arXiv subjects

Thomas H. Swift

Publications and source records attributed to Thomas H. Swift.

3 recordsLinked to original sources

arXiv2026

A Superconducting Phase Transition Single-Electron Transistor

Quantum computers require fast and accurate methods for qubit state detection. Phase-transition sensors exploit the abrupt change between two physical states of a material to achieve enhanced sensitivity and have enabled advanced detectors for quantum technologies, such as superconducting nanowire single-photon detectors. However, this sensing principle has not yet been applied to semiconductor spin qubits. Here, we demonstrate a superconducting phase-transition radio-frequency single-electron transistor (PTSET), a charge sensor for semiconductor spin qubits whose response is enhanced by a superconducting-to-normal phase transition. The transition is engineered by linking the sensor current to a low-critical-current, high-kinetic-inductance inductor integrated into the radio-frequency matching network. We demonstrate improvements in sensitivity of one and two orders of magnitude over conventional rfSETs in the large- and small-signal regimes, respectively. Our results establish phase-transition sensing as a route towards ultrasensitive, integrated charge sensors for semiconductor quantum computing and point to broader applications, including cryogenic photon detection for radio astronomy.

quant-ph↗

arXiv2025

Spin Readout in a 22 nm Node Integrated Circuit

Constructing a quantum computer capable of broad and important applications is likely to require millions of addressable physical qubits, posing the challenge of large-scale integration of quantum systems with classical electronics. Fully depleted silicon-on-insulator CMOS technology has been used to develop a range of cryogenic electronic components for the control and readout of different qubit modalities interfaced on separate chips. However, recent measurements of quantum dots on this technology raise the tantalising prospect of realising control electronics and spin qubits on the same manufacturing platform, within a single integrated circuit (IC). Here, we demonstrate single-shot spin readout in addressable quantum dot devices within an IC fabricated using industry-standard 22 nm fully depleted silicon-on-insulator technology. We achieve spin-to-charge conversion via a ramped energy-selective measurement, detected using a radio-frequency single-electron transistor and addressed by on-chip cryogenic electronics. The observation of consistent readout visibilities exceeding 90% and millisecond spin relaxation times in two nominally identical devices within the addressable array supports the reproducibility of the unit cell. The successful observation of spin readout using this CMOS process marks a key step towards realising highly scalable and integrated spin qubits.

quant-ph↗

arXiv2025

Large-scale characterization of Single-Hole Transistors in 22-nm FDSOI CMOS Technology

State-of-the-art quantum processors have recently grown to reach 100s of physical qubits. As the number of qubits continues to grow, new challenges associated with scaling arise, such as device variability reduction and integration with cryogenic electronics for I/O management. Spin qubits in silicon quantum dots provide a platform where these problems may be mitigated, having demonstrated high control and readout fidelities and compatibility with large-scale manufacturing techniques of the semiconductor industry. Here, we demonstrate the monolithic integration of 384 p-type quantum dots, each embedded in a silicon transistor, with on-chip digital and analog electronics, all operating at deep cryogenic temperatures. The chip is fabricated using 22-nm fully-depleted silicon-on-insulator (FDSOI) CMOS technology. We extract key quantum dot parameters by fast readout and automated machine learning routines to determine the link between device dimensions and quantum dot yield, variability, and charge noise figures. Overall, our results demonstrate a path to monolithic integration of quantum and classical electronics at scale.

cond-mat.mes-hall↗