How superfluid helium could make quantum computing more reliable

The proposed qubit uses superfluid helium-3, a rare form of liquid helium with unusual quantum properties. Because the helium is electrically neutral, the design may be less sensitive to some of the electromagnetic disturbances that affect many leading quantum computers.

Quantum computers use qubits to store and process information in ways that traditional computers cannot. Many existing quantum systems rely on superconducting circuits, but these circuits are highly sensitive to electromagnetic noise and stray charges, similar to static electricity that makes hair stick to a balloon.

Even tiny disturbances can destroy the fragile quantum information stored in a qubit. As more qubits are added, controlling these errors becomes increasingly difficult, making scalability one of the central challenges in quantum computing.

What is the SHOQ quantum device?

In a study published in npj Quantum Information, researchers from Surrey’s Quantum Science Group describe an alternative qubit design based on superfluid helium-3, which can flow without friction.

The device, called the superfluid helium oscillator quantum (SHOQ) device, uses charge-neutral superfluid helium. Since helium has no electrical charge, the design is naturally protected from certain types of electromagnetic noise.

Predicted error rate is about 100 times lower

The researchers say the SHOQ device is the first reported superfluid-based qubit design. According to their calculations, its predicted error rate could be about 100 times lower than that of traditional superconducting qubits.

Dr Priya Sharma, Daphne Jackson Fellow, Hybrid Quantum Systems Research Fellow in the Department of Mathematics and Physics at the University of Surrey, and lead author of the study, said:

“We’re not the first to think about the individual components behind this idea, but what we’re the first to do is put them together into a microfluidic device and consider the specific details of allowing the device to function as a qubit.

“The math tells us it should work. We’ve taken what we already know about superfluid helium and quantum technology and turned it into an educated design with the parameters and specifications we need to build it. The next step is to build a prototype and test those predictions.”

The researchers say the SHOQ device could be integrated with superconducting quantum technology rather than replacing existing quantum computing hardware.

This approach could allow different types of qubits to perform different roles within the same quantum system, depending on their strengths.

Could superfluid helium qubits become quantum memory?

One long-term possibility is to use SHOQ devices as a form of quantum memory. In this setup, superfluid-based qubits could store quantum information while other hardware performs computations.

Dr Eran Ginosar, Associate Professor in the Department of Physics and Institute of Advanced Technology at the University of Surrey and co-author of the study, said:

“You don’t necessarily need one type of qubit to do everything; different quantum technologies may be combined to take advantage of the strengths of each.

“Superfluid helium gives us the opportunity to explore a fundamentally different type of quantum hardware. If the predicted performance can be demonstrated experimentally, it could eventually work in parallel with existing superconducting technologies as part of a larger quantum system.”

Researchers plan to build a SHOQ prototype

The team’s next step is to build a prototype and test whether the predicted performance can be reproduced in a real device. This work is supported by an IAA Commercialization Fellowship awarded to Dr Priya Sharma.

The SHOQ device must operate at extremely low temperatures, conditions that researchers have already achieved in previous experiments using superfluid helium-3.

The project was led by the University of Surrey in collaboration with Professor Jens Koch from Northwestern University in the United States. Koch is one of the researchers behind the development of the transmon, a superconducting qubit design now widely used in quantum computing.