  We introduce a cyclic quantum battery model, based on an interacting
bipartite system, weakly coupled to a thermal bath. The working cycle of the
battery consists of four strokes: system thermalization, disconnection of
subsystems, ergotropy extraction, and reconnection. The thermal bath acts as a
charger in the thermalization stroke, while ergotropy extraction is possible
because the ensuing thermal state is no longer passive after the disconnection
stroke. Focusing on the case of two interacting qubits, we show that phase
coherence, in the presence of non-trivial correlations between the qubits, can
be exploited to reach working regimes with efficiency higher than 50% while
providing finite ergotropy. Our protocol is illustrated through a simple and
feasible circuit model of a cyclic superconducting quantum battery.
Furthermore, we simulate the considered cycle on superconducting IBM quantum
machines. The good agreement between the theoretical and simulated results
strongly suggests that our scheme for cyclic quantum batteries can be
successfully realized in superconducting quantum hardware.
