intramolecular proton transfer (ESIPT) and discuss the possible origins of the process: tunneling of the reactive proton, vibrationally enhanced tunneling, and multidimensional wave packet dynamics of the entire system. Comparison of the measured kinetics for the protonated and the deuterated form of 2-(2‧-hydroxyphenyl)benzothiazole (HBT) to numerical simulations allows us to ascribe the characteristic 50 fs time found for the ESIPT solely to a ballistic wave packet motion along skeletal coordinates that mainly affect the donor acceptor distance. Tunneling is not found to be decisive.
Control of wave packets in lithium dimers with a state-selected pump-probe scheme
NASA Astrophysics Data System (ADS)
Dai, Xingcan
A state-selected pump-probe scheme is used to control wave packet dynamics in Li2. In this scheme, a cw laser selects one electronic transition from the thermally populated ground state to the launch state A1Sigmau+ of Li2, from which an ultrashort pump pulse creates a superstition state on the electronic states of Li2 followed by another ultrashort pulse to excite the wave packet to the ground state of Li2+. Usually, an unperturbed level at the A1Sigmau+ state of Li2 is selected by the cw laser pulses. However, if the level of A1Sigmau+ is perturbed by b3piu, and then the wave packets that consist of the triplet states as well as the singlet states of Li2 are detected from the mixed levels. Since one of the triplet states is predissociative, the fast decay of the amplitudes of the wave packets that have the components of this predissociative state is observed. In order to study coherent multiphoton processes, Raman wave packets are created and manipulated with a pulse shaping system. The phase difference between the amplitude coefficients induced by resonant and off-resonant Raman transitions is shown directly by comparing the phases of the Raman wave packets excited by the resonant and off-resonant Raman transitions. The ionization processes employed in the probe step of the state-selective pump-probe scheme is fully explored in the second pulse shaping system in the path of the probe beam. It shows that the direct transitions from the electronic states involved in the wave packets are unlikely; while the autoionization and collision induced ionization from highly-excited Rydberg states are the main sources of the final ion signals. Some degree of the control of the wave packet dynamics is realized by shaping the probe pulses. The decoherence rates of quantum beats at the shelf region of the E1Sigma g+ state are measured to test theoretical results about pure dephasing rate in Li2. Finally, some schemes and preliminary results on physical realization of quantum
NASA Technical Reports Server (NTRS)
Sharafeddin, Omar A.; Judson, Richard S.; Kouri, Donald J.; Hoffman, David K.
1990-01-01
The novel wave-packet propagation scheme presented is based on the time-dependent form of the Lippman-Schwinger integral equation and does not require extensive matrix inversions, thereby facilitating application to systems in which some degrees of freedom express the potential in a basis expansion. The matrix to be inverted is a function of the kinetic energy operator, and is accordingly diagonal in a Bessel function basis set. Transition amplitudes for various orbital angular momentum quantum numbers are obtainable via either Fourier transform of the amplitude density from the time to the energy domain, or the direct analysis of the scattered wave packet.
Attosecond probe of valence-electron wave packets by subcycle sculpted laser fields.
Xie, Xinhua; Roither, Stefan; Kartashov, Daniil; Persson, Emil; Arbó, Diego G; Zhang, Li; Gräfe, Stefanie; Schöffler, Markus S; Burgdörfer, Joachim; Baltuška, Andrius; Kitzler, Markus
2012-05-11
We experimentally and theoretically demonstrate a self-referenced wave-function retrieval of a valence-electron wave packet during its creation by strong-field ionization with a sculpted laser field. Key is the control over interferences arising at different time scales. Our work shows that the measurement of subcycle electron wave-packet interference patterns can serve as a tool to retrieve the structure and dynamics of the valence-electron cloud in atoms on a sub-10-as time scale.
Quantum-electrodynamic treatment of photoemission by a single-electron wave packet
Corson, John P.; Peatross, Justin
2011-11-15
A quantum-field-theory description of photoemission by a laser-driven single-electron wave packet is presented. We show that, when the incident light is represented with multimode coherent states then, to all orders of perturbation theory, the relative phases of the electron's constituent momenta have no influence on the amount of scattered light. These results are extended using the Furry picture, where the (unidirectional) arbitrary incident light pulse is treated nonperturbatively with Volkov functions. This analysis increases the scope of our prior results in [Phys. Rev. A 84, 053831 (2011)], which demonstrate that the spatial size of the electron wave packet does not influence photoemission.
Effect of bound electron wave packet displacement on the multiphoton ionization of a lithium atom
NASA Astrophysics Data System (ADS)
Jheng, Shih-Da; Jiang, T. F.
2017-10-01
We study numerically the strong-field single ionization of a Li atom over a wide range of wavelengths (400 nm–1600 nm) in the multiphoton regime. By observing the behavior of the ionization probabilities and the occupation of excited states, we found that the occupied 2p state in different wavelength regimes exhibit different bound electron wave packet motion. The motion is in phase in the long-wavelength regime, out of phase in the short-wavelength regime and lagged when the wavelength is close to resonance with the 2p state. We then demonstrate how these different motions of the bound electron wave packet affect the ionization probability.
A Gaussian wave packet phase-space representation of quantum canonical statistics.
Coughtrie, David J; Tew, David P
2015-07-28
We present a mapping of quantum canonical statistical averages onto a phase-space average over thawed Gaussian wave-packet (GWP) parameters, which is exact for harmonic systems at all temperatures. The mapping invokes an effective potential surface, experienced by the wave packets, and a temperature-dependent phase-space integrand, to correctly transition from the GWP average at low temperature to classical statistics at high temperature. Numerical tests on weakly and strongly anharmonic model systems demonstrate that thermal averages of the system energy and geometric properties are accurate to within 1% of the exact quantum values at all temperatures.
Generation of Quasiclassical Bohr-Like Wave Packets Using Half-Cycle Pulses
Mestayer, J. J.; Wyker, B.; Dunning, F. B.; Reinhold, Carlos O; Yoshida, S.; Burgdorfer, J.
2008-08-01
We demonstrate the experimental realization of Bohr-like atoms by applying a pulsed unidirectional field, termed a half-cycle pulse (HCP), to atoms in quasi-two-dimensional near-circular states. This leads to creation of localized wave packets that travel in near-circular orbits and mimic the dynamics of an electron in the original Bohr model of the hydrogen atom. This motion can be followed for several orbital periods before the localization of the wave packet is lost due to dephasing. We show, however, that localization can be recovered by application of further HCPs.
The Many Faces of Ice and Nonlinear Interferometry
NASA Astrophysics Data System (ADS)
Shultz, Mary Jane
Ice is likely the most ubiquitous solid in the Universe, yet even here on Earth its surface contains many mysteries. At atmospheric pressure, the stable form of ice is hexagonal ice; known as Ih. This contribution will present data about (i) equilibrium growth at the ice-water interface, (ii) procedures to generate any targeted ice face, and (iii) vibrational spectra of the ice-air interface. Contrary to common belief, the stable ice-water interfaces does not consist of the basal face; rather it consists of pyramidal or prism faces. Growth results from a balance between the molecular density and the top half-bilayer configuration. Arguments reminiscent of Pauling's residual entropy of ice generate the configurational contribution. Prism faces are favored due to greater entropy. Ice grows cryptomorphologically: the macroscopic sample does not reveal the crystalline axes. Locating the crystal axes as well as generating authentic faces for fundamental studies use a combination of the birefringence of ice and etch profiles. Surface vibrational spectroscopy supports an ice model consisting of extended, cooperative motion and beyond-bonding-partner determination of hydrogen bond strength. The surface vibrational spectrum is probed with the nonlinear spectroscopy sum frequency generation (SFG). Currently, nonlinearity limits use of SFG to diagnose interactions. This limitation can be circumvented by measuring the full, complex spectrum. We will report initial results from a newly invented nonlinear interferometer that reveals the full complex spectrum.
Time-evolution of wave-packets in topological insulators (Presentation Recording)
NASA Astrophysics Data System (ADS)
Ferreira, Gerson J.; Penteado, Poliana H.; Egues, José Carlos
2015-09-01
The electronic structure of topological insulators (TIs) are well described Dirac-like equations, e.g. the BHZ model, with a mass term that changes sign at some interface. This simplistic description includes a pseudo-spin-orbit coupling that is intrinsic to the Dirac Hamiltonian. Consequently, the TIs share common properties with the Dirac equation. Among them, the interference between positive and negative energy bands leads to the relativistic oscillatory motion known as the Zitterbewegung. Here we discuss the ballistic time-evolution (pico and nanoseconds) of wave-packets in TIs in the presence of an external electric field. We show that the guiding center of large wave-packets have a finite motion transversal to the electric field equivalent to side-jump in Rashba GaAs. However, for narrow wave-packets the dynamics change and the guiding center description is not complete. We also discuss the reflection of a wave-packet colliding with the edge of the system and the effects of the edge states. Acknowledgement: We acknowledge support from CAPES, CPNq, FAPEMIG, FAPESP, and NAP Q-NANO from PRP/USP.
Bulut, N; Castillo, J F; Bañares, L; Aoiz, F J
2009-12-31
The dynamics and kinetics of the Li + H2(+) reaction have been studied by means of quantum mechanical (QM) real wave packet, wave packet with flux operator, and quasiclassical trajectory (QCT) calculations on the ab initio potential energy surface of Martinazzo et al. [J. Chem. Phys., 2003, 119, 21]. Total initial state-selected reaction probabilities for the title reaction have been calculated for total angular momentum J = 0 at collision energies from threshold up to 1 eV. Wave packet reaction probabilities at selected values of the total angular momentum up to J = 60 are obtained using the centrifugal sudden approximation (CSA). Integral cross sections and rate constants have been calculated from the wave packet reactions probabilities by means of a refined J-shifting method and the separable rotation approximation in combination with the CSA for J > 0. The calculated rate constants as function of temperature show an Arrhenius type behavior. The QM results are found to be in overall good agreement with the corresponding QCT data.
Airy wave packet for a particle in a time-dependent linear potential
NASA Astrophysics Data System (ADS)
Berrehail, Mounira; Benchiheub, Nadjet
2017-01-01
We studied the quantum motion of a particle in the presence of a time-dependent linear potential by using an operator invariant that is quadratic in p and linear in x within the framework of the Lewis-Riesenfeld invariant. The special invariant operator in this work is demonstrated to be Hermitian operator that has an Airy wave packet as its eigenfunctions.
Beam-plasma instability and density holes: Langmuir wave-packet formation and particle acceleration
NASA Astrophysics Data System (ADS)
Sgattoni, A.; Amiranoff, F.; Briand, C.; Henri, P.; Grech, M.; Riconda, C.
2017-07-01
The role of density perturbations of the background plasma in the development of Langmuir waves generated by beam-plasma instabilities is a very debated issue in space physics. The presence of clumpy electrostatic wave-packets (in particular Langmuir waves), from in situ observations, is indeed puzzling. Several processes have been proposed to explain the formation of waveforms, such as Stochastic Growth Theory and trapping in eigenmodes. Here we explore another mechanism considering the seeding of the beam-plasma instability by density holes. We have performed several 1D-1V Vlasov simulations in the electrostatic limit. We show that in the presence of a density hole, a large amplitude solitary wave-packet of Langmuir waves is formed and that it evolves towards clumpier waveforms. Moreover, the large-amplitude wave-packets generated near the hole can reach saturation and accelerate the electrons of the beam: their velocity distribution is strongly distorted, leading to a multi-peaked structure that generates new unstable modes having phase velocities both larger and smaller than the average speed of the beam. The relationship between the wave amplitude and the characteristics of the density hole is also described, showing how the electron beam may select specific holes to generate enhanced localised Langmuir wave-packets.
Propagation of electromagnetic wave packets in iron-yttrium garnet plates and films
Visatskas, A.V.; Ivashka, V.P.; Meshkauskas, I.I.
1987-10-01
The propagation of wave packets and harmonic waves in iron-yttrium garnet (YIG) polycrystalline plates and single-crystalline films is studied. The basic parameters of the waves are determined with the use of the equations for a flat waveguide and also the equations of magnetostatics. The theoretical results agree well with the experimental results.
Second-order corrections to neutrino two-flavor oscillation parameters in the wave packet approach
NASA Astrophysics Data System (ADS)
Bernardini, A. E.; Guzzo, M. M.; Torres, F. R.
2006-11-01
We report about an analytic study involving the intermediate wave packet formalism for quantifying the physically relevant information which appears in the neutrino two-flavor conversion formula and helping us to obtain more precise limits and ranges for neutrino flavor oscillation. By following the sequence of analytic approximations where we assume a strictly peaked momentum distribution and consider the second-order corrections in a power series expansion of the energy, we point out a residual time-dependent phase which, coupled with the spreading/slippage effects, can subtly modify the neutrino-oscillation parameters and limits. Such second-order effects are usually ignored in the relativistic wave packet treatment, but they present an evident dependence on the propagation regime so that some small modifications to the oscillation pattern, even in the ultra-relativistic limit, can be quantified. These modifications are implemented in the confrontation with the neutrino-oscillation parameter range (mass-squared difference Δm2 and the mixing angle θ) where we assume the same wave packet parameters previously noticed in the literature in a kind of toy model for some reactor experiments. Generically speaking, our analysis parallels the recent experimental purposes which are concerned with higher precision parameter measurements. To summarize, we show that the effectiveness of a more accurate determination of Δm2 and θ depends on the wave packet width a and on the averaged propagating energy flux E¯ which still correspond to open variables for some classes of experiments.
Realization of the wave-packet-collapse-a viewpoint to the quantum measurement theory
NASA Astrophysics Data System (ADS)
Lu-ming, Duan; Guang-can, Guo
1995-11-01
An interpretion of the wave-packet-collapse (WPC) in the system of quantum mechanics is given. We find a connection between the WPC and the limitation to the measurement precision determined by the quantum fluctuation. A simple and explicit relation about them is obtained.
NASA Astrophysics Data System (ADS)
Tsubouchi, Masaaki; Momose, Takamasa
2007-06-01
Laser pulse shaping which was developed in near infrared (NIR) has been recently extended into mid infrared (MIR: 3 -- 10 μm). In the presented study, the signal output (NIR: 1.1 -- 1.5 μm) of an optical parametric amplifier was shaped with a Dazzler, and mixed in a AgGaS2 crystal with the idler pulse to generate MIR pulses. Although the relation between the shapes of NIR and MIR light is complicated due to DFG process in the crystal with finite (2 mm) thickness, the shape of MIR light can be completely characterized by comparing with calculated profiles. The shaped MIR light which is well characterized can be used to manipulate rovibrational wave packet on the electronic ground state. We simulated the wave packet motion and its observable by solving the time-dependent Schr"odinger equation, and discussed how the shape of MIR pulse is transferred into the wave packet. Application of rovibrational wave packet manipulation to quantum computation will be discussed.
Scattering of quantum wave packets by shallow potential islands: a quantum lens.
Goussev, Arseni; Richter, Klaus
2013-05-01
We consider the problem of quantum scattering of a localized wave packet by a weak Gaussian potential in two spatial dimensions. We show that, under certain conditions, this problem bears close analogy with that of focusing (or defocusing) of light rays by a thin optical lens: Quantum interference between straight paths yields the same lens equation as for refracted rays in classical optics.
Wave packet theory of dynamic stimulated Raman spectra in femtosecond pump-probe spectroscopy.
Sun, Zhigang; Jin, Zhongqi; Lu, J; Zhang, Dong H; Lee, Soo-Y
2007-05-07
The quantum theory for stimulated Raman spectroscopy from a moving wave packet using the third-order density matrix and polarization is derived. The theory applies, in particular, to the new technique of femtosecond broadband stimulated Raman spectroscopy (FSRS). In the general case, a femtosecond actinic pump pulse first prepares a moving wave packet on an excited state surface which is then interrogated with a coupled pair of picosecond Raman pump pulse and a femtosecond Raman probe pulse and the Raman gain in the direction of the probe pulse is measured. It is shown that the third-order polarization in the time domain, whose Fourier transform governs the Raman gain, is given simply by the overlap of a first-order wave packet created by the Raman pump on the upper electronic state with a second-order wave packet on the initial electronic state that is created by the coupling of the Raman pump and probe fields acting on the molecule. Calculations are performed on model potentials to illustrate and interpret the FSRS spectra.
Changing the relative amplitudes of wave packets to induce nonlocal effects
Ryff, L.C.B. )
1995-01-01
Three experiments are discussed in which nonlocal effects can be induced by changing the relative amplitudes of wave packets. Unlike previous experiments, in which nonlocal effects were induced by means of polarizers or phase shifters, in the proposed experiments nonlocal effects can be induced by means of variable beam splitters.
Single electron wave packets probed by Hanbury-Brown and Twiss interferometry
NASA Astrophysics Data System (ADS)
Feve, Gwendal; Bocquillon, Erwann; Parmentier, Francois; Grenier, Charles; Berroir, Jean-Marc; Degiovanni, Pascal; Glattli, Christian; Placais, Bernard; Cavanna, Antonella; Jin, Yong
2012-02-01
The ballistic propagation of electronic waves in the quantum Hall edge channels of a 2DEG bears strong analogies with photon optics which inspired a whole set of experiments, including the realization of electronic Mach-Zehnder [1] and Hanbury-Brown and Twiss [2] interferometers. So far, these experiments have been performed with continuous sources, but the recent realization of on-demand single electron emitters [3] has risen the hope to reach, in these experiments, the single charge control. We report here on the first realization of a Hanbury-Brown and Twiss experiment on a single electron beam generated by the single electron emitter recently developed by our group [3]. Using the chiral edge channels of the quantum Hall effect, single electron emitted by the source are directed towards an electronic beam-splitter. From the low frequency current correlations at the output of the beam splitter, we are able to count and characterize the elementary excitations produced by the source. By analyzing their antibunching with thermal excitations, we show that we are able to shape single particle states in a tuneable way. [1] Ji et al., Nature 422, 415 (2003) [2] Henny et al., Science 284 296 (1999) [3] Fève et al., Science 316, 1169 (2007)
Propagation of Gaussian wave packets in complex media and application to fracture characterization
NASA Astrophysics Data System (ADS)
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
Balskus, Karolis; Fleming, Melissa; McCracken, Richard A; Zhang, Zhaowei; Reid, Derryck T
2016-03-01
By exploiting the correlation between changes in the wavelength and the carrier-envelope offset frequency (f(CEO)) of the signal pulses in a synchronously pumped optical parametric oscillator, we show that f(CEO) can be stabilized indefinitely to a few megahertz in a 333 MHz repetition-rate system. Based on a position-sensitive photodiode, the technique is easily implemented, requires no nonlinear interferometry, has a wide capture range, and is compatible with feed-forward techniques that can enable f(CEO) stabilization at loop bandwidths far exceeding those currently available to OPO combs.
NASA Astrophysics Data System (ADS)
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
Quantum dynamics of solid Ne upon photo-excitation of a NO impurity: A Gaussian wave packet approach
Unn-Toc, W.; Meier, C.; Halberstadt, N.; Uranga-Pina, Ll.; Rubayo-Soneira, J.
2012-08-07
A high-dimensional quantum wave packet approach based on Gaussian wave packets in Cartesian coordinates is presented. In this method, the high-dimensional wave packet is expressed as a product of time-dependent complex Gaussian functions, which describe the motion of individual atoms. It is applied to the ultrafast geometrical rearrangement dynamics of NO doped cryogenic Ne matrices after femtosecond laser pulse excitation. The static deformation of the solid due to the impurity as well as the dynamical response after femtosecond excitation are analyzed and compared to reduced dimensionality studies. The advantages and limitations of this method are analyzed in the perspective of future applications to other quantum solids.
NASA Astrophysics Data System (ADS)
Cheng, Yan; Chini, Michael; Wang, Xiaowei; González-Castrillo, Alberto; Palacios, Alicia; Argenti, Luca; Martín, Fernando; Chang, Zenghu
2016-08-01
Attosecond science promises to allow new forms of quantum control in which a broadband isolated attosecond pulse excites a molecular wave packet consisting of a coherent superposition of multiple excited electronic states. This electronic excitation triggers nuclear motion on the molecular manifold of potential energy surfaces and can result in permanent rearrangement of the constituent atoms. Here, we demonstrate attosecond transient absorption spectroscopy (ATAS) as a viable probe of the electronic and nuclear dynamics initiated in excited states of a neutral molecule by a broadband vacuum ultraviolet pulse. Owing to the high spectral and temporal resolution of ATAS, we are able to reconstruct the time evolution of a vibrational wave packet within the excited B'Σ1u+ electronic state of H2 via the laser-perturbed transient absorption spectrum.
NASA Astrophysics Data System (ADS)
Yang, Sheng-Jun; Bao, Xiao-Hui; Pan, Jian-Wei
2015-05-01
Coherent manipulation of single-photon wave packets is essentially important for optical quantum communication and quantum information processing. In this paper, we realize controllable splitting and modulation of single-photon-level pulses by using a tripod-type atomic medium. The adoption of two control beams enable us to store one signal pulse into superposition of two distinct atomic collective excitations. By controlling the time delay between the two control pulses, we observe splitting of a stored wave packet into two temporally distinct modes. By controlling the frequency detuning of the control beams, we observe both temporal and frequency-domain interference of the retrieval signal pulses, which provides a method for pulse modulation and multisplitting of the signal photons.
Decoherence and the fate of an infalling wave packet: Is Alice burning or fuzzing?
NASA Astrophysics Data System (ADS)
Chowdhury, Borun D.; Puhm, Andrea
2013-09-01
Recently, Almheiri, Marolf, Polchinski, and Sully have suggested a Gedankenexperiment to test black hole complementarity. They claim that the postulates of black hole complementarity are mutually inconsistent and choose to give up the “absence of drama” for an infalling observer. According to them, the black hole is shielded by a firewall no later than Page time. This has generated some controversy. We find that an interesting picture emerges when we take into account objections from the advocates of fuzzballs. We reformulate Almheiri, Marolf, Polchinski, and Sully’s Gedankenexperiment in the decoherence picture of quantum mechanics and find that low energy wave packets interact with the radiation quanta rather violently while high energy wave packets do not. This is consistent with Mathur’s recent proposal of fuzzball complementarity for high energy quanta falling into fuzzballs.
Localizing high-lying Rydberg wave packets with two-color laser fields
NASA Astrophysics Data System (ADS)
Larimian, Seyedreza; Lemell, Christoph; Stummer, Vinzenz; Geng, Ji-Wei; Roither, Stefan; Kartashov, Daniil; Zhang, Li; Wang, Mu-Xue; Gong, Qihuang; Peng, Liang-You; Yoshida, Shuhei; Burgdörfer, Joachim; Baltuška, Andrius; Kitzler, Markus; Xie, Xinhua
2017-08-01
We demonstrate control over the localization of high-lying Rydberg wave packets in argon atoms with phase-locked orthogonally polarized two-color laser fields. With a reaction microscope, we measure ionization signals of high-lying Rydberg states induced by a weak dc field and blackbody radiation as a function of the relative phase between the two-color fields. We find that the dc-field-ionization yield of high-lying Rydberg argon atoms oscillates with the relative two-color phase with a period of 2 π while the photoionization signal by blackbody radiation shows a period of π . Accompanying simulations show that these observations are a clear signature of the asymmetric localization of electrons recaptured into very elongated (low angular momentum) high-lying Rydberg states after conclusion of the laser pulse. Our findings thus open an effective pathway to control the localization of high-lying Rydberg wave packets.
Complex time dependent wave packet technique for thermal equilibrium systems - Electronic spectra
NASA Technical Reports Server (NTRS)
Reimers, J. R.; Wilson, K. R.; Heller, E. J.
1983-01-01
A time dependent wave packet method is presented for the rapid calculation of the properties of systems in thermal equilibrium and is applied, as an illustration, to electronic spectra. The thawed Gaussian approximation to quantum wave packet dynamics combined with evaluation of the density matrix operator by imaginary time propagation is shown to give exact electronic spectra for harmonic potentials and excellent results for both a Morse potential and for the band contours of the three transitions of the visible electronic absorption spectrum of the iodine molecule. The method, in principle, can be extended to many atoms (e.g., condensed phases) and to other properties (e.g., infrared and Raman spectra and thermodynamic variables).
Wave packet dynamics of an atomic ion in a Paul trap
NASA Astrophysics Data System (ADS)
Hashemloo, A.; Dion, C. M.; Rahali, G.
2016-07-01
Using numerical simulations of the time-dependent Schrödinger equation, we study the full quantum dynamics of the motion of an atomic ion in a linear Paul trap. Such a trap is based on a time-varying, periodic electric field and hence corresponds to a time-dependent potential for the ion, which we model exactly. We compare the center-of-mass motion with that obtained from classical equations of motion, as well as to results based on a time-independent effective potential. We also study the oscillations of the width of the ion’s wave packet, including close to the border between stable (bounded) and unstable (unbounded) trajectories. Our results confirm that the center-of-mass motion always follows the classical trajectory, that the width of the wave packet is bounded for trapping within the stability region, and therefore that the classical trapping criterion is fully applicable to quantum motion.
Delay-time distribution in the scattering of time-narrow wave packets. (I)
NASA Astrophysics Data System (ADS)
Smilansky, Uzy
2017-05-01
This is the first of two subsequent publications where the probability distribution of delay-times in scattering of wave packets is discussed. The probability distribution is expressed in terms of the on-shell scattering matrix, the dispersion relation of the scattered beam and the wave packet envelope. In the monochromatic limit (poor time resolution) the mean delay-time coincides with the expression derived by Eisenbud and Wigner and generalized by Smith more than half a century ago. In the opposite limit, and within the semi-classical approximation, the resulting distribution coincides with the result obtained using classical mechanics or geometrical optics. The general expression interpolates smoothly between the two extremes. An application for the scattering of electromagnetic waves in networks of RF transmission lines will be discussed in the next paper to illustrate the method in an experimentally relevant context.
Upstream and downstream wave packets associated with low-Mach number interplanetary shocks
NASA Astrophysics Data System (ADS)
Goncharov, O.; Å afránková, J.; Němeček, Z.; Přech, L.; PitÅa, A.; Zastenker, G. N.
2014-11-01
Wave packets are frequently observed upstream and/or downstream of shocks in a magnetized plasma. We present a comparison of Wind and Spektr-R observations of 27 interplanetary low-Mach number (<5.5) shocks that reveals that (1) the wavelengths of both upstream and downstream waves conserve over the spacecraft separation, (2) in the frequency range of 0.5-5 Hz, their wavelengths are directly proportional to the shock ramp thickness that is controlled by the ion thermal gyroradius, and (3) the phase shift between density and temperature variations within downstream wave packets is about 90°. These results emphasize a role of kinetic processes in the formation of low-Mach number shocks.
Quantum-electrodynamic treatment of photoemission by a single-electron wave packet
NASA Astrophysics Data System (ADS)
Corson, John P.; Peatross, Justin
2011-11-01
A quantum-field-theory description of photoemission by a laser-driven single-electron wave packet is presented. We show that, when the incident light is represented with multimode coherent states then, to all orders of perturbation theory, the relative phases of the electron's constituent momenta have no influence on the amount of scattered light. These results are extended using the Furry picture, where the (unidirectional) arbitrary incident light pulse is treated nonperturbatively with Volkov functions. This analysis increases the scope of our prior results in [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.84.053831 84, 053831 (2011)], which demonstrate that the spatial size of the electron wave packet does not influence photoemission.
Quantum and classical dynamics of Langmuir wave packets.
Haas, F; Shukla, P K
2009-06-01
The quantum Zakharov system in three spatial dimensions and an associated Lagrangian description, as well as its basic conservation laws, are derived. In the adiabatic and semiclassical cases, the quantum Zakharov system reduces to a quantum modified vector nonlinear Schrödinger (NLS) equation for the envelope electric field. The Lagrangian structure for the resulting vector NLS equation is used to investigate the time dependence of the Gaussian-shaped localized solutions, via the Rayleigh-Ritz variational method. The formal classical limit is considered in detail. The quantum corrections are shown to prevent the collapse of localized Langmuir envelope fields, in both two and three spatial dimensions. Moreover, the quantum terms can produce an oscillatory behavior of the width of the approximate Gaussian solutions. The variational method is shown to preserve the essential conservation laws of the quantum modified vector NLS equation. The possibility of laboratory tests in the next generation intense laser-solid plasma compression experiment is discussed.
System-level physics of autonomous nanorobots for hard chemistry and wave packet engineering
NASA Astrophysics Data System (ADS)
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'.
Wave packet revivals in a graphene quantum dot in a perpendicular magnetic field
Torres, J. J.
2010-10-15
We study the time evolution of localized wave packets in graphene quantum dots in a perpendicular magnetic field, focusing on the quasiclassical and revival periodicities, for different values of the magnetic field intensities in a theoretical framework. We have considered contributions of the two inequivalent points in the Brillouin zone. The revival time has been found as an observable that shows the break valley degeneracy.
HEAVY ION HEATING DUE TO INTERACTIONS WITH OUTWARD AND INWARD ALFVEN WAVE PACKETS
Galinsky, V. L.; Shevchenko, V. I.
2012-06-01
The study of simultaneous cyclotron interactions of heavy ions with outward- and inward-propagating Alfven wave packets in the solar wind was self-consistently conducted with wave-packet dynamics. It was shown that, even when the ratio of intensities of the Alfven waves propagating from the Sun and the inward propagating waves are rather large (a factor of 10 or more), the distribution function of the ions simultaneously interacting with both of the wave packets drastically differs from the distribution function formed by the interaction of ions with waves only propagating from the Sun. In the latter case, the ions acquire a shell-like distribution; in the former case, a new non-shell-type distribution with much larger effective temperatures is formed. The temporal dynamics of the ion-distribution function and the self-consistent modification of the wave-power spectral density for both the outward and inward waves were also investigated. The results refute claims by Isenberg and Hollweg that the outward-propagating waves generate the inward waves through the instability of their resonant particle shell distribution.
NASA Astrophysics Data System (ADS)
Chowdhury, P.; Home, D.; Majumdar, A. S.; Mousavi, S. V.; Mozaffari, M. R.; Sinha, S.
2012-01-01
The weak equivalence principle of gravity is examined at the quantum level in two ways. First, the position detection probabilities of particles described by a non-Gaussian wave packet projected upwards against gravity around the classical turning point and also around the point of initial projection are calculated. These probabilities exhibit mass dependence at both these points, thereby reflecting the quantum violation of the weak equivalence principle. Second, the mean arrival time of freely falling particles is calculated using the quantum probability current, which also turns out to be mass dependent. Such a mass dependence is shown to be enhanced by increasing the non-Gaussianity parameter of the wave packet, thus signifying a stronger violation of the weak equivalence principle through a greater departure from Gaussianity of the initial wave packet. The mass dependence of both the position detection probabilities and the mean arrival time vanishes in the limit of large mass. Thus, compatibility between the weak equivalence principle and quantum mechanics is recovered in the macroscopic limit of the latter. A selection of Bohm trajectories is exhibited to illustrate these features in the free fall case.
Bispectral Analysis of a Langmuir Wave Packet Associated with a Solar Type III Radio Burst
NASA Astrophysics Data System (ADS)
Golla, T.; MacDowall, R. J.; Bergamo, M.
2012-12-01
We present the observations of an intense localized wave packet, obtained by the STEREO spacecraft in the source region of a solar type III radio burst. The FFT spectrum of this wave packet contains a primary peak at the local electron plasma frequency, fpe (Langmuir waves), and two secondary peaks, one at 2fpe (second harmonic) and a second one at 3fpe (third harmonic). The wavelet based time-frequency spectrogram indicates that these spectral peaks are coincident in time. It is found that the bicoherence spectrum, computed using the wavelet based bispectral analysis technique contains two peaks, one at (fpe, fpe) and a second one at (2fpe, fpe). The high values of the bicoherences of these spectral peaks, which quantify the phase coherences amongst the harmonic components provide unambiguous evidence for the three wave interactions L + L' -> T2f{pe}, and L + T2f{pe} -> T3f{pe} in the waveform data, where L and L' are the oppositely propagating Langmuir waves, and T2f{pe} and T3f{pe} are the second and third harmonic electromagnetic waves, respectively. The peak intensity and short duration of this wave packet, which indicate that it is probably a collapsing soliton formed as a result of oscillating two stream instability (OTSI), strongly suggest that the L and L' probably correspond to the OTSI excited oppositely propagating Langmuir waves.
NASA Astrophysics Data System (ADS)
Kuo, F. S.; Lue, H. Y.; Fern, C. L.; Röttger, J.; Fukao, S.; Yamamoto, M.
