Capacitive crosstalk in gate-based dispersive sensing of spin qubits

TL;DR

This paper investigates radio-frequency crosstalk in gate-based dispersive sensing of spin qubits, demonstrating how resonator quality factors and device capacitances influence crosstalk and proposing strategies to mitigate it.

Contribution

It provides a quantitative analysis of crosstalk mechanisms in superconducting resonator-coupled quantum dot devices and suggests design considerations to reduce interference.

Findings

Crosstalk scales with resonator quality factor and mutual capacitance.

Ring-up of the resonator occurs when neighboring gates are driven at resonator frequency.

Lowering qubit frequencies below the resonator frequency suppresses crosstalk.

Abstract

In gate-based dispersive sensing, the response of a resonator attached to a quantum dot gate is detected by a reflected radio-frequency signal. This enables fast readout of spin qubits and tune up of arrays of quantum dots, but comes at the expense of increased susceptibility to crosstalk, as the resonator can amplify spurious signals and induce fluctuations in the quantum dot potential. We attach tank circuits with superconducting NbN inductors and internal quality factors $Q_{\mathrm{i}}$>1000 to the interdot barrier gate of silicon double quantum dot devices. Measuring the interdot transition in transport, we quantify radio-frequency crosstalk that results in a ring-up of the resonator when neighbouring plunger gates are driven with frequency components matching the resonator frequency. This effect complicates qubit operation and scales with the loaded quality factor of the resonator, the mutual capacitance between device gate electrodes, and with the inverse of the parasitic capacitance to ground. Setting qubit frequencies below the resonator frequency is expected to substantially suppress this type of crosstalk.