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The quantum battery works like a sponge that absorbs light but won't release it without a forced squeeze. The inspiration came from bacteria's natural solar traps: capturing solar photons, they transfer energy almost losslessly, as proven by spectroscopy. Physicists recreated this principle by assembling atoms into a ring and placing them in a mirrored cavity. The collective behavior of the atoms created a one-way valve effect: energy easily enters, but the way back is blocked. This achieves entropic irreversibility — a concept developed by Ludwig Boltzmann.

This effect arises from quantum connections between the atoms. Regular batteries lose energy with each charge, but the quantum version promises near-perfect efficiency. The size of the ring affects performance: small rings deliver power faster, while large ones store more. With weak coupling to the cavity, output increases, but strong coupling turns the battery into a simple buffer.

Bacteria mastered this trick billions of years ago, transferring light with efficiency close to 100%. Now engineers dream of creating gadgets that charge in an instant and hold their charge forever.

Original abstract

as written by the authors arXiv:2603.15268

We propose a theoretical model of a fully functional nonreciprocal quantum battery inspired by the architecture of bacterial light-harvesting complexes. We assign functional roles to collective quantum optical subradiant and superradiant states and introduce a unimodal cavity to assist storage. The transition rates are obtained from an effective non-Hermitian Hamiltonian, tailored to the battery geometry which are fed into a master equation to unravel the time evolution. We investigate the complete thermodynamic performance including storage, leakage, ergotropy, work extraction, flux, and power. We observe optimization at different ring sizes, each peaking at its specific energetic function. Strong coupling between the ring and central system enhances the battery's ability to store energy but reduces the ability of power output. The ergotropy exceeds capacity and approaches it linearly with increasing system size, with an optimal small-size regime that disappears under strong coupling.