2009-10-01
We study the horizontal structure of the atmospheric gravity waves (AGW) in the height ranges between 6 and 22 km observed using the MU radar at Shigaraki in Japan, during a 3 day period in January and a 4 day period in August 1988. The data were divided by double Fourier transformation into a data set of upward moving waves and a data set of downward moving waves for independent analysis. The phase and group velocity tracing technique was applied to measure the vertical group and phase velocity as well as the characteristic period of the gravity wave packet. Then the dispersion equation of the linear theory of AGW was solved to obtain its intrinsic wave period - horizontal wavelength and horizontal group velocity - and the vertical flux of horizontal momentum associated with each wave packet was estimated to help determine the direction of the characteristic horizontal wave vector. The results showed that the waves with periods in the range of 30 min~6 h had horizontal scales ranging from 20 km to 1500 km, vertical scales from 4 km to 15 km, and horizontal phase velocities from 15 m/s to 60 m/s. The upward moving wave packets of wave period of 2 h~6 h had horizontal group velocities mainly toward east-south-east and northeast in winter, and mainly in the section between the directions of west-north-west and north in summer.
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.
NASA Astrophysics Data System (ADS)
Reduzzi, M.; Chu, W.-C.; Feng, C.; Dubrouil, A.; Hummert, J.; Calegari, F.; Frassetto, F.; Poletto, L.; Kornilov, O.; Nisoli, M.; Lin, C.-D.; Sansone, G.
2016-03-01
The coherent interaction with ultrashort light pulses is a powerful strategy for monitoring and controlling the dynamics of wave packets in all states of matter. As light presents an oscillation period of a few femtoseconds (T = 2.6 fs in the near infrared spectral range), an external optical field can induce changes in a medium on the sub-cycle timescale, i.e. in a few hundred attoseconds. In this work, we resolve the dynamics of autoionizing states on the femtosecond timescale and observe the sub-cycle evolution of a coherent electronic wave packet in a diatomic molecule, exploiting a tunable ultrashort extreme ultraviolet pulse and a synchronized infrared field. The experimental observations are based on measuring the variations of the extreme ultraviolet radiation transmitted through the molecular gas. The different mechanisms contributing to the wave packet dynamics are investigated through theoretical simulations and a simple three level model. The method is general and can be extended to the investigation of more complex systems.
Electron dynamics following photoionization: Decoherence due to the nuclear-wave-packet width
NASA Astrophysics Data System (ADS)
Vacher, Morgane; Steinberg, Lee; Jenkins, Andrew J.; Bearpark, Michael J.; Robb, Michael A.
2015-10-01
The advent of attosecond techniques opens up the possibility to observe experimentally electron dynamics following ionization of molecules. Theoretical studies of pure electron dynamics at single fixed nuclear geometries in molecules have demonstrated oscillatory charge migration at a well-defined frequency but often neglecting the natural width of the nuclear wave packet. The effect on electron dynamics of the spatial delocalization of the nuclei is an outstanding question. Here, we show how the inherent distribution of nuclear geometries leads to dephasing. Using a simple analytical model, we demonstrate that the conditions for a long-lived electronic coherence are a narrow nuclear wave packet and almost parallel potential-energy surfaces of the states involved. We demonstrate with numerical simulations the decoherence of electron dynamics for two real molecular systems (paraxylene and polycyclic norbornadiene), which exhibit different decoherence time scales. To represent the quantum distribution of geometries of the nuclear wave packet, the Wigner distribution function is used. The electron dynamics decoherence result has significant implications for the interpretation of attosecond spectroscopy experiments since one no longer expects long-lived oscillations.
ACCELERATION OF THE SOLAR WIND BY ALFVEN WAVE PACKETS
Galinsky, V. L.; Shevchenko, V. I.
2013-01-20
A scale separation kinetic model of the solar wind acceleration is presented. The model assumes an isotropic Maxwellian distribution of protons and a constant influx of outward propagating Alfven waves with a single exponent Kolmogorov-type spectrum at the base of a coronal acceleration region ({approx}2 R {sub Sun }). Our results indicate that nonlinear cyclotron resonant interaction taking energy from Alfven waves and depositing it into mostly perpendicular heating of protons in initially weakly expanding plasma in a spherically non-uniform magnetic field is able to produce the typical fast solar wind velocities for the typical plasma and wave conditions after expansion to about 5-10 solar radii R {sub Sun }. The acceleration model takes into account the gravity force and the ambipolar electric field, as well as the mirror force, which plays the most important role in driving the solar wind acceleration. Contrary to the recent claims of Isenberg, the cold plasma dispersion only slightly slows down the acceleration and actually helps in obtaining the more realistic fast solar wind speeds.
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.
Nonlinear coda wave interferometry for the global evaluation of damage levels in complex solids.
Zhang, Yuxiang; Tournat, Vincent; Abraham, Odile; Durand, Olivier; Letourneur, Stéphane; Le Duff, Alain; Lascoup, Bertrand
2017-01-01
A nonlinear acoustic method to assess the damage level of a complex medium is discussed herein. Thanks to the highly nonlinear elastic signatures of cracks or, more generally, internal solid contacts, this method is able to distinguish between contributions from linear wave scattering by a heterogeneity and contributions from nonlinear scattering by a crack or unbounded interface. The coda wave interferometry (CWI) technique is applied to reverberated and scattered waves in glass plate samples featuring various levels of damage. The ultrasonic coda signals are recorded in both the absence and presence of an independent and lower-frequency elastic "pump" wave, before being analyzed by CWI. The monitored CWI parameters quantifying changes in these coda signals, which therefore quantify the nonlinear wave-mixing effects between the coda and pump waves, are found to be dependent on the damage level in the sample. A parametric study is also performed to analyze the influence of sensor positions and average temperature on the method's output. The reported results could be applied to the non-destructive testing and evaluation of complex-shape materials and multiple scattering samples, for which conventional ultrasonic methods show strong limitations. Copyright © 2016 Elsevier B.V. All rights reserved.
Zhou, Zhennan
2014-09-01
In this paper, we approximate the semi-classical Schrödinger equation in the presence of electromagnetic field by the Hagedorn wave packets approach. By operator splitting, the Hamiltonian is divided into the modified part and the residual part. The modified Hamiltonian, which is the main new idea of this paper, is chosen by the fact that Hagedorn wave packets are localized both in space and momentum so that a crucial correction term is added to the truncated Hamiltonian, and is treated by evolving the parameters associated with the Hagedorn wave packets. The residual part is treated by a Galerkin approximation. We prove that, with the modified Hamiltonian only, the Hagedorn wave packets dynamics give the asymptotic solution with error O(ε{sup 1/2}), where ε is the scaled Planck constant. We also prove that, the Galerkin approximation for the residual Hamiltonian can reduce the approximation error to O(ε{sup k/2}), where k depends on the number of Hagedorn wave packets added to the dynamics. This approach is easy to implement, and can be naturally extended to the multidimensional cases. Unlike the high order Gaussian beam method, in which the non-constant cut-off function is necessary and some extra error is introduced, the Hagedorn wave packets approach gives a practical way to improve accuracy even when ε is not very small.
NASA Astrophysics Data System (ADS)
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, <" separators=" Ψ1 ( 2 ) ( p r ∗ , p u , t ) | , that is prepared on the lower electronic e1 PES by a broadband (fs) probe pulse, Epr(t), acting on the first-order wave packet. In off-resonant FSRS, |" separators=" Ψ2 ( 1 ) ( p u , t ) > 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 <" separators=" Ψ1 ( 2 ) ( p r ∗ , p u , t ) | will oscillate along those coordinates thus giving rise to similar oscillations in P(3)(t) with the frequencies of the reporter modes. So, by recovering P(3)(t) from the FSRS spectrum, we are able to deduce information on the time-dependent quantum-mechanical wave packet averaged frequencies, ω ¯ j ( t ) , of the reporter modes j along the trajectory of |" separators=" Ψ1 ( 0 ) ( t ) > . 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
Wu, Yue-Chao; Zhao, Bin; Lee, Soo-Y
2016-02-07
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, |Ψ2(1)(pu,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, <Ψ1(2)(pr(∗),pu,t)|, that is prepared on the lower electronic e1 PES by a broadband (fs) probe pulse, Epr(t), acting on the first-order wave packet. In off-resonant |FSRS, Ψ2(1)(pu,t)> resembles the zeroth order wave packet |Ψ1(0)(t)> on the lower PES spatially, but with a force on |Ψ2(1)(pu,t)> along the coordinates of the reporter modes due to displacements in the equilibrium position, so that <Ψ1(2)(pr(∗),pu,t)| will oscillate along those coordinates thus giving rise to similar oscillations in P(3)(t) with the frequencies of the reporter modes. So, by recovering P(3)(t) from the FSRS spectrum, we are able to deduce information on the time-dependent quantum-mechanical wave packet averaged frequencies, ω̄j(t), of the reporter modes j along the trajectory of |Ψ1 (0)(t)>. 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 ω̄j(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
NASA Astrophysics Data System (ADS)
Méndez-Fragoso, Ricardo; Cabrera-Trujillo, Remigio
2015-05-01
The determination of the maximum number of atoms and the density profile of an ultra-cold wave-packet, under confinement conditions by an attractive impurity near the de-localization threshold, have been an open problem in ultra-cold atom physics. In this work, we study the effect of a wave-guide impurity on an ultra-cold matter wave-packet at the threshold of de-localization. The impurity is modeled by a 1-D square well potential with depth V 0 and length 2 R 0. Coupling of the square well potential to a contact impurity of strength β at the center is also considered. The time-independent non-linear Schrödinger equation describing a Bose-Einstein condensate at the delocalization threshold is exactly solved. The density profile, maximum non-linear coupling constant, g max, and maximum number of atoms, N max, prompt to be localized by the defect potential in the ground and first excited states are also reported. It is shown that g max and the density profiles become only functions of the reduced impurity size ξ = √ V 0 R 0. It is also found that the first excited state at the threshold of de-localization exists only for ξ ≥ π/(2√2), always holding a lower number of atoms than the corresponding ground state for the same reduced impurity size. Also, the addition of a repulsive contact impurity leads to a non-linear coupling constant at the de-localization threshold lower than that of the square well potential. In spite of the non-linear character of the Gross-Pitaevskii equation, it is found that a general scaling-law holds for defects with the same ξ, related with the same g max, having the same reduced density profile in the quasi-free direction. We report the full width at half maximum for the wave-function and density profile, finding a large spread for small reduced confining conditions. Implications of these results for the determination of the wave-packet properties under confinement in atom chip and Bose-Einstein condensates are presented with the
White, Alexander James; Tretiak, Sergei; Mozyrsky, Dima V.
2016-04-25
Accurate simulation of the non-adiabatic dynamics of molecules in excited electronic states is key to understanding molecular photo-physical processes. Here we present a novel method, based on a semiclassical approximation, that is as efficient as the commonly used mean field Ehrenfest or ad hoc surface hopping methods and properly accounts for interference and decoherence effects. This novel method is an extension of Heller's thawed Gaussian wave-packet dynamics that includes coupling between potential energy surfaces. By studying several standard test problems we demonstrate that the accuracy of the method can be systematically improved while maintaining high efficiency. The method is suitablemore » for investigating the role of quantum coherence in the non-adiabatic dynamics of many-atom molecules.« less
White, Alexander James; Tretiak, Sergei; Mozyrsky, Dima V.
2016-04-25
Accurate simulation of the non-adiabatic dynamics of molecules in excited electronic states is key to understanding molecular photo-physical processes. Here we present a novel method, based on a semiclassical approximation, that is as efficient as the commonly used mean field Ehrenfest or ad hoc surface hopping methods and properly accounts for interference and decoherence effects. This novel method is an extension of Heller's thawed Gaussian wave-packet dynamics that includes coupling between potential energy surfaces. By studying several standard test problems we demonstrate that the accuracy of the method can be systematically improved while maintaining high efficiency. The method is suitable for investigating the role of quantum coherence in the non-adiabatic dynamics of many-atom molecules.
Complex time paths for semiclassical wave packet propagation with complex trajectories
NASA Astrophysics Data System (ADS)
Petersen, Jakob; Kay, Kenneth G.
2014-08-01
The use of complex-valued trajectories in semiclassical wave packet methods can lead to problems that prevent calculation of the wave function in certain regions of the configuration space. We investigate this so-called bald spot problem in the context of generalized Gaussian wave packet dynamics. The analysis shows that the bald spot phenomenon is essentially due to the complex nature of the initial conditions for the trajectories. It is, therefore, expected to be a general feature of several semiclassical methods that rely on trajectories with such initial conditions. A bald region is created when a trajectory, needed to calculate the wave function at a given time, reaches a singularity of the potential energy function in the complex plane at an earlier, real time. This corresponds to passage of a branch point singularity across the real axis of the complex time plane. The missing portions of the wave function can be obtained by deforming the time path for the integration of the equations of motion into the complex plane so that the singularity is circumvented. We present examples of bald spots, singularity times, and suitable complex time paths for one-dimensional barrier transmission in the Eckart and Gaussian systems. Although the bald regions for the Eckart system are often localized, they are found to be semi-infinite for the Gaussian system. For the case of deep tunneling, the bald regions for both systems may encompass the entire portion of space occupied by the transmitted wave packet. Thus, the use of complex time paths becomes essential for a treatment of barrier tunneling.
Observational evidence for the collapsing Langmuir wave packet in a solar type III radio burst
NASA Astrophysics Data System (ADS)
Thejappa, G.; MacDowall, R. J.; Bergamo, M.
2013-07-01
High time resolution observations from the STEREO spacecraft show that in solar type III radio bursts, Langmuir waves often occur as very intense one-dimensional magnetic field aligned field structures. One of these events represents the most intense Langmuir wave packet with
NASA Astrophysics Data System (ADS)
Brackhagen, O.; Kühn, O.; Manz, J.; May, V.; Meyer, R.
1994-06-01
The dynamics of cyclic systems with four equivalent potential minima is studied here from two different points of view. The solution of the time-dependent Schrödinger equation provides insight into the coherent wave packet motion. The resulting reaction mechanism involves relocalization between opposite, not neighboring potential minima. The inclusion of an environment within a density matrix description leads to dissipation and therefore to a transition from coherent to incoherent dynamics. The theoretical considerations are applied to a simple model of the cyclic motion of a proton in a molecular framework.
Piecewise Adiabatic Population Transfer in a Molecule via a Wave Packet
Shapiro, Evgeny A.; Peer, Avi; Ye Jun; Shapiro, Moshe
2008-07-11
We propose a class of schemes for robust population transfer between quantum states that utilize trains of coherent pulses, thus forming a generalized adiabatic passage via a wave packet. We study piecewise stimulated Raman adiabatic passage with pulse-to-pulse amplitude variation, and piecewise chirped Raman passage with pulse-to-pulse phase variation, implemented with an optical frequency comb. In the context of production of ultracold ground-state molecules, we show that with almost no knowledge of the excited potential, robust high-efficiency transfer is possible.
Turbulence generation during the head-on collision of Alfvénic wave packets
NASA Astrophysics Data System (ADS)
Pezzi, O.; Malara, F.; Servidio, S.; Valentini, F.; Parashar, T. N.; Matthaeus, W. H.; Veltri, P.
2017-08-01
The description of the Moffatt and Parker problem recently revisited by O. Pezzi et al. [Astrophys. J. 834, 166 (2017), 10.3847/1538-4357/834/2/166] is here extended by analyzing the features of the turbulence produced by the interaction of two colliding Alfvénic wave packets in a kinetic plasma. Although the approach based on the presence of linear modes features is still helpful in characterizing some low-energy fluctuations, other signatures, which go beyond the pure linear modes analysis, are recovered, such as the significant weakening of clear dispersion relations and the production of zero frequency fluctuations.
Tunnelling time of a gaussian wave packet through two potential barriers
NASA Astrophysics Data System (ADS)
Petrillo, Vittoria; Olkhovsky, Vladislav
2005-09-01
The resonant and non-resonant dynamies of a Gaussian quantum wave packet travelling through a double barrier system is studied as a function of the initial characteristics of the spectrum and of the parameters of the potential. The behaviour of the tunnelling time shows that there are situations where the Hartman effect occurs, while, when the resonances are dominant, and in particular for b>π/Δk (b being the inter-barrier distance and Δk the spectrum width), the tunnelling time becomes very large and the Hartman effect does not take place.
Time-reversal-symmetric single-photon wave packets for free-space quantum communication.
Trautmann, N; Alber, G; Agarwal, G S; Leuchs, G
2015-05-01
Readout and retrieval processes are proposed for efficient, high-fidelity quantum state transfer between a matter qubit, encoded in the level structure of a single atom or ion, and a photonic qubit, encoded in a time-reversal-symmetric single-photon wave packet. They are based on controlling spontaneous photon emission and absorption of a matter qubit on demand in free space by stimulated Raman adiabatic passage. As these processes do not involve mode selection by high-finesse cavities or photon transport through optical fibers, they offer interesting perspectives as basic building blocks for free-space quantum-communication protocols.
Three-Dimensional Momentum Imaging of Electron Wave Packet Interference in Few-Cycle Laser Pulses
Gopal, R.; Simeonidis, K.; Moshammer, R.; Ergler, Th.; Duerr, M.; Kurka, M.; Kuehnel, K.-U.; Tschuch, S.; Schroeter, C.-D.; Bauer, D.; Ullrich, J.; Rudenko, A.; Herrwerth, O.; Uphues, Th.; Schultze, M.; Goulielmakis, E.; Uiberacker, M.; Lezius, M.; Kling, M. F.
2009-07-31
Using a reaction microscope, three-dimensional (3D) electron (and ion) momentum (P) spectra have been recorded for carrier-envelope-phase (CEP) stabilized few-cycle (approx5 fs), intense (approx4x10{sup 14} W/cm{sup 2}) laser pulses (740 nm) impinging on He. Preferential emission of low-energy electrons (E{sub e}<15 eV) to either hemisphere is observed as a function of the CEP. Clear interference patterns emerge in P space at CEPs with maximum asymmetry, interpreted as attosecond interferences of rescattered and directly emitted electron wave packets by means of a simple model.
Steering the Electron in H{sub 2}{sup +} by Nuclear Wave Packet Dynamics
Fischer, Bettina; Kremer, Manuel; Pfeifer, Thomas; Feuerstein, Bernold; Sharma, Vandana; Schroeter, Claus Dieter; Moshammer, Robert; Ullrich, Joachim; Thumm, Uwe
2010-11-26
By combining carrier-envelope phase (CEP) stable light fields and the traditional method of optical pump-probe spectroscopy we study electron localization in dissociating H{sub 2}{sup +} molecular ions. Localization and localizability of electrons is observed to strongly depend on the time delay between the two CEP-stable laser pulses with a characteristic periodicity corresponding to the oscillating molecular wave packet. Variation of the pump-probe delay time allows us to uncover the underlying physical mechanism for electron localization, which are two distinct sets of interfering dissociation channels that exhibit specific temporal signatures in their asymmetry response.
Imaging and control of interfering wave packets in a dissociating molecule.
Skovsen, Esben; Machholm, Mette; Ejdrup, Tine; Thøgersen, Jan; Stapelfeldt, Henrik
2002-09-23
Using two identical 110 femtosecond (fs) optical pulses separated by 310 fs, we launch two dissociative wave packets in I2. We measure the square of the wave function as a function of both the internuclear separation, /Psi(R)/(2), and of the internuclear velocity, /Psi(v(R))/(2), by ionizing the dissociating molecule with an intense 20 fs probe pulse. Strong interference is observed in both /Psi(R)/(2) and in /Psi(v(R))/(2). The interference, and therefore the shape of the wave function, is controlled through the phase difference between the two dissociation pulses in good agreement with calculations.
NASA Astrophysics Data System (ADS)
Grabowski, Paul; Markmann, Andreas; Murillo, Michael; Graziani, Frank; Cimarron Collaboration
2011-10-01
During inertial confinement fusion, matter evolves from a solid condensed matter phase through the warm dense matter (WDM) regime to a hot dense matter. In WDM, quantum mechanical effects are important because of both Fermi-Dirac statistics and the rate of electrons transitioning in and out of bound states is large. The time-dependent temperature and quickly changing local environment require a time-dependent quantum method. A converged dynamical quantum simulation is intractable for more than a few particles. Instead, we take as a feasible goal to match the statistical properties of a warm dense plasma. The time-dependent variational principle gives a framework for producing equations of motion. A commonly used ansatz is a Hartree product of isotropic Gaussian wave packets (wave packet molecular dynamics). The resulting dynamics do not produce the right statistics. We therefore introduce a plane wave basis and discuss its advantages and test its ability to reproduce radial distribution functions produced by hyper-netted chain calculations.
NASA Astrophysics Data System (ADS)
Grabowski, Paul; Markmann, Andreas; Surh, Mike; Murillo, Michael; Graziani, Frank
2012-02-01
During inertial confinement fusion, matter evolves from a solid condensed matter phase through the warm dense matter (WDM) regime to a hot dense matter. In WDM, quantum mechanical effects are important because of both Fermi-Dirac statistics and the rate of electrons transitioning in and out of bound states is large. The time-dependent temperature and quickly changing local environment require a time-dependent quantum method. A converged dynamical quantum simulation is intractable for more than a few particles. Instead, we take as a feasible goal to match the statistical properties of a warm dense plasma. The time-dependent variational principle gives a framework for producing equations of motion. A commonly used variational form is a Hartree product of isotropic Gaussian wave packets (wave packet molecular dynamics). The resulting dynamics do not produce the right statistics. We therefore introduce a plane wave basis and discuss its advantages and test its ability to reproduce radial distribution functions produced by hyper-netted chain calculations.
NASA Astrophysics Data System (ADS)
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).
The phase delay and its complex time: From stationary states up to wave packets
Grossel, Ph.
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.
Wave packet simulation of nonadiabatic dynamics in highly excited 1,3-dibromopropane.
Brogaard, Rasmus Y; Møller, Klaus B; Sølling, Theis I
2008-10-23
We have conducted wave packet simulations of excited-state dynamics of 1,3-dibromopropane (DBP) with the aim of reproducing the experimental results of the gas-phase pump-probe experiment by Kotting et al. [ Kotting, C. ; Diau, E. W.-G. ; Sølling, T. I. ; Zewail, A. H. J. Phys. Chem. A 2002, 106, 7530 ]. In the experiment, DBP is excited to a Rydberg state 8 eV above the ground state. The interpretation of the results is that a torsional motion of the bromomethylene groups with a vibrational period of 680 fs is activated upon excitation. The Rydberg state decays to a valence state, causing a dissociation of one of the carbon bromine bonds on a time scale of 2.5 ps. Building the theoretical framework for the wave packet propagation around this model of the reaction dynamics, the simulations reproduce, to a good extent, the time scales observed in the experiment. Furthermore, the simulations provide insight into how the torsion motion influences the bond breakage, and we can conclude that the mechanism that delays the dissociation is solely the electronic transition from the Rydberg state to the valence state and does not involve, for example, intramolecular vibrational energy redistribution (IVR).
Monte Carlo wave packet approach to dissociative multiple ionization in diatomic molecules
NASA Astrophysics Data System (ADS)
Leth, Henriette Astrup; Madsen, Lars Bojer; Mølmer, Klaus
2010-05-01
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 separately for each molecular charge state. Our model circumvents the solution of a multiparticle Schrödinger equation and makes it possible to extract the kinetic energy release spectrum via the Coulomb explosion channel as well as the physical origin of the different structures in the spectrum. 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.
Time-dependent quantum wave packet dynamics to study charge transfer in heavy particle collisions
NASA Astrophysics Data System (ADS)
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.
Photodissociation dynamics of the pyridinyl radical: Time-dependent quantum wave-packet calculations
NASA Astrophysics Data System (ADS)
Ehrmaier, Johannes; Picconi, David; Karsili, Tolga N. V.; Domcke, Wolfgang
2017-03-01
The H-atom photodissociation reaction from the pyridinyl radical (C5H5NH ) via the low-lying π σ* excited electronic state is investigated by nonadiabatic time-dependent quantum wave-packet dynamics calculations. A model comprising three electronic states and three nuclear coordinates has been constructed using ab initio multi-configurational self-consistent-field and multi-reference perturbation theory methods. Two conical intersections among the three lowest electronic states have been characterized in the framework of the linear vibronic-coupling model. Time-dependent wave-packet simulations have been performed using the multi-configuration time-dependent Hartree method. The population dynamics of the diabatic and adiabatic electronic states and the time-dependent dissociation behavior are analyzed for various vibrational initial conditions. The results provide detailed mechanistic insight into the photoinduced H-atom dissociation process from a hypervalent aromatic radical and show that an efficient dissociation reaction through two conical intersections is possible.
Scattering of twisted electron wave packets by atoms in the Born approximation
NASA Astrophysics Data System (ADS)
Karlovets, D. V.; Kotkin, G. L.; Serbo, V. G.; Surzhykov, A.
2017-03-01
The potential scattering of electrons carrying nonzero quanta of the orbital angular momentum (OAM) is studied in a framework of the generalized Born approximation, developed in our recent paper [D. V. Karlovets, G. L. Kotkin, and V. G. Serbo, Phys. Rev. A 92, 052703 (2015), 10.1103/PhysRevA.92.052703]. We treat these so-called twisted electrons as spatially localized wave packets. The simple and convenient expressions are derived for a number of scattering events in collision of such a vortex electron with a single potential, located at a given impact parameter with respect to the wave packet's axis. The more realistic scenarios are also considered with either localized (mesoscopic) targets or infinitely wide (macroscopic) ones that consist of randomly distributed atoms. Dependence of the electron-scattering pattern on the size and on the relative position of the target is studied in detail for all three scenarios of the single-potential, mesoscopic, and macroscopic targets made of hydrogen in the ground 1 s state. The results demonstrate that the angular distribution of the outgoing electrons can be very sensitive to the OAM and to kinematic parameters of the focused twisted beams, as well as to composition of the target. Scattering of vortex electrons by atoms can, therefore, serve as a valuable tool for diagnostics of such beams.
Phase mixing of relativistically intense longitudinal wave packets in a cold plasma
NASA Astrophysics Data System (ADS)
Mukherjee, Arghya; Sengupta, Sudip
2016-09-01
Phase mixing of relativistically intense longitudinal wave packets in a cold homogeneous unmagnetized plasma has been studied analytically and numerically using the Dawson Sheet Model. A general expression for phase mixing time ( ω p t m i x ) as a function of amplitude of the wave packet (δ) and width of the spectrum ( Δ k / k ) has been derived. It is found that the phase mixing time crucially depends on the relative magnitude of amplitude "δ" and the spectral width " Δ k / k ". For Δ k / k ≤ 2 ωp 2 δ 2 / c 2 k 2 , ω p t m i x scales with δ as ˜ 1 / δ 5 , whereas for Δ k / k > 2 ωp 2 δ 2 / c 2 k 2 , ω p t m i x scales with δ as ˜ 1 / δ 3 , where ωp is the non-relativistic plasma frequency and c is the speed of light in vacuum. We have also verified the above theoretical scalings using numerical simulations based on the Dawson Sheet Model.
Coherent structural trapping through wave packet dispersion during photoinduced spin state switching
Lemke, Henrik T.; Kjær, Kasper S.; Hartsock, Robert; ...
2017-05-24
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 dispersionmore » 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.« less
A wavelet based time-frequency analysis of wave packet fractional revivals
NASA Astrophysics Data System (ADS)
Ghosh, Suranjana; Banerji, Jagannath
2007-06-01
We show that the time-frequency analysis of the autocorrelation function based on its wavelet transform [1], is a better tool to resolve fractional revivals [2] of a wave packet than the usual time domain analysis. We study the above for two different systems like a Rydberg atom [3] and a diatomic molecular system [4] and show that the present method can resolve fractional revivals of higher order than what can be achieved by the time domain analysis. This advantage is crucial in reconstructing the initial state of the wave packet when its coherent structure is short-lived and decays before it is fully revived. References: [1] R. M. Rao and A. S. Bopardikar, Wavelet Transforms: Introduction to Theory and Applications (ADDISON-WESLEY, 2000). [2] I. Sh. Averbukh and N. F. Perelman, Phys. Lett. A 139, 449 (1989); R. W. Robinett, Phys. Rep. 392, 1 (2004) and references therein; J. Banerji and S. Ghosh, J. Phys. B 39, 1113 (2006). [3] Z. D. Gaeta and C. R. Stroud, Jr., Phys. Rev. A 42, 6308 (1990). [4] S. Ghosh, A. Chiruvelli, J. Banerji and P. K. Panigrahi, Phys. Rev. A 70, 053813 (2006).
Iyengar, Srinivasan S; Jakowski, Jacek
2005-03-15
A methodology to efficiently conduct simultaneous dynamics of electrons and nuclei is presented. The approach involves quantum wave packet dynamics using an accurate banded, sparse and Toeplitz representation for the discrete free propagator, in conjunction with ab initio molecular dynamics treatment of the electronic and classical nuclear degree of freedom. The latter may be achieved either by using atom-centered density-matrix propagation or by using Born-Oppenheimer dynamics. The two components of the methodology, namely, quantum dynamics and ab initio molecular dynamics, are harnessed together using a time-dependent self-consistent field-like coupling procedure. The quantum wave packet dynamics is made computationally robust by using adaptive grids to achieve optimized sampling. One notable feature of the approach is that important quantum dynamical effects including zero-point effects, tunneling, as well as over-barrier reflections are treated accurately. The electronic degrees of freedom are simultaneously handled at accurate levels of density functional theory, including hybrid or gradient corrected approximations. Benchmark calculations are provided for proton transfer systems and the dynamics results are compared with exact calculations to determine the accuracy of the approach.
Coherent structural trapping through wave packet dispersion during photoinduced spin state switching
NASA Astrophysics Data System (ADS)
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.
NASA Astrophysics Data System (ADS)
Fan, Rongwei; He, Ping; Chen, Deying; Xia, Yuanqin; Yu, Xin; Wang, Jialing; Jiang, Yugang
2013-02-01
Based on ultrafast laser pulses, time-resolved resonance enhancement coherent anti-Stokes Raman scattering (RE-CARS) is applied to investigate wave-packet dynamics in gaseous iodine. The effects of air pressure on the wave-packet dynamics of iodine molecules are studied at pressures ranging from 1.5 Torr to 750 Torr. The RE-CARS signals are recorded in a gas cell filled with a mixture of about 0.3 Torr iodine in air buffer gas at room temperature. The revivals and fractional revival structures in the wave-packet signal are found to gradually disappear with rising air pressure up to 750 Torr, and the decay behaviors of the excited B-state and ground X-state become faster with increasing air pressure, which is due to the collision effects of the molecules and the growing complexity of the spectra at high pressures.
NASA Astrophysics Data System (ADS)
Chenu, Aurélia; Combescot, Monique
2017-06-01
Free classical particles have well-defined momentum and position, while free quantum particles have well-defined momentum but a position fully delocalized over the sample volume. We develop a many-body formalism based on wave-packet operators that connects these two limits, the thermal energy being distributed between the state spatial extension and its thermal excitation. The corresponding mixed quantum-classical states, which render the Boltzmann operator diagonal, are the physically relevant states when the temperature is finite. The formulation of many-body Hamiltonians in terms of these thermally excited wave packets and the resulting effective scatterings is provided.
Tracking nuclear wave-packet dynamics in molecular oxygen ions with few-cycle infrared laser pulses
De, S.; Bocharova, I. A.; Magrakvelidze, M.; Ray, D.; Cao, W.; Thumm, U.; Cocke, C. L.; Bergues, B.; Kling, M. F.; Litvinyuk, I. V.
2010-07-15
We have tracked nuclear wave-packet dynamics in doubly charged states of molecular oxygen using few-cycle infrared laser pulses. Bound and dissociating wave packets were launched and subsequently probed via a pair of 8-fs pulses of 790 nm radiation. Ionic fragments from the dissociating molecules were monitored by velocity-map imaging. Pronounced oscillations in the delay-dependent kinetic energy release spectra were observed. The occurrence of vibrational revivals permits us to identify the potential curves of the O{sub 2} dication which are most relevant to the molecular dynamics. These studies show the accessibility to the dynamics of such higher-charged molecules.
Burenkov, I. A.; Tikhonova, O. V.
2010-06-15
We consider features of absorption and emission of external laser field quanta by a broad (in the momentum representation) electron wave packet during its scattering from a potential center. Various scattering modes for the electron wave packet in a high-intensity laser field are analyzed using perturbation theory of potential energy. It is found that the absorption of laser field energy by an electron is substantially more effective as compared to the case of a plane wave. The important role of a number of interference effects associated with the large width of the initial electron momentum distribution is demonstrated.
Phase-stepping interferometry: methods for reducing errors caused by camera nonlinearities.
