Steady state current fluctuations and dynamical control in a nonequilibrium single-site Bose-Hubbard system

TL;DR

This paper explores energy transfer and noise in a nonequilibrium single-site Bose-Hubbard system, revealing how nonlinear interactions influence transfer behaviors and uncovering reversal phenomena in energy pumping.

Contribution

It introduces a quantum kinetic framework with full counting statistics to analyze steady state energy flux, noise, and geometric-phase effects in a Bose-Hubbard model, highlighting nonlinear interaction impacts.

Findings

Nonmonotonic energy transfer behavior due to Bose-Hubbard interactions

In strong repulsion limit, system behavior matches the spin-boson model

Reversal of energy pump observed with increased repulsion

Abstract

We investigate nonequilibrium energy transfer in a single-site Bose-Hubbard model coupled to two thermal baths. By including a quantum kinetic equation combined with full counting statistics, we investigate the steady state energy flux and noise power. The influence of the nonlinear Bose-Hubbard interaction on the transfer behaviors is analyzed, and the nonmonotonic features are clearly exhibited. Particularly, in the strong on-site repulsion limit, the results become identical with the nonequilibrium spin-boson model. We also extend the quantum kinetic equation to study the geometric-phase-induced energy pump. An interesting reversal behavior is unraveled by enhancing the Bose-Hubbard repulsion strength.