TL;DR: Scientists have built a quantum battery prototype that can produce an electrical current after charging in femtoseconds, marking a step forward for a technology that has largely remained theoretical and limited to small-scale lab experiments. The prototype is far from replacing conventional batteries, but it provides evidence that quantum effects could eventually enable faster energy transfer in quantum hardware and other specialized systems.
The device, developed by a team led by CSIRO quantum science researcher James Quach, is designed to take advantage of a quantum effect called superabsorption. In simple terms, the more molecules involved, the faster the system can absorb energy.
That is the opposite of what happens with conventional batteries, which generally take longer to charge as they get larger. The work does not mean quantum batteries are ready to replace those used in phones, laptops, or electric vehicles. The prototype stores only a small amount of energy and holds it for nanoseconds. Still, researchers say the experiment demonstrates that energy can be rapidly absorbed and extracted from a quantum battery.
The prototype uses an optical microcavity made of two mirrors separated by about 100 nanometers. The space between the mirrors is filled with organic dye molecules. A laser shines into the cavity, causing the light and molecules to interact strongly.
That interaction creates hybrid light-matter states. The molecules do not absorb energy independently, as they would in a classical system. Instead, they respond collectively.
The battery charges in femtoseconds, or quadrillionths of a second. It can retain energy for nanoseconds, about six orders of magnitude longer than the charging period.
Quach's team first demonstrated superabsorption in 2022. The newer experiment added the ability to extract an electrical current. The current remains small, but demonstrating it is an important step toward making a quantum battery useful beyond a physics experiment.
Quantum batteries are not expected to compete with conventional batteries simply by storing more energy. Their main attraction is the possibility of very fast charging and precise energy delivery.
Dario Ferraro, an associate professor of physics at the University of Genova, told the BBC that quantum batteries are intended to improve the speed and control of energy delivery rather than significantly increase the amount of energy a battery can store.
For now, the gap between the prototype and a useful power source remains wide. The device can hold only a few billion electron volts of energy and retains it for a very short time. A real-world system would need far greater capacity and much longer storage times.
Quach said his group has built a hybrid design intended to address those limitations. It combines quantum components for rapid charging with classical layers that can store energy for longer. He said the team is preparing a paper on the work.
The researchers also plan to link multiple microscopic batteries together. "If we do those two things, then we're on our way to being able to power a conventional device," Quach said.
The optical microcavity system has one practical advantage: It operates at room temperature. Other quantum-battery designs use superconducting materials, which are already important in quantum computing but require extremely cold operating conditions.
Superconducting systems can operate at temperatures below -150°C. "This is fine for quantum computers, but not so useful to power your mobile phone," Quach said.
Mauro Paternostro, a quantum physicist at Queen's University Belfast, said the optical approach is a strong way to demonstrate that quantum charging can work. However, he added that it may be difficult to draw energy from such a system in a controlled and useful way. "A microcavity gives you a beautiful ensemble demonstration, but poor control over getting the energy back out in a useful, directed form," he said.
The first practical use of quantum batteries, if they reach that point, may be in quantum hardware rather than consumer electronics. Quantum computers already rely on specialized equipment, and some use superconducting systems that operate at cryogenic temperatures.
Quach said a quantum battery could eventually help reduce energy use in quantum devices and support faster, more reliable operation. However, those benefits have not yet been demonstrated.
Ferraro said quantum effects are fragile and can break down when the system interacts with its environment. He expects quantum batteries to remain most useful in quantum-scale applications. "In my view... quantum batteries are unlikely to replace conventional batteries in everyday applications such as mobile phones or electric vehicles," Ferraro said. "Their natural domain is the quantum scale."
The latest prototype does not settle that debate. It does show that researchers can use quantum effects to charge a system quickly and extract an electrical current. The next challenge is building a device that can store more energy, hold it longer, and release it where it is needed.