Quick charging of a quantum battery with superposed trajectories

We propose charging protocols for quantum batteries based on quantum superpositions of trajectories. Specifically, we consider that a qubit (the battery) interacts with multiple cavities or a single cavity at various positions, where the cavities act as chargers. Further, we introduce a quantum control prepared in a quantum superposition state, allowing the battery to be simultaneously charged by multiple cavities (the multiple-charger protocol) or a single cavity with different entry positions (the single-charger protocol). To assess the battery's performance, we evaluate the maximum extractable work, referred to as ergotropy. The primary discovery lies in the quick charging effect, wherein we prove that the increase in ergotropy stems from the quantum coherence initially present in the quantum control. Moreover, the induced “Dicke-type interference effect” in the single-charger protocol can further lead to a “perfect charging phenomenon”, enabling a complete conversion of the stored energy into extractable work across the entire charging process, with just two entry positions in superposition. Furthermore, we propose circuit models for these charging protocols and conduct proof-of-principle demonstrations on IBMQ and IonQ quantum processors. The results validate our theoretical predictions, demonstrating a clear enhancement in ergotropy. Published by the American Physical Society 2024