Fast charging of Dicke quantum batteries.

Quantum information theorems state that it is possible to exploit collective quantum resources to greatly enhance the charging power of quantum batteries, miniaturized devices able to fastly store energy outperforming their classical counterparts. In this direction, we investigate a model of a quantum battery that can be engineered in solid-state and molecular platforms for quantum electrodynamics. It consists of $N$ two-level systems coupled to a single photonic mode in a cavity. We contrast this collective model ("Dicke quantum battery"), to the one in which each two-level system is coupled to its own separate cavity mode ("Rabi quantum battery"). We demonstrate the emergence of a quantum advantage in the charging power of collective QBs, which is further enhanced by properly engineering a more exotic two-photon matter-radiation coupling. The first experimental evidence of this phenomenology has been reported very recently in a system where fluorescent organic molecules play the role of two-level systems embedded in a microcavity.