Schödel, René; Nicolaus, Arnold; Bönsch, Gerhard
2002-01-01
Phase errors that arise in phase-stepping interferometry are discussed. Investigations were performed by use of a Twyman-Green interferometer equipped with a compensation plate with a variable and servo-controlled tilt angle. With this instrument, phase-stepping errors can be reduced to a negligible level. There are, however, phase errors that are caused by camera nonlinearities. Two methods for minimizing these errors are presented. The first method is based on the simple idea that the interference intensity at the output of a two-beam interferometer has an exact cosine shape. The camera signals were monitored as a function of the tilt angle of the compensation plate, and the deviation from the cosine form was used to produce a correction. The second method is based on the idea that, under specific conditions, errors of an average of two phase measurements may compensate for each other. Numerical calculations were performed and give evidence of this hypothesis. Each method, the signal-correction and the averaging method, drastically reduces errors in evaluation of phases. The combination of both methods is a powerful tool that allows precise phase data to be obtained with an uncertainty, in the range lambda/2000 approximately 0.3 nm, that is caused mainly by signal noise.
On the Quantum Potential and Pulsating Wave Packet in the Harmonic Oscillator
Dubois, Daniel M.
2008-10-17
A fundamental mathematical formalism related to the Quantum Potential factor, Q, is presented in this paper. The Schroedinger equation can be transformed to two equations depending on a group velocity and a density of presence of the particle. A factor, in these equations, was called ''Quantum Potential'' by D. Bohm and B. Hiley. In 1999, I demonstrated that this Quantum Potential, Q, can be split in two Quantum Potentials, Q{sub 1}, and Q{sub 2}, for which the relation, Q=Q{sub 1}+Q{sub 2}, holds. These two Quantum Potentials depend on a fundamental new variable, what I called a phase velocity, u, directly related to the probability density of presence of the wave-particle, given by the modulus of the wave function. This paper gives some further developments for explaining the Quantum Potential for oscillating and pulsating Gaussian wave packets in the Harmonic Oscillator. It is shown that the two Quantum Potentials play a central role in the interpretation of quantum mechanics. A breakthrough in the formalism of the Quantum Mechanics could be provoked by the physical properties of these Quantum Potentials. The probability density of presence of the oscillating and pulsating Gaussian wave packets in the Harmonic Oscillator is directly depending on the ratio Q{sub 2}/Q{sub 1} of the two Quantum Potentials. In the general case, the energy of these Gaussian wave packets is not constant, but is oscillating. The energy is given by the sum of the kinetic energy, T, the potential energy, V, and the two Quantum Potentials: E=T+V+Q{sub 1}+Q{sub 2}. For some conditions, given in the paper, the energy can be a constant. The first remarkable result is the fact that the first Quantum Potential, Q{sub 1}, is related to the ground state energy, E{sub 0}, of the Quantum Harmonic Oscillator: Q{sub 1}=h-bar {omega}/2=E{sub 0}. The second result is related to the property of the second Quantum Potential, Q{sub 2}, which plays the role of an anti-potential, Q{sub 2}=-V(x), where V is
Wave packet motions coupled to electron transfer in reaction centers of Chloroflexus aurantiacus.
Yakovlev, Andrei G; Shkuropatova, Tatiana A; Vasilieva, Lyudmila G; Shkuropatov, Anatoli Ya; Shuvalov, Vladimir A
2008-08-01
Transient absorption difference spectroscopy with approximately 20 femtosecond (fs) resolution was applied to study the time and spectral evolution of low-temperature (90 K) absorbance changes in isolated reaction centers (RCs) of Chloroflexus (C.) aurantiacus. In RCs, the composition of the B-branch chromophores is different with respect to that of purple bacterial RCs by occupying the B(B) binding site of accessory bacteriochlorophyll by bacteriopheophytin molecule (Phi(B)). It was found that the nuclear wave packet motion induced on the potential energy surface of the excited state of the primary electron donor P* by approximately 20 fs excitation leads to a coherent formation of the states P+Phi(B)(-) and P+B(A)(-) (B(A) is a bacteriochlorophyll monomer in the A-branch of cofactors). The processes were studied by measuring coherent oscillations in kinetics of the absorbance changes at 900 nm and 940 nm (P* stimulated emission), at 750 nm and 785 nm (Phi(B) absorption bands), and at 1,020-1028 nm (B(A)(-) absorption band). In RCs, the immediate bleaching of the P band at 880 nm and the appearance of the stimulated wave packet emission at 900 nm were accompanied (with a small delay of 10-20 fs) by electron transfer from P* to the B-branch with bleaching of the Phi(B) absorption band at 785 nm due to Phi(B)(-) formation. These data are consistent with recent measurements for the mutant HM182L Rb. sphaeroides RCs (Yakovlev et al., Biochim Biophys Acta 1757:369-379, 2006). Only at a delay of 120 fs was the electron transfer from P* to the A-branch observed with a development of the B(A)(-) absorption band at 1028 nm. This development was in phase with the appearance of the P* stimulated emission at 940 nm. The data on the A-branch electron transfer in C. aurantiacus RCs are consistent with those observed in native RCs of Rb. sphaeroides. The mechanism of charge separation in RCs with the modified B-branch pigment composition is discussed in terms of coupling between
NASA Astrophysics Data System (ADS)
Walterscheid, R. L.; Heale, C. J.; Snively, J. B.
2016-12-01
A question of fundamental importance is the altitudes to which waves originating in the lower atmosphere can propagate. It is well-known that high-frequency waves may propagate to great heights, while slow waves are damped at lower altitudes. Less well known is that the nature of the disturbance, whether it is a localized wave packet excited by transient forcing or a steady-state wave excited by sustained forcing, also controls wave decay. Wave packets may diminish in amplitude by the spreading of wave energy due to dispersion, whereas steady-state waves are already fully dispersed. For steady-state waves dissipation always gives an increase in the vertical wavelength, for wavepackets localization (bandwidth) plays a key role and depending on the degree of localization scale-dependent dissipation may preferentially absorb either short vertical wavelength components of a wavetrain (slow waves), or long vertical wavelength components (fast waves). If the dispersed wavetrain is long compared to the scale height for kinematic viscosity then clipping of the waveform occurs that preferentially damps fast waves with longer vertical wavelengths at the leading edge of the packet, with the result that the central wavelength decreases. This causes the dissipating packet to ascend slower and damp sooner than would be indicated by the inviscid group velocity [Heale et al., JGR, 2014]. On the other hand, if the wavepacket is highly localized initially and remains that way (is not too dispersive) so that viscosity does not vary too strongly across the packet then the small scale components are damped first because the rate of dissipation is higher for these components. This shifts the central wavelength to larger values and causes the dissipating packets to ascent higher and more rapidly than inviscid theory would indicate [Walterscheid, JGR, 2013]. The theory of wave packet propagation subject to decay in a viscous media will be reviewed and results of calculations with a time
Two-center interferences and nuclear wave packet imaging in dissociating H2+ molecule
NASA Astrophysics Data System (ADS)
Picon, Antonio; Bahabad, Alon; Kapteyn, Henry C.; Murnane, Margaret M.; Becker, Andreas
2011-05-01
Double-slit like interferences similar to those observed by Young in his experiment with light appear also in the photoionization of diatomic molecules. The partial electron waves ejected from the two atomic centers of the molecule take the role of the coherent light waves emerging from the two holes in Youngs experiment. We analyze theoretically and numerically a pump-probe scenario with two attosecond pulses in the hydrogen molecular ion. The first attosecond pulse induces the dissociation of the molecule, the second attosecond pulse is ionizing the molecule. By varying the delay between the pump and probe pulses we show how the two-center interferences allow to image main features of the nuclear wave packet, namely its velocity, internuclear distance, and spreading. Supported by Postdoctoral Program of the Spanish Government and NSF.
Wave-packet analysis of strong-field ionization of sodium in the quasistatic regime*
NASA Astrophysics Data System (ADS)
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.
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.
Scattering of an electronic wave packet by a one-dimensional electron-phonon-coupled structure
NASA Astrophysics Data System (ADS)
Brockt, C.; Jeckelmann, E.
2017-02-01
We investigate the scattering of an electron by phonons in a small structure between two one-dimensional tight-binding leads. This model mimics the quantum electron transport through atomic wires or molecular junctions coupled to metallic leads. The electron-phonon-coupled structure is represented by the Holstein model. We observe permanent energy transfer from the electron to the phonon system (dissipation), transient self-trapping of the electron in the electron-phonon-coupled structure (due to polaron formation and multiple reflections at the structure edges), and transmission resonances that depend strongly on the strength of the electron-phonon coupling and the adiabaticity ratio. A recently developed TEBD algorithm, optimized for bosonic degrees of freedom, is used to simulate the quantum dynamics of a wave packet launched against the electron-phonon-coupled structure. Exact results are calculated for a single electron-phonon site using scattering theory and analytical approximations are obtained for limiting cases.
NASA Astrophysics Data System (ADS)
Dey, Bijoy K.; Askar, Attila; Rabitz, H.
1998-11-01
This paper explores the quantum fluid dynamical (QFD) representation of the time-dependent Schrödinger equation for the motion of a wave packet in a high dimensional space. A novel alternating direction technique is utilized to single out each of the many dimensions in the QFD equations. This technique is used to solve the continuity equation for the density and the equation for the convection of the flux for the quantum particle. The ability of the present scheme to efficiently and accurately describe the dynamics of a quantum particle is demonstrated in four dimensions where analytical results are known. We also apply the technique to the photodissociation of NOCl and NO2 where the systems are reduced to two coordinates by freezing the angular variable at its equilibrium value.
Monitoring coherent electron wave packet excitation dynamics by two-color attosecond laser pulses
NASA Astrophysics Data System (ADS)
Yuan, Kai-Jun; Bandrauk, André D.
2016-11-01
We propose a method to monitor coherent electron wave packet (CEWP) excitation dynamics with two-color attosecond laser pulses. Simulations are performed on aligned H2+ by numerically solving the three-dimensional time-dependent Schrödinger equation with combinations of a resonant linearly polarized λl= 100/70 nm pump pulse and a circularly polarized λc=5 nm attosecond probe pulse. It is found that time dependent diffraction patterns in molecular frame photoelectron angular distributions (MFPADs) produced by the circular probe pulse exhibit sensitivity to the molecular alignments and time-dependent geometry of the CEWPs during and after the coherent excitation between the ground and excited states induced by the linear pump pulse. The time dependent MFPADs are described by an ultrafast diffraction model for the ionization of the bound CEWPs.
Scattered-wave-packet formalism with applications to barrier scattering and quantum transistors.
Chou, Chia-Chun; Wyatt, Robert E
2011-11-01
The scattered wave formalism developed for a quantum subsystem interacting with reservoirs through open boundaries is applied to one- or two-dimensional barrier scattering and quantum transistors. The total wave function is divided into incident and scattered components. Markovian outgoing wave boundary conditions are imposed on the scattered or total wave function by either the ratio or polynomial methods. For barrier scattering problems, accurate time-dependent transmission probabilities are obtained through the integration of the modified time-dependent Schrödinger equations for the scattered wave function. For quantum transistors, the time-dependent transport is studied for a quantum wave packet propagating through the conduction channel of a field effect transistor. This study shows that the scattered wave formalism significantly reduces computational effort relative to other open boundary methods and demonstrates wide applications to quantum dynamical processes.
Tunneling wave packets of atoms from intense elliptically polarized fields in natural geometry
NASA Astrophysics Data System (ADS)
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.
New concept for the pairing anti-halo effect as a localized wave packet of quasiparticles
NASA Astrophysics Data System (ADS)
Hagino, K.; Sagawa, H.
2017-02-01
The pairing anti-halo effect is a phenomenon that a pairing correlation suppresses a divergence of nuclear radius, which happens for single-particle states with orbital angular momenta of l =0 and 1 in the limit of vanishing binding energy. While this effect has mainly been discussed in terms of Hartree-Fock-Bogoliubov (HFB) theory, we here use a three-body model and provide its new intuitive concept as a localized wave packet for a quasiparticle, that is, a coherent superposition of a weakly bound and continuum wave functions due to a pairing interaction. We show that the one-particle density in the three-body model can be directly expressed with such quasiparticle wave functions, which have a close analog to wave functions in the HFB approximation.
Optical parametric amplification of X-shaped localised wave-packets
Dubietis, A; Smilgevicius, V; Stabinis, A; Valiulis, G; Piskarskas, A
2009-07-31
The general concepts for generation and amplification of the X-pulses in optical parametric amplifiers under the plane-wave and localised (Bessel beam, or more generally, X-pulse) pump are reviewed. It is shown numerically and experimentally that X-pulse phase-matching gives rise to spontaneous emergence of the localised light structures in the regime of the parametric frequency down-conversion. The parametric amplification technique of localised waves is extended to the chirped X-pulse optical parametric amplification concept, which allows one to achieve few optical cycle, high-peak power localised wave packets for laser-matter interactions. (special issue devoted to the 80th birthday of s.a. akhmanov)
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.
Rapid propagation of a Bloch wave packet excited by a femtosecond ultraviolet pulse
NASA Astrophysics Data System (ADS)
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.
Scaling of Wave-Packet Dynamics in an Intense Midinfrared Field
Tate, J.; Agostini, P.; DiMauro, L. F.; Auguste, T.; Salieres, P.; Muller, H. G.
2007-01-05
A theoretical investigation is presented that examines the wavelength scaling from near-visible (0.8 {mu}m) to midinfrared (2 {mu}m) of the photoelectron distribution and high harmonics generated by a 'single' atom in an intense electromagnetic field. The calculations use a numerical solution of the time-dependent Schroedinger equation (TDSE) in argon and the strong-field approximation in helium. The scaling of electron energies ({lambda}{sup 2}), harmonic cutoff ({lambda}{sup 2}), and attochirp ({lambda}{sup -1}) agree with classical mechanics, but it is found that, surprisingly, the harmonic yield follows a {lambda}{sup -(5-6)} scaling at constant intensity. In addition, the TDSE results reveal an unexpected contribution from higher-order returns of the rescattering electron wave packet.
Scattering of Light by Electron Wave Packets: Size Doesn't Matter
NASA Astrophysics Data System (ADS)
Corson, John; Glasgow, Scott; Acosta, Sebastian; Ware, Michael; Peatross, Justin
2011-05-01
In support of a current experiment, we investigate light scattering by individual free electrons in an intense laser focus using full second quantization. This addresses the question of whether emission from a large electron packet will be suppressed owing to interference between different parts of the packet. Textbook treatments of Compton scattering generally use exact momentum states, but packets necessarily superpose many momentum states with the possibility of quantum interference (see J. Peatross, C. Muller, K. Hatsagortsyan, and C. H. Keitel, Phys. Rev. Lett. 100, 153601, 2008). We investigate the details of this interference for both single- photon and coherent-state scattering. Kinematic constraints eliminate interference in the case of unidirectional stimulation, whether the scattering is single- or multi-photon in nature. To all orders of perturbation theory, the scattering exhibits no dependence on the relative phases of constituent momenta, and thus no dependence on wave packet size.
Transverse, longitude shift and deflected angle from the spin Hall effect of a Gaussian wave packet
NASA Astrophysics Data System (ADS)
Gao, Jie; Wu, Hai-Ying; Yu, Yi-cong; Wang, Xue-Hua
2015-05-01
Replacing the saddle-point approximation extensively adopted in previous literature, an exact expression for the Fourier transformation of electric field distributions of reflected and refracted polarised Gaussian beams is derived to investigate the spin Hall effect of light. A general method based upon the partial differential of the light intensity distributions of the reflected and refracted propagating beams is presented to determine the beam shifts from the spin Hall effect of light. Compared with the previous integration method along one direction reported in the literature, our method not only is much more explicit, but also enables us simultaneously to obtain the transverse and longitude shifts of the reflected and refracted wave packets. Furthermore, at any propagation distance away from the interface between two optical media, the shifts of the propagating beams and their split ones can be analytically expressed by means of transverse- and longitude-deflected angles.
NASA Astrophysics Data System (ADS)
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.
Wessels, Philipp; Vogel, Andreas; Tödt, Jan-Niklas; Wieland, Marek; Meier, Guido; Drescher, Markus
2016-02-24
The analysis of isolated spin-wave packets is crucial for the understanding of magnetic transport phenomena and is particularly interesting for applications in spintronic and magnonic devices, where isolated spin-wave packets implement an information processing scheme with negligible residual heat loss. We have captured microscale magnetization dynamics of single spin-wave packets in metallic ferromagnets in space and time. Using an optically driven high-current picosecond pulse source in combination with time-resolved scanning Kerr microscopy probed by femtosecond laser pulses, we demonstrate phase-sensitive real-space observation of spin-wave packets in confined permalloy (Ni80Fe20) microstripes. Impulsive excitation permits extraction of the dynamical parameters, i.e. phase- and group velocities, frequencies and wave vectors. In addition to well-established Damon-Eshbach modes our study reveals waves with counterpropagating group- and phase-velocities. Such unusual spin-wave motion is expected for backward volume modes where the phase fronts approach the excitation volume rather than emerging out of it due to the negative slope of the dispersion relation. These modes are difficult to excite and observe directly but feature analogies to negative refractive index materials, thus enabling model studies of wave propagation inside metamaterials.
NASA Astrophysics Data System (ADS)
Wessels, Philipp; Vogel, Andreas; Tödt, Jan-Niklas; Wieland, Marek; Meier, Guido; Drescher, Markus
2016-02-01
The analysis of isolated spin-wave packets is crucial for the understanding of magnetic transport phenomena and is particularly interesting for applications in spintronic and magnonic devices, where isolated spin-wave packets implement an information processing scheme with negligible residual heat loss. We have captured microscale magnetization dynamics of single spin-wave packets in metallic ferromagnets in space and time. Using an optically driven high-current picosecond pulse source in combination with time-resolved scanning Kerr microscopy probed by femtosecond laser pulses, we demonstrate phase-sensitive real-space observation of spin-wave packets in confined permalloy (Ni80Fe20) microstripes. Impulsive excitation permits extraction of the dynamical parameters, i.e. phase- and group velocities, frequencies and wave vectors. In addition to well-established Damon-Eshbach modes our study reveals waves with counterpropagating group- and phase-velocities. Such unusual spin-wave motion is expected for backward volume modes where the phase fronts approach the excitation volume rather than emerging out of it due to the negative slope of the dispersion relation. These modes are difficult to excite and observe directly but feature analogies to negative refractive index materials, thus enabling model studies of wave propagation inside metamaterials.
Vubangsi, M.; Tchoffo, M.; Fai, L. C.; Pisma’k, Yu. M.
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. .
Wessels, Philipp; Vogel, Andreas; Tödt, Jan-Niklas; Wieland, Marek; Meier, Guido; Drescher, Markus
2016-01-01
The analysis of isolated spin-wave packets is crucial for the understanding of magnetic transport phenomena and is particularly interesting for applications in spintronic and magnonic devices, where isolated spin-wave packets implement an information processing scheme with negligible residual heat loss. We have captured microscale magnetization dynamics of single spin-wave packets in metallic ferromagnets in space and time. Using an optically driven high-current picosecond pulse source in combination with time-resolved scanning Kerr microscopy probed by femtosecond laser pulses, we demonstrate phase-sensitive real-space observation of spin-wave packets in confined permalloy (Ni80Fe20) microstripes. Impulsive excitation permits extraction of the dynamical parameters, i.e. phase- and group velocities, frequencies and wave vectors. In addition to well-established Damon-Eshbach modes our study reveals waves with counterpropagating group- and phase-velocities. Such unusual spin-wave motion is expected for backward volume modes where the phase fronts approach the excitation volume rather than emerging out of it due to the negative slope of the dispersion relation. These modes are difficult to excite and observe directly but feature analogies to negative refractive index materials, thus enabling model studies of wave propagation inside metamaterials. PMID:26906113
NASA Astrophysics Data System (ADS)
Efremov, M. A.; Petropavlovsky, S. V.; Fedorov, Mikhail V.; Schleich, Wolfgang P.; Yakovlev, V. P.
2005-08-01
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 decay of the atomic wave function away from the field nodes due to spontaneous transitions to nonresonance states and the quantum broadening of the wave packets formed in the close vicinity of field nodes. Coordinate-dependent amplitudes and phases of the two-dimensional wave packets were found for the jg=0 <--> je=1 transition.
NASA Astrophysics Data System (ADS)
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
Nuclear-wave-packet dynamics mapped out by two-center interference in the HeH2+ molecule
NASA Astrophysics Data System (ADS)
Schüler, M.; Pavlyukh, Y.; Berakdar, J.
2014-06-01
Photoemission from diatomic molecules closely resembles the Young-type double-slit experiment where each of the two atomic sites represents a coherent emission source. When the photoelectron wavelength becomes commensurate with the effective interatomic distance, the resulting spatial interference gives rise to oscillations in the photoionization total and differential cross sections. This phenomenon provides detailed information on the molecular geometry, a fact that can be utilized for probing the nuclear dynamics triggered by the interaction with a laser field. We demonstrate how this coherent wave-packet evolution can be traced by observing the photoelectron angular distribution. Based on ab initio scattering calculations we perform a proof-of-principle reconstruction of the nuclear-wave-packet evolution in the HeH2+ molecule.
Time-dependent wave packet study of the one atom cage effect in I2-Ar Van der Waals complexes
NASA Astrophysics Data System (ADS)
Zamith, S.; Meier, C.; Halberstadt, N.; Beswick, J. A.
1999-01-01
We performed a time-dependent wave packet study to investigate the fragmentation and recombination of the I2-Ar Van der Waals complex following excitation above the B-state dissociation limit. Based on a recently published ab initio potential energy surface of the ground state [C. F. Kunz, I. Burghardt, and B. Hess, J. Chem. Phys. 109, 359 (1998)], we studied the possible kinematic origin of the "one-atom cage effect" by three-dimensional wave packet propagation within the rotational infinite order sudden approximation. We found that final vibrational distributions depend strongly on the ground and excited state equilibrium geometries. Taking uncertainties in the excited state potential into account, we confirm a possible kinematic origin of the one-atom cage effect from a collinear isomer of the I2-Ar complex, initially proposed by Valentini and Cross [J. J. Valentini and J. B. Cross, J. Chem. Phys. 77, 572 (1982)].
NASA Astrophysics Data System (ADS)
Thiem, Stefanie; Schreiber, Michael
2012-06-01
We study the quantum diffusion in quasiperiodic tight-binding models in one, two, and three dimensions. First, we investigate a class of one-dimensional quasiperiodic chains, in which the atoms are coupled by weak and strong bonds aligned according to the metallic-mean sequences. The associated generalized labyrinth tilings in d dimensions are then constructed from the direct product of d such chains, which allows us to consider rather large systems numerically. The electronic transport is studied by computing the scaling behavior of the mean-square displacement of the wave packets with respect to time. The results reveal the occurrence of anomalous diffusion in these systems. By extending a renormalization group approach, originally proposed for the golden-mean chain, we show also for the silver-mean chain as well as for the higher-dimensional labyrinth tilings that in the regime of strong quasiperiodic modulation the wave-packet dynamics are governed by the underlying quasiperiodic structure.
Dynamics of zero-energy nonspreading non-Gaussian wave packets for a class of central potentials
Makowski, Adam J. Pepłowski, Piotr
2013-10-15
Zero-energy wave packets, coherent states, are constructed in such a way that they retain their shape during the time evolution for a large class of central potentials. The packets are not of the Gaussian type with −r{sup 2} dependence but, instead, their shape is determined by −r{sup 1/(μ+1/2)} with −1/2<μ<1/2. A very close quantum–classical correspondence is also shown, i.e., the well localized states travel along suitable classical trajectories. -- Highlights: •Central potentials are considered. •Nonspreading, non-Gaussian wave packets are constructed. •Time evolution of the zero-energy packets is studied. •Quantum–classical correspondence is discussed.
Magnetic antenna excitation of whistler modes. III. Group and phase velocities of wave packets
NASA Astrophysics Data System (ADS)
Urrutia, J. M.; Stenzel, R. L.
2015-07-01
The properties of whistler modes excited by single and multiple magnetic loop antennas have been investigated in a large laboratory plasma. A single loop excites a wavepacket, but an array of loops across the ambient magnetic field B0 excites approximate plane whistler modes. The single loop data are measured. The array patterns are obtained by linear superposition of experimental data shifted in space and time, which is valid in a uniform plasma and magnetic field for small amplitude waves. Phasing the array changes the angle of wave propagation. The antennas are excited by an rf tone burst whose propagating envelope and oscillations yield group and phase velocities. A single loop antenna with dipole moment across B0 excites wave packets whose topology resembles m = 1 helicon modes, but without radial boundaries. The phase surfaces are conical with propagation characteristics of Gendrin modes. The cones form near the antenna with comparable parallel and perpendicular phase velocities. A physical model for the wave excitation is given. When a wave burst is applied to a phased antenna array, the wave front propagates both along the array and into the plasma forming a "whistler wing" at the front. These laboratory observations may be relevant for excitation and detection of whistler modes in space plasmas.
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.
Real wave packet and quasiclassical trajectory studies of the H+ + LiH reaction.
Bulut, N; Castillo, J F; Aoiz, F J; Bañares, L
2008-02-14
Time-dependent real wave packet (RWP) and quasiclassical trajectory (QCT) calculations have been carried out to study the H(+) + LiH reaction on the ab initio potential-energy surface of Martinazzo et al. [J. Chem. Phys., 2003, 119, 11241]. Total initial state-selected and final state-resolved reaction probabilities for the two possible reaction channels, H(2)(+) + Li and LiH + H(+), have been calculated for total angular momentum J=0 at a broad range of collision energies. Integral cross sections and thermal rate coefficients have been calculated using the QCT method and from the corresponding J=0 RWP reaction probabilities by means of a capture model. The calculated thermal rate coefficients are found to be nearly independent of temperature in the 100-500 K interval with a value of approximately 10(-9) cm(3) s(-1), which is in good agreement with estimates used in evolutionary models of early-Universe lithium chemistry. The RWP results are found to be in good agreement overall with the corresponding QCT calculations.
NASA Astrophysics Data System (ADS)
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.
Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets
Pullen, M. G.; Wolter, B.; Le, A. -T.; Baudisch, M.; Sclafani, M.; Pires, H.; Schroter, C. D.; Ullrich, J.; Moshammer, R.; Pfeifer, T.; Lin, C. D.; Biegert, J.
2016-06-22
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 pg) 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 O_{2} and C_{2}H_{2} molecules, with π_{g} and π_{u} symmetries, respectively, and where their ionization probabilities do not maximize along their molecular axes. As a result, while this removes a serious bottleneck for laser-induced diffraction imaging, we find unexpectedly strong backscattering contributions from low-Z atoms.
Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets
Pullen, M. G.; Wolter, B.; Le, A. -T.; ...
2016-06-22
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 pg) 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 ofmore » the structure of randomly oriented O2 and C2H2 molecules, with πg and πu symmetries, respectively, and where their ionization probabilities do not maximize along their molecular axes. As a result, while this removes a serious bottleneck for laser-induced diffraction imaging, we find unexpectedly strong backscattering contributions from low-Z atoms.« less
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.
Wave-packet continuum-discretization approach to ion-atom collisions: Nonrearrangement scattering
NASA Astrophysics Data System (ADS)
Abdurakhmanov, I. B.; Kadyrov, A. S.; Bray, I.
2016-08-01
A general single-center close-coupling approach based on a continuum-discretization procedure is developed to calculate excitation and ionization processes in ion-atom collisions. The continuous spectrum of the target is discretized using stationary wave packets constructed from the Coulomb wave functions, the eigenstates of the target Hamiltonian. Such continuum discretization allows one to generate pseudostates with arbitrary energies and distribution. These features are ideal for detailed differential ionization studies. The approach starts from the semiclassical three-body Schrödinger equation for the scattering wave function and leads to a set of coupled differential equations for the transition probability amplitudes. To demonstrate its utility the method is applied to calculate collisions of antiprotons with atomic hydrogen. A comprehensive set of benchmark results from integrated to fully differential cross sections for antiproton-impact ionization of hydrogen in the energy range from 1 keV to 1 MeV is provided. Contrary to previous predictions, we find that at low incident energies the singly differential cross section has a maximum away from the zero emission energy. This feature could not be seen without a fine discretization of the low-energy part of the continuum.
'Superluminal paradox' in wave packet propagation and its quantum mechanical resolution
NASA Astrophysics Data System (ADS)
Sokolovski, D.; Akhmatskaya, E.
2013-12-01
We analyse in detail the reshaping mechanism leading to apparently 'superluminal' advancement of a wave packet traversing a classically forbidden region. In the coordinate representation, a barrier is shown to act as an effective beamsplitter, recombining envelopes of the freely propagating pulse with various spacial shifts. Causality ensures that none of the constituent envelopes are advanced with respect to free propagation, yet the resulting pulse is advanced due to a peculiar interference effect, similar to the one responsible for 'anomalous' values which occur in Aharonov's 'weak measurements'. In the momentum space, the effect is understood as a bandwidth phenomenon, where the incident pulse probes local, rather than global, analytical properties of the transmission amplitude T(p). The advancement is achieved when T(p) mimics locally an exponential behaviour, similar to the one occurring in Berry's 'superoscillations'. Seen in a broader quantum mechanical context, the 'paradox' is but a consequence of an attempt to obtain 'which way?' information without destroying the interference between the pathways of interest. This explains, to a large extent, the failure to adequately describe tunnelling in terms of a single 'tunnelling time'.
NASA Astrophysics Data System (ADS)
Rudinsky, S.; Sanz, A. S.; Gauvin, R.
2017-03-01
The numerical analysis of the diffraction features rendered by transmission electron microscopy typically relies either on classical approximations (Monte Carlo simulations) or quantum paraxial tomography (the multislice method and any of its variants). Although numerically advantageous (relatively simple implementations and low computational costs), they involve important approximations and thus their range of applicability is limited. To overcome such limitations, an alternative, more general approach is proposed, based on an optimal combination of wave-packet propagation with the on-the-fly computation of associated Bohmian trajectories. For the sake of clarity, but without a loss of generality, the approach is used to analyze the diffraction of an electron beam by a thin aluminum slab as a function of three different incidence (working) conditions which are of interest in electron microscopy: the probe width, the tilting angle, and the beam energy. Specifically, it is shown that, because there is a dependence on particular thresholds of the beam energy, this approach provides a clear description of the diffraction process at any energy, revealing at the same time any diversion of the beam inside the material towards directions that cannot be accounted for by other conventional methods, which is of much interest when dealing with relatively low energies and/or relatively large tilting angles.
Rudinsky, S; Sanz, A S; Gauvin, R
2017-03-14
The numerical analysis of the diffraction features rendered by transmission electron microscopy typically relies either on classical approximations (Monte Carlo simulations) or quantum paraxial tomography (the multislice method and any of its variants). Although numerically advantageous (relatively simple implementations and low computational costs), they involve important approximations and thus their range of applicability is limited. To overcome such limitations, an alternative, more general approach is proposed, based on an optimal combination of wave-packet propagation with the on-the-fly computation of associated Bohmian trajectories. For the sake of clarity, but without a loss of generality, the approach is used to analyze the diffraction of an electron beam by a thin aluminum slab as a function of three different incidence (working) conditions which are of interest in electron microscopy: the probe width, the tilting angle, and the beam energy. Specifically, it is shown that, because there is a dependence on particular thresholds of the beam energy, this approach provides a clear description of the diffraction process at any energy, revealing at the same time any diversion of the beam inside the material towards directions that cannot be accounted for by other conventional methods, which is of much interest when dealing with relatively low energies and/or relatively large tilting angles.
Scattering of twisted particles: Extension to wave packets and orbital helicity
Ivanov, I. P.; Serbo, V. G.
2011-09-15
High-energy photons and other particles carrying nonzero orbital angular momentum (OAM) emerge as a new tool in high-energy physics. Recently, it was suggested to generate high-energy photons with nonzero OAM (twisted photons) by the Compton backscattering of twisted optical photons on relativistic electron beams. Twisted electrons in the intermediate energy range have also been demonstrated experimentally; twisted protons and other particles can, in principle, be created in a similar way. Collisions of energetic twisted states can offer a new look at particle properties and interactions. A theoretical description of twisted particle scattering developed previously treated them as pure Bessel states and ran into difficulty when describing the OAM of the final twisted particle at nonzero scattering angles. Here we develop further this formalism by incorporating two additional important features. First, we treat the initial OAM state as a wave packet of a finite transverse size rather than a pure Bessel state. This realistic assumption allows us to resolve the existing controversy between two theoretical analyses for nonforward scattering. Second, we describe the final twisted particle in terms of the orbital helicity: the OAM projection on its average direction of propagation rather than on the fixed reaction axis. Using this formalism, we determine to what extent the twisted state is transferred from the initial to final OAM particle in a generic scattering kinematics. As a particular application, we prove that in the Compton backscattering the orbital helicity of the final photon stays close to the OAM projection of the initial photon.
