Whether superconducting transistors could help quantum computers

[Maisie92]

A lovely article about superconducting transistors and whether they could solve one of the more practical headaches in quantum computing. Most quantum computers keep their qubits inside cryostats at temperatures close to absolute zero. The problem is that normal semiconductor control electronics cannot work at those temperatures, so they sit outside and connect to the qubits through a large number of wires. That wiring is complicated, bulky and a common point of failure

The idea is to build control circuits that can work inside the cryostat alongside the qubits. A start-up called S-Transistors is working on this using Josephson junction field effect transistors, or JJFETs, building on a 2025 paper by Yusheng Xiong and colleagues. Josephson junctions are already a basic component in superconducting qubits, so the technology fits naturally into the same environment. It is a neat way of solving the problem from the inside

The mechanism works by passing enough current through the junction to briefly switch off its superconductivity, which creates a voltage pulse that can be detected. S-Transistors claims it can now manufacture these devices at scale. If that holds up, control electronics could sit right next to the qubits and remove much of the tangle of wiring. That is a big claim for a young company

The main alternative is cryogenic CMOS, which uses conventional semiconductor manufacturing to make circuits that work at low temperatures. That has the advantage of building on existing chip factories, but it does not reach the near absolute zero performance that superconducting options might offer. Both approaches are trying to solve the same problem of scaling quantum computers beyond a few hundred qubits

Posch presents it neutrally, as something that could bring practical quantum computing a little bit closer. It is the kind of unglamorous engineering that often matters more than headline qubit counts. Do you think wiring and control electronics are an underrated bottleneck? And which approach would you back, superconducting transistors or cryogenic CMOS?

Will Superconducting Transistors Help Quantum Computers?hackaday.com