For the last decade or so, quantum batteries have long promised near-instantaneous charging by exploiting quantum effects such as superabsorption. However, their potential has been hampered by one critical flaw: stored energy leaks away in nanoseconds. Unlike conventional lithium-ion batteries – which rely on slow chemical reactions and face issues of charging speed, degradation, and resource demand – quantum batteries store and release energy through light–matter interactions, opening the door to faster, more compact devices.
In a new study published in PRX Energy, researchers at RMIT University and CSIRO tackled the short-lifetime problem by engineering multilayer optical microcavities that channel absorbed energy into molecular triplet states, which can hold energy far longer than bright singlet states. Using steady-state and time-resolved emission spectroscopy, the team tracked how cavity detuning influenced energy transfer, revealing conditions where triplet populations – and thus storage times – were maximized.
The best-performing device stored energy for over 40 microseconds, more than a thousand times longer than previous demonstrations. While still short of conventional batteries, the result marks a significant leap forward for scalable quantum designs that could one day combine ultrafast charging with practical storage.
To explore the implications of this breakthrough and the hurdles still ahead, we spoke with Daniel Tibben, PhD candidate at RMIT University and co-author of the study.
Could you explain, in a nutshell, how a quantum battery works – and what sets it apart from traditional batteries?
A quantum battery is a storage device that aims to harness quantum mechanics to enhance the battery’s performance. Rather than storing and releasing energy through conventional chemical reactions, like in traditional batteries, these devices harness quantum effects such as superposition and light–matter interactions to enable much faster charging and potentially greater energy storage capabilities. On our device, an optical microcavity traps and confines light to a small volume where we place our “charging molecules.” This energy is then funnelled from the quantum charging states to a storage layer, which is able to retain energy a thousand times longer than previous efforts.
What motivated your team to focus on extending the storage lifetime of quantum batteries?
Our design builds on the so-called “Dicke quantum battery” – a system where many molecules work collectively to absorb light energy extremely quickly. In fact, the more molecules you add, the faster the charging rate grows – faster than a simple one-to-one increase. The drawback is that as the number of molecules increases, the stored energy is also lost more quickly. To solve this, we added a secondary “storage” layer, allowing the device to hold energy up to a thousand times longer than before.
Was there a key breakthrough or “eureka” moment during development?
A key breakthrough in our study came when we systematically varied the thickness of our devices to control how light interacts with the charging molecules. As we characterized our devices by measuring their emission, we noticed that for the first few iterations, the changes were subtle. Then, with the fourth device, we observed a striking drop in emission intensity – a promising sign that the storage layer was being efficiently populated. This was our ‘eureka’ moment, although we still had to be careful to rule out the possibility that this drop was simply due to energy loss elsewhere in the system.
What are some of the biggest technical or measurement challenges in studying and optimizing quantum batteries?
Our device uses an optical microcavity to confine and concentrate light into a very small region, where the charging molecules are located. A trade-off arises, however, between how effectively the cavity traps light and how easily we can measure the light emitted from the device. Because this design inevitably reduces the emission signal, we carefully normalized the output of each device against a reference to ensure the data could be compared fairly and accurately.
Light-sensitive molecules can also exchange energy directly over very short distances (less than 10 nm) through a process known as Förster resonance energy transfer (FRET) – which can cause unwanted battery discharging. Although FRET is widely used in biology to study molecular interactions, it acts in our device as an unwanted pathway that’s able to reduce the efficiency of energy transfer from charging to storage layer. To prevent this, we introduced an optically inert spacer layer – thicker than the FRET distance – between the charging and storage layers. This ensures the two types of molecules interact only through the light confined in the cavity – a feature that is central to achieving our quantum advantage.
How does your approach compare to other quantum battery designs or strategies currently being explored?
Many proposed quantum battery designs remain largely theoretical, with only a few implemented in practical experiments. What sets ours apart is not only its scalability, but also its compatibility with existing electronic technologies. Furthermore, it operates under standard room-temperature conditions and simultaneously achieves both longer energy storage and rapid collective charging through Dicke superabsorption.
In comparison, alternative quantum battery platforms tend to have significant practical limitations; superconducting circuits and semiconductor quantum dots require extremely low, cryogenic temperatures, which complicates integration and large-scale use. Nuclear spin-based systems typically focus on individual or small numbers of spins, making them difficult to scale or incorporate into conventional devices. Although these other platforms each demonstrate important aspects of quantum battery operation – such as precise control over charging, efficient transfer of energy between components, or exceptionally long energy retention – none (to date) have succeeded in combining rapid collective charging with significantly extended storage in a single, room-temperature, and electronically integratable system.
Looking ahead, what kinds of applications or technologies might benefit most from quantum batteries?
This work opens the door to the integration of other chemical systems into quantum battery prototypes – a capability that represents an important conceptual advance. If the storage time of these devices can be extended further to the seconds, hours or even days-long scale, the materials explored in these prototypes could theoretically power a new generation of low-energy, portable electronics. This includes wearable sensors, small processors and other compact devices, bringing quantum-enhanced energy storage closer to practical reality.
What are the next steps for your team?
The team is currently working on integrating these types of devices with typical electronic circuits to allow for energy extraction as an electrical current. Research on this by the team is currently under peer-review, which you can read about in more detail here.
Looking to the future, the key challenges will be in developing ways to hold energy for timescales comparable to conventional batteries, while also maintaining the distinctive quantum advantages offered by polariton-mediated interactions that result in extremely fast battery charging. In principle, this class of quantum batteries could allow near instantaneous charging and rapid energy delivery on demand, and overcoming the current limitation of short storage times could position these devices to rival traditional batteries, such as lithium-ion, for certain applications.
Newsletters
Receive the latest analytical science news, personalities, education, and career development – weekly to your inbox.
