arXiv subjects

A. P. Meilakhs

Publications and source records attributed to A. P. Meilakhs.

7 recordsLinked to original sources

arXiv2026

Non-coherent evolution of closed weakly interacting system leads to equidistribution of probabilities of microstates

We introduce a concept of non-coherent evolution of macroscopic quantum systems. We show that for weakly interacting systems such evolution is a Markovian stochastic process. The transition rates between system states, which characterize the process, are determined by Fermi's golden rule. Such evolution is time-irreversible and leads to the equidistribution of probabilities across every state of the system. Furthermore, we investigate the time dependence of the mean numbers of particles in single-particle states and find that, under the given assumptions, it is governed by the Boltzmann collision integral. The proposed mechanism that transforms time-reversible unitary evolution into time-irreversible stochastic evolution is non-coherence. In the presented theory, the non-coherence is not associated with interaction with a heat bath, but rather with the finite spectral width of quantum states. This understanding of non-coherence is analogous to the one used in wave optics. Thus, we present a novel approach to the famous arrow of time problem.

quant-ph↗

arXiv2025

The derivation of the Liouville equation from the Schrodinger equation and its implications

We present a new way of deriving classical mechanics from quantum mechanics. A key feature of the method is its compatibility with the standard approach used to derive transition rates between quantum states due to interactions. We apply the developed method to derive the main formulas of physical kinetics. We observe that, through the Liouville equation, we can deduce the non-collision part of the Boltzmann equation, and that, through the matrix of transition rates, we can deduce the collision integral. As a final result of the manuscript, we derive the Boltzmann equation from the Schrödinger equation as a single piece of formal mathematical manipulation, without any non-rigorous plausible reasoning used to glue together its different parts.

quant-ph↗

arXiv2023

Transmission of waves and particles through the interface: reversibility and coherence

We examine the transmission of quantum particles (phonons, electrons, and photons) across interfaces, identifying universal patterns in diverse physical scenarios. Starting with classical wave equations, we quantize them and derive kinetic equations. Those are matching conditions for the distribution functions of particles at the interface. We note the time irreversibility of the derived kinetic equations -- an essential feature for accurately describing irreversible processes like heat transport. We identify the juncture in our derivation where the time symmetry of wave equations is disrupted, it is the assumption of the non-coherence of incident waves. Consequently, we infer that non-coherent transmission through the interface exhibits time irreversibility. We propose an experiment to validate this hypothesis.

cond-mat.other↗

arXiv2023

Electronic Kapitza conductance and related kinetic coefficients at an interface between n-type semiconductors

We calculate the Kapitza conductance, which is the proportionality coefficient between heat flux and temperature jump at the interface, for the case of two conducting solids separated by the interface. We show that for conducting solids in a non-equilibrium state, there should also arise the electrochemical potential jump at the interface. Hence to describe linear transport at the interface we need three kinetic coefficients: interfacial analogs of electric and heat conductances and interfacial analog of the Seebeck coefficient. We calculate these coefficients for the case of an interface between n-type semiconductors. We perform calculations in the framework of Boltzmann transport theory. We have found out that the interfacial analog of the Seebeck coefficient for some range of parameters of the considered semiconductors, has a high value of about $10^{-3}$ V/K. Thus this effect has the potential to be used for the synthesis of effective thermoelectric materials.

cond-mat.mes-hall↗

arXiv2021

Calculation of Kapitza resistance with kinetic equation

A new method is introduced for calculation of interfacial thermal resistance in the case of heat transport through the interface by phonons. A unique feature of the method is taking into account all the consequences of a non-equilibrium character of phonon distribution functions during the heat transport. We introduce a model set of transmission and reflection amplitudes of phonons at the interface based on the most common in the literature Diffusive Mismatch Model. For the proposed model we derive an exact analytical solution. The problem is also solved for a set of transmission and reflection amplitudes characterized by a free parameter. We found that the calculation results are in a good agreement with the experimental data.

cond-mat.other↗

arXiv2021

Nonequilibrium distribution function in the presence of a heat flux at the interface between two crystals

A one-dimensional harmonic chain model is used to study the non-equilibrium distribution function of phonons induced by a heat flux across the interface between two crystals. Conditions are derived which govern the matching of distribution functions on both sides of the interface. A generalization of the Enskog--Chapman method for calculating the Kapitza conductance is introduced. A precise relation is obtained under some simplifications. This version contains improved translation, modernized notation, and corrects one mistake, that does not affect the final formulae.

cond-mat.other↗

arXiv2016

New explanation of Raman peak redshift in nanoparticles

In this letter, we propose a new model that explains the Raman peak downshift observed in nanoparticles with respect to bulk materials. The proposed model takes into account discreteness of the vibrational spectra of nanoparticles. For crystals with a cubic lattice (Diamond, Silicon, Germanium) we give a relation between the displacement of Raman peak position and the size of nanoparticles. The proposed model does not include any uncertain parameters, unlike the conventionally used phonon confinement model (PCM), and can be employed for unambiguous nanoparticles size estimation.

cond-mat.mes-hall↗