Optimal control of a dissipative micromaser quantum battery in the ultrastrong coupling regime

TL;DR

This paper explores how dissipative effects and optimal control in the ultrastrong coupling regime can enhance the performance and stability of a micromaser quantum battery, balancing rapid charging with energy stability.

Contribution

It introduces a control strategy that optimizes charging and stabilizes stored energy in a dissipative, ultrastrong coupling micromaser quantum battery.

Findings

Counter-rotating terms improve charging speed in USC regime.

Dissipation leads to finite energy and ergotropy in steady state.

Optimized control enhances charging and stabilizes ergotropy.

Abstract

We investigate the open system dynamics of a micromaser quantum battery operating in the ultrastrong coupling (USC) regime under environmental dissipation. The battery consists of a single-mode electromagnetic cavity sequentially interacting, via the Rabi Hamiltonian, with a stream of qubits acting as chargers. Dissipative effects arise from the weak coupling of the qubit-cavity system to a thermal bath. Non-negligible in the USC regime, the counter-rotating terms substantially improve the charging speed, but also lead, in the absence of dissipation, to unbounded energy growth and highly mixed cavity states. Dissipation during each qubit-cavity interaction mitigates these detrimental effects, yielding steady-state of finite energy and ergotropy. Optimal control on qubit preparation and interaction times enhances battery's performance in: (i) Maximizing the stored ergotropy trhough an optimized charging protocol; (ii) Stabilizing the stored ergotropy against dissipative losses through an optimized measurement-based passive-feedback strategy. Overall, our numerical results demonstrate that the interplay of ultrastrong light-matter coupling, controlled dissipation, and optimized control strategies enables micromaser quantum batteries to achieve both enhanced charging performance and long-term stability under realistic conditions.