A Tiny Superinductor Built Into a Silicon Chip

Researchers have built a superconducting inductor inside a commercially manufactured silicon chip and combined it with a quantum dot to make a sensitive charge detector. Published November 4 in Nature Electronics, the experiment gives quantum-hardware designers a potential route to shrinking the circuitry that listens to individual electrons.

The team, led by researchers at Quantum Motion with university and nanoGUNE collaborators, used titanium nitride already present in GlobalFoundries’ 22-nanometer fully depleted silicon-on-insulator process. Reusing a material built into a commercial manufacturing platform could make such components easier to integrate alongside other electronics.

The inductor occupies 18 square micrometers. The researchers report a power signal-to-noise ratio of 4,500 with four nanoseconds of integration, corresponding to an inferred one-picosecond sensitivity benchmark. The one-picosecond figure is extrapolated from the charge-sensing result; spin-qubit measurements are planned next.

The immediate achievement is charge sensing. The team identifies fast, high-fidelity spin readout as its next step, integrating the resonator with multigate transistors. NanoGUNE’s announcement says the researchers are targeting operation “well below the microsecond timescale.”

Why quantum hardware needs this component

A silicon spin qubit stores information in the spin state of an electron. Reading that information can involve converting a spin-dependent event into a detectable change in charge. The surrounding electronics must then distinguish a small signal quickly enough and reliably enough for the quantum processor to use the answer.

An inductor and a capacitor form a resonator that responds strongly around a particular radio frequency. Coupled to a charge-sensitive transistor, it allows changes in the device to appear in a reflected radio signal. This is the principle behind a radio-frequency single-electron transistor, or rfSET. Shrinking that supporting circuitry matters when the qubits themselves are tiny.

Ordinary chip inductors are patterned as coils. A superconducting film can exploit a different contribution, kinetic inductance, arising from the inertia of the paired electrons carrying current. That offers a way to obtain substantial inductance from a narrow strip. A superinductor combines substantial inductance with sufficiently high intrinsic impedance.

In this experiment the inductance changes with electrical drive. The researchers use that nonlinear response to improve sensitivity. Increasing power has a limit, however: enough drive destroys the superconducting state and the useful resonance disappears. The two film variants also have superconducting transition temperatures of approximately 0.75 and 1.1 kelvin.

A manufacturing advantage with a system-level test ahead

GlobalFoundries describes 22FDX as one of the platforms being explored for integrated quantum control and readout. Its broader strategy is to extend established semiconductor processes to quantum hardware. The new experiment brings a charge-sensing component into that manufacturing approach.

Integration has competing consequences. Shorter connections can help reduce unwanted electrical effects, but nearby control circuitry can introduce heat and interference. A separate 2025 Nature study, “Spin-qubit control with a milli-kelvin CMOS chip,” tested silicon spin qubits driven by closely integrated electronics. It found little impact on single- and two-qubit gate performance in its implementation, while identifying heat and crosstalk as central design concerns.

Testing the new superinductor alongside spin qubits will show how it performs within a processor. Those experiments would measure readout fidelity, disturbance of neighboring qubits and operation while several sensors are active.

The 18-square-micrometer figure describes the inductor. Capacitors, wiring, amplifiers, control equipment and refrigeration still belong in the system budget. How compact the full readout system becomes will depend on the surrounding design.

More of a quantum processor’s support circuitry could eventually be designed into a familiar silicon manufacturing process. The next milestone is to show that this compact charge-sensing component can read spin qubits accurately, repeatedly and without compromising the devices around it.

Sources

1. Swift et al., “A nonlinear superinductor in a deep-submicrometre integrated circuit,” Nature Electronics, November 4, 2026. DOI: 10.1038/s41928-026-01728-8. Primary experiment and numerical results.

2. CIC nanoGUNE, “A new superinductor created within a silicon integrated circuit,” November 4, 2026. Participating-institution announcement and quoted next-step timescale.

3. Swift et al., “A superinductor in a deep sub-micron integrated circuit,” arXiv:2507.13202, earlier preprint. Background on rfSET operation and measurement methodology; journal version governs reported results.

4. GlobalFoundries, “How GlobalFoundries is manufacturing quantum at scale,” April 14, 2026. Manufacturer’s account of its integration strategy.

5. “Spin-qubit control with a milli-kelvin CMOS chip,” Nature (2025). DOI: 10.1038/s41586-025-09157-x. Independent background experiment on cryogenic control integration.