Rapid microwave-only characterization and readout of quantum dots using multiplexed gigahertz-frequency resonators

TL;DR

This paper demonstrates a microwave-only method for rapid, high-fidelity characterization and readout of quantum dots using multiplexed gigahertz-frequency resonators, eliminating the need for traditional DC measurements.

Contribution

It introduces a microwave-based technique for extracting conductance and detecting charge tunneling in quantum dots, enabling fast, multiplexed measurements without DC calibration.

Findings

Accurate high-frequency admittance measurement correlates with DC conductance.

Microsecond-scale charge detection with high signal-to-noise ratio.

Multiplexed resonator approach enables rapid charge stability mapping.

Abstract

Superconducting resonators enable fast characterization and readout of mesoscopic quantum devices. Finding ways to perform measurements of interest on such devices using resonators only is therefore of great practical relevance. We report the experimental investigation of an InAs nanowire multi-quantum dot device by probing GHz resonators connected to the device. First, we demonstrate accurate extraction of the DC conductance from measurements of the high-frequency admittance. Because our technique does not rely on DC calibration, it could potentially obviate the need for DC measurements in semiconductor qubit devices. Second, we demonstrate multiplexed gate sensing and the detection of charge tunneling on microsecond time scales. The GHz detection of dispersive resonator shifts allows rapid acquisition of charge-stability diagrams, as well as resolving charge tunneling in the device with a signal-to-noise ratio of up to 15 in one microsecond. Our measurements show that GHz-frequency resonators may serve as a universal tool for fast tune-up and high-fidelity readout of semiconductor qubits.