Quantum Charging Advantage in Superconducting Solid-State Batteries.

Quantum battery, as a novel energy storage device, offers the potential for unprecedented efficiency and performance beyond the capabilities of classical systems, with broad implications for future quantum technologies. Here, we experimentally demonstrate quantum charging advantage (QCA) in a scalable solid-state quantum battery. More specifically, we show how double-excitation Hamiltonians for two-level systems promote scalable QCA with standard methods. We effectively implement the collective evolution of quantum systems with two up to 12 battery cells in a superconducting quantum processor, and study the performance of quantum charging compared to its uncorrelated classical counterpart. The model considered is a linear chain of superconducting transmon qubits with only nearest-neighbor and pairwise interactions, which constitute the simplest model of a multi-cell quantum battery. Our results empirically realize substantial QCA without the necessity of adopting long-range and many-body interactions and showcase the quantum features of the QB charging processes with measurements of nonzero coherent ergotropy, incoherent ergotropy, and entanglement, revealing a promising prospect for further developments of efficient and experimentally feasible protocols for QCA.