Dissipative dynamics in the cavity-mediated energy transfer process between ultrastrong coupled devices.

We analyze the coherent energy transfer process between a quantum charger and a quantum battery mediated by the photons in a resonant cavity. Exploiting a fully numerical analysis it is possible to consider both strong and ultra-strong coupling, which allows an improvement of the energy transfer performances compared to the limiting weak-coupling scenario. In particular, the ultra-strong coupling regime allows a faster energy transfer process and, even when the system is off-resonance, it allows to achieve an almost complete energy transfer. Moreover, in the present analysis the system is considered to be open and consequently affected by dissipation due to interactions with the environment. In particular, a lossy cavity can affect the dynamics of the system, therefore the study of the stability of the considered device in this condition is extremely important in view of possible experimental implementations.