Influence of orbital symmetry on diffraction imaging with rescattering electron wave packets
Pullen, M. G.; Wolter, B.; 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 πg) 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 πg and πu symmetries, respectively, and where their ionization probabilities do not maximize along their molecular axes. While this removes a serious bottleneck for laser-induced diffraction imaging, we find unexpectedly strong backscattering contributions from low-Z atoms. PMID:27329236
NASA Astrophysics Data System (ADS)
Mahapatra, Susanta; Ritschel, Thomas
2003-04-01
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 2+. 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 C2v configuration, are extended for the Cs 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 2+ excited electronic states mediated by conical intersections is also examined and discussed.
Electron-nuclear wave-packet dynamics through a conical intersection
NASA Astrophysics Data System (ADS)
Hader, Kilian; Albert, Julian; Gross, E. K. U.; Engel, Volker
2017-02-01
We investigate the coupled electron-nuclear dynamics in a model system showing a conical intersection (CoIn) between two excited state potential energy surfaces. Within the model, a single electron and nucleus move in two dimensions in an external static field. It is demonstrated that the nuclear density conserves its initial Gaussian shape when directly passing the CoIn, whereas the electronic density remains approximately constant. This is in sharp contrast to the picture which evolves from an analysis within the basis of adiabatic electronic states. There, dramatic changes are seen in the dynamics of the different nuclear components of the total wave function. It is thus documented that, in the case of a highly efficient population transfer between the respective adiabatic states, neither the nuclear nor the electronic density is influenced by the existence of a CoIn. This is the case because the nuclear-electronic wave packet moves on the complete potential energy surface which changes its topology smoothly as a function of all particle coordinates.
Vibrational wave packet dynamics in NaK: The A 1Σ+ state
NASA Astrophysics Data System (ADS)
Andersson, L. Mauritz; Karlsson, Hans O.; Goscinski, Osvaldo; Berg, Lars-Erik; Beutter, Matthias; Hansson, Tony
1999-02-01
A combined experimental and theoretical study of the vibrational wave packet dynamics for the NaK molecule in the A 1Σ+ state is presented. The experiment utilises a 790 nm one-colour femtosecond pump-probe scheme with detection of a previously not reported dissociation pathway of the 3 1Π+ state, leading to the Na(3p)+K(4s) product channel. The dissociation is suggested to proceed via either collisionally mediated processes or a molecular cascading process via the 4 1Σ+ state, which crosses several states correlating to the Na(3p)+K(4s) limit. Time-dependent quantum mechanical calculations are used for studying the dynamics in detail. Simulations are performed both for 790 nm and for 766 nm, to relate also to earlier studies. The previous interpretations of the probe processes are revised. Inclusion of vibrational and rotational temperature effects are shown to be crucial for explaining the shape of the signal and the vibrational period, and leads to excellent agreement with the experiments.
Dynamics of zero-energy nonspreading non-Gaussian wave packets for a class of central potentials
NASA Astrophysics Data System (ADS)
Makowski, Adam J.; Pepłowski, Piotr
2013-10-01
Zero-energy wave packets, coherent states, are constructed in such a way that they retain their shape during the time evolution for a large class of central potentials. The packets are not of the Gaussian type with -r2 dependence but, instead, their shape is determined by -r with -1/2<μ<1/2. A very close quantum-classical correspondence is also shown, i.e., the well localized states travel along suitable classical trajectories.
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.
Following dynamic nuclear wave packets in N{sub 2},O{sub 2}, and CO with few-cycle infrared pulses
De, S.; Magrakvelidze, M.; Bocharova, I. A.; Ray, D.; Cao, W.; Li, H.; Wang, Z.; Laurent, G.; Thumm, U.; Ben-Itzhak, I.; Cocke, C. L.; Znakovskaya, I.; Kling, M. F.; Litvinyuk, I. V.
2011-10-15
We study the evolution of nuclear wave packets launched in molecular nitrogen, oxygen, and carbon monoxide by intense 8-fs infrared pulses. We use velocity map imaging to measure the momentum of the ion fragments when these wave packets are interrogated by a second such pulse after a variable time delay. Both quasibound and dissociative wave packets are observed. For the former, measurements of bound-state oscillations are used to identify the participating states and, in some cases, extract properties of the relevant potential-energy surfaces. Vibrational structure is resolved in both energy and oscillation frequencies for the cations of oxygen and carbon monoxide, displaying the same quantum wave-packet motion in both energy and time domains. In addition, vibrational structure is seen in the dication of carbon monoxide in a situation where the energy resolution by itself is inadequate to resolve the structure.
NASA Astrophysics Data System (ADS)
Brenny, Benjamin J. M.; Polman, Albert; García de Abajo, F. Javier
2016-10-01
Swift electrons generate coherent transition radiation (TR) when crossing a material surface, as well as surface plasmon polaritons (SPPs) when the material is metallic. We present analytical and numerical calculations that describe the time- and space-dependent electric fields of TR and SPPs induced by 30-300 keV electrons on a Drude metal surface. The generated SPPs form wave packets a few-hundred femtoseconds in duration, depending on the material permittivity. High-frequency components close to the plasmon resonance are strongly damped, causing the wave packets to shift to lower frequencies as they propagate further. TR is emitted to the far field as ultrashort wave packets consisting of just a few optical cycles, with an intensity and angle dependence that is determined by the material permittivity. The excitation reaches its peak amplitude within a few femtoseconds and then drops off strongly for longer times. From a correlation between material permittivity and the calculated emission behavior, we determine qualitative predictions of the TR evolution for any given material. The results presented here provide key insights into the mechanisms enabling swift electrons to serve as nanoscale optical excitation sources.
NASA Astrophysics Data System (ADS)
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.
NASA Technical Reports Server (NTRS)
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.
Nonlinear gravity waves in the water flow with inhomogeneous vorticity
NASA Astrophysics Data System (ADS)
Abrashkin, Anatoly; Pelinovsky, Efim
2016-04-01
Nonlinear Schrodinger equation is derived for weakly modulated nonlinear wave packets in the infinite-depth water flow with inhomogeneous vorticity. Governing 2-D equations are written in Lagrangian variables. Nonlinear Schrodinger equation is obtained in the third order of perturbation theory taking into account weak non-uniform vortex current. Two limiting cases are analyzed. The first one corresponds to the uniform surface flow and is described by the classic nonlinear Schrodinger equation allowed the modulational instability. The second one is the Gerstner's wave packet. In this limiting case the nonlinear term is absent confirming known fact that nonlinear Gerstner's wave has the linear dispersion relation.
NASA Technical Reports Server (NTRS)
Neuhauser, Daniel; Baer, Michael; Judson, Richard S.; Kouri, Donald J.
1989-01-01
The first successful application of the three-dimensional quantum body frame wave packet approach to reactive scattering is reported for the H + H2 exchange reaction on the LSTH potential surface. The method used is based on a procedure for calculating total reaction probabilities from wave packets. It is found that converged, vibrationally resolved reactive probabilities can be calculated with a grid that is not much larger than required for the pure inelastic calculation. Tabular results are presented for several energies.
‘Superluminal paradox’ in wave packet propagation and its quantum mechanical resolution
Sokolovski, D.; Akhmatskaya, E.
2013-12-15
We analyse in detail the reshaping mechanism leading to apparently ‘superluminal’ advancement of a wave packet traversing a classically forbidden region. In the coordinate representation, a barrier is shown to act as an effective beamsplitter, recombining envelopes of the freely propagating pulse with various spacial shifts. Causality ensures that none of the constituent envelopes are advanced with respect to free propagation, yet the resulting pulse is advanced due to a peculiar interference effect, similar to the one responsible for ‘anomalous’ values which occur in Aharonov’s ‘weak measurements’. In the momentum space, the effect is understood as a bandwidth phenomenon, where the incident pulse probes local, rather than global, analytical properties of the transmission amplitude T(p). The advancement is achieved when T(p) mimics locally an exponential behaviour, similar to the one occurring in Berry’s ‘superoscillations’. Seen in a broader quantum mechanical context, the ‘paradox’ is but a consequence of an attempt to obtain ‘which way?’ information without destroying the interference between the pathways of interest. This explains, to a large extent, the failure to adequately describe tunnelling in terms of a single ‘tunnelling time’. -- Highlights: •Apparent superluminality is described in the language of quantum measurements. •A barrier acts as a beamsplitter delaying copies of the initial pulse. •In the coordinate space the effect is similar to what occurs in ‘weak measurements’. •In the momentum space it relies on superoscillations in the transmission amplitude. •It is an interference effect, unlikely to be explained in simpler physical terms.
Reconstruction and control of a time-dependent two-electron wave packet
NASA Astrophysics Data System (ADS)
Ott, Christian; Kaldun, Andreas; Argenti, Luca; Raith, Philipp; Meyer, Kristina; Laux, Martin; Zhang, Yizhu; Blättermann, Alexander; Hagstotz, Steffen; Ding, Thomas; Heck, Robert; Madroñero, Javier; Martín, Fernando; Pfeifer, Thomas
2014-12-01
The concerted motion of two or more bound electrons governs atomic and molecular non-equilibrium processes including chemical reactions, and hence there is much interest in developing a detailed understanding of such electron dynamics in the quantum regime. However, there is no exact solution for the quantum three-body problem, and as a result even the minimal system of two active electrons and a nucleus is analytically intractable. This makes experimental measurements of the dynamics of two bound and correlated electrons, as found in the helium atom, an attractive prospect. However, although the motion of single active electrons and holes has been observed with attosecond time resolution, comparable experiments on two-electron motion have so far remained out of reach. Here we show that a correlated two-electron wave packet can be reconstructed from a 1.2-femtosecond quantum beat among low-lying doubly excited states in helium. The beat appears in attosecond transient-absorption spectra measured with unprecedentedly high spectral resolution and in the presence of an intensity-tunable visible laser field. We tune the coupling between the two low-lying quantum states by adjusting the visible laser intensity, and use the Fano resonance as a phase-sensitive quantum interferometer to achieve coherent control of the two correlated electrons. Given the excellent agreement with large-scale quantum-mechanical calculations for the helium atom, we anticipate that multidimensional spectroscopy experiments of the type we report here will provide benchmark data for testing fundamental few-body quantum dynamics theory in more complex systems. They might also provide a route to the site-specific measurement and control of metastable electronic transition states that are at the heart of fundamental chemical reactions.
Reconstruction and control of a time-dependent two-electron wave packet.
Ott, Christian; Kaldun, Andreas; Argenti, Luca; Raith, Philipp; Meyer, Kristina; Laux, Martin; Zhang, Yizhu; Blättermann, Alexander; Hagstotz, Steffen; Ding, Thomas; Heck, Robert; Madroñero, Javier; Martín, Fernando; Pfeifer, Thomas
2014-12-18
The concerted motion of two or more bound electrons governs atomic and molecular non-equilibrium processes including chemical reactions, and hence there is much interest in developing a detailed understanding of such electron dynamics in the quantum regime. However, there is no exact solution for the quantum three-body problem, and as a result even the minimal system of two active electrons and a nucleus is analytically intractable. This makes experimental measurements of the dynamics of two bound and correlated electrons, as found in the helium atom, an attractive prospect. However, although the motion of single active electrons and holes has been observed with attosecond time resolution, comparable experiments on two-electron motion have so far remained out of reach. Here we show that a correlated two-electron wave packet can be reconstructed from a 1.2-femtosecond quantum beat among low-lying doubly excited states in helium. The beat appears in attosecond transient-absorption spectra measured with unprecedentedly high spectral resolution and in the presence of an intensity-tunable visible laser field. We tune the coupling between the two low-lying quantum states by adjusting the visible laser intensity, and use the Fano resonance as a phase-sensitive quantum interferometer to achieve coherent control of the two correlated electrons. Given the excellent agreement with large-scale quantum-mechanical calculations for the helium atom, we anticipate that multidimensional spectroscopy experiments of the type we report here will provide benchmark data for testing fundamental few-body quantum dynamics theory in more complex systems. They might also provide a route to the site-specific measurement and control of metastable electronic transition states that are at the heart of fundamental chemical reactions.
Vectorial optical field reconstruction by attosecond spatial interferometry
NASA Astrophysics Data System (ADS)
Carpeggiani, P.; Reduzzi, M.; Comby, A.; Ahmadi, H.; Kühn, S.; Calegari, F.; Nisoli, M.; Frassetto, F.; Poletto, L.; Hoff, D.; Ullrich, J.; Schröter, C. D.; Moshammer, R.; Paulus, G. G.; Sansone, G.
2017-06-01
An electrical pulse E(t) is defined completely by its time-dependent amplitude and polarization direction. For optical pulses the manipulation and characterization of the light polarization state is fundamental because of its relevance in several scientific and technological fields. In this work, we demonstrate the complete temporal reconstruction of the electric field of few-cycle pulses with a complex time-dependent polarization. Our experimental approach is based on extreme ultraviolet interferometry with isolated attosecond pulses and on the demonstration that the motion of an attosecond electron wave packet is sensitive to perturbing fields only along the direction of its motion. By exploiting the sensitivity of interferometric techniques and by controlling the emission and acceleration direction of the wave packet, pulses with energies as low as a few hundreds of nanojoules can be reconstructed. Our approach reveals the possibility to characterize completely the electric field of the pulses typically used in visible pump-probe spectroscopy.
NASA Astrophysics Data System (ADS)
Abdurakhmanov, I. B.; Kadyrov, A. S.; Bray, I.; Bartschat, K.
2017-08-01
The recently developed wave-packet continuum-discretization approach [I. B. Abdurakhmanov, A. S. Kadyrov, and I. Bray, Phys. Rev. A 94, 022703 (2016), 10.1103/PhysRevA.94.022703] is extended to antiproton-helium collisions. The helium target is treated as a three-body Coulomb system using a frozen-core approximation, in which the electron-electron correlation within the target is accounted for through the static interaction. The Schrödinger equation for the helium target is solved numerically to yield bound and continuum states of the active electron. The resulting continuum state is used to construct wave-packet pseudostates with arbitrary energies. The energies of the pseudostates are chosen in a way that is ideal for detailed differential ionization studies. Two-electron target wave functions, formed from the bound and continuum wave-packet states of the active electron and the 1 s orbital of He+, are then utilized in the single-center semiclassical impact-parameter close-coupling scheme. A comprehensive set of benchmark results, from angle-integrated to fully differential cross sections for antiproton impact single ionization of helium in the energy range from 1 keV to 1 MeV, is provided. Furthermore, we use our single-center convergent close-coupling approach to study fully differential single ionization of helium by 1-MeV proton impact. The calculated results are in good agreement with recent experimental measurements [H. Gassert, O. Chuluunbaatar, M. Waitz, F. Trinter, H.-K. Kim, T. Bauer, A. Laucke, C. Müller, J. Voigtsberger, M. Weller et al., Phys. Rev. Lett. 116, 073201 (2016), 10.1103/PhysRevLett.116.073201] for all considered geometries.
NASA Astrophysics Data System (ADS)
Li, H.; Mignolet, B.; Wachter, G.; Skruszewicz, S.; Zherebtsov, S.; Süßmann, F.; Kessel, A.; Trushin, S. A.; Kling, Nora G.; Kübel, M.; Ahn, B.; Kim, D.; Ben-Itzhak, I.; Cocke, C. L.; Fennel, T.; Tiggesbäumker, J.; Meiwes-Broer, K.-H.; Lemell, C.; Burgdörfer, J.; Levine, R. D.; Remacle, F.; Kling, M. F.
2015-03-01
Strong laser fields can be used to trigger an ultrafast molecular response that involves electronic excitation and ionization dynamics. Here, we report on the experimental control of the spatial localization of the electronic excitation in the C60 fullerene exerted by an intense few-cycle (4 fs) pulse at 720 nm. The control is achieved by tailoring the carrier-envelope phase and the polarization of the laser pulse. We find that the maxima and minima of the photoemission-asymmetry parameter along the laser-polarization axis are synchronized with the localization of the coherent electronic wave packet at around the time of ionization.
NASA Astrophysics Data System (ADS)
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.
Lin Shiying; Guo Hua
2006-08-15
We describe the implementation of a quantum mechanical method to calculate state-to-state differential cross sections for atom-diatom reactive scattering processes. The key ingredient of this approach is the efficient and accurate propagation of a real scattering wave packet in the Chebyshev order domain, from which the S-matrix elements can be extracted. This approach is implemented with Open MP and applied to compute differential and integral cross sections for the direct H+H{sub 2} abstraction reaction and the more challenging N({sup 2}D)+H{sub 2} insertion reaction.
NASA Astrophysics Data System (ADS)
Ohsawa, Tomoki
2015-09-01
We show that the Siegel upper half space is identified with the Marsden-Weinstein quotient obtained by symplectic reduction of the cotangent bundle with O(2 d)-symmetry. The reduced symplectic form on corresponding to the standard symplectic form on turns out to be a constant multiple of the symplectic form on obtained by Siegel. Our motivation is to understand the geometry behind two different formulations of the Gaussian wave packet dynamics commonly used in semiclassical mechanics. Specifically, we show that the two formulations are related via the symplectic reduction.
Zhao, Bin; Sun, Zhigang; Guo, Hua
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 + D2 reaction with all partial waves. Excellent agreement with benchmark integral and differential cross sections is achieved.
NASA Astrophysics Data System (ADS)
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.
Zhao, Bin; Sun, Zhigang E-mail: hguo@unm.edu; Guo, Hua E-mail: hguo@unm.edu
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.
NASA Astrophysics Data System (ADS)
Liu, Li; Muckerman, James T.
1997-09-01
Vibrational eigenvalues with estimated errors <5×10-2 cm-1 and their corresponding eigenfunctions for J=0 5D (planar) acetylene modeled by the Halonen-Child-Carter potential-energy surface are obtained using an energy-shifted, imaginary-time Lanczos propagation of symmetry-adapted wave packets. A lower resolution (˜4 cm-1) vibrational eigenspectrum of the system is also calculated by the Fourier transform of the autocorrelation of an appropriate wave packet. The eigenvalues from both approaches are in excellent agreement. The wave function of the molecule is represented in a direct-product discrete variable representation (DVR) with nearly 300 000 grid points. Our results are compared with the previously reported theoretical and experimental values. We use our 69 computed eigenstates as a basis to perform an optimal control simulation of selective two-photon excitation of the symmetric CH-stretch mode with an infrared, linearly polarized, transform-limited, and subpicosecond-picosecond laser pulse. The resulting optimal laser pulses, which are then tested on the full DVR grid, fall within the capabilities of current powerful, subpicosecond, and tunable light sources.
Wasilewski, Wojciech; Raymer, M. G.
2006-06-15
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 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 atomic polarization using the anti-Stokes scattering process. We prove that the readout process can also be decomposed into multiple mode pairs, each pair undergoing independent evolution analogous to a beam-splitter transformation. We show that this process can have unit efficiency under realistic experimental conditions. The shape of the output light wave packet can be predicted. In the case of unit readout efficiency it contains only excitations originating from a specified atomic excitation mode.
NASA Astrophysics Data System (ADS)
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.
Sanz, A.S.; Martínez-Casado, R.; Peñate-Rodríguez, H.C.; Rojas-Lorenzo, G.; Miret-Artés, S.
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.
NASA Astrophysics Data System (ADS)
Wang, Lei-Ming; Zhang, Lingxiao; Seideman, Tamar; Petek, Hrvoje
2012-10-01
We study by numerical simulations the excitation and propagation dynamics of coupled surface plasmon polariton (SPP) wave packets (WPs) in optically thin Ag films and a bulk Ag/vacuum interface under the illumination of a subwavelength slit by 400 nm continuous wave (cw) and femtosecond pulsed light. The generated surface fields include contributions from both SPPs and quasicylindrical waves, which dominate in different regimes. We explore aspects of the coupled SPP modes in Ag thin films, including symmetry, propagation, attenuation, and the variation of coupling with incident angle and film thickness. Simulations of the electromagnetic transients initiated with femtosecond pulses reveal new features of coupled SPP WP generation and propagation in thin Ag films. Our results show that, under pulsed excitation, the SPP modes in an Ag thin film break up into two distinct bound surface wave packets characterized by marked differences in symmetries, group velocities, attenuation lengths, and dispersion properties. The nanometer spatial and femtosecond temporal scale excitation and propagation dynamics of the coupled SPP WPs are revealed in detail by movies recording the evolution of their transient field distributions.
NASA Astrophysics Data System (ADS)
Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji
2007-03-01
The application of single-walled carbon nanotubes as the ideal ballistic conductors is expected. However, the electronic current saturates at the high-bias regime due to electron-phonon scattering. In order to improve the conductivity, understanding of the scattering mechanism is highly required. We investigated the electron-phonon coupling effect on the conductance in single-walled carbon nanotubes using the time-dependent wave-packet approach under a tight-binding approximation [1]. The vibrational atomic displacements in real space are introduced through the time-dependent change of the transfer energies. We solve the time-dependent Schr"odinger equation and obtain the time-dependent diffusion coefficients of the electronic wave packets. From these data, we can extract the coherence length and then the conductance. We found that the optical phonon decreases the conductance of metallic carbon nanotubes, because the propagating speed of electron is reduced by the electron-phonon scattering. Furthermore, we clarify the difference of the scattering effects on the conductivity of the metallic nanotube and the semiconducting one. [1] S. Roche et al., PRL 95 (2005) 076803
NASA Technical Reports Server (NTRS)
Judson, Richard S.; Kouri, Donald J.; Neuhauser, Daniel; Baer, Michael
1990-01-01
An alternative time-dependent wave-packet method for treating three-dimensional gas phase reactive atom-diatom collisions is presented. The method employs a nonreactive body-frame wave packet propagation procedure, made possible by judicious use of absorbing optical potentials, a novel scheme for interpolating the wave function from coordinates in one arrangement to those in another and the fact that the time-dependent Schroedinger equation is an initial-value problem. The last feature makes possible a computationally viable and accurate procedure for changing from one arrangement's coordinates to another. In addition, the method allows the determination of S-matrix elements over a wide range of energies from a single wave-packet propagation. The method is illustrated by carrying out detailed calculations of inelastic and reactive scattering in the H + H2 system using the Liu-Siegbahn-Truhlar-Horowitz potential surface.
NASA Technical Reports Server (NTRS)
Judson, Richard S.; Kouri, Donald J.; Neuhauser, Daniel; Baer, Michael
1990-01-01
An alternative time-dependent wave-packet method for treating three-dimensional gas phase reactive atom-diatom collisions is presented. The method employs a nonreactive body-frame wave packet propagation procedure, made possible by judicious use of absorbing optical potentials, a novel scheme for interpolating the wave function from coordinates in one arrangement to those in another and the fact that the time-dependent Schroedinger equation is an initial-value problem. The last feature makes possible a computationally viable and accurate procedure for changing from one arrangement's coordinates to another. In addition, the method allows the determination of S-matrix elements over a wide range of energies from a single wave-packet propagation. The method is illustrated by carrying out detailed calculations of inelastic and reactive scattering in the H + H2 system using the Liu-Siegbahn-Truhlar-Horowitz potential surface.
Quantum wave packet study of nonadiabatic effects in O({sup 1}D) + H{sub 2} {yields} OH + H
Gray, S.K.; Petrongolo, C.; Drukker, K.; Schatz, G.C.
1999-11-25
The authors develop a wave packet approach to treating the electronically nonadiabatic reaction dynamics of O({sup 1}D) + H{sub 2} {yields} OH + H, allowing for the 1{sup 1}A{prime} and 2{sup 1}A{prime} potential energy surfaces and couplings, as well as the three internal nuclear coordinates. Two different systems of coupled potential energy surfaces are considered, a semiempirical diatomics-in-molecules (DIM) system due to Kuntz, Niefer, and Sloan, and a recently developed ab initio system due to Dobbyn and Knowles (DK). Nonadiabatic quantum results, with total angular momentum J = 0, are obtained and discussed. Several single surface calculations are carried out for comparison with the nonadiabatic results. Comparisons with trajectory surface hopping (TSH) calculations, and with approximate quantum calculations, are also included. The electrostatic coupling produces strong interactions between the 1{sup 1}A{prime} and 2{sup 1}A{prime} states at short range (where these states have a conical intersection) and weak but, interestingly, nonnegligible interactions between these states at longer range. The wave packet results show that if the initial state is chosen to be effectively the 1A{prime} state (for which insertion to form products occurs on the adiabatic surface), then there is very little difference between the adiabatic and coupled surface results. In either case the reaction probability is a relatively flat function of energy, except for resonant oscillations. However, the 2A{prime} reaction, dynamics (which involves a collinear transition state) is strongly perturbed by nonadiabatic effects in two distinct ways. At energies above the transition state barrier, the diabatic limit is dominant, and the 2A{prime} reaction probability is similar to that for 1A{double{underscore}prime}, which has no coupling with the other surfaces. At energies below the barrier, the authors find a significant component of the reaction probability from long range electronic
Hyeon-Deuk, Kim; Ando, Koji
2014-05-07
Liquid para-hydrogen (p-H2) is a typical quantum liquid which exhibits strong nuclear quantum effects (NQEs) and thus anomalous static and dynamic properties. We propose a real-time simulation method of wave packet (WP) molecular dynamics (MD) based on non-empirical intra- and inter-molecular interactions of non-spherical hydrogen molecules, and apply it to condensed-phase p-H2. The NQEs, such as WP delocalization and zero-point energy, are taken into account without perturbative expansion of prepared model potential functions but with explicit interactions between nuclear and electron WPs. The developed MD simulation for 100 ps with 1200 hydrogen molecules is realized at feasible computational cost, by which basic experimental properties of p-H2 liquid such as radial distribution functions, self-diffusion coefficients, and shear viscosities are all well reproduced.
NASA Astrophysics Data System (ADS)
Bhowmick, Somnath; B, Renjith; Mishra, Manoj K.; Sarma, Manabendra
2012-08-01
Effect of electron correlation on single strand breaks (SSBs) induced by low energy electron (LEE) has been investigated in a fragment excised from a DNA, viz., 2'-deoxycytidine-3'-monophosphate [3'-dCMPH] molecule in gas phase at DFT-B3LYP/6-31+G(d) accuracy level and using local complex potential based time dependent wave packet (LCP-TDWP) approach. The results obtained, in conjunction with our earlier investigation, show the possibility of SSB at very low energy (0.15 eV) where the LEE transfers from π* to σ* resonance state which resembles a SN2 type mechanism. In addition, for the first time, an indication of quantum mechanical tunneling in strand breaking is seen from the highest anionic bound vibrational state (χ5), which may have a substantial role during DNA damage.
Hyeon-Deuk, Kim; Ando, Koji
2014-05-07
Liquid para-hydrogen (p-H{sub 2}) is a typical quantum liquid which exhibits strong nuclear quantum effects (NQEs) and thus anomalous static and dynamic properties. We propose a real-time simulation method of wave packet (WP) molecular dynamics (MD) based on non-empirical intra- and inter-molecular interactions of non-spherical hydrogen molecules, and apply it to condensed-phase p-H{sub 2}. The NQEs, such as WP delocalization and zero-point energy, are taken into account without perturbative expansion of prepared model potential functions but with explicit interactions between nuclear and electron WPs. The developed MD simulation for 100 ps with 1200 hydrogen molecules is realized at feasible computational cost, by which basic experimental properties of p-H{sub 2} liquid such as radial distribution functions, self-diffusion coefficients, and shear viscosities are all well reproduced.
NASA Astrophysics Data System (ADS)
Sornsakdanuphap, Jirapong; Suanpoot, Pradoong; Hong, Young June; Ghimire, Bhagirath; Cho, Guangsup; Uhm, Han Sup; Kim, Doyoung; Kim, Yun Ji; Choi, Eun Ha
2017-06-01
The propagation velocities ( u g ) of argon plasma jet are obtained by intensified charge coupled device (ICCD) camera images at fixed gate width time of 5 ns. The propagation velocities in upstream and downstream regions are in the order of 104 - 105 m/s. The plasma ambipolar diffusion velocities are measured to be in the order of 10 - 102 m/s. Plasma jet discharges are generated by sinusoidal power supply in varying voltages from 2 to 4 kV at repetition frequency of about 40 kHz. By employing convective wave packet model, the electron temperature ( T e ) inside plasma bullet for argon non-thermal atmospheric pressure plasma jet is estimated to be about 1.18 eV. Also, the electron density ( n e ) is found to be 8.0 × 1014 - 2.5 × 1015 cm-3.
NASA Astrophysics Data System (ADS)
Yukino, H.; Saito, A.; Sakanoi, T.; Otsuka, Y.
2014-12-01
The spatial scale of the atmospheric gravity wave in the mesosphere and the lower thermosphere was analyzed using the simultaneous observational data of ISS-IMAP and an all-sky imager at Hawaii. There are a plenty of previous studies that discuss the relationship between the wave structures of the mesospheric airglow and the tropospheric events. The problem of the ground-based observation of the airglow is that it cannot distinguish spatial variations from temporal variations for the structures whose scale size is larger than its field-of-view. ISS-IMAP started the observation in October, 2012 to survey the atmospheric gravity waves whose horizontal scale size is 50 km and longer. The spatial resolution of the VIsible-light and infrared Spectrum Imager (VISI) of ISS-IMAP/VISI imaging observation is from 10 km to 25 km. Simultaneous observations start from March 14, 2013. The atmospheric gravity waves that detected by VISI in 762 nm were compared with the observations of ground-based all-sky imagers in 557.7 nm. The generation and the propagation of the atmospheric gravity waves were investigated with this simultaneous observation. The relationship between the tropospheric events and the atmospheric gravity waves in the mesosphere is studied with the wide field-of-view observation by VISI/ISS-IMAP, and the continuous observation of the ground-based imagers. VISI frequently observed wave packets whose scale size is 1,000-2,000 km. These wave packets were observed by the ground-based imager as a series of waves whose wave length is 20-40 km, and that continue for 5-6 hours. The generation, the propagation and the distraction of the atmospheric gravity waves will be discussed in this presentation.
Nonlinear self-contraction of electron waves
NASA Technical Reports Server (NTRS)
Intrator, T.; Chan, C.; Hershkowitz, N.; Diebold, D.
1984-01-01
Laboratory evidence is presented of modulationally unstable electron wave packets which can be described by a nonlinear geometrical optics theory. Growth times for self-contraction are found to be much faster than ion response times and the bursts do not appear to be related to Zakharov Langmuir-wave collapse.
NASA Astrophysics Data System (ADS)
Walczak, Pierre; Mezzapesa, Francesco; Bouakline, Abderrahmane; Ambre, Julien; Bouissou, Stéphane; Barland, Stéphane
2017-04-01
Inelastic strain analysis of rock under stress is of first importance to build up adequate theory of inelastic deformation and failure of geomaterials. The latter is crucial to have a better understanding of natural processes such as landsliding or seismic fault activity. In laboratory experiments, a rock sample can be easily stressed and different methods are used to study the deformation as for exemple X-ray tomography, or digital image correlation. But during the compression process of the sample, these technique don't allow to access the 3-D strain tensor. We present a laboratory experiment in which we investigate the real time deformation of a granular rock material subjected to different mechanical perturbations. Our work provides a novel optical technique in the geoscientific context for studying the wave propagation and the fracture phenomenon. The experimental measurement of the sample deformation is performed by nonlinear laser interferometry. The principle is based on the so-called self-mixing technique : a beam emitted by a semiconductor laser diode is reinjected into the emitter after reflection on the sample surface. The self-mixing signal in the laser diode can be measured on an integrated photodiode or even more simply by measuring the voltage across the laser diode. In both cases, we have a compact device allowing to observe in real time the direction and amplitude of the motion of the sample surface with a resolution of the half-wavelength of the laser (1.3 micrometers) at microsecond time scales. In the experiment, our rock like sample which is actually made from a finely ground powder of TiO2 is submitted to a constant load. Then we have performed two different experiments in which we have applied either a uniaxial or a transversal mechanical perturbation. The surface displacement is measured by two self-mixing interferometers localized to each side of the sample. In the case of uniaxial perturbation, we have observed nonlinear compression waves
NASA Astrophysics Data System (ADS)
Stimson, Michael Jay
1997-12-01
Demonstrations of several frequency resolved incoherent field non-linear interferometric spectroscopies are presented with emphasis on applications to coherent Raman scattering (two incoherent field actions- I(2)CRS). The properties of the incoherent (noisy) laser sources used for time resolution of ultrafast dynamics are explored in detail theoretically and experimentally. A new technique for the measurement of noisy light correlation functions (I(2)FROG-two incoherent field actions in frequency resolved optical gating) is developed theoretically and used for experimental explorations of the nature of noisy optical fields and their relation to coherent short pulsed optical fields. I(2)FROG and I(2)CRS signals are frequency dispersed and multichannel detected, which when combined with interferometric time resolution allows the creation of two-dimensional representations of these signals (spectrally resolved interferograms, or spectrograms). Spectrograms offer a large redundancy in the sampling of signals, thus allowing great precision in the measurement of observable parameters. In I(2)FROG, the observable parameters characterize the noisy light in the form of the intensity and phase of cross correlation functions between beams of broadband light. In I(2)CRS, the observable parameters quantify material properties such as lineshape parameters, transition frequencies and ratios of resonant to non-resonant contributions to molecular hyperpolarizability tensor elements. Algorithms for the recovery of the observable parameters are developed and applied to the spectrograms derived from many condensed phase materials. Systems explored via spectrogram representation include pure substances and non-reactive mixtures. A novel modification of the original I(2)CRS experiment is presented in which spectrally tailored fields are used to control the properties of the I(2)CRS signals. Newly predicted fifth order signals (I(3)FOOCRS-three incoherent field actions in fifth order
NASA Astrophysics Data System (ADS)
El-Labany, S. K.; El-Taibany, W. F.; Zedan, N. A.
