Non-linear wave packet dynamics of coherent states

We have compared the non-linear wave packet dynamics of coherent states of various symmetry groups and found that certain generic features of non-linear evolution are present in each case. Thus the initial coherent structures are quickly destroyed but are followed by Schrödinger cat formation and revival. We also report important differences in their evolution.     

Attosecond electron wave packet dynamics in strong laser fields

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 (approximately 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.     

Hamiltonian approach for wave packet dynamics: Beyond Gaussian wave functions

It is known that Gaussian wave packet dynamics can be written in terms of Hamilton equations in the extended phase space. We construct several generalizations of this approach that include non-Gaussian wave packets. These generalizations lead to the further extension of the phase space while retaining the Hamilton structure of the equations of motion.     

Isotope-selective femtosecond wave packet dynamics: The rare molecule

For the first time, the femtosecond real-time vibrational dynamics of the rare ^41,41K₂ isotope, excited to the electronic state, could be selectively studied by means of time-resolved three photon ionization. A vibrational period of fs is determined. Superimposed, a beat structure with a period of 20 ps is observed. A detailed Fourier analysis reveals a strong band of three lines centered around 65.5 cm^-1. A significant perturbation of the wave packet caused by spin-orbit coupling of the A and the crossing state is found. This perturbation is the reason for the fast dephasing of the initially generated wave packet within about 10 ps. The spectrogram of the real-time data shows total revivals of the wave packet at 20 ps and 40 ps. Fractional revivals are found for times around 10 ps and 30 ps. Due to high intensity effects a remarkable slightly broadened line at 90 cm^-1 appears and can be assigned to the wave packet propagation generated in the dimer's ground state by impulsive stimulated Raman scattering. Revivals of this ground state wave packet are found at 17ps and 34ps. A comparison with other isotopes of K₂ is given. Received: 9 February 1998 / Revised: 15 May 1998 / Accepted: 2 June 1998     

Electron wave packet dynamics in twisted nonlinear ladders with correlated disorder

Within a tight-binding Hamiltonian approach, we study the dynamics of one-electron wave packets in a twisted ladder geometry with adiabatic electron-phonon interaction. The electron-phonon coupling is taken into account in the time-dependent Schrödinger equation through a cubic nonlinearity. This physical scenario incorporates several relevant ingredients to study the electronic wave packet dynamics in DNA-like segments. In the absence of nonlinearity, a random sequence of nucleotides pairs makes the wave packets remain localized, according to the standard picture of the Anderson localization. However, when the electron-phonon interaction is turned on, Anderson localization is suppressed and a subdiffusive regime takes place. Further, we show that the wave packet trapping can be controlled by an external field perpendicular to the helicity axis of the double-strand chain.     

Clocking ultrafast wave packet dynamics in molecules through UV-induced symmetry breaking

We investigate the use of UV-pump-UV-probe schemes to trace the evolution of nuclear wave packets in excited molecular states by analyzing the asymmetry of the electron angular distributions resulting from dissociative ionization. The asymmetry results from the coherent superposition of gerade and ungerade states of the remaining molecular ion in the region where the nuclear wave packet launched by the pump pulse in the neutral molecule is located. Hence, the variation of this asymmetry with the time delay between the pump and the probe pulses parallels that of the moving wave packet and, consequently, can be used to clock its field-free evolution. The performance of this method is illustrated for the H(2) molecule.     

Semiclassical dynamics of electron wave packet states with phase vortices

We consider semiclassical higher-order wave packet solutions of the Schr?dinger 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.     

Effect of temporal disorder on wave packet dynamics in one-dimensional kicked lattices

Inspired by the recent experimental progress in noisy kicked rotor systems,we investigate the effect of temporal disorder or quasi-periodicity in one-dimensional kicked lattices with pulsed on-site potential.We found that,unlike the spatial disorder or quasi-periodicity which usually leads to localization,the effect of the temporal one is more complex and depends on the spatial configuration.If the kicked on-site potential is periodic in real space,then the wave packet will stay diffusive in the presence of temporal disorder or quasi-periodicity.On the other hand,if the kicked on-site potential is spatially quasi-periodic,then the temporal disorder or quasi-periodicity may lead to a shift of the transition point of the dynamical localization and destroy the dynamical localization in a certain parameter range.The results we obtained can be readily tested by experiments and may help us better understand the dynamical localization.     

The frame bundle picture of Gaussian wave packet dynamics in semiclassical mechanics

Letters in Mathematical Physics - Recently Ohsawa (Lett Math Phys 105:1301–1320, 2015) has studied the Marsden–Weinstein–Meyer quotient of the manifold $$T^*\mathbb {R}^n\times...     

Steering the electron in H2(+) by nuclear wave packet dynamics

By combining carrier-envelope phase (CEP) stable light fields and the traditional method of optical pump-probe spectroscopy we study electron localization in dissociating H2(+) 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.     

Wave packet dynamics in a semiconductor superlattice

We examine the time development of a wave packet in a superlattice miniband in a constant electric field, explicitly determining the time dependence of the probability density. Our analytic results permit the identification of breathing motion of the wave packet as well as Bloch oscillatory motion of its center-of-mass. The dynamical development of a Gaussian wave packet is exhibited, showing the appearance of images of the initial wave packet in nearby superlattice cells, exemplifying their participation in Bloch oscillatory and breathing motions.     

Self-constriction of a wave packet in a non-linear medium

The possibility of a controlled deformation of a wave packet in the non-linear medium is discussed. The exact analytical solutions, describing, in the bounds of non-linear geometrical optics, the pulse envelope evolution and the non-linear modulation of such a packet, are found.     

Entangled two-photon wave packet in a dispersive medium

We report an experimental study of group-velocity dispersion effect on an entangled two-photon wave packet, generated via spontaneous parametric down-conversion and propagating through a dispersive medium. Even in the case of using cw laser beam for pump, the biphoton wave packet and the second-order correlation function spread significantly. The study and understanding of this phenomenon is of great importance for quantum information applications, such as quantum communication and distant clock synchronization.     

Momentum distribution dynamics of a Tonks-Girardeau gas: Bragg reflections of a quantum many-body wave packet

The momentum distribution (MD) dynamics of a Tonks-Girardeau (TG) gas is studied in the context of Bragg reflections of a many-body wave packet. We find strong suppression of a Bragg reflection peak for a large and dense TG wave packet; our observation illustrates the dependence of the MD on the interactions and wave function symmetry. The MD is calculated from the reduced single-particle density matrix (RSPDM). We develop a method for calculating the RSPDM of a TG gas, which is operative for a large number of particles, and does not depend on the external potential and the state of the system. The method is based on a formula expressing the RSPDM via a dynamically evolving single-particle basis.