Performance Analysis of a Two‐Mode Micromaser Quantum Battery

Abstract A two‐mode micromaser quantum battery (QB) is investigated, where a quantized cavity field is charged by a stream of V‐type three‐level atoms. Within an open quantum systems framework, stored energy, ergotropy, charging power, and fluctuations are analyzed under different coherence conditions of the atomic charger. It is first showed that coherence between the two degenerate excited states of the charger enhances both the average stored energy and the amount of extractable work. Using the concept of global ergotropy, it is further demonstrated that correlations between the two cavity modes enable work extraction beyond the local contributions. Furthermore, it is shown that, among the different coherence configurations, ground–excited state coherence emerges as the most effective, simultaneously enhancing energy storage, extractable work, and stability. Finally, by applying a geometric power bound based on Fisher information and energy variance, it is showed that coherent charging protocols approach the ultimate charging limit more closely than incoherent ones. These findings establish atomic coherence and intermode correlations as valuable thermodynamic resources and highlight the two‐mode micromaser as a minimal yet versatile platform for multimode quantum batteries.