2015-07-01
Cylindrical and spherical amplitude modulations of dust acoustic (DA) solitary wave envelopes in a strongly coupled dusty plasma containing nonthermal distributed ions are studied. Employing a reductive perturbation technique, a modified nonlinear Schrödinger equation including the geometrical effect is derived. The influences of nonthermal ions, polarization force, and the geometries on the modulational instability conditions are analyzed and the possible rogue wave structures are discussed in detail. It is found that the spherical DA waves are more structurally stable to perturbations than the cylindrical ones. Possible applications of these theoretical findings are briefly discussed.
El-Labany, S. K. Zedan, N. A.; El-Taibany, W. F. E-mail: eltaibany@du.edu.eg
2015-07-15
Cylindrical and spherical amplitude modulations of dust acoustic (DA) solitary wave envelopes in a strongly coupled dusty plasma containing nonthermal distributed ions are studied. Employing a reductive perturbation technique, a modified nonlinear Schrödinger equation including the geometrical effect is derived. The influences of nonthermal ions, polarization force, and the geometries on the modulational instability conditions are analyzed and the possible rogue wave structures are discussed in detail. It is found that the spherical DA waves are more structurally stable to perturbations than the cylindrical ones. Possible applications of these theoretical findings are briefly discussed.
Jenet, F. A.; Melatos, A.; Robinson, P. A.
2007-10-15
Zakharov simulations of nonlinear wave collapse in continuously driven two-dimensional, electromagnetic strong plasma turbulence with electron thermal speeds v{>=}0.01c show that for v < or approx. 0.1c, dipole radiation occurs near the plasma frequency, mainly near arrest, but for v > or approx. 0.1c, a new mechanism applies in which energy oscillates between trapped Langmuir and transverse modes until collapse is arrested, after which trapped transverse waves are advected into incoherent interpacket turbulence by an expanding annular density well, where they detrap. The multipole structure, Poynting flux, source current, and radiation angular momentum are computed.
Combining 2D synchrosqueezed wave packet transform with optimization for crystal image analysis
NASA Astrophysics Data System (ADS)
Lu, Jianfeng; Wirth, Benedikt; Yang, Haizhao
2016-04-01
We develop a variational optimization method for crystal analysis in atomic resolution images, which uses information from a 2D synchrosqueezed transform (SST) as input. The synchrosqueezed transform is applied to extract initial information from atomic crystal images: crystal defects, rotations and the gradient of elastic deformation. The deformation gradient estimate is then improved outside the identified defect region via a variational approach, to obtain more robust results agreeing better with the physical constraints. The variational model is optimized by a nonlinear projected conjugate gradient method. Both examples of images from computer simulations and imaging experiments are analyzed, with results demonstrating the effectiveness of the proposed method.
Bulut, Niyazi; Kłos, Jacek; Alexander, Millard H
2012-03-14
We present converged exact quantum wave packet calculations of reaction probabilities, integral cross sections, and thermal rate coefficients for the title reaction. Calculations have been carried out on the ground 1(2)A' global adiabatic potential energy surface of Deskevich et al. [J. Chem. Phys. 124, 224303 (2006)]. Converged wave packet reaction probabilities at selected values of the total angular momentum up to a partial wave of J = 140 with the HCl reagent initially selected in the v = 0, j = 0-16 rovibrational states have been obtained for the collision energy range from threshold up to 0.8 eV. The present calculations confirm an important enhancement of reactivity with rotational excitation of the HCl molecule. First, accurate integral cross sections and rate constants have been calculated and compared with the available experimental data.
NASA Astrophysics Data System (ADS)
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.
NASA Technical Reports Server (NTRS)
Neuhauser, Daniel; Baer, Michael; Judson, Richard S.; Kouri, Donald J.
1990-01-01
This paper describes a new approach to the study of atom-diatom reactive collisions in three dimensions employing wave packets and the time-dependent Schroedinger equation. The method uses a projection operator approach to couple the inelastic and reactive portions of the total wave function and optical potentials to circumvent the necessity of using product arrangement coordinates. Reactive transition probabilities are calculated from the state resolved flux of the wave packet as it leaves the interaction region in the direction of the reactive arrangement channel. The present approach is used to obtain such vibrationally resolved probabilities for the three-dimensional H + H2 (J = 0) hydrogen exchange reaction, using a body-fixed system of coordinates.
NASA Technical Reports Server (NTRS)
Neuhauser, Daniel; Baer, Michael; Judson, Richard S.; Kouri, Donald J.
1990-01-01
This paper describes a new approach to the study of atom-diatom reactive collisions in three dimensions employing wave packets and the time-dependent Schroedinger equation. The method uses a projection operator approach to couple the inelastic and reactive portions of the total wave function and optical potentials to circumvent the necessity of using product arrangement coordinates. Reactive transition probabilities are calculated from the state resolved flux of the wave packet as it leaves the interaction region in the direction of the reactive arrangement channel. The present approach is used to obtain such vibrationally resolved probabilities for the three-dimensional H + H2 (J = 0) hydrogen exchange reaction, using a body-fixed system of coordinates.
NASA Astrophysics Data System (ADS)
Malakar, Y.; Zohrabi, M.; Pearson, W. L.; Kaderiya, B.; Kanaka Raju, P.; Ben-Itzhak, I.; Rolles, D.; Rudenko, A.
2015-05-01
As a prototypical polyatomic system with well-studied photodissociation dynamics, the iodomethane molecule (CH3I) has recently been used to test novel quantum control schemes, and to investigate charge transfer processes after X-ray absorption. These applications require a detailed understanding of CH3I behavior in intense laser pulses. Here we present the results of a time-resolved Coulomb explosion imaging experiment that maps both, bound and dissociating nuclear wave packets in singly and doubly charged ionic states of CH3I. Measuring energies and emission angles of coincident ionic fragments as a function of time delay between two 25 fs, 800 nm pump and probe pulses, we track the propagation of different dissociation pathways, vibrational motion of the molecule and its impulsive alignment. In particular, a periodic (~ 130 fs) feature in the delay-dependent ion energy spectra can be assigned to C-I stretching vibrations in the two lowest cationic states, and exhibits intriguing correlation with the oscillations observed in the laser pump/X-ray probe experiment on charge transfer at LCLS. This work was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Science, Office of Science, U.S. Department of Energy.
ACCURATE TIME-DEPENDENT WAVE PACKET STUDY OF THE H{sup +}+LiH REACTION AT EARLY UNIVERSE CONDITIONS
Aslan, E.; Bulut, N.; Castillo, J. F.; Banares, L.; Aoiz, F. J.; Roncero, O.
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.
Accurate time-dependent wave packet study of the Li + H₂⁺ reaction and its isotopic variants.
Aslan, E; Bulut, N; Castillo, J F; Bañares, L; Roncero, O; Aoiz, F J
2012-01-12
The dynamics and kinetics of the Li + H₂⁺ reaction and its isotopic variants (D₂⁺ and T₂⁺) have been studied by using a time-dependent wave packet (TDWP) coupled-channel (CC) method on the ab initio potential energy surface (PES) of Martinazzo et al. [J. Chem. Phys. 2003, 119, 21]. Total initial v = 0, j = 0 state-selected reaction probabilities for the Li + H₂⁺ reaction and its isotopic variants have been calculated from the threshold up to 1 eV for total angular momenta J from 0 to 90. Integral cross sections have been evaluated from the reaction probabilities at collision energies from threshold (≈0.2 eV) up to 1.0 eV collision. The calculated rate constants as a function of temperature show an Arrhenius type behavior in the 200 ≤ T ≤ 1000 K temperature interval. It has been found to be a considerable large intermolecular kinetic isotope effect. The TDWP-CC results are in overall good agreement with those obtained applying the TDWP Centrifugal-Sudden (CS) approximation, showing that the CS approximation is rather accurate for the title reaction.
NASA Astrophysics Data System (ADS)
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.
NASA Astrophysics Data System (ADS)
Sarantseva, T. S.; Silaev, A. A.; Manakov, N. L.
2017-04-01
An analytic expression for the electron wave packet (EWP) describing high-order harmonic generation (HHG) by atoms in an intense laser field with small ellipticity is derived quantum mechanically in the tunneling limit within the time-dependent effective range theory. This result is valid over a wide interval of returned electron energies in the HHG plateau region and generalizes the previous result for HHG rates obtained by Frolov M V et al (2012 Phys. Rev. A 86 063406) only for the HHG plateau cutoff region. It is shown that the most important difference from the case of a linearly polarized field originates from a nonzero electron energy at the moment of ionization in an elliptically polarized field that, in turn, results in the dependence of ionization factor in the EWP on the returning electron energy. Our analytic result for the EWP averaged over interference oscillations in the HHG spectrum is applied for analysis of the laser wavelength scaling of the HHG yield induced by an elliptically polarized midinfrared laser field as well as for the improvement of the recently suggested method of elliptic HHG spectroscopy for retrieving both the energy and angular dependence of the photorecombination cross section of the target atom (see Frolov M V et al 2016 Phys. Rev. A 93 031403).
NASA Astrophysics Data System (ADS)
Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji
2017-01-01
We present a wave-packet dynamical approach to charge transport using maximally localized Wannier functions based on density functional theory including van der Waals interactions. We apply it to the transport properties of pentacene and rubrene single crystals and show the temperature-dependent natures from bandlike to thermally activated behaviors as a function of the magnitude of external static disorder. We compare the results with those obtained by the conventional band and hopping models and experiments.
NASA Astrophysics Data System (ADS)
Berk, N. F.
2014-03-01
We present a general approach to analyzing elastic scattering for those situations where the incident beam is prepared as an incoherent ensemble of wave packets of a given arbitrary shape. Although wave packets, in general, are not stationary solutions of the Schrödinger equation, the analysis of elastic scattering data treats the scattering as a stationary-state problem. We thus must gate the wave packet, coherently distorting its shape in a manner consistent with the elastic condition. The resulting gated scattering amplitudes (e.g., reflection coefficients) thus are weighted coherent sums of the constituent plane-wave scattering amplitudes, with the weights determined by the shape of the incident wave packet as "filtered" by energy gating. We develop the gating formalism in general and apply it to the problem of neutron scattering from ruled gratings described by Majkrzak et al. in a companion paper. The required exact solution of the associated problem of plane-wave reflection from gratings also is derived.
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.
Formation of wave packets in the Ostrovsky equation for both normal and anomalous dispersion
Grimshaw, Roger; Stepanyants, Yury; Alias, Azwani
2016-01-01
It is well known that the Ostrovsky equation with normal dispersion does not support steady solitary waves. An initial Korteweg–de Vries solitary wave decays adiabatically through the radiation of long waves and is eventually replaced by an envelope solitary wave whose carrier wave and envelope move with different velocities (phase and group velocities correspondingly). Here, we examine the same initial condition for the Ostrovsky equation with anomalous dispersion, when the wave frequency increases with wavenumber in the limit of very short waves. The essential difference is that now there exists a steady solitary wave solution (Ostrovsky soliton), which in the small-amplitude limit can be described asymptotically through the solitary wave solution of a nonlinear Schrödinger equation, based at that wavenumber where the phase and group velocities coincide. Long-time numerical simulations show that the emergence of this steady envelope solitary wave is a very robust feature. The initial Korteweg–de Vries solitary wave transforms rapidly to this envelope solitary wave in a seemingly non-adiabatic manner. The amplitude of the Ostrovsky soliton strongly correlates with the initial Korteweg–de Vries solitary wave. PMID:26997887
Formation of wave packets in the Ostrovsky equation for both normal and anomalous dispersion.
Grimshaw, Roger; Stepanyants, Yury; Alias, Azwani
2016-01-01
It is well known that the Ostrovsky equation with normal dispersion does not support steady solitary waves. An initial Korteweg-de Vries solitary wave decays adiabatically through the radiation of long waves and is eventually replaced by an envelope solitary wave whose carrier wave and envelope move with different velocities (phase and group velocities correspondingly). Here, we examine the same initial condition for the Ostrovsky equation with anomalous dispersion, when the wave frequency increases with wavenumber in the limit of very short waves. The essential difference is that now there exists a steady solitary wave solution (Ostrovsky soliton), which in the small-amplitude limit can be described asymptotically through the solitary wave solution of a nonlinear Schrödinger equation, based at that wavenumber where the phase and group velocities coincide. Long-time numerical simulations show that the emergence of this steady envelope solitary wave is a very robust feature. The initial Korteweg-de Vries solitary wave transforms rapidly to this envelope solitary wave in a seemingly non-adiabatic manner. The amplitude of the Ostrovsky soliton strongly correlates with the initial Korteweg-de Vries solitary wave.
Non-Gaussian wave packet dynamics in anharmonic potential: Cumulant expansion treatment
NASA Astrophysics Data System (ADS)
Toutounji, Mohamad
2015-03-01
This manuscript utilizes cumulant expansion as an alternative algebraic approach to evaluating integrals and solving a system of nonlinear differential equations for probing anharmonic dynamics in condensed phase systems using Morse oscillator. These integrals and differential equations become harder to solve as the anharmonicity of the system goes beyond that of Morse oscillator description. This algebraic approach becomes critically important in case of Morse oscillator as it tends to exhibit divergent dynamics and numerical uncertainties at low temperatures. The autocorrelation function is calculated algebraically and compared to the exact one for they match perfectly. It is also compared to the approximate autocorrelation function using the differential equations technique reported in Toutounji (2014) for weak and strong electron-phonon coupling cases. It is found that the present cumulant method is more efficient, and easier to use, than the exact expression. Deviation between the approximate autocorrelation function and the exact autocorrelation function starts to arise as the electron-phonon coupling strength increases. The autocorrelation function obtained using cumulants identically matches the exact autocorrelation function, thereby surpassing the approach presented in Toutounji (2014). The advantage of the present methodology is its applicability to various types of electron-phonon coupling cases. Additionally, the herein approach only uses algebraic techniques, thereby avoiding both the divergence integral and solving a set of linear first- and second-order partial differential equations as was done in previous work. Model calculations are presented to demonstrate the accuracy of the herein work.
Bulut, N; Castillo, J F; Jambrina, P G; Kłos, J; Roncero, O; Aoiz, F J; Bañares, L
2015-12-17
Accurate quantum reactive scattering time-dependent wave packet close-coupling calculations have been carried out to determine total reaction probabilities and integral cross sections for the O(+) + H2 → OH(+) + H reaction in a range of collision energies from 10(-3) eV up to 1.0 eV for the H2 rovibrational states (v = 0; j = 0, 1, 2) and (v = 1; j = 0) using the potential energy surface (PES) by Martı́nez et al. As expected for a barrierless reaction, the reaction cross section decays rapidly with collision energy, Ec, following a behavior that nearly corresponds to that predicted by the Langevin model. Rotational excitation of H2 into j = 1, 2 has a very moderate effect on reactivity, similarly to what happens with vibrational excitation below Ec ≈ 0.3 eV. However, at higher collision energies the cross section increases notably when H2 is promoted to v = 1. This effect is explained by resorting to the effective potentials in the entrance channel. The integral cross sections have been used to calculate rate constants in the temperature range 200-1000 K. A good overall agreement has been found with the available experimental data on integral cross sections and rate constants. In addition, time-independent quantum mechanical and quasi-classical trajectory (QCT) calculations have been performed on the same PES aimed to compare the various methodologies and to discern the detailed mechanism of the title reaction. In particular, the analysis of individual trajectories has made it possible to explain, in terms of the coupling between reagent relative velocity and the topography of the PES, the presence of a series of alternating maxima and minima in the collision energy dependence of the QCT reaction probabilities for the reactions with H2(v=0,1,j=0), which are absent in the quantum mechanical calculations.
NASA Astrophysics Data System (ADS)
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)].
Coherent states for the nonlinear harmonic oscillator
Ghosh, Subir
2012-06-15
Wave packets for the quantum nonlinear oscillator are considered in the generalized coherent state framework. To first order in the nonlinearity parameter the coherent state behaves very similar to its classical counterpart. The position expectation value oscillates in a simple harmonic manner. The energy-momentum uncertainty relation is time independent as in a harmonic oscillator. Various features (such as the squeezed state nature) of the coherent state have been discussed.
Neutrino Intensity Interferometry: Measuring Protoneutron Star Radii During Core-Collapse Supernovae
NASA Astrophysics Data System (ADS)
Wright, Warren P.; Kneller, James P.
2017-08-01
Intensity interferometry is a technique that has been used to measure the size of sources ranging from the quark-gluon plasma formed in heavy ion collisions to the radii of stars. We investigate using the same technique to measure protoneutron star (PNS) radii with the neutrino signal received from a core-collapse supernovae. Using a full wave-packet analysis, including the neutrino mass for the first time, we derive criteria where the effect can be expected to provide the desired signal, and find that neutrinos from the next Galactic supernova should contain extractable PNS radius information.
ERIC Educational Resources Information Center
Berry, M. V.; Balazs, N. L.
1979-01-01
Explains properties of the Airy packet that show that quantum wave functions correspond to a family of orbits and not to a single particle. Introducing the Airy packet into elementary quantum mechanics courses is recommended. (HM)
Sun, Zhigang; Yang, Weitao; Zhang, Dong H
2012-02-14
The efficiency of the numerical propagators for solving the time-dependent Schrödinger equation in the wave packet approach to reactive scattering is of vital importance. In this Perspective, we first briefly review the propagators used in quantum reactive scattering calculations and their applications to triatomic reactions. Then we present a detailed comparison of about thirty higher-order split operator propagators for solving the Schrödinger equation with their applications to the wave packet evolution within a one-dimensional Morse potential, and the total reaction probability calculations for the H + HD, H + NH, H + O(2), and F + HD reactions. These four triatomic reactions have quite different dynamic characteristics and thus provide a comprehensive picture of the relative advantages of these higher-order propagation methods for describing reactive scattering dynamics. Our calculations reveal that the most often used second-order split operator method is typically more efficient for a direct reaction, particularly for those involving flat potential energy surfaces. However, the optimal higher-order split operator methods are more suitable for a reaction with resonances and intermediate complexes or a reaction experiencing potential energy surface with fluctuations of considerable amplitude. Three 4th-order and one 6th-order split operator methods, which are most efficient for solving reactive scattering in various conditions among the tested ones, are recommended for general applications. In addition, a brief discussion on the relative performance between the Chebyshev real wave packet method and the split operator method is given. The results in this Perspective are expected to stimulate more applications of (high-order) split operators to the quantum reactive scattering calculation and other related problems.
NASA Astrophysics Data System (ADS)
Majkrzak, Charles F.; Metting, Christopher; Maranville, Brian B.; Dura, Joseph A.; Satija, Sushil; Udovic, Terrence; Berk, Norman F.
2014-03-01
The primary purpose of this investigation is to determine the effective coherent extent of the neutron wave packet transverse to its mean propagation vector k when it is prepared in a typical instrument used to study the structure of materials in thin film form via specular reflection. There are two principal reasons for doing so. One has to do with the fundamental physical interest in the characteristics of a free neutron as a quantum object, while the other is of a more practical nature, relating to the understanding of how to interpret elastic scattering data when the neutron is employed as a probe of condensed-matter structure on an atomic or nanometer scale. Knowing such a basic physical characteristic as the neutron's effective transverse coherence can dictate how to properly analyze specular reflectivity data obtained for material film structures possessing some amount of in-plane inhomogeneity. In this study we describe a means of measuring the effective transverse coherence length of the neutron wave packet by specular reflection from a series of diffraction gratings of different spacings. Complementary nonspecular measurements of the widths of grating reflections were also performed, which corroborate the specular results. (This paper principally describes measurements interpreted according to the theoretical picture presented in a companion paper.) Each grating was fabricated by lift-off photolithography patterning of a nickel film (approximately 1000 Å thick) formed by physical vapor deposition on a flat silicon crystal surface. The grating periods ranged from 10 μm (5 μm Ni stripe, 5 μm intervening space) to several hundred microns. The transverse coherence length, modeled as the width of the wave packet, was determined from an analysis of the specular reflectivity curves of the set of gratings.
NASA Astrophysics Data System (ADS)
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.
Sahoo, Tapas; Ghosh, Sandip; Adhikari, Satrajit; Sharma, Rahul; Varandas, António J C
2014-07-03
We explore a coupled three-dimensional (3D) time-dependent wave packet formalism in hyperspherical coordinates for a 4D reactive scattering problem on the lowest adiabatic singlet surface (1(1)A') of the D(+) + H2 reaction. The coupling among the wavepackets arises through quantization of the rotation matrix, which represents the orientation of the three particles in space. The required transformation from Jacobi to hyperspherical coordinates and vice versa during initialization and projection of the wave packet on the asymptotic state(s), and the coupled equations of motion, are briefly discussed. With the long-range potential known to contribute significantly on the D(+) + H2 system, we demonstrate the workability of our approach, where the convergence profiles of the reaction probability for the reactive noncharge transfer (RNCT) process [D(+) + H2(v=0, j=0,1) → HD(v',j') + H(+)] are shown for three different collisional energies (1.7, 2.1, and 2.5 eV) with respect to the helicity (K) and total angular momentum (J) quantum numbers. The calculated reactive cross-section is presented as a function of the collision energy for two different initial states of the diatom (v = 0, j = 0, 1).
NASA Astrophysics Data System (ADS)
Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji
2010-08-01
We present an order- N [O(N)] calculation method for the quantum electron transport of huge systems up to 80 million atoms. Based on the linear-response Kubo-Greenwood formula, we calculate the conductance through time-dependent diffusion coefficients using the time-dependent wave-packet diffusion approach, which treats the electron wave-packet motion with an O(N) and very high-speed calculation. Combining with molecular-dynamics simulations, we can study the temperature dependence of electron transport properties of materials from atomistic viewpoints from ballistic to diffusive regimes. We apply the present calculation method to transport of the carbon nanotubes (CNTs) with various lengths at various temperatures. In metallic CNTs, the mean-free paths are in good agreements with recent experiments, which reach about 500 nm at room temperature and increase up to several micrometers at low temperature. We find that the resistance increases almost linearly with temperature and takes larger values than expected in the quasiballistic regime. In semiconducting CNTs, the mobilities are affected strongly by the contacts with metallic electrodes through Schottky barriers. The mobilities are maximally 30000cm2/Vs and cut-off frequencies of 300 GHz at room temperature. These calculated results provide useful information to the design of CNT field-effect-transistor devices.
Chmura, Bartosz; Lan, Zhenggang; Rode, Michal F; Sobolewski, Andrzej L
2009-10-07
The photoinduced electron-driven proton-transfer dynamics of the water-dimer system has been investigated by time-dependent quantum wave-packet calculations. The main nuclear degrees of freedom driving the system from the Frank-Condon region to the S(0)-S(1) conical intersection are the distance between the oxygen atoms and the displacement of the hydrogen atom from the oxygen-oxygen bond center. Two important coupling modes have been investigated: Rotation of the H-donating water dangling proton and asymmetric stretching of the H-accepting water dangling protons' O(a)H bonds. Potential energy surfaces of the ground and lowest excited electronic states have been constructed on the basis of ab initio calculations. The time-dependent quantum wave-packet propagation has been employed within the (2 + 1)-dimensional systems for the description of the nonadiabatic dynamics of water dimer. The effects of the initial vibrational state of the system on the electronic population transfer and dissociation dynamics are presented. To approximate the photochemical behavior of water dimer in bulk water, we add a boundary condition into the (2 + 1)-dimensional systems to simulate the existence of water bulk. The results provide insight into the mechanisms of excited state deactivation of the water-dimer system in gas phase and in bulk water through the electron-driven proton-transfer process.
Lee, Gyeongjin; Kim, Junwoo; Kim, So Young; Kim, Dong Eon; Joo, Taiha
2017-01-10
Coherent nuclear wave packet motions in an electronic excited state of a molecule are measured directly by time-resolved spontaneous fluorescence spectroscopy with an unprecedented time resolution by using two-photon absorption excitation and fluorescence upconversion by noncollinear sum frequency generation. With an estimated time resolution of approximately 25 fs, wave packet motions of vibrational modes up to 1600 cm(-1) are recorded for coumarin 153 in ethanol. Two-color transient absorption at 13 fs time resolution are measured to confirm the result. Vibrational displacements between the ground and excited states and Huang-Rhys factors (HRFs) are calculated by quantum mechanical methods and are compared with the experimental results. HRFs calculated by density functional theory (DFT) and time-dependent DFT reproduce the experiment adequately. This fluorescence-based method provides a unique and direct way to obtain the vibrational spectrum of a molecule in an electronic excited state and the HRFs, as well as the dynamics of excited states, and it might provide information on the structure of an excited state through the HRFs.
NASA Astrophysics Data System (ADS)
Artemyev, Anton N.; Müller, Anne D.; Hochstuhl, David; Cederbaum, Lorenz S.; Demekhin, Philipp V.
2016-04-01
The direct ionization of the helium atom by intense coherent high-frequency short laser pulses is investigated theoretically from first principles. To this end, we solve numerically the time-dependent Schrödinger equation for the two-electron wave packet and its interaction with the linearly polarized pulse by the efficient time-dependent restricted-active-space configuration-interaction method (TD-RASCI). In particular, we consider photon energies which are nearly resonant for the 1 s →2 p excitation in the He+ ion. Thereby, we investigate the dynamic interference of the photoelectrons of the same kinetic energy emitted at different times along the pulse in the two-electron system. In order to enable observation of the dynamic interference in the computed spectrum, the electron wave packets were propagated on large spatial grids over long times. The computed photoionization spectra of He exhibit pronounced interference patterns the complexity of which increases with the decrease of the photon energy detuning and with the increase of the pulse intensity. Our numerical results pave the way for experimental verification of the dynamic interference effect at presently available high-frequency laser pulse sources.
Koner, Debasish; Panda, Aditya N.; Barrios, Lizandra; González-Lezana, Tomás
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.
NASA Astrophysics Data System (ADS)
Millour, F.
2014-09-01
This paper serves as an introduction to the current book. It provides the basic notions of long-baseline optical/infrared interferometry prior to reading all the subsequent chapters, and is not an extended introduction to the field.
NASA Astrophysics Data System (ADS)
Düll, Wolf-Patrick; Schneider, Guido; Wayne, C. Eugene
2016-05-01
In 1968 V.E. Zakharov derived the Nonlinear Schrödinger equation for the two-dimensional water wave problem in the absence of surface tension, that is, for the evolution of gravity driven surface water waves, in order to describe slow temporal and spatial modulations of a spatially and temporarily oscillating wave packet. In this paper we give a rigorous proof that the wave packets in the two-dimensional water wave problem in a canal of finite depth can be approximated over a physically relevant timespan by solutions of the Nonlinear Schrödinger equation.
Linear and Nonlinear Anderson Localization in a Curved Potential
NASA Astrophysics Data System (ADS)
Claudio, Conti
2014-03-01
Disorder induced localization in the presence of nonlinearity and curvature is investigated. The time-resolved three-dimensional expansion of a wave packet in a bent cigar shaped potential with a focusing Kerr-like interaction term and Gaussian disorder is numerically analyzed. A self-consistent analytical theory, in which randomness, nonlinearity and geometry are determined by a single scaling parameter, is reported, and it is shown that curvature enhances localization.
NASA Astrophysics Data System (ADS)
Ishii, Hiroyuki; Kobayashi, Nobuhiko; Hirose, Kenji
2010-03-01
Using a time-dependent wave-packet diffusion method[1], which treats the quantum electron transport problems of huge systems of up to 80 million atoms, combining with molecular dynamics simulations, we study the electron transport of carbon nanotubes from ballistic to diffusive regimes from an atomistic viewpoint in the unified way. We can simulate the effects of electron- phonon couplings on the transport properties of the nanotubes at various temperatures. We confirm that the obtained mean free path and mobility agree well with recent experimental observations and theoretical calculations, and succeed in evaluating the resistance in entire regime between ballistic and diffusive transport limits. We clarify the resistance is remarkably different from that at the two transport limits, when the length of nanotubes is comparable to the mean free path. [1]H.Ishii, N.Kobayashi, and K.Hirose, Appl.Phys.Express 1(2008) 123002.
Artemyev, Anton N.; Müller, Anne D.; Demekhin, Philipp V.; Hochstuhl, David
2015-06-28
A theoretical method to study the angle-resolved multiphoton ionization of polyatomic molecules is developed. It is based on the time-dependent formulation of the Single Center (TDSC) method and consists in the propagation of single-active-electron wave packets in the effective molecular potentials in the presence of intense laser pulses. For this purpose, the time-dependent Schrödinger equation for one electron, moving in a molecular field and interacting with an arbitrary laser pulse, is solved in spherical coordinates by an efficient numerical approach. As a test, the method is applied to the one- and two-photon ionizations of a model methane-like chiral system by circularly polarized short intense high-frequency laser pulses. Thereby, we analyze the photoelectron circular dichroism (PECD) in the momentum distribution. The considered model application illustrates the capability of the TDSC method to study multiphoton PECD in fixed-in-space and randomly oriented chiral molecules.
Ge, Xin-Lei; Du, Hui; Guo, Jing; Liu, Xue-Shen
2015-04-06
By solving a two-dimensional time-dependent Schrödinger equation we investigate high harmonic generation (HHG) and isolated attosecond pulse generation for the H2+ molecular ion in a circularly polarized laser pulse combined with a Terahertz (THz) field. The harmonic intensity can be greatly enhanced and a continuum spectrum can be obtained when a THz field is added. The HHG process is studied by the semi-classical three-step model and the time-frequency analysis. Our studies show that only short trajectories contribute to HHG. Furthermore, we present the temporal evolution of the probability density of electron wave packet, which perfectly shows a clear picture of the electron's two-time recombination when a THz field is added, and it is the main mechanism of HHG. By superposing the harmonics in the range of 216-249 eV, an isolated attosecond pulse with a duration of about 69 attoseconds can be generated.
NASA Astrophysics Data System (ADS)
Artemyev, Anton N.; Müller, Anne D.; Hochstuhl, David; Demekhin, Philipp V.
2015-06-01
A theoretical method to study the angle-resolved multiphoton ionization of polyatomic molecules is developed. It is based on the time-dependent formulation of the Single Center (TDSC) method and consists in the propagation of single-active-electron wave packets in the effective molecular potentials in the presence of intense laser pulses. For this purpose, the time-dependent Schrödinger equation for one electron, moving in a molecular field and interacting with an arbitrary laser pulse, is solved in spherical coordinates by an efficient numerical approach. As a test, the method is applied to the one- and two-photon ionizations of a model methane-like chiral system by circularly polarized short intense high-frequency laser pulses. Thereby, we analyze the photoelectron circular dichroism (PECD) in the momentum distribution. The considered model application illustrates the capability of the TDSC method to study multiphoton PECD in fixed-in-space and randomly oriented chiral molecules.
NASA Astrophysics Data System (ADS)
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.
