An international team of physicists has presented the first prototype of a "quantum battery", which demonstrates a full working cycle - from super-absorption of light through energy storage to extraction of electric current. The device uses collective quantum states to achieve power scaling, which violates intuitive classical concepts - the larger the battery, the faster it charges.

What is a "quantum battery"

By "quantum battery", scientists understand a device for storing energy, in which charging and discharging are controlled by quantum-mechanical effects such as entanglement, collective states and controlled interaction with light. Unlike classical lithium-ion cells, where adding more capacity inevitably increases charging time, in quantum batteries, theoretical models predict "superextensive" scaling - the charging power grows faster than the size of the system.

The core of the prototype is an optical microcavity - a multilayer "sandwich" structure in which organic semiconductor molecules are enclosed. When light enters it, it collectively connects with the ensemble of molecules and forms hybrid light-matter states, known as polaritons, which are the basis of super-absorption.

The effect of super-absorption: when "the more, the faster"

The key mechanism behind ultra-fast charging is the so-called "super-absorption" - a collective quantum effect, in which many identical absorbing elements act as one common "super-antenna" for light. In such a mode, the charging speed does not increase linearly with the number of elements, but can grow faster, and in some schemes it theoretically reaches a scaling in which the charging time decreases proportionally to the number of particles.

In the optical microcavity, super-absorption manifests itself through the collective connection of N molecules to the same limited light mode, so that the effective interaction force increases approximately as the square root of N. This leads to a counterintuitive result: the charging time increases more slowly than the capacity - the larger battery can be charged not only not slower, but even faster per unit volume.

Theoretical developments show that with properly organized collective states, it is possible to reach a mode in which the charging time scales inversely proportionally to the number of quantum elements, and not only to its root, which opens the way to truly "ultra-fast charging".

The prototype: from light to electric current

A recently published study describes a prototype "quantum battery" that for the first time demonstrates a full cycle - super-absorption, metastable storage and electric discharge with superextensive power. The device is a multilayer microcavity, tuned in resonance with the transition between the ground and first excited state of an absorbing molecule, combined with a donor-acceptor interface for charge separation.

The process takes place in several steps: first, the incident light excites polariton states in the microcavity, which collectively absorb energy "in bulk" thanks to super-absorption. Then, the energy is quickly transferred to long-lived triplet states via intersystem crossing, which stabilizes the charge for times many times longer than the ultra-short charging process.

Finally, the energy gradient at the interface between the molecular layer and the acceptor material drives the separation of charges and the generation of a measurable electric current - so the quantum battery not only "absorbs" light, but also emits it as electrical energy.

First experimental prototype with superextensive power

The authors of the latest research emphasize that until now, quantum batteries have been primarily a theoretical concept with limited experimental demonstrations, focusing only on individual phases such as fast charging or storage. However, the new prototype integrates into one device "superextensive charging, metastable energy storage and superextensive electric discharge", thus offering a "prototypical framework for practical quantum batteries".

Researchers also report the first experimental observation of stationary electrical power that scales superlinearly with the size of the system - a phenomenon that was not predicted in previous models and that has a direct impact on devices operating at low light and "always-charging" mode. This means that by increasing the number of absorbing units, not only is more energy stored, but it can also be extracted more efficiently.

Another scientific group also reports a prototype "quantum battery" that "charges the faster, the bigger it gets". A similar organic microcavity is used there, and the ultra-fast charging dynamics are confirmed by femtosecond laser spectroscopy in a specialized laboratory.

Collective quantum states and the role of entanglement

The fundamental physics behind the effect relies on collective states in which the individual "cells" of the battery - for example, molecules or qubits - do not act independently, but are quantum-correlated. Such states can be described as an "averaged" superposition, in which the system absorbs and emits energy as a whole, rather than as a sum of individual parts.

Theoretical studies show that entanglement can increase the effective interaction force with the energy source and allow scaling of the charging speed of the Θ(N−1) type - i.e. the charging time to decrease inversely proportionally to the number of elements. Thus, "collective charging" provides a fundamentally new resource for energy management, unavailable to classical batteries.

At the same time, the leakage of coherence and dissipation play a dual role - if the quantum oscillations are not controlled, the system can "discharge" just as fast as it charges. That is why part of the experimental efforts are aimed at finding modes in which noise and losses paradoxically stabilize energy storage, instead of destroying it.

Potential applications: from quantum technologies to electric vehicles

Although the current prototypes are far from practical implementation, the principle of super-absorption and superextensive charging outlines ambitious scenarios. Among them are ultra-fast charging energy buffers for quantum processors, high-efficiency light-harvesting systems in low light, and future batteries for electric vehicles that can charge almost instantly if quantum effects are realized on scalable platforms.

Popular science analyses emphasize that "the larger the quantum battery, the faster it charges", which is exactly the opposite of the known intuition from classical lithium-ion systems. Nevertheless, the researchers themselves warn that the technology is in a "very early phase" and that a definitive breakthrough for consumer devices will require a rethinking of materials, architectures, and the way quantum coherence is managed in real, noisy environments.

Along with organic microcavities, alternative platforms are being investigated - from ultra-cold atoms in potential wells to solid-state systems, in which collective charging can be realized at higher temperatures and in more massive structures. If these efforts are successful, a "quantum battery" with super-absorption could turn from a laboratory prototype into a key element of future energy infrastructure - from large-scale smart grids to personal devices.