Designing Quantum Batteries

The recent interest in quantum technologies is driven by the potential power of quantum mechanics. Quantum batteries (QBs) are specifically designed to harness the unique properties of quantum thermodynamics to build batteries that are fundamentally different from conventional batteries. Here we discuss an open systems approach designed using hybrid quantum systems involving spin ensembles collectively coupled to an engineered reservior. We show that a simple single battery connected to the charger achieves both superextensive capacity and a power density that scales with the number of spins N in the battery. However one would also like to charge multiple batteries at the same time. We discuss a protocol that efficiently charges multiple quantum batteries coupled to different thermal reservoirs in parallel using a single charger. Our approach leads to a collective speed-up in the charging time, addressing a key challenge in quantum-enhanced energy transfer with significant theoretical and practical implications.