Superconducting Transistors to Solve Quantum Computing Woes

A quantum computer can be an ungainly thing, because even the most elegant qubit-housing cryostat usually sprouts a thicket of control cables.

Most qubits don’t work above a fraction of a degree above absolute zero, but the conventional electronics that control the qubits don’t work in the cryogenic cold. Hence connecting cables need to route information out of the cryostat. The more qubits a computer has, the more cables it needs. More than an eyesore, this overgrowth is a problem for scaling quantum computers. The wires are a pathway for heat that can destabilize the sensitive qubits.

Engineers can clear some of the cable weeds if they get control electronics that work in the cold, next to the chilly qubits. A month-old startup named S-Transistors has a plan: Make the needed circuits out of superconducting transistors that can operate in the qubit’s ultra-cold environment.

Spun off from Finland’s VTT Technical Research Centre, the Espoo-based firm did not invent the superconducting transistor. Instead, S-Transistors thinks they have made a breakthrough in making superconducting transistors in the fab. They plan to put their first circuits on the market in 2027.

“We don’t claim to make the best superconducting transistors, but we can make a lot of them on wafer-scale, and we can actually be the first to start combining them into new kinds of superconducting integrated circuits that didn’t exist before,” says Heorhii Bohuslavskyi, CEO and co-founder of S-Transistors and formerly a researcher at VTT.