Work extraction from a quantum battery charged through an array of coupled cavities

Abstract: We investigate the problem of work extraction from a cavity-based quantum battery that is remotely charged via a transmission line composed of an array of coupled single-mode cavities. For uniform coupling along the line, we show that the ergotropy of the battery, evaluated at the point of maximum power transfer, decreases with the length of the charging line and vanishes beyond a critical size. By carefully engineering the initial state of the charger, nonzero ergotropy can still be harvested even beyond this critical length. We further examine scenarios in which the charging line is initialized in an entangled state, as well as configurations with nonuniform, parabolically varying coupling strengths. In the latter case, we demonstrate that high ergotropy values can be restored, highlighting the potential of spatially engineered interactions to enhance quantum battery performance.