Jakowski, Jacek; Sumner, Isaiah; Iyengar, Srinivasan S
2006-09-01
In a recent publication, we introduced a computational approach to treat the simultaneous dynamics of electrons and nuclei. The method is based on a synergy between quantum wave packet dynamics and ab initio molecular dynamics. Atom-centered density-matrix propagation or Born-Oppenheimer dynamics can be used to perform ab initio dynamics. In this paper, wave packet dynamics is conducted using a three-dimensional direct product implementation of the distributed approximating functional free-propagator. A fundamental computational difficulty in this approach is that the interaction potential between the two components of the methodology needs to be calculated frequently. Here, we overcome this problem through the use of a time-dependent deterministic sampling measure that predicts, at every step of the dynamics, regions of the potential which are important. The algorithm, when combined with an on-the-fly interpolation scheme, allows us to determine the quantum dynamical interaction potential and gradients at every dynamics step in an extremely efficient manner. Numerical demonstrations of our sampling algorithm are provided through several examples arranged in a cascading level of complexity. Starting from a simple one-dimensional quantum dynamical treatment of the shared proton in [Cl-H-Cl](-) and [CH3-H-Cl](-) along with simultaneous dynamical treatment of the electrons and classical nuclei, through a complete three-dimensional treatment of the shared proton in [Cl-H-Cl](-) as well as treatment of a hydrogen atom undergoing donor-acceptor transitions in the biological enzyme, soybean lipoxygenase-1 (SLO-1), we benchmark the algorithm thoroughly. Apart from computing various error estimates, we also compare vibrational density of states, inclusive of full quantum effects from the shared proton, using a novel unified velocity-velocity, flux-flux autocorrelation function. In all cases, the potential-adapted, time-dependent sampling procedure is seen to improve the
Nonlinear modes of the tensor Dirac equation and CPT violation
NASA Technical Reports Server (NTRS)
Reifler, Frank J.; Morris, Randall D.
1993-01-01
Recently, it has been shown that Dirac's bispinor equation can be expressed, in an equivalent tensor form, as a constrained Yang-Mills equation in the limit of an infinitely large coupling constant. It was also shown that the free tensor Dirac equation is a completely integrable Hamiltonian system with Lie algebra type Poisson brackets, from which Fermi quantization can be derived directly without using bispinors. The Yang-Mills equation for a finite coupling constant is investigated. It is shown that the nonlinear Yang-Mills equation has exact plane wave solutions in one-to-one correspondence with the plane wave solutions of Dirac's bispinor equation. The theory of nonlinear dispersive waves is applied to establish the existence of wave packets. The CPT violation of these nonlinear wave packets, which could lead to new observable effects consistent with current experimental bounds, is investigated.
Non-Linear Analysis of the Elastic Behaviour of a Translation Device for X-Ray Interferometry
NASA Astrophysics Data System (ADS)
Mana, G.; Vattaneo, F.; Zosi, G.
1989-01-01
A tridimensional, non-linear, finite-element analysis, supplementing a previous bidimensional linear analysis, was applied to characterize the performance of a zerodur translation device for X-ray fringe scanning. The effects of errors deriving from machining tolerances or of parasitic force components are taken into account. Optimization criteria indicate that residual tilt angles can be reduced to less than 1 nrad over a displacement of 120 μm, obtained with a driving force of about 1 N. Each point of the upper platform moves in the vertical plane along an almost circular trajectory.
Cruz, Hans; Schuch, Dieter; Castaños, Octavio; Rosas-Ortiz, Oscar
2015-09-15
The sensitivity of the evolution of quantum uncertainties to the choice of the initial conditions is shown via a complex nonlinear Riccati equation leading to a reformulation of quantum dynamics. This sensitivity is demonstrated for systems with exact analytic solutions with the form of Gaussian wave packets. In particular, one-dimensional conservative systems with at most quadratic Hamiltonians are studied.
NASA Astrophysics Data System (ADS)
Bertrand, Tabi Conrad; Alidou, Mohamadou; Crepin, Kofané Timoleon
2009-06-01
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 Schrödinger 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.
Karzova, M.; Yuldashev, P.; Khokhlova, V.; Ollivier, S.; Blanc-Benon, Ph.
2015-10-28
Mach stem is a well-known structure typically observed in the process of strong (acoustic Mach numbers greater than 0.4) step-shock waves reflection from a rigid boundary. However, this phenomenon has been much less studied for weak shocks in nonlinear acoustic fields where Mach numbers are in the range from 0.001 to 0.01 and pressure waveforms have more complicated waveforms than step shocks. The goal of this work was to demonstrate experimentally how nonlinear reflection occurs in air for very weak spherically divergent acoustic spark-generated pulses resembling an N-wave. Measurements of reflection patterns were performed using a Mach-Zehnder interferometer. A thin laser beam with sub-millimeter cross-section was used to obtain the time resolution of 0.4 µs, which is 6 times higher than the time resolution of the condenser microphones. Pressure waveforms were reconstructed using the inverse Abel transform applied to the phase of the signal measured by the interferometer. The Mach stem formation was observed experimentally as a result of collision of the incident and reflected shock pulses. It was shown that irregular reflection of the pulse occurred in a dynamic way and the length of the Mach stem increased linearly while the pulse propagated along the surface. Since the front shock of the spark-generated pulse was steeper than the rear shock, irregular type of reflection was observed only for the front shock of the pulse while the rear shock reflection occurred in a regular regime.
NASA Astrophysics Data System (ADS)
Karzova, M.; Yuldashev, P.; Ollivier, S.; Khokhlova, V.; Blanc-Benon, Ph.
2015-10-01
Mach stem is a well-known structure typically observed in the process of strong (acoustic Mach numbers greater than 0.4) step-shock waves reflection from a rigid boundary. However, this phenomenon has been much less studied for weak shocks in nonlinear acoustic fields where Mach numbers are in the range from 0.001 to 0.01 and pressure waveforms have more complicated waveforms than step shocks. The goal of this work was to demonstrate experimentally how nonlinear reflection occurs in air for very weak spherically divergent acoustic spark-generated pulses resembling an N-wave. Measurements of reflection patterns were performed using a Mach-Zehnder interferometer. A thin laser beam with sub-millimeter cross-section was used to obtain the time resolution of 0.4 µs, which is 6 times higher than the time resolution of the condenser microphones. Pressure waveforms were reconstructed using the inverse Abel transform applied to the phase of the signal measured by the interferometer. The Mach stem formation was observed experimentally as a result of collision of the incident and reflected shock pulses. It was shown that irregular reflection of the pulse occurred in a dynamic way and the length of the Mach stem increased linearly while the pulse propagated along the surface. Since the front shock of the spark-generated pulse was steeper than the rear shock, irregular type of reflection was observed only for the front shock of the pulse while the rear shock reflection occurred in a regular regime.
NASA Technical Reports Server (NTRS)
Vangrass, Frank
1992-01-01
This semi-annual progress report provides an overview of the work performed during the first six months of Grant NAG 1 1423, titled 'GPS Interferometry'. The Global Positioning System (GPS) is a satellite-based positioning and timing system. Through the use of interferometric processing techniques, it is feasible to obtain sub-decimeter position accuracies for an aircraft in flight. The proposed duration of this Grant is three years. During the first year of the Grant, the efforts are focussed on two topics: (1) continued development of GPS Interferometry core technology; and (2) rapid technology demonstration of GPS interferometry through the design and implementation of a flight reference/autoland system. Multipath error has been the emphasis of the continued development of GPS Interferometry core technology. The results have been documented in a Doctoral Dissertation and a conference paper. The design and implementation of the flight reference/autoland system is nearing completion. The remainder of this progress report summarizes the architecture of this system.
Nonlinear lattice waves in heterogeneous media
NASA Astrophysics Data System (ADS)
Laptyeva, T. V.; Ivanchenko, M. V.; Flach, S.
2014-12-01
We discuss recent advances in the understanding of the dynamics of nonlinear lattice waves in heterogeneous media, which enforce complete wave localization in the linear wave equation limit, especially Anderson localization for random potentials, and Aubry-André localization for quasiperiodic potentials. Additional nonlinear terms in the wave equations can either preserve the phase-coherent localization of waves, or destroy it through nonintegrability and deterministic chaos. Spreading wave packets are observed to show universal features in their dynamics which are related to properties of nonlinear diffusion equations.
Shallow water modal evolution due to nonlinear internal waves
NASA Astrophysics Data System (ADS)
Badiey, Mohsen; Wan, Lin; Luo, Jing
2017-09-01
Acoustic modal behavior is reported for an L-shape hydrophone array during the passage of a strong nonlinear internal wave packet. Acoustic track is nearly parallel to the front of nonlinear internal waves. Through modal decomposition at the vertical array, acoustic modes are identified. Modal evolution along the horizontal array then is examined during a passing internal wave. Strong intensity fluctuations of individual modes are observed before and during the internal waves packet passes the fixed acoustic track showing a detailed evolution of the waveguide modal behavior. Acoustic refraction created either uneven distribution of modal energy over the horizontal array or additional returns observable at the entire L-shape array. Acoustic ray-mode simulations are used to phenomenologically explain the observed modal behavior.
Effect of nonlinear instability on gravity-wave momentum transport
NASA Technical Reports Server (NTRS)
Dunkerton, Timothy J.
1987-01-01
This paper investigates the nonlinear instability of internal gravity waves and the effects of their nonlinear interaction on momentum flux, using simple theoretical and numerical models. From the result of an analysis of parametric instability of a two-dimensional internal gravity wave as discussed by Yeh and Liu (1981) and Klostermeyer (1982), a group trajectory length scale for a gravity wave packet was determined, expressed in terms of the dominant vertical wavelenght and the degree of convective saturation. It is shown that this analysis justifies the Eikonal saturation method for relatively transient packets, that are well below the saturation amplitude, propagating in a slowly varying mean flow. Conversely, linear theory fails for persistent disturbances and trasient wave packets near convective saturation.
Shallow water modal evolution due to nonlinear internal waves
NASA Astrophysics Data System (ADS)
Badiey, Mohsen; Wan, Lin; Luo, Jing
2017-07-01
Acoustic modal behavior is reported for an L-shape hydrophone array during the passage of a strong nonlinear internal wave packet. Acoustic track is nearly parallel to the front of nonlinear internal waves. Through modal decomposition at the vertical array, acoustic modes are identified. Modal evolution along the horizontal array then is examined during a passing internal wave. Strong intensity fluctuations of individual modes are observed before and during the internal waves packet passes the fixed acoustic track showing a detailed evolution of the waveguide modal behavior. Acoustic refraction created either uneven distribution of modal energy over the horizontal array or additional returns observable at the entire L-shape array. Acoustic ray-mode simulations are used to phenomenologically explain the observed modal behavior.
NASA Astrophysics Data System (ADS)
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
Nonreciprocal Wave Propagation Through Open, Discrete Nonlinear Schrödinger Dimers
NASA Astrophysics Data System (ADS)
Lepri, Stefano; Casati, Giulio
We consider asymmetric (nonreciprocal) wave transmission through a layered nonlinear, non mirror-symmetric system described by the one-dimensional Discrete Nonlinear Schrödinger equation with spatially varying coefficients embedded in an otherwise linear lattice. Focusing on the simplest case of two nonlinear sites (the dimer), we compute exact scattering solutions such that waves with the same frequency and incident amplitude impinging from left and right directions have different transmission coefficients. The stability of some particular solutions is addressed. We show that oscillatory instability may lead to the formation of stable extended states coexisting with a nonlinear defect mode oscillating at a different frequency. Numerical simulations of wave packet scattering are presented. Gaussian wave packets with the same amplitude arriving from opposite directions on the dimer are indeed trasmitted very differently. Moreover, asymmetric transmission is sensitively dependent on the input parameters, akin to the case of chaotic scattering.
A self-consistent theory of localization in nonlinear random media
NASA Astrophysics Data System (ADS)
Cherroret, Nicolas
2017-01-01
The self-consistent theory of localization is generalized to account for a weak quadratic nonlinear potential in the wave equation. For spreading wave packets, the theory predicts the destruction of Anderson localization by the nonlinearity and its replacement by algebraic subdiffusion, while classical diffusion remains unaffected. In 3D, this leads to the emergence of a subdiffusion-diffusion transition in place of the Anderson transition. The accuracy and the limitations of the theory are discussed.
Cheng, Dahai; Yuan, Jiuchuang; Chen, Maodu
2014-01-09
Time-dependent wave packet (TDWP) and quasiclassical trajectory (QCT) calculations have been carried out for the reaction S(3P) + HD(X1Σg+) at the lowest 13A″ state with both rotational and vibrational excitations of reactant HD. The calculated integral cross sections from QCT agree fairly well with the TDWP calculations. The reaction probability results from TDWP show that the reaction displays a strong tendency to the SD channel. When the reactant HD is vibrationally excited, both channels are promoted apparently. The vibration of the HD bond tends to reduce the difference of reactivity between the two channels. The detailed state-to-state differential cross sections (DCSs) are calculated. These distributions show some significant characters of the barrier-type reactions. At the same time, the scattering width of product SD has a certain relationship with its rotation excitation. For the vector properties, P(θr), P(r), and P(θr,r) distributions are calculated by QCT, and the increased collision energy weakens the rotational polarization of the SD molecule.
An, Heesun; Baeck, Kyoung Koo
2011-11-24
An earlier time-dependent quantum wave packet propagation study of the photochemistry of Ph-OH [J. Chem. Phys. 2005, 122, 224315] is extended to investigate isotope effects (for Ph-OD) and the dynamics initiated by direct (vibronically induced) excitation to the (1)πσ* state. The isotope effect is significant only when the initially excited state is (1)ππ*, that is, there are noticeable changes not only in the time scale but also in the branching ratio (Ã/X̃) for the electronic states of the product Ph-O radical. In contrast, the isotope effect on the dynamics initiated by direct excitation to the (1)πσ* state is very small. Our most important observation for the dynamics initiated by direct excitation to the (1)πσ* state is that the initial excitation of the O-H stretch mode does not result in a noticeable enhancement of the product Ph-O radical in the Ã state, which corresponds to a dissociating H atom with low kinetic energy. The initial excitation of the CCOH torsion mode is the main reason for the enhancement of the product Ph-O radical in the Ã state that was observed in a vibrationally mediated two-photon experiment [J. Chem. Phys.2008, 128, 104307].
NASA Astrophysics Data System (ADS)
Sun, Zhigang; Lou, Nanquan; Nyman, Gunnar
2005-02-01
Time-dependent wave packet calculations of the (A 2A2←X 2B1) absorption and Raman spectra of the OClO molecule are reported. The Fourier grid Hamiltonian method in three dimensions is employed. The X 2B1 ground state ab initio potential energy surface reported by Peterson [J. Chem. Phys. 109, 8864 (1998)] is used together with his corresponding A 2A2 state surface or the revised surface of the A 2A2 state by Xie and Guo [Chem. Phys. Lett. 307, 109 (1999)]. Radau coordinates are used to describe the vibrations of a nonrotating OClO molecule. The split-operator method combined with fast Fourier transform is applied to propagate the wave function. We find that the ab initio A 2A2 potential energy surface better reproduces the detailed structures of the absorption spectrum at long wavelength, while the revised surface of the A 2A2 state, consistent with the work of Xie and Guo, better reproduces the overall shape and the energies of the vibrational levels. Both surfaces of the A 2A2 state can reasonably reproduce the experimental Raman spectra but neither does so in detail for the numerical model employed in the present work.
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.
NASA Astrophysics Data System (ADS)
Yuan, T.; Heale, C. J.; Snively, J. B.
2016-12-01
Utilizing observations from the Na lidar at Utah State University and the nearby Mesospheric Temperature Mapper (MTM) at Bear Lake Observatory (BLO) [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 September 2nd, 2011, to study the waves' evolution as a packet propagates upward. The lidar observed temperature perturbation was dominated by close to a 1-hour modulation at 100 km during the early hours, but gradually evolved into a 1.5-hour 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 utilized to simulate the observed GW 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.
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.
Gómez-Carrasco, S.; González-Sánchez, L.; Roncero, O.
2014-03-20
The dynamics and kinetics of the LiH + H reaction have been studied by using an accurate quantum reactive time-dependent wave packet method on the ab initio ground electronic state potential energy surfaces (PES) developed earlier. Reaction probabilities for the two possible reaction channels, the LiH + H→ H{sub 2} + Li depletion process and the LiH + H→H + LiH hydrogen exchange reaction, have been calculated from 1 meV up to 1.0 eV collision energies for total angular momenta J from 0 to 80. State-to-state and total integral cross sections for the LiH-depletion and H-exchange channels of the reaction have been calculated over this collision energy range. It is found that the LiH-depletion channel is dominant in the whole range of collision energies for both PESs. Accurate total rate coefficients have been calculated on both surfaces from 100 K to 2000 K and are significantly larger than previous empirical estimates and previous J-shifting results. In addition, the present accurate calculations present noticeable differences with previous calculations using the centrifugal sudden approximation.
NASA Astrophysics Data System (ADS)
Sauer, K.; Sydora, R. D.
2016-07-01
Recently, it has been shown that Langmuir oscillations (LOs) at the plasma frequency can be driven by an electron current without any electrostatic instability. This current may appear due to a (small) drift of the whole electron population against the ions or by beam electrons after their relaxation to a plateau-like distribution. The consequences of LOs for nonlinear wave phenomena in this scenario are studied by means of kinetic plasma simulations. It is shown that the electric field of LOs can act as a pump wave and generate Langmuir envelope solitons via the modulational instability. In this way, both counterstreaming Langmuir and ion-acoustic waves arise with the same wave number. For solar wind conditions the Doppler shift leads to the generation of satellite peaks with frequencies symmetric around the plasma frequency. Simultaneously, a peak appears in the ion-acoustic branch. These results agree well with recent STEREO observations in the solar wind.
Nonlinear evolution of astrophysical Alfven waves
Spangler, S.R.
1984-11-01
Nonlinear Alfven waves were studied using the derivative nonlinear Schrodinger equation as a model. The evolution of initial conditions, such as envelope solitons, amplitude-modulated waves, and band-limited noise was investigated. The last two furnish models for naturally occurring Alfven waves in an astrophysical plasma. A collapse instability in which a wave packet becomes more intense and of smaller spatial extent was analyzed. It is argued that this instability leads to enhanced plasma heating. In studies in which the waves are amplified by an electron beam, the instability tends to modestly inhibit wave growth. (ESA)
NASA Astrophysics Data System (ADS)
Sauer, K.; Malaspina, D.; Pulupa, M.
2016-12-01
Instead of starting with an unstable electron beam, our focus is directed on the nonlinear response of Langmuir oscillations which are driven after beam stabilization by the still persisting current of the (stable) two-electron plasma. The velocity distribution function of the second population forms a plateau with weak damping over a more or less extended wave number range k. As shown by PIC simulations, this so-called plateau plasma drives primarily Langmuir oscillations at the plasma frequency ωe with k=0 over long times without remarkable change of the distribution function. The Langmuir oscillations, however, act as pump wave for parametric decay by which an electron-acoustic wave slightly below ωe and a counter-streaming ion-acoustic wave are generated. Both high-frequency waves have nearly the same amplitude which is simply given by the product of plateau density and velocity. Beating of these two wave types leads to pronounced Langmuir amplitude modulation, in good agreement with solar wind and foreshock WIND observations where waveforms and electron distribution functions have simultaneously been analyzed.
Zanchet, A; Roncero, O; González-Lezana, T; Rodríguez-López, A; Aguado, A; Sanz-Sanz, C; Gómez-Carrasco, S
2009-12-31
The state-to-state differential cross sections for some atom + diatom reactions have been calculated using a new wave packet code, MAD-WAVE3, which is described in some detail and uses either reactant or product Jacobi coordinates along the propagation. In order to show the accuracy and efficiency of the coordinate transformation required when using reactant Jacobi coordinates, as recently proposed [ J. Chem. Phys. 2006 , 125 , 054102 ], the method is first applied to the H + D(2) reaction as a benchmark, for which exact time-independent calculations are also performed. It is found that the use of reactant coordinates yields accurate results, with a computational effort slightly lower than that when using product coordinates. The H(+) + D(2) reaction, with the same masses but a much deeper insertion well, is also studied and exhibits a completely different mechanism, a complex-forming one which can be treated by statistical methods. Due to the longer range of the potential, product Jacobi coordinates are more efficient in this case. Differential cross sections for individual final rotational states of the products are obtained based on exact dynamical calculations for some selected total angular momenta, combined with the random phase approximation to save the high computational time required to calculate all partial waves with very long propagations. The results obtained are in excellent agreement with available exact time-independent calculations. Finally, the method is applied to the Li + HF system for which reactant coordinates are very well suited, and quantum differential cross sections are not available. The results are compared with recent quasiclassical simulations and experimental results [J. Chem. Phys. 2005, 122, 244304]. Furthermore, the polarization of the product angular momenta is also analyzed as a function of the scattering angle.
Rubio-Lago, L; García-Vela, A; Arregui, A; Amaral, G A; Bañares, L
2009-11-07
The photodissociation of methyl iodide at different wavelengths in the red edge of the A-band (286-333 nm) has been studied using a combination of slice imaging and resonance enhanced multiphoton ionization detection of the methyl fragment in the vibrational ground state (nu=0). The kinetic energy distributions (KED) of the produced CH(3)(nu=0) fragments show a vibrational structure, both in the I((2)P(3/2)) and I( *)((2)P(1/2)) channels, due to the contribution to the overall process of initial vibrational excitation in the nu(3)(C-I) mode of the parent CH(3)I. The structures observed in the KEDs shift toward upper vibrational excited levels of CH(3)I when the photolysis wavelength is increased. The I((2)P(3/2))/I( *)((2)P(1/2)) branching ratios, photofragment anisotropies, and the contribution of vibrational excitation of the parent CH(3)I are explained in terms of the contribution of the three excited surfaces involved in the photodissociation process, (3)Q(0), (1)Q(1), and (3)Q(1), as well as the probability of nonadiabatic curve crossing (1)Q(1)<--(3)Q(0). The experimental results are compared with multisurface wave packet calculations carried out using the available ab initio potential energy surfaces, transition moments, and nonadiabatic couplings, employing a reduced dimensionality (pseudotriatomic) model. A general qualitative good agreement has been found between theory and experiment, the most important discrepancies being in the I((2)P(3/2))/[I((2)P(3/2))+I( *)((2)P(1/2))] branching ratios. Inaccuracies of the available potential energy surfaces are the main reason for the discrepancies.
NASA Astrophysics Data System (ADS)
Zhao, Juan
2013-04-01
We investigated spin-orbit-induced intersystem crossing effects in the title reaction by the time-dependent wave-packet method combined with an extended split operator scheme. We performed non-adiabatic calculations of the fine-structure-resolved cross section and adiabatic calculations of integral cross section. The calculations are based on the potential energy surfaces of 3A' and the two degenerate 3A'' states [S. Rogers, D. Wang, A. Kuppermann, and S. Walch, J. Phys. Chem. A 104, 2308 (2000)], 10.1021/jp992985g, together with the spin-orbit coupling matrix [B. Maiti and G. C. Schatz, J. Chem. Phys. 119, 12360 (2003)], 10.1063/1.1623481 and singlet 1A' potential energy surface [J. Dobbyn and P. J. Knowles, Faraday Discuss. 110, 247 (1998)]. The results of the O(3P) + D2 are similar to those of the O(3P) + H2 reaction. The product spin state-resolved reaction cross section and the total reaction cross section both show that the adiabatic channel is dominant in all cases, and the non-adiabatic channels have cross sections of several orders of magnitude smaller than the adiabatic channels at high collision energy. Although the cross sections caused by the intersystem crossing effects in the O(3P) + D2 reaction are larger than those in the O(3P) + H2 reaction, the differences in non-adiabaticity between these two reaction systems are quite modest. Based on the results of the O(3P) + H2 reaction, we can predict that the influence of spin-orbit on the total reaction cross sections of the O(3P) + D2 reaction is also insignificant. However, these non-adiabatic effects can be reflected in the presence of some forward-scattering in the angular distribution for the OD product.
NASA Astrophysics Data System (ADS)
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.
NASA Astrophysics Data System (ADS)
Roura, Albert
2017-04-01
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 promising scheme that overcomes these problems by compensating the effects of the gravity gradients and circumvents the fundamental limitations due to Heisenberg's uncertainty principle. Furthermore, it relaxes the experimental requirements on initial colocation by several orders of magnitude.
Mark Kasevich
2016-07-12
Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newtonâs constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?
Mark Kasevich
2008-05-07
Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?
Kasevich, Mark
2008-05-08
Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?
Complex master slave interferometry.
Rivet, Sylvain; Maria, Michael; Bradu, Adrian; Feuchter, Thomas; Leick, Lasse; Podoleanu, Adrian
2016-02-08
A general theoretical model is developed to improve the novel Spectral Domain Interferometry method denoted as Master/Slave (MS) Interferometry. In this model, two functions, g and h are introduced to describe the modulation chirp of the channeled spectrum signal due to nonlinearities in the decoding process from wavenumber to time and due to dispersion in the interferometer. The utilization of these two functions brings two major improvements to previous implementations of the MS method. A first improvement consists in reducing the number of channeled spectra necessary to be collected at Master stage. In previous MSI implementation, the number of channeled spectra at the Master stage equated the number of depths where information was selected from at the Slave stage. The paper demonstrates that two experimental channeled spectra only acquired at Master stage suffice to produce A-scans from any number of resolved depths at the Slave stage. A second improvement is the utilization of complex signal processing. Previous MSI implementations discarded the phase. Complex processing of the electrical signal determined by the channeled spectrum allows phase processing that opens several novel avenues. A first consequence of such signal processing is reduction in the random component of the phase without affecting the axial resolution. In previous MSI implementations, phase instabilities were reduced by an average over the wavenumber that led to reduction in the axial resolution.
NASA Astrophysics Data System (ADS)
Thomas, J. A.; Lerczak, J. A.; Moum, J. N.
2016-08-01
A two-dimensional array of 14 seafloor pressure sensors was deployed to measure properties of tidally generated, nonlinear, high-frequency internal waves over a 14 km by 12 km area west of Stellwagen Bank in Massachusetts Bay during summer 2009. Thirteen high-frequency internal wave packets propagated through the region over 6.5 days (one packet every semidiurnal cycle). Propagation speed and direction of wave packets were determined by triangulation, using arrival times and distances between triads of sensor locations. Wavefront curvature ranged from straight to radially spreading, with wave speeds generally faster to the south. Waves propagated to the southwest, rotating to more westward with shoreward propagation. Linear theory predicts a relationship between kinetic energy and bottom pressure variance of internal waves that is sensitive to sheared background currents, water depth, and stratification. By comparison to seafloor acoustic Doppler current profiler measurements, observations nonetheless show a strong relationship between kinetic energy and bottom pressure variance. This is presumably due to phase-locking of the wave packets to the internal tide that dominates background currents and to horizontally uniform and relatively constant stratification throughout the study. This relationship was used to qualitatively describe variations in kinetic energy of the high-frequency wave packets. In general, high-frequency internal wave kinetic energy was greater near the southern extent of wavefronts and greatly decreased upon propagating shoreward of the 40 m isobath.
NASA Astrophysics Data System (ADS)
Xu, SiLiu; Belić, Milivoj R.
2015-05-01
We discuss three-dimensional (3D) light bullets (LBs) in a system of coupled nonlinear Schrödinger equations with spatially modulated diffraction and nonlinearity coefficients, under the action of a Bessel trapping potential. Exact spatiotemporal vector solitary waves, or LBs, are obtained using the method of separation of variables and the Hirota's bilinear method. An inverse solution procedure is introduced, in which the desired localized solutions of equations are proposed first and then the corresponding diffraction and nonlinearity coefficients determined. New 3D wave packets are built with the help of spherical harmonics in the form of multipole, necklace, and toroidal solitary pulses. Numerical solution of the full system of equations indicates that an initial wave in the form of such 3D wave packets is longlived but slowly changing along the propagation direction.
Nonlinear resonant Auger spectroscopy in CO using an x-ray pump-control scheme
NASA Astrophysics Data System (ADS)
Zhang, Song Bin; Kimberg, Victor; Rohringer, Nina
2016-12-01
In the present paper we propose nonlinear femtosecond x-ray pump-probe spectroscopy to study the vibrational dynamics of a core-excited molecular state and discuss numerical results in CO. A femtosecond pump resonantly excites the carbon core-excited 1 s -1 π* state of the CO molecule. A second strong probe (control) pulse is applied at variable delay and is resonantly coupled to a valence excited state of the molecule. The strong nonlinear coupling of the control pulse induces Rabi flopping between the two electronic states. During this process, a vibrational wave packet in the core-excited state is created, which can be effectively manipulated by changing the time delay between pump and control pulses. We present an analysis of the resonant Auger electron spectrum and the transient absorption or emission spectrum on the pump transition and discuss their information content for reconstruction of the vibrational wave packet.
NASA Technical Reports Server (NTRS)
Dowling, Jonathan P.
2000-01-01
Recently, several researchers, including yours truly, have been able to demonstrate theoretically that quantum photon entanglement has the potential to also revolutionize the entire field of optical interferometry, by providing many orders of magnitude improvement in interferometer sensitivity. The quantum entangled photon interferometer approach is very general and applies to many types of interferometers. In particular, without nonlocal entanglement, a generic classical interferometer has a statistical-sampling shot-noise limited sensitivity that scales like 1/Sqrt[N], where N is the number of particles (photons, electrons, atoms, neutrons) passing through the interferometer per unit time. However, if carefully prepared quantum correlations are engineered between the particles, then the interferometer sensitivity improves by a factor of Sqrt[N] (square root of N) to scale like 1/N, which is the limit imposed by the Heisenberg Uncertainty Principle. For optical (laser) interferometers operating at milliwatts of optical power, this quantum sensitivity boost corresponds to an eight-order-of-magnitude improvement of signal to noise. Applications are to tests of General Relativity such as ground and orbiting optical interferometers for gravity wave detection, Laser Interferometer Gravity Observatory (LIGO) and the European Laser Interferometer Space Antenna (LISA), respectively.
NASA Technical Reports Server (NTRS)
Dowling, Jonathan P.
2000-01-01
Recently, several researchers, including yours truly, have been able to demonstrate theoretically that quantum photon entanglement has the potential to also revolutionize the entire field of optical interferometry, by providing many orders of magnitude improvement in interferometer sensitivity. The quantum entangled photon interferometer approach is very general and applies to many types of interferometers. In particular, without nonlocal entanglement, a generic classical interferometer has a statistical-sampling shot-noise limited sensitivity that scales like 1/Sqrt[N], where N is the number of particles (photons, electrons, atoms, neutrons) passing through the interferometer per unit time. However, if carefully prepared quantum correlations are engineered between the particles, then the interferometer sensitivity improves by a factor of Sqrt[N] (square root of N) to scale like 1/N, which is the limit imposed by the Heisenberg Uncertainty Principle. For optical (laser) interferometers operating at milliwatts of optical power, this quantum sensitivity boost corresponds to an eight-order-of-magnitude improvement of signal to noise. Applications are to tests of General Relativity such as ground and orbiting optical interferometers for gravity wave detection, Laser Interferometer Gravity Observatory (LIGO) and the European Laser Interferometer Space Antenna (LISA), respectively.
Selection rules for the nonlinear interaction of internal gravity waves.
Jiang, Chung-Hsiang; Marcus, Philip S
2009-03-27
Two intersecting beams of internal gravity waves will generically create two wave packets by nonlinear interaction. The frequency of one packet will be the sum and that of the other packet will be the difference of the frequencies of the intersecting beams. In principle, each packet should form an "X" pattern, or "St. Andrew's cross" consisting of four beams outgoing from the point of intersection. Here we derive selection rules and show that most of the expected nonlinear beams are forbidden. These rules can also be applied to the reflection of a beam from a boundary.
Numerical simulation of nonlinear Lamb waves used in a thin plate for detecting buried micro-cracks.
Wan, Xiang; Zhang, Qing; Xu, Guanghua; Tse, Peter W
2014-05-15
Compared with conventional linear ultrasonic inspection methods, which are sensitive only to severe defects, nonlinear ultrasonic inspection methods are better for revealing micro-cracks in thin plates. However, most nonlinear ultrasonic inspection methods have only been experimentally investigated using bulk or Rayleigh waves. Numerical studies, especially numerical simulations of Lamb ultrasonic waves, have seldom been reported. In this paper, the interaction between nonlinear S0 mode Lamb waves and micro-cracks of various lengths and widths buried in a thin metallic plate was simulated using the finite element method (FEM). The numerical results indicate that after interacting with a micro-crack, a new wave-packet was generated in addition to the S0 mode wave-packet. The second harmonics of the S0 mode Lamb waves and the new wave-packet were caused by nonlinear acoustic effects at the micro-crack. An amplitude ratio indicator is thus proposed for the early detection of buried micro-cracks.
Numerical Simulation of Nonlinear Lamb Waves Used in a Thin Plate for Detecting Buried Micro-Cracks
Wan, Xiang; Zhang, Qing; Xu, Guanghua; Tse, Peter W.
