Quantum batteries – the promise of micromasers

Researchers at Korea’s Institute for Basic Science have found that micromasers could be a platform to build next-gen quantum batteries.

Micromasers – single atom masers, the microwave analogue of a laser – have long been studied for their quantum properties and now the researchers, from the IBS’s Centre for Theoretical Physics of Complex Systems have shown that they have features that allow them to serve as excellent models of quantum batteries.

A quantum battery is a quantum mechanical system in which energy is stored in an electromagnetic field or the qubits, charged by a stream of photons, i.e. in essence light.

One of the main concerns when trying to use an electromagnetic field to store energy is that in principle, the electromagnetic field could absorb an enormous amount of energy, potentially more than what is necessary. In real world terms an analogy would be a plugged-in smartphone, which continues to increase its charge indefinitely.

Have you read?
Quantum batteries: next-gen storage in sight
Safeguarding the stability of the grid

However, the researchers found that this cannot happen in micromasers. The electromagnetic field quickly reaches a final configuration, or steady state, whose energy can be determined and set a priori when building the micromaser. This property ensures protection from the risks of overcharging.

The researchers also found that the final configuration of the electromagnetic field is in a pure state, with no memory of the qubits that are used during the charging. This latter property is key for a quantum battery, enabling all the stored energy to be extracted and used without the need to keep track of the qubits used during the charging process.

In addition, they showed that these features are robust and are not destroyed by changing the specific parameters defined in their study, holding promise for building an actual quantum battery with the imperfections that are unavoidable in the building process.

Alongside this work, a group of European researchers have shown that micromasers also offer the ‘quantum advantage’, i.e. the property of quantum batteries that all the cells within the battery can be charged simultaneously, unlike classical batteries in which the charging of cells occurs in parallel independently of each other.

With these findings, the IBS researchers have suggested that the micromaser could be considered as a promising new platform that can be used to build quantum batteries. The two groups have launched a collaboration to further explore possible models with the hope to benchmark and experimentally test the performances of micromaser-based quantum battery devices.

In other recent work, the IBS researchers have shown that with the ‘quantum advantage’ quantum batteries can achieve quadratic scaling in charging speed. Applied in real world terms to the example of a typical electric vehicle with a battery with 200 cells, quantum charging would lead to a 200 times speedup over classical batteries, reducing the charging time from 10 hours to about 3 minutes, or with high speed charging from 30 minutes to a few seconds.