Cavity-Mediated Charging of a Graphene Excitonic Quantum Battery

This study investigates the charging and work-extraction performance of a quantum battery (QB) implemented using intervalley excitons in strained graphene. By embedding these excitons within a driven-dissipative optical microcavity, the authors explore how light-matter coupling, external pumping, and cavity losses influence the battery's ability to store and release energy.

The researchers model the system as two effective two-level excitonic qubits coupled to a single quantized cavity mode via a Tavis-Cummings interaction. One exciton acts as the charger, while the other serves as the battery. The system's dynamics are analyzed using an open-system master equation, accounting for cavity photon decay and exciton relaxation. The study evaluates performance using ergotropy—a measure of the maximum work extractable from a quantum state via cyclic unitary operations—under both incoherent and coherent pumping protocols.

The analysis reveals that the battery's performance is highly sensitive to the pumping regime. Under coherent driving, the maximum transient ergotropy increases monotonically with pumping strength. However, the steady-state ergotropy exhibits non-monotonic behavior, peaking near the threshold where the pumping rate matches the cavity decay rate. This indicates an optimal operating point where energy injection is balanced against dissipative losses. Conversely, incoherent pumping is shown to increase the mixedness of the system, which reduces the extractable work compared to coherent driving.

This work demonstrates that strain-engineered graphene in microcavities provides a viable, controllable platform for quantum energy storage. By highlighting the role of cavity engineering and the importance of balancing pumping rates with dissipation, the study offers a framework for designing more efficient quantum batteries in solid-state systems, moving the field closer to practical, scalable implementations.