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Gate Reflectometry in a Minimal Kitaev Chain Device

Yining Zhang, Ivan Kulesh, Sebastiaan L.D. ten Haaf, Nick van Loo, Francesco Zatelli, Tijl Degroote, Christian G. Prosko, and Srijit Goswami*

  • *Contact author: s.goswami@tudelft.nl
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PRX Quantum 7, 020317 – Published 28 April, 2026

DOI: https://doi.org/10.1103/7367-wbp9

Abstract

Hybrid quantum dot (QD)-superconductor system can be used to realize Majorana zero modes in artificial Kitaev chains. These chains provide a promising platform for the realization of Majorana qubits. Radio-frequency gate reflectometry is a fast, noninvasive, and sensitive technique that can be used to read out such qubits. In this work, we use gate reflectometry to probe two QDs coupled via a semiconductor-superconductor hybrid segment. We demonstrate that gate sensing can resolve charge stability diagrams and clearly distinguish between elastic cotunneling and crossed-Andreev reflection, the two key processes that allow one to form a Kitaev chain. Furthermore, we show that this information is accessible, even when the system is completely decoupled from the normal leads. In this closed regime, we show that the observed quantum-capacitance signal is indicative of parity switching between the even and odd ground states. Our measurements in both open and closed regimes confirm that gate reflectometry captures the essential features of interdot coupling and parity dynamics.

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Popular Summary

Artificial Kitaev chains could be used to create Majorana-based qubits; however, it is important to develop tools to read out such qubits. Here, we show that a fast and noninvasive technique called gate reflectometry can probe a pair of quantum dots coupled through a superconductor. This approach can distinguish how the two quantum dots coupled to each other, which is crucial information to engineer the system to the Majorana sweet spot. It also works when the device is fully isolated from external leads, revealing changes in the system’s parity through its capacitive response. Together, these results demonstrate that gate reflectometry can capture both coupling and parity dynamics in quantum dot-superconductor hybrid devices. This technique could become an important tool for building and operating future Majorana-based qubits.

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PRX Quantum 7, 020317– Published 28 April, 2026
  • Received 18 September 2025
  • Accepted 19 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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