November 04, 2026 -- In research published today in Nature Electronics, the Quantum Motion team has demonstrated a superinductor built into a standard silicon chip that shrinks a key qubit sensor by 10,000 times. Combining these integrated compact superconducting elements with the vast capabilities of modern silicon ICs will open up further opportunities for innovation in silicon spin quantum computing as well as other low-power cryoelectronics.

Reading out silicon spin qubits requires a charge sensor. The most widely used charge sensor is the radio-frequency single-electron transistor (rfSET), however to operate the sensor needs a high inductance. On a CMOS chip, that inductance is normally supplied by a spiral inductor. This component, which can be seen by eye on a 3x3mm chip, is orders of magnitude larger than the nanometer-sized qubits it serves. This difference in size limits the number of qubits that can be operated on each CMOS chip.

Quantum Motion engineers have shown in this recent paper how to remove the spiral inductor altogether. Quantum Motion uses the 22nm FDSOI process from Global Foundries to fabricate their chips. This process includes a thin film of titanium nitride (TiN) in its transistor gate stack. Below about 1 K, that film becomes superconducting, providing an inductance large enough to make a superinductor. The team then paired this superinductor with a quantum dot, creating a fully integrated rfSET.

The result is a footprint reduction of more than four orders of magnitude, together with a minimum integration time of 1 ± 0.3 ps, compared with 625 ps for the previous state of the art. Part of the gain comes from the integration itself, which reduces parasitics. The rest comes from operating in a new regime, where the non-linear inductance of the TiN film enhances the readout signal at high power.

Staff Quantum Engineer at Quantum Motion and lead author, Tom Swift said, “In quantum computing we talk a lot about scalability, but we focus mainly on the qubits themselves. In reality, we need to think about the scalability of the entire system and in particular how we might scale to a million-qubit system. With that goal in mind, we need to consider how we can make all of the different aspects of a quantum computer, the readout, the control, smaller and if possible, as close to the same size as the qubits themselves.”

The next step for the research team is to combine the rfSET with arrays of silicon spin qubits to demonstrate high-speed, high-fidelity spin readout well below the microsecond timescale. Combining high-performance integrated readout with industrial CMOS manufacturing, Quantum Motion continues to build the case that spin qubits are the most viable route toward building a large-scale, fault-tolerant quantum computer.

VP of Quantum Engineering at Quantum Motion and Professor of Quantum Computing Hardware at CIC nanoGUNE, Fernando González-Zalba said, “Using the superinductors native to the CMOS process, we have shown a way to meet all the requirements for spin qubit readout. We’ve created a method with a compact on-chip footprint that while being low-power is extremely sensitive. I believe with this demonstration we have shown the way to solve the readout problem for semiconductor spin qubits.”

This work included contributions from: Tom Swift, Alberto Gomez-Saiz, Fabio Olivieri, Gorka Aizpurua-Iraola, Manuel Suárez-Rodríguez, James Kirkman, Grayson Noah, Mathieu de Kruijf, Felix-Ekkehard von Horstig, John Morton and M. Fernando Gonzalez-Zalba.