Multimode RF Reflectometry for Spin Qubit Readout and Device Characterization

TL;DR

This paper presents a multimode superconducting inductor architecture enabling multi-frequency RF reflectometry for efficient spin qubit readout and device characterization, demonstrating high-fidelity single-shot measurements and broad tunneling rate extraction.

Contribution

Introduction of a multimode superconducting inductor design that allows multi-frequency RF reflectometry for improved qubit readout and device analysis.

Findings

Achieved RF reflectometry at multiple frequencies up to 2 GHz.

Demonstrated single-shot spin readout with 98% fidelity in 8 microseconds.

Extracted tunneling rates and identified charge defects across a broad frequency range.

Abstract

We introduce a multimode superconducting inductor architecture that enables radio-frequency reflectometry at multiple discrete frequencies up to 2 GHz, addressing limitations of conventional single-mode designs. The spiral inductor's distributed inter-turn capacitance yields distinct resonant modes with varied impedance-matching conditions. By probing a quantum dot across several modes, we extract tunneling rates over a broad frequency range and identify signatures of nearby charge defects. Using one of the higher-order modes, we demonstrate single-shot spin readout via a radio-frequency single-electron transistor (RF-SET), achieving singlet-triplet readout with an integration time of 8 us and a readout fidelity of 98%. These results establish multimode inductance as a scalable and flexible component for fast spin-qubit readout and device-quality characterization.