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arXiv · 2608.27045

A Superconducting Phase Transition Single-Electron Transistor

Gorka Aizpurua-Iraola·Thomas H. Swift·Felix-Ekkehard von Horstig·Domenic Prete·James Kirkman·Grayson M. Noah·Fabio Olivieri·Alberto Gomez-Saiz·M. Fernando Gonzalez-Zalba
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Abstract

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.

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Gorka Aizpurua-Iraola, Thomas H. Swift, Felix-Ekkehard von Horstig, Domenic Prete, James Kirkman, Grayson M. Noah, Fabio Olivieri, Alberto Gomez-Saiz, M. Fernando Gonzalez-Zalba. 2026-08-27. A Superconducting Phase Transition Single-Electron Transistor. https://arxiv.org/abs/2608.27045

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