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Surrey physicists design a superfluid-helium qubit predicted to make about 100 times fewer errors
Surrey physicists have designed a superfluid-helium qubit that, by their calculations, would err about 100 times less often than superconducting qubits. No device has been built yet, so the figure is a prediction until the team's planned prototype measures it.
The Scientist · Science desk
What happened
- The SHOQ device would hold quantum information in superfluid helium-3, and because helium has no electric charge it should be shielded from certain kinds of electromagnetic noise.
- According to the researchers, their study in npj Quantum Information is the first reported design for a qubit based on a superfluid.
- Building a prototype is the next step, supported by an IAA Commercialisation Fellowship awarded to lead author Priya Sharma.
- Any working device would have to operate at extremely low temperatures, according to the university's release.
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Why it matters
- contradiction The ScienceDaily headline frames the work as a quantum computer breakthrough, while the lead author's own phrase, "an educated design", places it at the stage before any device exists.
- constraint Until the prototype reports, anyone evaluating qubit hardware has only a calculated figure to set against error rates measured on working superconducting chips.
- capability If the prediction holds in hardware, a superconducting processor could hand quantum information to a helium qubit for storage, splitting memory and computation across two kinds of device.
The 100-fold figure is a ratio, and the University of Surrey's release gives only one side of it [16]. The team's calculations put the SHOQ device's error rate about 100 times below that of "conventional superconducting qubits" [3]. The release does not say which superconducting design sets that baseline, which error measure is being compared, or what absolute rate the helium device is expected to reach.
The physical case is easier to follow. Superconducting circuits are highly sensitive to electromagnetic noise and stray electrical charges, and those errors get harder to control as more qubits are added [5]. Superfluid helium-3, a liquid that flows without friction [12], avoids the charge problem because it is neutral. The release limits the protection to "certain types" of electromagnetic noise [2]. How much of the predicted gain survives in hardware depends on what share of a real device's errors those types cause.
This is a design study. Priya Sharma, the lead author [14], was specific about what is new. "We are not the first to think about the individual components behind this idea, but what we have done for the first time is bring them together in a microfluidic device and work out the specific details that could enable the device to function as a qubit," she said [6]. A calculation of that kind can show that the parameters fit together into a working qubit. It cannot measure how long a real device holds its state. "The maths tells us that it should work," Sharma said [7].
The team presents the device as a companion to superconducting hardware [8]. Eran Ginossar, a co-author [15], said: "We don't necessarily need one type of qubit to do everything. Combining different quantum technologies could allow us to take advantage of the strengths of each." [9]
In my view the paper's value is that it makes a prediction a prototype can falsify. Sharma described the order of work the same way: "The next step is to make a prototype and put those predictions to the test." [7]
What to watch
- Whether the Surrey prototype reports a measured error rate or coherence time, and how close it comes to the predicted 100-fold improvement.
- Whether the npj Quantum Information paper or follow-up work names the superconducting baseline and the error metric behind the 100-fold comparison.
- Any demonstration of quantum information moving between a SHOQ device and a superconducting qubit, the step the memory role depends on.