Dissipative Quantum Battery in the Ultrastrong Coupling Regime Between Two Oscillators

TL;DR

This paper introduces an open quantum battery using a two-mode ultrastrongly coupled bosonic system, demonstrating enhanced energy storage and ergotropy through combined coupling effects and system control.

Contribution

It reveals how combined beam-splitter and squeezing interactions, along with electromagnetic vector potential effects, optimize energy and ergotropy in quantum batteries.

Findings

Charging energy and ergotropy are significantly enhanced in the ultrastrong coupling regime.

Control of initial states enables unidirectional energy flow.

Steady-state energy and ergotropy increase with temperature and coupling strength.

Abstract

In this work, we propose an open quantum battery that stores and releases energy by employing a two-mode ultrastrongly coupled bosonic system, with one mode (the charger) coupled to an independent heat reservoir. Our results demonstrate that both the charging energy and ergotropy of the quantum batteries can be significantly enhanced within the ultra-strong coupling regime and across a broader temperature range in transient time. A unidirectional energy flow is achieved by controlling the system's initial state through its two-mode squeezed ground state. Furthermore, we show that the steady-state stored energy, along with its corresponding ergotropy, can be enhanced at larger temperatures and stronger coupling strengths. Notably, a purely beam-splitter or two-mode squeezing interaction yields zero ergotropy. These findings indicate that the enhanced stored energy and ergotropy of the quantum battery arises principally from the combined effects of beam-splitter and parametric amplification (squeezing) couplings. In addition, the presence of the squared electromagnetic vector potential term can prevent a phase transition and achieve a significant charging energy and high ergotropy in the deep-strong coupling regime. The results presented herein enhance our understanding of the operating principles of open bosonic quantum batteries.