2014-01-01
Compared with conventional linear ultrasonic inspection methods, which are sensitive only to severe defects, nonlinear ultrasonic inspection methods are better for revealing micro-cracks in thin plates. However, most nonlinear ultrasonic inspection methods have only been experimentally investigated using bulk or Rayleigh waves. Numerical studies, especially numerical simulations of Lamb ultrasonic waves, have seldom been reported. In this paper, the interaction between nonlinear S0 mode Lamb waves and micro-cracks of various lengths and widths buried in a thin metallic plate was simulated using the finite element method (FEM). The numerical results indicate that after interacting with a micro-crack, a new wave-packet was generated in addition to the S0 mode wave-packet. The second harmonics of the S0 mode Lamb waves and the new wave-packet were caused by nonlinear acoustic effects at the micro-crack. An amplitude ratio indicator is thus proposed for the early detection of buried micro-cracks. PMID:24834908
Asymmetric wave propagation in nonlinear systems.
Lepri, Stefano; Casati, Giulio
2011-04-22
A mechanism for asymmetric (nonreciprocal) wave transmission is presented. As a reference system, we consider a layered nonlinear, nonmirror-symmetric model described by the one-dimensional discrete nonlinear Schrödinger equation with spatially varying coefficients embedded in an otherwise linear lattice. We construct a class of exact extended solutions such that waves with the same frequency and incident amplitude impinging from left and right directions have very different transmission coefficients. This effect arises already for the simplest case of two nonlinear layers and is associated with the shift of nonlinear resonances. Increasing the number of layers considerably increases the complexity of the family of solutions. Finally, numerical simulations of asymmetric wave packet transmission are presented which beautifully display the rectifying effect.
Acoustic multipath arrivals in the horizontal plane due to approaching nonlinear internal waves.
Badiey, Mohsen; Katsnelson, Boris G; Lin, Ying-Tsong; Lynch, James F
2011-04-01
Simultaneous measurements of acoustic wave transmissions and a nonlinear internal wave packet approaching an along-shelf acoustic path during the Shallow Water 2006 experiment are reported. The incoming internal wave packet acts as a moving frontal layer reflecting (or refracting) sound in the horizontal plane. Received acoustic signals are filtered into acoustic normal mode arrivals. It is shown that a horizontal multipath interference is produced. This has previously been called a horizontal Lloyd's mirror. The interference between the direct path and the refracted path depends on the mode number and frequency of the acoustic signal. A mechanism for the multipath interference is shown. Preliminary modeling results of this dynamic interaction using vertical modes and horizontal parabolic equation models are in good agreement with the observed data.
NASA Astrophysics Data System (ADS)
Hsu, Hung-Chu; Kharif, Christian; Francius, Marc; Chen, Yang-Yih
2015-04-01
In this study a nonlinear Schrödinger equation governing the complex envelope of a capillary-gravity water wave train propagating on uniform vertical shear current is derived. When the vorticity and surface tension vanishes, the classical NLS equation is found. The influence of constant vorticity and surface tension on the well-known stability properties of weakly nonlinear wave packets is studied. It is demonstrated that vorticity and surface tension modifies significantly the modulational instability properties of weakly nonlinear plane waves, namely the growth rate and bandwidth. Comparison with a fully nonlinear approach is conducted, too.
Experimental evidence of directivity-enhancing mechanisms in nonlinear lattices
NASA Astrophysics Data System (ADS)
Ganesh, R.; Gonella, Stefano
2017-02-01
In this letter, we experimentally investigate the directional characteristics of propagating, finite-amplitude wave packets in lattice materials, with an emphasis on the functionality enhancement due to the nonlinearly generated higher harmonics. To this end, we subject a thin, periodically perforated sheet to out-of-plane harmonic excitations, and we design a systematic measurement and data processing routine that leverages the full-wavefield reconstruction capabilities of a laser vibrometer to precisely delineate the effects of nonlinearity. We demonstrate experimentally that the interplay of dispersion, nonlinearity, and modal complexity which is involved in the generation and propagation of higher harmonics gives rise to secondary wave packets with characteristics that conform to the dispersion relation of the corresponding linear structure. Furthermore, these nonlinearly generated wave features display modal and directional characteristics that are complementary to those exhibited by the fundamental harmonic, thus resulting in an augmentation of the functionality landscape of the lattice. These results provide a proof of concept for the possibility to engineer the nonlinear wave response of mechanical metamaterials through a geometric and topological design of the unit cell.
Gray, S.K. ); Wozny, C.E. )
1991-02-15
We present three-dimensional, time-dependent quantum studies on the van der Waals vibrational predissociation reactions of NeCl{sub 2}, HeCl{sub 2}, NeICl, and HeICl. A wave packet/basis set expansion approach is employed. The results for these systems agree reasonably well with experiment and time-independent quantum calculations, where available. The similarities and differences among the four systems are explored by detailed inspection of the propagating wave function. The rotational product distributions can be understood in terms of a unified fragmentation mechanism that depends on the product of the initial probability density with a classical force, and short time dynamics. Quantum interference effects are shown to play an important role in the helium cases. A semiclassical model is also advanced to account for some features of the product distributions.
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.
Synthetic Aperture Radar Interferometry
NASA Technical Reports Server (NTRS)
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.
Dynamics of quasicollapse in nonlinear Schrodinger systems with nonlocal interactions
Perez-Garcia; Konotop; Garcia-Ripoll
2000-09-01
We study the effect of nonlocality on some dynamical properties of a self-focusing nonlocal nonlinear Schrodinger system. Using a combination of moment techniques, time dependent variational methods, and numerical simulations, we present evidence in support of the hypothesis that nonlocal attractively interacting condensates cannot collapse under very general forms of the interaction. Instead there appear oscillations of the wave packet with a localized component whose size is of the order of the range of interactions. We discuss the implications of the results to collapse phenomena in Bose-Einstein condensates.
NASA Astrophysics Data System (ADS)
Xie, Xi-Yang; Tian, Bo; Jiang, Yan; Sun, Wen-Rong; Sun, Ya; Gao, Yi-Tian
2016-07-01
Under investigation in this paper is an inhomogeneous nonlinear system, which describes the marginally-unstable baroclinic wave packets in a geophysical fluid or ultra-short pulses in nonlinear optics with certain inhomogeneous medium existing. By virtue of a kind of the Darboux transformation, under the Painlevé integrable condition, the first- and second-order bright and dark rogue-wave solutions are derived. Properties of the first- and second-order bright and dark rogue waves with α(t), which measures the state of the basic flow, and β(t), representing the interaction of the wave packet and mean flow, are graphically presented and analyzed: α(t) and β(t) have no influence on the wave packet, but affect the correction of the basic flow. When we choose α(t) as a constant and linear function, respectively, the shapes of the first- and second-order dark rogue waves change, and the peak heights and widths of them alter with the value of β(t) changing.
Speckle interferometry of asteroids
NASA Technical Reports Server (NTRS)
Drummond, Jack
1988-01-01
This final report for NASA Contract NAGw-867 consists of abstracts of the first three papers in a series of four appearing in Icarus that were funded by the preceding contract NAGw-224: (1) Speckle Interferometry of Asteroids I. 433 Eros; (2) Speckle Interferometry of Asteroids II. 532 Herculina; (3) Speckle Interferometry of Asteroids III. 511 Davida and its Photometry; and the fourth abstract attributed to NAGw-867, (4) Speckle Interferometry of Asteroids IV. Reconstructed images of 4 Vesta; and a review of the results from the asteroid interferometry program at Steward Observatory prepared for the Asteroids II book, (5) Speckle Interferometry of Asteroids. Two papers on asteroids, indirectly related to speckle interferometry, were written in part under NAGw-867. One is in press and its abstract is included here: Photometric Geodesy of Main-Belt Asteroids. II. Analysis of Lightcurves for Poles, Periods and Shapes; and the other paper, Triaxial Ellipsoid Dimensions and Rotational Pole of 2 Pallas from Two Stellar Occultations, is included in full.
Predictive simulation of nonlinear ultrasonics
NASA Astrophysics Data System (ADS)
Shen, Yanfeng; Giurgiutiu, Victor
2012-04-01
Most of the nonlinear ultrasonic studies to date have been experimental, but few theoretical predictive studies exist, especially for Lamb wave ultrasonic. Compared with nonlinear bulk waves and Rayleigh waves, nonlinear Lamb waves for structural health monitoring become more challenging due to their multi-mode dispersive features. In this paper, predictive study of nonlinear Lamb waves is done with finite element simulation. A pitch-catch method is used to interrogate a plate with a "breathing crack" which opens and closes under tension and compression. Piezoelectric wafer active sensors (PWAS) used as transmitter and receiver are modeled with coupled field elements. The "breathing crack" is simulated via "element birth and death" technique. The ultrasonic waves generated by the transmitter PWAS propagate into the structure, interact with the "breathing crack", acquire nonlinear features, and are picked up by the receiver PWAS. The features of the wave packets at the receiver PWAS are studied and discussed. The received signal is processed with Fast Fourier Transform to show the higher harmonics nonlinear characteristics. A baseline free damage index is introduced to assess the presence and the severity of the crack. The paper finishes with summary, conclusions, and suggestions for future work.
Multi-Photon Quantum Interferometry
NASA Astrophysics Data System (ADS)
Bouwmeester, Dirk
2007-06-01
Based on the investigation of multi-photon entanglement, as produced by stimulated parametric down-conversion, a technique is presented to create heralded ``noon'' states. The relevance for interferometry will be discussed. Furthermore we explored the use of photon-number resolving detectors in Mach-Zehnder type of interferometers. Our current detectors can distinguish 0, 1, 2, to7, photon impacts. Although the overall collection and detection efficiency of photons is well below unity (about 0.3) the photon number resolving property is still very useful if combined with coherent input states since those state are eigenstates of the photon annihilation operator. First we analyze the coherent state interferometer with a single photon-number resolving detector, revealing the strong non-linear response of an interferometer in the case of Fock-state projection. Second, we use two such detectors together with a Baysian phase estimation strategy to demonstrate that it is possible to achieve the standard quantum limit independently from the true value of the phase shift. This protocol is unbiased and saturates the Cramer-Rao phase uncertainty bound and, therefore, is an optimal phase estimation strategy. As a final topic it will be shown how quantum interferometry combined with micromechanical structures can be used to investigate quantum superpositions and quantum decoherence of macroscopic objects.
ERIC Educational Resources Information Center
Altman, Thomas C.
1992-01-01
Describes a method to create holograms for use in different interferometry techniques. Students utilize these techniques in experiments to study the structural integrity of a clarinet reed and the effects of temperature on objects. (MDH)
Virtual Reference Interferometry: Theory & Experiment
NASA Astrophysics Data System (ADS)
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 (<1m) fibers and optical components. Characterization of chromatic dispersion on short length fiber and optical components is a very difficult challenge. Accurate measurement of first and second order dispersion is important for applications from optical component design to nonlinear photonics, sensing and communications. Techniques for short-length dispersion characterization are therefore critical to the development of many photonic systems. The current generation of short-length dispersion measurement techniques are either easy to operate but lack sufficient accuracy, or have sufficient accuracy but are difficult to operate. The use of a 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
Progress in electron- and ion-interferometry
NASA Astrophysics Data System (ADS)
Hasselbach, Franz
2010-01-01
sources. 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. Möllenstedt 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.
Propagation of femtosecond pulse with self-similar shape in medium with nonlinear absorption
NASA Astrophysics Data System (ADS)
Trofimov, Vyacheslav A.; Zakharova, Irina G.
2015-05-01
We investigate the propagation of laser pulse with self-similar shape in homogeneous medium with various mechanisms of nonlinear absorption: multi-photon absorption or resonant nonlinearity under detuning the frequency, corresponding to energy transition, from the current frequency of wave packet, or nonlinear absorption with its saturation. Both types of sign for frequency detuning are considered. This results in appearance of a refractive index grating which induced a laser pulse self-action. We analyze also the influence of the laser pulse self-modulation due to cubic nonlinearity on existence of the laser pulse propagation mode with self-similar shape. We develop an analytical solution of the corresponding nonlinear eigenfunction problem for laser pulse propagation in medium with nonlinear absorption. This solution is confirmed by computer simulation of the eigenfunction problem for Schrödinger equation with considered nonlinearity. This mode of laser pulse propagation is very important for powerful TW laser pulse propagating in glass.
González, M G; Rodríguez, J D; Rubio-Lago, L; García-Vela, A; Bañares, L
2011-09-28
The photodissociation of CH(3)I in the blue edge (217-230 nm) of the A-band has been studied using a combination of slice imaging and resonance enhanced multiphoton ionization (REMPI) detection of the CH(3) fragment in the vibrational ground state (ν = 0). The profiles of the CH(3) (ν = 0) kinetic energy distributions and the photofragment anisotropies are interpreted in terms of the contribution of the excited surfaces involved in the photodissociation process, as well as the probability of non-adiabatic curve crossing between the (3)Q(0) and (1)Q(1) states. In the studied region, unlike in the central part of the A-band where absorption to the (3)Q(0) state dominates, the I((2)P(J)), with J = 1/2, 3/2, in correlation with CH(3) (ν = 0) kinetic energy distributions show clearly two contributions of different anisotropy, signature of the competing adiabatic and non-adiabatic dynamics, whose ratio strongly depends on the photolysis wavelength. The experimental results are compared with multisurface wave packet calculations carried out using the available ab initio potential energy surfaces, transition moments, and non-adiabatic couplings, employing a reduced dimensionality model. A good qualitative agreement is found between experiment and theory and both show evidence of reverse (3)Q(0)←(1)Q(1) non-adiabatic dynamics at the bluest excitation wavelengths both in the fragment kinetic energy and angular distributions.
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
Bartolomei, Massimiliano; Hernández, Marta I; Campos-Martínez, José
2005-02-08
A time-dependent wave packet method has been used to study different competing products of H(2)+H(2) collisions: four center reaction, collision induced dissociation, reactive dissociation, and three-body complex formation. A three-degree-of-freedom reduced dimensionality model has been used for five different geometries of the colliding complex (parallel H, crossed X, collinear L, and two T-shaped geometries T(I) and T(II)), with reactants in selected vibrational states with one diatom vibrationally "hot" and the other one vibrationally "cold." Product probabilities have been calculated using two potential energy surfaces [J. Chem. Phys. 101, 4004 (1994); J. Chem. Phys. 116, 666 (2002)] in order to compare their performance in the dynamics. The regions of the potential energy surfaces responsible of the threshold behavior of the probabilities have been identified. Overall, we have found that the most recent potential energy surface is less anisotropic, provides a smaller propensity for insertion-type processes, and gives lower energy thresholds.
NASA Technical Reports Server (NTRS)
Thorpe, James I.
2009-01-01
An overview of LISA Long-Arm Interferometry is presented. The contents include: 1) LISA Interferometry; 2) Constellation Design; 3) Telescope Design; 4) Constellation Acquisition; 5) Mechanisms; 6) Optical Bench Design; 7) Phase Measurement Subsystem; 8) Phasemeter Demonstration; 9) Time Delay Interferometry; 10) TDI Limitations; 11) Active Frequency Stabilization; 12) Spacecraft Level Stabilization; 13) Arm-Locking; and 14) Embarassment of Riches.
Optical Long Baseline Interferometry
NASA Astrophysics Data System (ADS)
Le Bouquin, Jean-Baptiste
Optical Long Baseline Interferometry provides unrivalled angular resolution on bright and compact astrophysical sources. The link between the observables (interferometric phase and contrast) and the image of the source is a Fourier transform expressed first by van Cittert and Zernike. Depending on the source size and the amount of information collected, the analysis of these Fourier components allows a measurement of the typical source size, a parametric modelling of its spatial structures, or a model-independent image reconstruction to be carried. In the past decades, optical long baseline interferometry provided fundamental measurements for astronomy (ex. Cepheids distances, surface-brightness relations) as well as iconic results such as the first images of stellar surfaces other than the Sun. Optical long baseline interferometers exist in the Northern and Southern hemisphere and are open to the astronomical community with modern level of support. We provide in this chapter an introduction to the fundamental principles of optical interferometry and introduce the currently available facilities.
Multiple telescope infrared interferometry
NASA Technical Reports Server (NTRS)
Townes, C. H.; Sutton, E. C.
1981-01-01
The advantages of multiple telescope infrared interferometry are discussed in detail, using the 10 micron region as a specific example. Scale and seeing considerations are addressed, taking into account analytically the distorting effect of turbulent air and discussing the effect of water vapor on seeing. The usefulness of fringe phase determination to determine the intensities in the radiation field, and the effect of atmospheric fluctuations on their use, are considered. Astrometry by means of interferometry is extensively covered, with examples such as a plot of the fringe phase of o Ceti as a function of time compared with a theoretical fringe phase of the star with a fixed best-fit baseline. The sensitivity of an interferometer involving two receiving telescopes is considered. Finally, an example of a telescope design for 10-micron interferometry is described and depicted.
Simultaneous immersion Mirau interferometry
Lyulko, Oleksandra V.; Randers-Pehrson, Gerhard; Brenner, David J.
2013-01-01
A novel technique for label-free imaging of live biological cells in aqueous medium that is insensitive to ambient vibrations is presented. This technique is a spin-off from previously developed immersion Mirau interferometry. Both approaches utilize a modified Mirau interferometric attachment for a microscope objective that can be used both in air and in immersion mode, when the device is submerged in cell medium and has its internal space filled with liquid. While immersion Mirau interferometry involves first capturing a series of images, the resulting images are potentially distorted by ambient vibrations. Overcoming these serial-acquisition challenges, simultaneous immersion Mirau interferometry incorporates polarizing elements into the optics to allow simultaneous acquisition of two interferograms. The system design and production are described and images produced with the developed techniques are presented. PMID:23742552
NASA Technical Reports Server (NTRS)
Sargent, A. I.
2002-01-01
The Interferometry Science Center (ISC) is operated jointly by Caltech and JPL and is part of NASA's Navigator Program. The ISC has been created to facilitate the timely and successful execution of scientific investigations within the Navigator program, particularly those that rely on observations from NASA's interferometer projects. Currently, ISC is expected to provide full life cycle support for the Keck Interferometer, the Starlight mission, the Space Interferometry Mission, and the Terrestrial Planet Finder Mission. The nature and goals of ISc will be described.
NASA Technical Reports Server (NTRS)
Sargent, A. I.
2002-01-01
The Interferometry Science Center (ISC) is operated jointly by Caltech and JPL and is part of NASA's Navigator Program. The ISC has been created to facilitate the timely and successful execution of scientific investigations within the Navigator program, particularly those that rely on observations from NASA's interferometer projects. Currently, ISC is expected to provide full life cycle support for the Keck Interferometer, the Starlight mission, the Space Interferometry Mission, and the Terrestrial Planet Finder Mission. The nature and goals of ISc will be described.
2013 Interferometry Forum Report
NASA Astrophysics Data System (ADS)
van Belle, G.; Ridgway, S.; ten Brummelaar, T.
2014-04-01
The 2013 Interferometry Forum was organized around a list of topics - each topic had a moderator and an archivist. Each participant in the forum had one or more assignments - this was not a meeting for passive participation. The following summaries are a slightly edited version of those notes; conclusions and recommendations are presented at the end of the document(An expanded version of the Forum Report may be found online at the IAU Commission 54 website, http://iau-c54.wikispaces.com/2013+Interferometry+Forum).
Nonlinear Aharonov-Bohm Scattering by Optical Vortices
Neshev, Dragomir; Nepomnyashchy, Alexander; Kivshar, Yuri S.
2001-07-23
We study linear and nonlinear wave scattering by an optical vortex in a self-defocusing nonlinear Kerr medium. In the linear case, we find a splitting of a plane-wave front at the vortex proportional to its circulation, similar to what occurs in the scattered wave of electrons for the Aharonov-Bohm effect. For larger wave amplitudes, we study analytically and numerically the scattering of a dark-soliton stripe (a nonlinear analog of a small-amplitude wave packet) by a vortex and observe a significant asymmetry of the scattered wave. Subsequently, a wave-front splitting of the scattered wave develops into transverse modulational instability, ''unzipping'' the stripe into trains of vortices with opposite charges.
Nonlinear phonon interferometry at the Heisenberg limit
NASA Astrophysics Data System (ADS)
Cheung, Hil F. H.; Patil, Yogesh Sharad; Chang, Laura; Chakram, Srivatsan; Vengalattore, Mukund
2016-05-01
Interferometers operating at or close to quantum limits of precision have found wide application in tabletop searches for physics beyond the standard model, the study of fundamental forces and symmetries of nature and foundational tests of quantum mechanics. The limits imposed by quantum fluctuations and measurement backaction on conventional interferometers (δϕ 1 /√{ N}) have spurred the development of schemes to circumvent these limits through quantum interference, multiparticle interactions and entanglement. Here, we realize a prominent example of such schemes, the so-called SU(1,1) interferometer, in a fundamentally new platform in which the interfering arms are distinct flexural modes of a millimeter-scale mechanical resonator. We realize up to 15.4(3) dB of noise squeezing and demonstrate the Heisenberg scaling of interferometric sensitivity (δϕ 1 / N), corresponding to a 6-fold improvement in measurement precision over a conventional interferometer. We describe how our work extends the optomechanical toolbox and how it presents new avenues for studies of optomechanical sensing and studies of nonequilibrium dynamics of multimode optomechanical systems. This work was supported by the DARPA QuASAR program through a grant from the ARO, the ARO MURI on non-equilibrium manybody dynamics and an NSF INSPIRE award.
Manimala, James M; Sun, C T
2016-06-01
The amplitude-dependent dynamic response in acoustic metamaterials having nonlinear local oscillator microstructures is studied using numerical simulations on representative discrete mass-spring models. Both cubically nonlinear hardening and softening local oscillator cases are considered. Single frequency, bi-frequency, and wave packet excitations at low and high amplitude levels were used to interrogate the models. The propagation and attenuation characteristics of harmonic waves in a tunable frequency range is found to correspond to the amplitude and nonlinearity-dependent shifts in the local resonance bandgap for such nonlinear acoustic metamaterials. A predominant shift in the propagated wave spectrum towards lower frequencies is observed. Moreover, the feasibility of amplitude and frequency-dependent selective filtering of composite signals consisting of individual frequency components which fall within propagating or attenuating regimes is demonstrated. Further enrichment of these wave manipulation mechanisms in acoustic metamaterials using different combinations of nonlinear microstructures presents device implications for acoustic filters and waveguides.
Discrete- and finite-bandwidth-frequency distributions in nonlinear stability applications
NASA Astrophysics Data System (ADS)
Kuehl, Joseph J.
2017-02-01
A new "wave packet" formulation of the parabolized stability equations method is presented. This method accounts for the influence of finite-bandwidth-frequency distributions on nonlinear stability calculations. The methodology is motivated by convolution integrals and is found to appropriately represent nonlinear energy transfer between primary modes and harmonics, in particular nonlinear feedback, via a "nonlinear coupling coefficient." It is found that traditional discrete mode formulations overestimate nonlinear feedback by approximately 70%. This results in smaller maximum disturbance amplitudes than those observed experimentally. The new formulation corrects this overestimation, accounts for the generation of side lobes responsible for spectral broadening, and results in disturbance representation more consistent with the experiment than traditional formulations. A Mach 6 flared-cone example is presented.
Zhang, Zhaojun; Zhang, Dong H.
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.
NASA Astrophysics Data System (ADS)
Ghosh, Sandip; Mukherjee, Saikat; Mukherjee, Bijit; Mandal, Souvik; Sharma, Rahul; Chaudhury, Pinaki; Adhikari, Satrajit
2017-08-01
The workability of beyond Born-Oppenheimer theory to construct diabatic potential energy surfaces (PESs) of a charge transfer atom-diatom collision process has been explored by performing scattering calculations to extract accurate integral cross sections (ICSs) and rate constants for comparison with most recent experimental quantities. We calculate non-adiabatic coupling terms among the lowest three singlet states of H3+ system (11A', 21A', and 31A') using MRCI level of calculation and solve the adiabatic-diabatic transformation equation to formulate the diabatic Hamiltonian matrix of the same process [S. Mukherjee et al., J. Chem. Phys. 141, 204306 (2014)] for the entire region of nuclear configuration space. The nonadiabatic effects in the D+ + H2 reaction has been studied by implementing the coupled 3D time-dependent wave packet formalism in hyperspherical coordinates [S. Adhikari and A. J. C. Varandas, Comput. Phys. Commun. 184, 270 (2013)] with zero and non-zero total angular momentum (J) on such newly constructed accurate (ab initio) diabatic PESs of H3+. We have depicted the convergence profiles of reaction probabilities for the reactive non-charge transfer, non-reactive charge transfer, and reactive charge transfer processes for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. Finally, total and state-to-state ICSs are calculated as a function of collision energy for the initial rovibrational state (v = 0, j = 0) of the H2 molecule, and consequently, those quantities are compared with previous theoretical and experimental results.
Ghosh, Sandip; Mukherjee, Saikat; Mukherjee, Bijit; Mandal, Souvik; Sharma, Rahul; Chaudhury, Pinaki; Adhikari, Satrajit
2017-08-21
The workability of beyond Born-Oppenheimer theory to construct diabatic potential energy surfaces (PESs) of a charge transfer atom-diatom collision process has been explored by performing scattering calculations to extract accurate integral cross sections (ICSs) and rate constants for comparison with most recent experimental quantities. We calculate non-adiabatic coupling terms among the lowest three singlet states of H3(+) system (1(1)A('), 2(1)A('), and 3(1)A(')) using MRCI level of calculation and solve the adiabatic-diabatic transformation equation to formulate the diabatic Hamiltonian matrix of the same process [S. Mukherjee et al., J. Chem. Phys. 141, 204306 (2014)] for the entire region of nuclear configuration space. The nonadiabatic effects in the D(+) + H2 reaction has been studied by implementing the coupled 3D time-dependent wave packet formalism in hyperspherical coordinates [S. Adhikari and A. J. C. Varandas, Comput. Phys. Commun. 184, 270 (2013)] with zero and non-zero total angular momentum (J) on such newly constructed accurate (ab initio) diabatic PESs of H3(+). We have depicted the convergence profiles of reaction probabilities for the reactive non-charge transfer, non-reactive charge transfer, and reactive charge transfer processes for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. Finally, total and state-to-state ICSs are calculated as a function of collision energy for the initial rovibrational state (v = 0, j = 0) of the H2 molecule, and consequently, those quantities are compared with previous theoretical and experimental results.
Generalized parametric down conversion, many particle interferometry, and Bell's theorem
NASA Technical Reports Server (NTRS)
Choi, Hyung Sup
1992-01-01
A new field of multi-particle interferometry is introduced using a nonlinear optical spontaneous parametric down conversion (SPDC) of a photon into more than two photons. The study of SPDC using a realistic Hamiltonian in a multi-mode shows that at least a low conversion rate limit is possible. The down converted field exhibits many stronger nonclassical phenomena than the usual two photon parametric down conversion. Application of the multi-particle interferometry to a recently proposed many particle Bell's theorem on the Einstein-Podolsky-Rosen problem is given.
Nonlinear heating of ions by electron cyclotron frequency waves
NASA Astrophysics Data System (ADS)
Zestanakis, P. A.; Hizanidis, K.; Ram, A. K.; Kominis, Y.
2010-11-01
We study the nonlinear interaction of ions with electron cyclotron (EC) wave packets in a magnetized plasma. Previous studies have shown that such interactions with high frequency electrostatic lower hybrid waves can lead to coherent energization of ions. It requires the frequency bandwidth of the wave packet to be broader than the ion cyclotron frequency [1,2]. For the electromagnetic high frequency EC waves we have developed a more general theory, based on the Lie transform canonical perturbation method [3,4]. We apply the theory to the case of two overlapping EC beams. The wave frequency of each beam is assumed to be frequency modulated with a modulation bandwidth comparable to the ion cyclotron frequency. We present results for both X-mode and O-mode and illustrate the conditions for ion energization. [4pt] [1] D. Benisti, A. K. Ram, and A. Bers, Phys. Plasmas 5, 3224 (1998). [0pt] [2] A. K. Ram, A. Bers, and D. Benisti , J. Geophys. Res. 103, 9431 (1998). [0pt] [3] J.R. Cary and A.N. Kaufman, Phys. Fluids 24, 1238 (1981). [0pt] [4] R.L. Dewar, J. Phys A-Math. Gen 9, 2043 (1976).
Digitally Enhanced Heterodyne Interferometry
NASA Technical Reports Server (NTRS)
Shaddock, Daniel; Ware, Brent; Lay, Oliver; Dubovitsky, Serge
2010-01-01
Spurious interference limits the performance of many interferometric measurements. Digitally enhanced interferometry (DEI) improves measurement sensitivity by augmenting conventional heterodyne interferometry with pseudo-random noise (PRN) code phase modulation. DEI effectively changes the measurement problem from one of hardware (optics, electronics), which may deteriorate over time, to one of software (modulation, digital signal processing), which does not. DEI isolates interferometric signals based on their delay. Interferometric signals are effectively time-tagged by phase-modulating the laser source with a PRN code. DEI improves measurement sensitivity by exploiting the autocorrelation properties of the PRN to isolate only the signal of interest and reject spurious interference. The properties of the PRN code determine the degree of isolation.
NASA Technical Reports Server (NTRS)
Thorpe, James Ira
2010-01-01
A key challenge for all gravitational wave detectors in the detection of changes in the fractional difference between pairs of test masses with sufficient precision to measure astrophysical strains with amplitudes on the order of approx.10(exp -21). ln the case of the five million km arms of LISA, this equates to distance measurements on the ten picometer level. LISA interferometry utilizes a decentralized topology, in which each of the sciencecraft houses its own light sources, detectors, and electronics. The measurements made at each of the sciencecraft are then telemetered to ground and combined to extract the strain experienced by the constellation as a whole. I will present an overview of LISA interferometry and highlight some of the key components and technologies that make it possible.
NASA Astrophysics Data System (ADS)
Chum, Jaroslav; Cabrera, Miguel; Liu, Jann-Yenq; Laštovička, Jan; Mošna, Zbyšek; Fagre, Mariano; Fišer, Jiří; Burešová, Dalia
2017-04-01
The nonlinear behavior of acoustic waves and their dissipation in the upper atmosphere and ionosphere is explained on the basis of experimental data and numerical simulations. Two events are presented: a) Infrasound waves generated by vertical motion of the ground surface during the Mw 8.3 earthquake that occurred near Chilean coast on 16 September, 2015, are studied. It is shown that the infrasound waves changed their waveform in the upper atmosphere owing to nonlinear effects (large amplitudes). This change resulted in the formation of the "N-shaped" pulse that resembled a shock wave. At the same time the spectral content of the wave packet shifted toward the lower frequencies. The observation of co-seismic disturbance in the ionosphere at the altitude of about 200 km by continuous Doppler sounding at approximately 800 km horizontal distance from the epicenter is in good agreement with numerical solution of compressible fluid equations for the viscous atmosphere. b) Observation and numerical simulation of the co-seismic disturbance in the ionosphere over Taiwan, triggered by seismic waves generated by the Mw 7.8 earthquake in Nepal on 25 April 2015, reveal that even at the horizontal distance of about 3700 km from the epicenter, the nonlinear phenomena partly contribute to the change of the spectral content of the acoustic wave packet in the upper atmosphere. However, the N-shaped pulse was not observed at this distance.
Dynamical phase interferometry of cold atoms in optical lattices
London, Uri; Gat, Omri
2011-12-15
We study the propagation of cold-atom wave packets in an interferometer with a Mach-Zehnder topology based on the dynamical phase of Bloch oscillation in a weakly forced optical lattice with a narrow potential barrier that functions as a cold-atom wave-packet splitter. We calculate analytically the atomic wave function, and show that the expected number of atoms in the two outputs of the interferometer oscillates rapidly as a function of the angle between the potential barrier and the forcing direction with period proportional to the external potential difference across a lattice spacing divided by the lattice band energy scale. The interferometer can be used as a high-precision force probe whose principle of operation is different from current interferometers based on the overall position of Bloch oscillating wave packets.
Nonlinearity-reduced interferometer
NASA Astrophysics Data System (ADS)
Wu, Chien-ming
2007-12-01
Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as the frequency mixing, polarization mixing, polarization-frequency mixing, and the ghost reflections. An interferometer having accuracy in displacement measurement of less than one-nanometer is necessary in nanometrology. To meet the requirement, the periodic nonlinearity should be less than deep sub-nanometer. In this paper, a nonlinearity-reduced interferometry has been proposed. Both the linear- and straightness-interferometer were tested. The developed interferometer demonstrated of a residual nonlinearity less than 25 pm.
