arXiv subjects

Yu. Lozovik

Publications and source records attributed to Yu. Lozovik.

3 recordsLinked to original sources

arXiv1999

Transmission time of wave packets through tunneling barriers

The transmission of wave packets through tunneling barriers is studied in detail by the method of quantum molecular dynamics. The distribution function of the times describing the arrival of a tunneling packet in front of and behind a barrier and the momentum distribution function of the packet are calculated. The behavior of the average coordinate of a packet, the average momentum, and their variances is investigated. It is found that under the barrier a part of the packet is reflected and a Gaussian barrier increases the average momentum of the transmitted packet and its variance in momentum space.

quant-ph↗

arXiv1998

Quantum dynamics in canonical and micro-canonical ensembles. Part II. Tunneling in double well potential

In the second part of this paper in micro canonical ensemble the new numerical approach for consideration of quantum dynamics and calculations of the average values of quantum operators and time correlation functions in the Wigner representation of quantum statistical mechanics has been developed. The numerical results have been obtained for series of the average values of quantum operators as well as for the time correlation function characterizing the energy level structure, the momentum flow of tunneling particles at barrier crossing and the absorption spectra of electron in potential well. The developed quantum dynamics method was tested by comparison of numerical results with analytical estimations. Tunneling transitions and the effect of the quasi stationary state has been considered as the reason of the peculiarities in behaviour of the time correlation functions and position and momentum dispersions. Possibility of applying the developed approach to the theory of classical wave propagation in random media have been also considered. For classical waves some results have been obtained for Gaussian beam propagation in 2D and 3D waveguides.

quant-ph↗

arXiv1998

Quantum dynamics in canonical and micro-canonical ensembles. Part I. Anderson localization of electrons

The new numerical approach for consideration of quantum dynamics and calculations of the average values of quantum operators and time correlation functions in the Wigner representation of quantum statistical mechanics has been developed. The time correlation functions have been presented in the form of the integral of the Weyl's symbol of considered operators and the Fourier transform of the product of matrix elements of the dynamic propagators. For the last function the integral Wigner- Liouville's type equation has been derived. The numerical procedure for solving this equation combining both molecular dynamics and Monte Carlo methods has been developed. For electrons in disordered systems of scatterers the numerical results have been obtained for series of the average values of the quantum operators including position and momentum dispersions, average energy, energy distribution function as well as for the frequency dependencies of tensor of electron conductivity and permittivity according to quantum Kubo formula. Zero or very small value of static conductivity have been considered as the manifestation of Anderson localization of electrons in 1D case. Independent evidence of Anderson localization comes from the behaviour of the calculated time dependence of position dispersion.

cond-mat.dis-nn↗