Charging and self-discharging process of a quantum battery in composite environments

How to improve charging processes and suppress self-discharging processes has always been one of the key issues to achieve quantum batteries with high performance. Although a quantum battery is inevitably influenced by composite environments, this situation is still little understood, particularly regarding the influence of the memory effect of the composite environments and the coupling between composite environments. In this work, we investigate the effects of the composite environments, composed of two identical parts each containing a single cavity mode decaying to a reservoir, on the charging and self-discharging processes of a quantum battery. We show that increasing the two-mode coupling can effectively enhance the charging performance (i.e., the stored energy, the charging power, ergotropy) and restrain the self-discharging process (i.e., suppressing the process of dissipating the energy). However, different from the effect of two-mode coupling, we reveal that the memory effect of the reservoir in this composite environment is unfavorable to the charging process of the quantum battery, which is in sharp contrast to previous studies where the memory effect can significantly improve the charging performance of a quantum battery. Our results may benefit to the realization of quantum batteries with high performance under the actual complex environmental noise.