Capacitive crosstalk in gate-based dispersive sensing of spin qubits

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 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 neighboring 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.