Two European theoretical physicists have shown that it may be possible to build a near-perfect, entangled quantum battery. In the future, such quantum batteries might power the tiniest of devices — or provide power storage that is much more efficient than state-of-the-art lithium-ion battery packs.
To understand the concept of quantum batteries, we need to start (unsurprisingly) at a very low level. Today, most devices and machines that you interact with are governed by the rules of classical mechanics (Newton’s laws, friction, and so on). Classical mechanics are very accurate for larger systems, but they fall apart as we begin to analyze microscopic (atomic and sub-atomic) systems — which led to a new set of laws and theories that describe quantum mechanics.
In recent years, as our ability to observe and manipulate quantum systems has grown — thanks to machines such as the Large Hadron Collider and scanning tunneling electron microscopes — physicists have started theorizing about devices and machines that use quantum mechanics, rather than classical. In theory, these devices could be much smaller, more efficient, or simply act in rather unsurprising ways. In this case, Robert Alicki of the University of Gdansk in Poland, and Mark Fannes of the University of Leuven in Belgium, have defined a battery that stores and releases energy using quantum mechanics.
The increasing amount of energy that can be extracted from a quantum battery, as you increase the number of entangled copies. This graph probably won’t make much sense unless you’re a quantum physicist.
A quantum system (say, the single proton and electron in a hydrogen atom) has a quantum state, defined by the electron’s movements. (Quick aside: In our previous discussions of spintronics and quantum computing, it is the spin of the electron (clockwise, counterclockwise, etc.) that is converted into a qubit value). Some quantum states have a very small amount of energy that can be extracted, returning it to a passive, neutral state. In theory, according to Alicki and Fannes, it should be possible to build a quantum battery that is full of energy-rich quantum states — and then, somehow, recharge it when you run out of juice.
Better yet, the physicists also theorize that quantum entanglement could be used to create an even more efficient quantum battery. In essence, Alicki and Fannes say that you can link together any number of quantum batteries, allowing you to extract all of the stored energy in one big gulp (pictured above). Their research paper goes on to say that with enough entanglement, these batteries would be perfect — with no energy lost/wasted during charge or discharge.
As the Physics Arxiv Blog notes, such perfect energy transfer readily occurs in nature, such as during photosynthesis — but no one knows why. It’s just one possible explanation, of course, but maybe Gaea has a bit of a head start on quantum batteries.