arXiv subjects

Gennady Berman

Publications and source records attributed to Gennady Berman.

6 recordsLinked to original sources

arXiv2020

Axionic Dark Matter Halos in the Gravitational Field of Baryonic Matter

We consider a dark matter halo (DMH) of a spherical galaxy as a Bose-Einstein condensate of the ultra-light axions interacting with the baryonic matter. In the mean-field limit, we have derived the integro-differential equation of the Hartree-Fock type for the spherically symmetrical wave function of the DMH component. This equation includes two independent dimensionless parameters: (i) \b{eta}- the ratio of baryon and axion total mases and (ii) ξ- the ratio of characteristic baryon and axion spatial parameters. We extended our dissipation algorithm for studying numerically the ground state of the axion halo in the gravitational field produced by the baryonic component. We calculated the characteristic size, Xc, of DMH as a function of \b{eta} and ξ and obtained an analytical approximation for Xc.

astro-ph.CO↗

arXiv2015

Multiscale dynamics of open three-level quantum systems with two quasi-degenerate levels

We consider a three-level quantum system interacting with a bosonic thermal reservoir. Two energy levels of the system are nearly degenerate but well separated from the third one. The system-reservoir interaction constant is larger than the energy difference of the degenerate levels, but it is smaller than the separation between the latter and the remaining level. We show that the quasi-degeneracy of energy levels leads to the existence of a manifold of quasi-stationary states, and the dynamics exhibits two characteristic time scales. On the first, shorter one, initial states approach the quasi-stationary manifold. Then, on the much longer second time scale, the final unique equilibrium is reached.

quant-ph↗

arXiv2012

Electron Transfer Reactions: Generalized Spin-Boson Approach

We introduce a mathematically rigorous analysis of a generalized spin-boson system for the treatment of a donor-acceptor (reactant-product) quantum system coupled to a thermal quantum noise. The donor/acceptor probability dynamics describes transport reactions in chemical processes in presence of a noisy environment -- such as the electron transfer in a photosynthetic reaction center. Besides being rigorous, our analysis has the advantages over previous ones that (1) we include a general, non energy-conserving system-environment interaction, and that (2) we allow for the donor or acceptor to consist of multiple energy levels lying closely together. We establish explicit expressions for the rates and the efficiency (final donor-acceptor population difference) of the reaction. In particular, we show that the rate increases for a multi-level acceptor, but the efficiency does not.

math-ph↗

arXiv2003

Long time Evolution of Quantum Averages Near Stationary Points

We construct explicit expressions for quantum averages in coherent states for a Hamiltonian of degree 4 with a hyperbolic stagnation point. These expressions are valid for all times and "collapse" (i.e., become infinite) along a discrete sequence of times. We compute quantum corrections compared to classical expressions. These corrections become significant over a time period of order C log 1/\hbar.

quant-ph↗

arXiv2002

Asymptotic Theory for Quantum Bose Systems with Many Degrees of Freedom

We construct asymptotic expansions of Laplace type for the time-dependent quantum averages for Bose systems with many degrees of freedom, initially populated in coherent states. These solutions are localized in phase space, and they are different from the usual oscillating asymptotics for the quasi-classical wave functions. These expansions are valid on any fixed time interval, and caustics do not contribute to the asymptotics.

quant-ph↗

arXiv1994

Switching Nano-Device based on Rabi Oscillations

We consider a potential landscape composed of a well region separated from a "free" region by a barrier, such that one bound state and one quasi level exist in the well. A particle initially in the ground state can be activated to the quasi level by application of a micro wave field, and subsequently tunnel in the free region. The wave function is then emitted by "bursts" after each Rabi oscillation is completed, and the leakage current can be controlled by varying the amplitude of the external field, the barrier height/width, and the frequency mismatch.

cond-mat↗