Nonlinear plasmonics in a two-dimensional plasma layer
NASA Astrophysics Data System (ADS)
Eliasson, Bengt; Liu, Chuan Sheng
2016-05-01
The nonlinear electron dynamics in a two-dimensional (2D) plasma layer are investigated theoretically and numerically. In contrast to the Langmuir oscillations in a three-dimensional (3D) plasma, a well-known feature of the 2D system is the square root dependence of the frequency on the wavenumber, which leads to unique dispersive properties of 2D plasmons. It is found that for large amplitude plasmonic waves there is a nonlinear frequency upshift similar to that of periodic gravity waves (Stokes waves). The periodic wave train is subject to a modulational instability, leading to sidebands growing exponentially in time. Numerical simulations show the breakup of a 2D wave train into localized wave packets and later into wave turbulence with immersed large amplitude solitary spikes. The results are applied to systems involving massless Dirac fermions in graphene as well as to sheets of electrons on liquid helium.
Nonlinear global modes in wakes behind bluff bodies
NASA Astrophysics Data System (ADS)
Chomaz, Jean-Marc; Couairon, Arnaud
1999-11-01
We show, using a direct numerical simulation, that nonlinear destabilization of a parallel wake give rise to a saturated wave packet with fronts propagating at a velocity selected by the Dee & Langer criteria [Phys. Rev. Lett, 50, 383, (1985)]. In this spirit, a real wake will correspond to this front blocked by the body when it starts moving upstream. This idea explain why linear criteria based on absolute and convective instability has been successful in the past to explain the occurrence of strongly nonlinear self sustained mode. Further more the use of the Ginzburg-Landau equation with varying coefficients as a model gives quantitative predictions for scaling laws of the maximum amplitude an the spatial distribution of the self sustained oscillation that compare favorably with observations [Goujon-Durand et al. Phys. Rev. E, 50, 308, (1994)] and numerical simulations [Zielinska & Wesfreid, Phys. Fluids, 7, 1418, (1995)] of the wake behind bluff bodies.
Nonlinear acoustics in a dispersive continuum: Random waves, radiation pressure, and quantum noise
NASA Astrophysics Data System (ADS)
Cabot, M. A.
The nonlinear interaction of sound with sound is studied using dispersive hydrodynamics which derived from a variational principle and the assumption that the internal energy density depends on gradients of the mass density. The attenuation of sound due to nonlinear interaction with a background is calculated and is shown to be sensitive to both the nature of the dispersion and decay bandwidths. The theoretical results are compared to those of low temperature helium experiments. A kinetic equation which described the nonlinear self-inter action of a background is derived. When a Deybe-type cutoff is imposed, a white noise distribution is shown to be a stationary distribution of the kinetic equation. The attenuation and spectrum of decay of a sound wave due to nonlinear interaction with zero point motion is calculated. In one dimension, the dispersive hydrodynamic equations are used to calculate the Langevin and Rayleigh radiation pressures of wave packets and solitary waves.
Refraction of Wave Packets by Currents.
1982-04-01
occurs and N r 0.046 52 14. Ray trajectories for 14 second period waves in a parallel, following current patterned after the Circumpolar Current 53 -4. 15...8217. .... , .*... . .. .- .- , ..-. po Figure Page 16. Ray trajectories for 17 second period waves in a parallel, following current patterned after the...Ray trajectories for 7 second period waves in a parallel, following current patterned after the Gulf Stream .... 57 19. Ray trajectories for 7 second
Spatial interferometry in optical astronomy
NASA Technical Reports Server (NTRS)
Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude
1990-01-01
A bibliographic guide is presented to publications of spatial interferometry techniques applied to optical astronomy. Listings appear in alphabetical order, by first author, as well as in specific subject categories listed in chronological order, including imaging theory and speckle interferometry, experimental techniques, and observational results of astronomical studies of stars, the Sun, and the solar system.
Vibration Analysis by Speckle Interferometry,
The vibrational modes of complex systems can be visualized with high sensitivity by laser light speckle interferometry. Electronic speckle pattern...interferometry (ESPI), in contrast to holography, does not use photo-chemical storage media but shows a live image of the vibrational modes created by
Variable sensitivity moire interferometry
NASA Technical Reports Server (NTRS)
Johnson-Cole, Helen; Bennewitz, James H.; Gilbert, John A.
1991-01-01
This paper demonstrates that optical microlithography can be used to produce a crossed grating which diffracts light into multiple orders sufficient to record moire interferograms with sensitivities ranging from 2.0 to 0.285 micron/fringe. The grating profile produced by the method is analyzed to establish the diffraction efficiency in each diffraction order, and generalized expressions are given for variable sensitivity moire interferometry. Experimental tests are conducted to verify analytical arguments. In one of these tests, two different diffraction order pairs are used simultaneously to verify that surface displacement can be measured at different sensitivities.
Chromatic confocal spectral interferometry
Papastathopoulos, Evangelos; Koerner, Klaus; Osten, Wolfgang
2006-11-10
Chromatic confocal spectral interferomertry (CCSI) is a novel scheme for topography measurements that combines the techniques of spectral interferometry and chromatic confocal microscopy. This hybrid method allows for white-light interferometric detection with a high NA in a single-shot manner. To the best of our knowledge, CCSI is the first interferometric method that utilizes a confocally filtered and chromatically dispersed focus for detection and simultaneously allows for retrieval of the depth position of reflecting or scattering objects utilizing the phase (modulation frequency) of the interferometric signals acquired. With the chromatically dispersed focus, the depth range of the sensor is decoupled from the NA of the microscope objective.
Developments In Moire Interferometry
NASA Astrophysics Data System (ADS)
Post, Daniel
1982-06-01
Recent progress in high-sensitivity moire interferometry is reviewed. Interference patterns reveal full-field contour maps of in-plane displacements. Sensitivity corresponds to moire with 1200 lines/mm (30,480 //in.) for most examples, but approaches the theoretical limit of X/2 displacement per fringe in one demonstration. Techniques for producing cross-line phase gratings on specimens are described, as well as use of real and virtual reference gratings. Carrier patterns and optical filtering are used to cancel initial or no-load patterns. Diverse applications are illustrated.
Solitons and rogue waves for a nonlinear system in the geophysical fluid
NASA Astrophysics Data System (ADS)
Xie, Xi-Yang; Tian, Bo; Liu, Lei; Wu, Xiao-Yu; Jiang, Yan
2016-12-01
In this paper, we investigate a nonlinear system, which describes the marginally unstable baroclinic wave packets in the geophysical fluid. Based on the symbolic computation and Hirota method, bright one- and two-soliton solutions for such a system are derived. Propagation and collisions of the solitons are graphically shown and discussed with β, which reflects the collision between the wave packet and mean flow, α, which measures the state of the basic flow, and group velocity γ. γ is observed to affect the amplitudes of the solitons, and α can influence the solitons’ traveling directions. By virtue of the generalized Darboux transformation, the first- and second-order rogue-wave solutions are derived. Properties of the first- and second-order rogue waves are graphically presented and analyzed: The first-order rogue waves are shown in the figures. α has no effects on A, which is the amplitude of the wave packet, but with the increase of α, amplitude of B, which is a quantity measuring the correction of the basic flow, decreases. When β is chosen differently, A and B do not keep their shapes invariant. With the value of γ increasing, amplitudes of A and B become larger. The second-order rogue wave is presented, from which we observe that with α increasing, amplitude of B decreases, but α has no effects on A. Collision features of A and B alter with the value of β changing. When we make the value of γ larger, amplitudes of A and B increase.
Instability and dynamics of two nonlinearly coupled intense laser beams in a quantum plasma
NASA Astrophysics Data System (ADS)
Wang, Yunliang; Shukla, P. K.; Eliasson, B.
2013-01-01
We consider nonlinear interactions between two relativistically strong laser beams and a quantum plasma composed of degenerate electron fluids and immobile ions. The collective behavior of degenerate electrons is modeled by quantum hydrodynamic equations composed of the electron continuity, quantum electron momentum (QEM) equation, as well as the Poisson and Maxwell equations. The QEM equation accounts the quantum statistical electron pressure, the quantum electron recoil due to electron tunneling through the quantum Bohm potential, electron-exchange, and electron-correlation effects caused by electron spin, and relativistic ponderomotive forces (RPFs) of two circularly polarized electromagnetic (CPEM) beams. The dynamics of the latter are governed by nonlinear wave equations that include nonlinear currents arising from the relativistic electron mass increase in the CPEM wave fields, as well as from the beating of the electron quiver velocity and electron density variations reinforced by the RPFs of the two CPEM waves. Furthermore, nonlinear electron density variations associated with the driven (by the RPFs) quantum electron plasma oscillations obey a coupled nonlinear Schrödinger and Poisson equations. The nonlinearly coupled equations for our purposes are then used to obtain a general dispersion relation (GDR) for studying the parametric instabilities and the localization of CPEM wave packets in a quantum plasma. Numerical analyses of the GDR reveal that the growth rate of a fastest growing parametrically unstable mode is in agreement with the result that has been deduced from numerical simulations of the governing nonlinear equations. Explicit numerical results for two-dimensional (2D) localized CPEM wave packets at nanoscales are also presented. Possible applications of our investigation to intense laser-solid density compressed plasma experiments are highlighted.
Lagrange form of the nonlinear Schrödinger equation for low-vorticity waves in deep water
NASA Astrophysics Data System (ADS)
Abrashkin, Anatoly; Pelinovsky, Efim
2017-06-01
The nonlinear Schrödinger (NLS) equation describing the propagation of weakly rotational wave packets in an infinitely deep fluid in Lagrangian coordinates has been derived. The vorticity is assumed to be an arbitrary function of Lagrangian coordinates and quadratic in the small parameter proportional to the wave steepness. The vorticity effects manifest themselves in a shift of the wave number in the carrier wave and in variation in the coefficient multiplying the nonlinear term. In the case of vorticity dependence on the vertical Lagrangian coordinate only (Gouyon waves), the shift of the wave number and the respective coefficient are constant. When the vorticity is dependent on both Lagrangian coordinates, the shift of the wave number is horizontally inhomogeneous. There are special cases (e.g., Gerstner waves) in which the vorticity is proportional to the squared wave amplitude and nonlinearity disappears, thus making the equations for wave packet dynamics linear. It is shown that the NLS solution for weakly rotational waves in the Eulerian variables may be obtained from the Lagrangian solution by simply changing the horizontal coordinates.
Atomic Interferometry with Detuned Counter-Propagating Electromagnetic Pulses
Tsang, Ming -Yee
2014-09-05
Atomic fountain interferometry uses atoms cooled with optical molasses to 1 μK, which are then launched in a fountain mode. The interferometer relies on the nonlinear Raman interaction of counter-propagating visible light pulses. We present models of these key transitions through a series of Hamiltonians. Our models, which have been verified against special cases with known solutions, allow us to incorporate the effects of non-ideal pulse shapes and realistic laser frequency or wavevector jitter.
The evolution of nonlinear Alfven waves subject to growth and damping
NASA Astrophysics Data System (ADS)
Spangler, S. R.
1986-08-01
The effects of wave amplification (by streaming particle distributions) and damping (by ion-cyclotron resonance absorption) on the nonlinear evolution of Alfven waves are investigated theoretically. The results of numerical simulations based on the derivative-Schroedinger-equation model of Spangler and Sheerin (1983 and 1985) are presented graphically and characterized in detail, with an emphasis on astrophysical applications. Three phases of wave-packet evolution (linear, nonlinear-saturation, and postsaturation quasi-steady) are identified, and nonlinearity is found to transfer wave energy from growing or amplified wavenumbers to wavenumbers affected by damping. It is pointed out that although there are similarities between the solitonlike pulses predicted by the simulations and short-wavelength shocklet structures observed in the earth bow shock, the model does not explain why low-frequency waves stop growing in the vicinity of the bow shock.
Intellectual property in holographic interferometry
NASA Astrophysics Data System (ADS)
Reingand, Nadya; Hunt, David
2006-08-01
This paper presents an overview of patents and patent applications on holographic interferometry, and highlights the possibilities offered by patent searching and analysis. Thousands of patent documents relevant to holographic interferometry were uncovered by the study. The search was performed in the following databases: U.S. Patent Office, European Patent Office, Japanese Patent Office and Korean Patent Office for the time frame from 1971 through May 2006. The patent analysis unveils trends in patent temporal distribution, patent families formation, significant technological coverage within the market of system that employ holographic interferometry and other interesting insights.
Spectroscopic Low Coherence Interferometry
NASA Astrophysics Data System (ADS)
Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.
Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.
Deep frequency modulation interferometry.
Gerberding, Oliver
2015-06-01
Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers.
Optical Long Baseline Interferometry News
NASA Astrophysics Data System (ADS)
Lawson, P. R.; Malbet, F.
2005-12-01
The Optical Long Baseline Interferometry News is a website and forum for scientists, engineers, and students who share an interest in long baseline stellar interferometry. It was established in 1995 and is the focus of activity of the IAU Working Group on Optical/Infrared Interferometry. Here you will find links to projects devoted to stellar interferometry, news items, recent papers and preprints, and resources for further research. The email news forum was established in 2001 to complement the website and to facilitate exchanges and collaborations. The forum includes an email exploder and an archived list of discussions. You are invited to explore the forum and website at http://olbin.jpl.nasa.gov. Work by PRL was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Optical Interferometry Motivation and History
NASA Technical Reports Server (NTRS)
Lawson, Peter
2006-01-01
A history and motivation of stellar interferometry is presented. The topics include: 1) On Tides, Organ Pipes, and Soap Bubbles; 2) Armand Hippolyte Fizeau (1819-1896); 3) Fizeau Suggests Stellar Interferometry 1867; 4) Edouard Stephan (1837-1923); 5) Foucault Refractor; 6) Albert A. Michelson (1852-1931); 7) On the Application of Interference Methods to Astronomy (1890); 8) Moons of Jupiter (1891); 9) Other Applications in 19th Century; 10) Timeline of Interferometry to 1938; 11) 30 years goes by; 12) Mount Wilson Observatory; 13) Michelson's 20 ft Interferometer; 14) Was Michelson Influenced by Fizeau? 15) Work Continues in the 1920s and 30s; 16) 50 ft Interferometer (1931-1938); 17) Light Paths in the 50 ft Interferometer; 18) Ground-level at the 50 ft; 19) F.G. Pease (1881-1938); 20) Timeline of Optical Interferometry to 1970; 21) A New Type of Stellar Interferometer (1956); 22) Intensity Interferometer (1963- 1976; 23) Robert Hanbury Brown; 24) Interest in Optical Interferometry in the 1960s; 25) Interferometry in the Early 1970s; and 26) A New Frontier is Opened up in 1974.
Optical Interferometry Motivation and History
NASA Technical Reports Server (NTRS)
Lawson, Peter
2006-01-01
A history and motivation of stellar interferometry is presented. The topics include: 1) On Tides, Organ Pipes, and Soap Bubbles; 2) Armand Hippolyte Fizeau (1819-1896); 3) Fizeau Suggests Stellar Interferometry 1867; 4) Edouard Stephan (1837-1923); 5) Foucault Refractor; 6) Albert A. Michelson (1852-1931); 7) On the Application of Interference Methods to Astronomy (1890); 8) Moons of Jupiter (1891); 9) Other Applications in 19th Century; 10) Timeline of Interferometry to 1938; 11) 30 years goes by; 12) Mount Wilson Observatory; 13) Michelson's 20 ft Interferometer; 14) Was Michelson Influenced by Fizeau? 15) Work Continues in the 1920s and 30s; 16) 50 ft Interferometer (1931-1938); 17) Light Paths in the 50 ft Interferometer; 18) Ground-level at the 50 ft; 19) F.G. Pease (1881-1938); 20) Timeline of Optical Interferometry to 1970; 21) A New Type of Stellar Interferometer (1956); 22) Intensity Interferometer (1963- 1976; 23) Robert Hanbury Brown; 24) Interest in Optical Interferometry in the 1960s; 25) Interferometry in the Early 1970s; and 26) A New Frontier is Opened up in 1974.
Tunable, nonlinear Hong-Ou-Mandel interferometer
NASA Astrophysics Data System (ADS)
Oehri, D.; Pletyukhov, M.; Gritsev, V.; Blatter, G.; Schmidt, S.
2015-03-01
We investigate the two-photon scattering properties of a Jaynes-Cummings (JC) nonlinearity consisting of a two-level system (qubit) interacting with a single-mode cavity, which is coupled to two waveguides, each containing a single incident photon wave packet initially. In this scattering setup, we study the interplay between the Hong-Ou-Mandel (HOM) effect arising due to quantum interference and effective photon-photon interactions induced by the presence of the qubit. We calculate the two-photon scattering matrix of this system analytically and identify signatures of interference and interaction in the second-order auto- and cross-correlation functions of the scattered photons. In the dispersive regime, when qubit and cavity are far detuned from each other, we find that the JC nonlinearity can be used as an almost linear, in situ tunable beam splitter giving rise to ideal Hong-Ou-Mandel interference, generating a highly path-entangled two-photon NOON state of the scattered photons. The latter manifests itself in strongly suppressed waveguide cross-correlations and Poissonian photon number statistics in each waveguide. If the two-level system and the cavity are on resonance, the JC nonlinearity strongly modifies the ideal HOM conditions leading to a smaller degree of path entanglement and sub-Poissonian photon number statistics. In the latter regime, we find that photon blockade is associated with bunched autocorrelations in both waveguides, while a two-polariton resonance can lead to bunched as well as antibunched correlations.
Stellar Temporal Intensity Interferometry
NASA Astrophysics Data System (ADS)
Kian, Tan Peng
Stellar intensity interferometry was developed by Hanbury-Brown & Twiss [1954, 1956b, 1957, 1958] to bypass the diffraction limit of telescope apertures, with successful measurements including the determination of 32 stellar angular diameters using the Narrabri Stellar Intensity Interferometer [Hanbury-Brown et al., 1974]. This was achieved by measuring the intensity correlations between starlight received by a pair of telescopes separated by varying baselines b which, by invoking the van Cittert-Zernicke theorem [van Cittert, 1934; Zernicke, 1938], are related to the angular intensity distributions of the stellar light sources through a Fourier transformation of the equal-time complex degree of coherence gamma(b) between the two telescopes. This intensity correlation, or the second order correlation function g(2) [Glauber, 1963], can be described in terms of two-photoevent coincidence measurements [Hanbury-Brown, 1974] for our use of photon-counting detectors. The application of intensity interferometry in astrophysics has been largely restricted to the spatial domain but not found widespread adoption due to limitations by its signal-to-noise ratio [Davis et al., 1999; Foellmi, 2009; Jensen et al., 2010; LeBohec et al., 2008, 2010], although there is a growing movement to revive its use [Barbieri et al., 2009; Capraro et al., 2009; Dravins & Lagadec, 2014; Dravins et al., 2015; Dravins & LeBohec, 2007]. In this thesis, stellar intensity interferometry in the temporal domain is investigated instead. We present a narrowband spectral filtering scheme [Tan et al., 2014] that allows direct measurements of the Lorentzian temporal correlations, or photon bunching, from the Sun, with the preliminary Solar g(2)(tau = 0) = 1.3 +/- 0.1, limited mostly by the photon detector response [Ghioni et al., 2008], compared to the theoretical value of g(2)(0) = 2. The measured temporal photon bunching signature of the Sun exceeded the previous records of g(2)(0) = 1.03 [Karmakar et al
Extreme ultraviolet interferometry
Goldberg, Kenneth A.
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
Nonlinear dispersive similariton: spectral interferometric study
Zeytunyan, A S; Khachikyan, T J; Palandjan, K A; Esayan, G L; Muradyan, L Kh
2010-06-23
A similariton formed in a passive optical fibre is experimentally found and investigated by spectral interferometry completely characterising the complex radiation field. A nonlinear dispersive character of similariton formation leads to chirp linearisation and spectrotemporal similarity of this similariton. (nonlinear optical phenomena)
Preview of Blackbeard interferometry
NASA Astrophysics Data System (ADS)
Carter, M. J.
Blackbeard is a broadband VHF measurement satellite experiment designed and built by the Space Science and Technology Division of the Los Alamos National Laboratory. Blackbeard is a piggy-back experiment on the ALEXIS satellite to be launched into a 70 degree inclination orbit at an altitude of 750 km. The satellite experimental operation and data retrieval are controlled through a telemetry link from the Satellite Operations Center (SOC) located at Los Alamos, NM. The primary experimental objectives of Blackbeard are three-fold: (1) Study the dispersion of broad-band impulsive electromagnetic signals -- in particular, the higher-order amplitude and phase distortion due to propagation through the ionosphere. These depend on ionospheric conditions and irregularities. (2) Utilize RF interferometry and scintillation techniques in the low VHF-band to determine the size and extent of ionospheric irregularities and wave structure -- both natural and artificially induced. This narrow-band data will be used to categorize the ionospheric media as undisturbed, oscillatory, or turbulent. These parameters will then be input into transfer function simulations for broad-band propagation and compared with broad-band propagation data from Blackbeard. (3) Survey and characterize background noise in the VHF-band-consisting of (1) cataloging broadcast amplitudes and signatures and mapping their global pattern, and (2) cataloging the signatures of lightning events. Also, correlate emissions in the visible and VHF bands in an attempt to confirm broad-band RF emissions assumed to be associated with lightning.
Preview of Blackbeard interferometry
Carter, M.J.
1992-01-01
Blackbeard is a broadband VHF measurements satellite experiment designed and built by the Space Science and Technology division of the Los Alamos National Laboratory. Blackbeard is a piggy-back experiment on the ALEXIS satellite to be launched into a 70 degree inclination orbit at an altitude of 750 km. The satellite experimental operation and data retrieval are controlled through a telemetry link from the Satellite Operations Center (SOC) located at Los Alamos, NM. The primary experimental objectives of Blackbeard are three-fold: (1) Study the dispersion of broad-band impulsive electromagnetic signals -- in particular, the higher-order amplitude and phase distortion due to propagation through the ionosphere. These depend on ionospheric conditions and irregularities. (2) Utilize RF interferometry and scintillation techniques in the low VHF-band to determine the size and extent of ionospheric irregularities and wave structure -- both natural and artificially induced. This narrow-band data will be used to categorize the ionospheric media as undisturbed, oscillatory, or turbulent. These parameters will then be input into transfer function simulations for broad-band propagation and compared with broad-band propagation data from Blackbeard. (3) Survey and characterize background noise in the VHF-band-consisting of (1) cataloging broadcast amplitudes and signatures and mapping their global pattern, and (2) cataloging the signatures of lightning events. Also, correlate emissions in the visible and VHF bands in an attempt to confirm broad-band RF emissions assumed to be associated with lightning.
Preview of Blackbeard interferometry
Carter, M.J.
1992-09-01
Blackbeard is a broadband VHF measurements satellite experiment designed and built by the Space Science and Technology division of the Los Alamos National Laboratory. Blackbeard is a piggy-back experiment on the ALEXIS satellite to be launched into a 70 degree inclination orbit at an altitude of 750 km. The satellite experimental operation and data retrieval are controlled through a telemetry link from the Satellite Operations Center (SOC) located at Los Alamos, NM. The primary experimental objectives of Blackbeard are three-fold: (1) Study the dispersion of broad-band impulsive electromagnetic signals -- in particular, the higher-order amplitude and phase distortion due to propagation through the ionosphere. These depend on ionospheric conditions and irregularities. (2) Utilize RF interferometry and scintillation techniques in the low VHF-band to determine the size and extent of ionospheric irregularities and wave structure -- both natural and artificially induced. This narrow-band data will be used to categorize the ionospheric media as undisturbed, oscillatory, or turbulent. These parameters will then be input into transfer function simulations for broad-band propagation and compared with broad-band propagation data from Blackbeard. (3) Survey and characterize background noise in the VHF-band-consisting of (1) cataloging broadcast amplitudes and signatures and mapping their global pattern, and (2) cataloging the signatures of lightning events. Also, correlate emissions in the visible and VHF bands in an attempt to confirm broad-band RF emissions assumed to be associated with lightning.
Geometric time delay interferometry
Vallisneri, Michele
2005-08-15
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 interspacecraft 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 and intuitive approach to extend this interpretation to all TDI observables. Unlike the standard algebraic formalism, Geometric TDI provides a combinatorial algorithm to explore exhaustively the space of second-generation TDI observables (i.e., those that cancel laser noise in LISA-like interferometers with time-dependent arm lengths). Using this algorithm, I survey the space of second-generation TDI observables of length (i.e., number of component phase measurements) up to 24, and I identify alternative, improved forms of the standard second-generation TDI observables. The alternative forms have improved high-frequency gravitational-wave sensitivity in realistic noise conditions (because they have fewer nulls in the gravitational-wave and noise response functions), and are less susceptible to instrumental gaps and glitches (because their component phase measurements span shorter time periods)
Weakly nonlinear dynamics and fully nonlinear simulations of trapped waves on jet currents
NASA Astrophysics Data System (ADS)
Slunyaev, Alexey; Shrira, Victor
2014-05-01
The asymptotic modal approach developed in Shrira & Slunyaev (2014) for waves trapped by an opposing jet current is extended by examining the weakly nonlinear dynamics of trapped waves due to four-wave resonances. Evolution equations governing dynamics of an arbitrary number of wave packets have been derived. In particular, for a single mode the asymptotic procedure yields the integrable one-dimensional nonlinear Schrodinger equation (NLS). The NLS describes the evolution of modes along the current, while the modal structure is specified by the corresponding boundary value problem (BVP). When the current is weak in comparison with the wave celerity, the BVP reduces to the classic stationary Schrodinger equation with conditions of decay outside the jet, which allows exact solutions for a number of model current profiles. This enables us to find analytically the interaction coefficients in the dynamic equations. Thus, to the leading order a variety of analytic solutions to the evolution equation and the BVP specifying the trapped modes is readily available. A few such asymptotic solutions are tested in numerical simulations of the Euler equations. The equations are solved by means of the adapted High Order Spectral Method (West et al, 1987). Single trapped mode solutions are simulated: the uniform waves train, modulated wave train, and solitary wave packets. The weakly nonlinear theory is shown to be a reasonable first approximation to the solution even in the case of rather steep waves. Solitary patterns of trapped waves were found to be robust, though an insignificant radiation is observed in the course of their propagation, which suggests that the solitary wave patterns represent important elements of nonlinear dynamics of gravity waves on jet currents. Their presence in the stochastic wave field may result in significant deviation from the Gaussianity, and increase the extreme wave probability. Shrira, V.I., Slunyaev, A.V. Trapped waves on jet currents
Rogue-wave bullets in a composite (2+1)D nonlinear medium.
Chen, Shihua; Soto-Crespo, Jose M; Baronio, Fabio; Grelu, Philippe; Mihalache, Dumitru
2016-07-11
We show that nonlinear wave packets localized in two dimensions with characteristic rogue wave profiles can propagate in a third dimension with significant stability. This unique behavior makes these waves analogous to light bullets, with the additional feature that they propagate on a finite background. Bulletlike rogue-wave singlet and triplet are derived analytically from a composite (2+1)D nonlinear wave equation. The latter can be interpreted as the combination of two integrable (1+1)D models expressed in different dimensions, namely, the Hirota equation and the complex modified Korteweg-de Vries equation. Numerical simulations confirm that the generation of rogue-wave bullets can be observed in the presence of spontaneous modulation instability activated by quantum noise.
Nonlinear acoustic waves in the viscous thermosphere and ionosphere above earthquake
NASA Astrophysics Data System (ADS)
Chum, J.; Cabrera, M. A.; Mošna, Z.; Fagre, M.; Baše, J.; Fišer, J.
2016-12-01
The nonlinear behavior of acoustic waves and their dissipation in the upper atmosphere is studied on the example of infrasound waves generated by vertical motion of the ground surface during the Mw 8.3 earthquake that occurred about 46 km from Illapel, Chile on 16 September 2015. To conserve energy, the amplitude of infrasound waves initially increased as the waves propagated upward to the rarefied air. When the velocities of air particles became comparable with the local sound speed, the nonlinear effects started to play an important role. Consequently, the shape of waveform changed significantly with increasing height, and the original wave packet transformed to the "N-shaped" pulse resembling a shock wave. A unique observation by the continuous Doppler sounder at the altitude of about 195 km is in good agreement with full wave numerical simulation that uses as boundary condition the measured vertical motion of the ground surface.
Deformations and strains in adhesive joints by moire interferometry
NASA Technical Reports Server (NTRS)
Post, D.; Czarnek, R.; Wood, J.; John, D.; Lubowinski, S.
1984-01-01
Displacement fields in a thick adherend lap joint and a cracked lap shear specimen were measured by high sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherent surfaces. Loading sequences ranged from modest loads to near-failure loads. Quantitative results are given for displacements and certain strains in the adhesive and along the adhesive/adherend boundary lines. The results show nonlinear displacements and strains as a function of loads or stresses and they show viscoelastic or time-dependent response. Moire interferometry is an excellent method for experimental studies of adhesive joint performance. Subwavelength displacement resolution of a few micro-inches, and spatial resolution corresponding to 1600 fringes/inch (64 fringes/mm), were obtained in these studies. The whole-field contour maps offer insights not available from local measurements made by high sensitivity gages.
Phase and fringe order determination in wavelength scanning interferometry.
Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel
2016-04-18
A method to obtain unambiguous surface height measurements using wavelength scanning interferometry with an improved repeatability, comparable to that obtainable using phase shifting interferometry, is reported. Rather than determining the conventional fringe frequency-derived z height directly, the method uses the frequency to resolve the fringe order ambiguity, and combine this information with the more accurate and repeatable fringe phase derived z height. A theoretical model to evaluate the method's performance in the presence of additive noise is derived and shown to be in good agreement with experiments. The measurement repeatability is improved by a factor of ten over that achieved when using frequency information alone, reaching the sub-nanometre range. Moreover, the z-axis non-linearity (bleed-through or ripple error) is reduced by a factor of ten. These order of magnitude improvements in measurement performance are demonstrated through a number of practical measurement examples.
100-Picometer Interferometry for EUVL
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.
Noise-assisted Ramsey interferometry
NASA Astrophysics Data System (ADS)
Dorner, U.
2013-12-01
I analyze a metrological strategy for improving the precision of frequency estimation via Ramsey interferometry with strings of atoms in the presence of correlated dephasing. This strategy does not employ entangled states but rather a product state which evolves into a stationary state under the influence of correlated dephasing. It is shown that by using this state an improvement in precision compared to standard Ramsey interferometry can be gained. This improvement is not an improvement in scaling; i.e., the estimation precision has the same scaling with the number of atoms as the standard quantum limit but gains an improvement proportional to the free evolution time in the Ramsey interferometer. Since a stationary state is used, this evolution time can be substantially larger than in standard Ramsey interferometry which is limited by the coherence time of the atoms.
Bandwidth in bolometric interferometry
NASA Astrophysics Data System (ADS)
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
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.
Nonlinear interferometric vibrational imaging.
Marks, Daniel L; Boppart, Stephen A
2004-03-26
Coherent anti-Stokes Raman scattering (CARS) processes are "coherent," but the phase of the anti-Stokes radiation is lost by most incoherent spectroscopic CARS measurements. We propose a Raman microscopy imaging method called nonlinear interferometric vibrational imaging, which measures Raman spectra by obtaining the temporal anti-Stokes signal through nonlinear interferometry. With a more complete knowledge of the anti-Stokes signal, we show through simulations that a high-resolution Raman spectrum can be obtained of a molecule in a single pulse using broad band radiation. This could be useful for identifying the three-dimensional spatial distribution of molecular species in tissue.
Precision geodesy via radio interferometry.
NASA Technical Reports Server (NTRS)
Hinteregger, H. F.; Shapiro, I. I.; Robertson, D. S.; Knight, C. A.; Ergas, R. A.; Whitney, A. R.; Burke, B. F.; Rogers, A. E. E.; Moran, J. M.; Clark, T. A.
1972-01-01
Very-long-baseline interferometry experiments, involving observations of extragalactic radio sources, were performed in 1969 to determine the vector separations between antenna sites in Massachusetts and West Virginia. The 845.130-kilometer baseline was estimated from two separate experiments. The results agreed with each other to within 2 meters in all three components and with a special geodetic survey to within 2 meters in length; the differences in baseline direction as determined by the survey and by interferometry corresponded to discrepancies of about 5 meters. The experiments also yielded positions for nine extragalactic radio sources and allowed the hydrogen maser clocks at the two sites to be synchronized.
The development of astronomical interferometry
NASA Astrophysics Data System (ADS)
Quirrenbach, Andreas
2009-08-01
Astronomical interferometry was pioneered by Fizeau and Michelson in the 19th century. In the 1920s, the first stellar diameters were measured. The development of radio interferometry began in the 1950s, and led to the construction of powerful synthesis arrays operating at cm, mm, and sub-mm wavelengths. Modern computer and control technology has enabled the interferometric combination of light from separate telescopes also in the visible and infrared regimes. Imaging with milliarcsecond resolution and astrometry with microarcsecond precision have thus become reality.