Marcus V. S. Bonanca | Searcharxiv

arXiv2025

Strong-damping limit of quantum Brownian motion in a disordered environment

We consider a microscopic model of an inhomogeneous environment where an arbitrary quantum system is locally coupled to a harmonic bath via a finite-range interaction. We show that in the overdamped regime the position distribution obeys a classical Kramers-Moyal equation that involves an infinite number of higher derivatives, implying that the finite bath correlation length leads to non-Gaussian Markovian noise. We analytically solve the equation for a harmonically bound particle and analyze its non-Gaussian diffusion as well as its steady-state properties.

cond-mat.stat-mech↗

arXiv2025

Nonequilibrium fluctuation relations for non-Gaussian processes

Non-Gaussian noise is omnipresent in systems where the central-limit theorem is inapplicable. We here investigate the stochastic thermodynamics of small systems that are described by a general Kramers-Moyal equation that includes both Gaussian and non-Gaussian white noise contributions. We obtain detailed and integral fluctuation relations for the nonequilibrium entropy production of these Markov processes in the regime of weak noise. As an application, we analyze the properties of driven objects that are locally coupled to a heat bath via a finite-range interaction, by considering an overdamped particle that is pulled by a moving harmonic potential. We find that reducing the bath interaction range increases non-Gaussian features, and strongly suppresses the average nonequilibrium entropy production. We further discuss a generalized detailed-balance condition.

cond-mat.stat-mech↗