The World's First Quantum Phase Battery Is Here

The battery, which represents a big step in quantum computing, consists of an indium arsenide nanowire in contact with aluminum superconducting leads.
Chris Young

You might have been privy to the quantum computing hype. If you haven't, here's how it goes: if they deliver on their potential, quantum computers will be able to tackle problems that would require hundreds if not thousands of years for a classical computer to solve.

And now, in a big step for quantum computing, we have the first functioning quantum phase battery.


Quantum versus classical batteries

Batteries are ubiquitous in our everyday lives, with lithium-ion batteries being the most commonly used type — though interesting alternatives are, in fact, in development.

The quantum phase battery is a different beast altogether. While classical batteries convert chemical energy into voltage, which powers electronic circuits, quantum technologies use circuits or devices based on superconducting materials.

The World's First Quantum Phase Battery Is Here
The IBM Q System 1 quantum computer, Source: IBM

In superconducting materials, currents flow without the need for an applied voltage. Therefore, when it comes to quantum computers, there is no need for a classical battery.

Supercurrents get their name from the fact that they do not exhibit any energy losses. They are induced from a phase difference of the wave function of the quantum circuit, rather than from a voltage.

This means that a quantum device able to provide a persistent phase difference can be seen as a quantum phase battery, which induces supercurrents in a quantum circuit.

Building a functioning quantum phase battery

That is exactly what Francesco Giazotto and Elia Strambini from the NEST-CNR Institute, Pisa have built. They built on the work of Sebastian Bergeret and Ilya Tokatly, both Donostia international Physics Center (DIPC) associate researchers, who devised the idea of a quantum phase battery in 2015.

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Bergeret and Tokatly's idea consisted in a combination of superconducting, and magnetic materials with an intrinsic relativistic effect, called spin-orbit coupling. 

Giazotto and Strambini's contribution was to identify a suitable material combination that allowed them to fabricate the first quantum phase battery. Their results are now published in the journal Nature Nanotechnology.

Their quantum phase battery consists of an n-doped InAs nanowire forming the core of the battery (the pile) and Al superconducting leads as poles. It is charged by applying an external magnetic field, which then can be switched off.

Cristina Sanz-Fernández and Claudio Guarcello, also from CFM, adapted the theory to simulate the experimental findings.

The battery is being further developed and improved at CFM premises in a collaboration between the Nanophysics Lab and the Mesoscopic Physics Group. These advances could contribute to enormous advances that many say will come from the field of quantum computing.

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