A superfluid helium qubit could make 100 times fewer errors, on paper
Key takeaways
- University of Surrey researchers published the first reported design for a qubit based on superfluid helium-3.
- Their calculations predict error rates around 100 times lower than conventional superconducting qubits.
- No prototype exists yet, and building one is the team's next step.
Around 100 times fewer errors. That is what calculations predict for a new superfluid qubit design from the University of Surrey, built on superfluid helium-3 rather than the superconducting circuits most quantum computers use today. The study, published in npj Quantum Information, is the first reported design for a superfluid-based qubit, according to the university's release on Nanowerk.
The important word there is design, because nobody has built one yet.
How a superfluid qubit works
Superfluid helium-3 is a form of liquid helium that flows without friction at extremely low temperatures. The proposed device, called the Superfluid Helium Oscillator Quantum (SHOQ) device, holds quantum information in quantised oscillations of that fluid inside a microfluidic chip.
The appeal is that the helium carries no electric charge. Superconducting qubits are very sensitive to electromagnetic noise and stray charges, which scramble the information they hold and make error rates hard to control as machines grow. A charge-neutral fluid should simply ignore some of that noise.
Why fewer quantum errors matter
Errors are the bottleneck for useful quantum computing. Today's machines spend most of their physical qubits on error correction, which is why the gap between the two kinds of qubit matters so much; we explain it in logical vs physical qubits. A qubit that starts out 100 times cleaner would need far less of that overhead.
The team is not pitching it as a replacement. Lead author Dr Priya Sharma says "the maths tells us that it should work", and the paper shows how the device could connect to existing superconducting hardware. One suggested use is quantum memory, holding information while other qubits do the calculating. Surrey worked with Professor Jens Koch at Northwestern University, one of the researchers behind the transmon, which has become the most widely used superconducting qubit design.
What to watch next
The next milestone is a prototype. The team is now working toward one, backed by a commercialisation fellowship awarded to Sharma, and the very low temperatures the device needs have already been reached in superfluid helium-3 experiments. Until a real chip hits that predicted error rate, 100 times is a target rather than a result.
