Quantum batteries harness quantum effects to circumvent the limitations of ordinary devices imposed by entropy — a measure of disorder and energy losses. Imagine a bucket under a powerful jet: filling is lightning-fast. But the bucket has holes: the environment constantly drains the energy.
Scientists realized you don’t need to plug the holes — just make the water invisible to them. Two sources of wave coherence — internal (in the charger) and external (a specially rhythmically squeezed environment) — together create a “dark state” for the battery. In it, energy becomes locked and stops leaking, even though the holes remain.
This principle, familiar from spectroscopy, promises quantum storage devices capable of holding charge with virtually no losses.
Interestingly, "dark states" already save energy in nature: some photosynthesis processes use similar mechanisms to transfer sunlight deep into cells without losses.