Quantum Phase Battery : A Milestone in the World of Quantum Computing

Hello readers! You might be au fait with the power of quantum computing through our blog  Quantum Supremacy in which we discussed how a Quantum computer beats even the best supercomputers in solving a specific problem.

And recently, the latest advancement as the next step in the world of quantum technology is the discovery of the first-ever quantum phase battery.

Now you might be wondering, how come quantum physics intervene in batteries, right? Let's rewind the basics once again!

Quantum technology works by using the principles of quantum mechanics (the physics of subatomic particles).In quantum technologies, circuits or devices are based on superconducting materials. The quantum phase battery represents an essential element for quantum technologies based on phase coherence.

The term "quantum phase battery" needs basic knowledge of some quantum physics-related terms supercurrents and phase coherence for the principle behind the working of this battery.

How does it work?

Before discussing this great discovery, the more obvious question to be answered is how does it work and what makes it different and better than classical ones.

Batteries have been there to power the circuits and we have been using them from the time it was just a classical battery, a Volta's Pile, the first electrical battery that could continuously provide electric current to the circuit, to the Li-ion batteries most commonly being used in everyday life. 

These batteries convert the chemical energy into a voltage, which can then be used as a power source for the working of electronic circuits.

But what if the current could be made to flow without the need of any applied voltage. Is this possible? In quantum technology, such currents are termed as Supercurrents. 

The term got the super attribute for the fact that these currents do not exhibit any energy losses and are not dependent anymore on any voltage to be applied. 

They are induced not from a voltage but from a phase difference of the wave function of the quantum circuit, which is directly related to the wave nature of the matter.

A quantum device that could be able to provide and maintain a persistent phase bias to the wave function can be seen as a quantum phase battery, which induces supercurrents in the electronic circuits.

Hence the quantum technology provides such materials that could power the circuits with these Supercurrents therefore there will be no need for those classical batteries anymore.

This is exactly what a team of researchers has claimed to build out of this theory and have proposed the experimental and theoretical results that led to the fabrication of the first quantum phase battery; which consists of Indium Arsenide (InAs) nanowire in contact with aluminum super leads. 

The n-doped InAs nanowire forms the core of the battery (the pile) and Aluminium superconducting leads as poles. The battery is charged by applying an external magnetic field, which then can be switched off.

Sebastian Bergeret from the Mesoscopic physics group at the Materials Physics Center (CFM, CSIC-UPV/EHU), a joint initiative of Consejo Superior de Investigaciones Científicas (CSIC) and the University of the Basque Country (UPV/EHU), and Ilya Tokatly, Ikerbasque Professor in the Nano-Biospectroscopy group of the UPV/EHU, both Donostia International Physics Center (DIPC) associate researchers had devised the idea of such a quantum phase battery in 2015.

They proposed a theoretical system with the properties needed to build the phase battery. Bergeret and Tokatly's idea of such a device consisted of a combination of superconducting and magnetic materials with an effect, called spin-orbit coupling.

Spin-orbit coupling (SOC) can be regarded as a form of effective magnetic field 'seen' by the spin of the electron in the rest frame.SOC is one of the relativistic effects and it occurs whenever a particle with non-zero spin moves around a region with a finite electric field.

A few years later Francesco Giazotto and Elia Strambini from the NEST-CNR Institute, Pisa, identified a suitable material combination and fabricated the first quantum phase battery.

Scientists noted, “…...We find that the ferromagnetic polarization of the unpaired-spin states is efficiently converted into a persistent phase bias φ0 across the wire, leading to the anomalous Josephson effect. 

We apply an external in-plane magnetic field and, thereby, achieve continuous tuning of φ0. Hence, we can charge and discharge the quantum phase battery.

……. Our results demonstrate how the combined action of spin-orbit coupling and exchange interaction induces a strong coupling between charge, spin, and superconducting phase, able to break the phase rigidity of the system.”

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

This battery is further being improved at CFM premises in a collaboration between the Nanophysics Lab and the Mesoscopic Physics Group. 

Some researchers have proposed a new idea that these quantum batteries could use qubits built either from superconductors or from semiconducting quantum dots.  

"Any sufficiently advanced technology is indistinguishable from magic".Quantum technologies have been turning this aspect around -what if we use quantum physics to build quantum devices.

This device like other quantum devices contributes to the advancements made in the quantum technology world and it is now expected to see quantum technology revolutionize more and more in the near future.

This was all about the latest advancement in Quantum Computing and we hope you found it informative and interesting. Do like and share this blog with all your tech geeks and your suggestions in the comments will be highly appreciated!