Today’s batteries lose efficiency – or “age” – through use, but theoretical quantum batteries might be immune to the problem if they are charged wirelessly.
Quantum batteries could be charged wirelessly and more effectively with the help of a hollow metal tube and an electromagnetic field.
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| Batteries of the future could be quantum pinkeyes/Shutterstock |
Quantum batteries are a new and still largely theoretical form of energy storage device that can charge extraordinarily quickly thanks to quantum effects. While this property would make quantum batteries useful in the future for powering electric vehicles or smartphones, theory suggests that quantum batteries are susceptible to disturbances from their environment, which means they could spontaneously lose charge or undergo “ageing” – losing efficiency over time, akin to the way a smartphone’s rechargeable battery performs less well with use.
Jun-Hong An at Lanzhou University in China and his colleagues wanted to remedy this by devising a new charging procedure.
Instead of starting with the quantum battery and its charger physically touching one another, they studied what would happen if each was placed in a different part of a “waveguide” – a thin, metal tube with a rectangular cross-section. They also assumed that the waveguide would be filled with an electromagnetic field.
Such a field always has an effect on electrically charged objects, so the researchers used quantum theory to derive equations describing how the battery and the charger would be affected within this waveguide. Then, they used a computer to solve the equations and determined how the battery’s energy would change as time passed – in other words, how it would charge wirelessly.
An says that the quantum effects that make quantum batteries work are known to be fragile, so it would be reasonable to expect that the theoretical wireless charging approach would be inefficient because of the physical distance between the battery and charger, and because the electromagnetic field in the waveguide would disturb those effects.
But his team’s calculations suggested the opposite. He says that the battery and the charger interacting with the same electromagnetic field “induced ideal charging” and the quantum battery became “immune to ageing”.
The battery and the charger were like “two boys swimming in a lake” he says, where they could get enveloped in all sorts of shared disturbances and waves. He adds that it was a real discovery that this could be helpful for charging rather than just destroying any coherent interaction between the two.
“The importance of batteries is hard to overstate, but the mechanisms of quantum battery ageing are also notoriously hard to counteract,” says Karen Hovhannisyan at the University of Potsdam in Germany. The new design is experimentally feasible because similar waveguides are commonly used in other experiments. But Hovhannisyan says that the researchers’ theoretical study involved a very simple battery, so there may be challenges in adapting the scheme to more complicated devices.
Because past studies of quantum batteries showed that entangling several of them can make them charge faster, An and his colleagues are now interested in adding more devices to their charging scheme. He says that the theoretical charging approach could also be tested experimentally by building the battery and the charger from tiny defective diamonds that are already used for quantum communication.
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