Qubit Measurement by Multichannel Driving

TL;DR

This paper introduces a novel qubit measurement method using multichannel driving near a bosonic mode's frequency, achieving faster measurement speeds and higher fidelity compared to traditional dispersive readout, with experimental validation on superconducting qubits.

Contribution

The paper presents a new measurement protocol that accelerates qubit readout and improves fidelity by driving near the bosonic mode frequency, validated through experiments.

Findings

Achieved near 100% reduction in measurement error compared to conventional methods.

Demonstrated the ability to reset the resonator to vacuum after measurement.

Validated the protocol experimentally with superconducting qubits.

Abstract

We theoretically propose and experimentally implement a method of measuring a qubit by driving it close to the frequency of a dispersively coupled bosonic mode. The separation of the bosonic states corresponding to different qubit states begins essentially immediately at maximum rate, leading to a speedup in the measurement protocol. Also the bosonic mode can be simultaneously driven to optimize measurement speed and fidelity. We experimentally test this measurement protocol using a superconducting qubit coupled to a resonator mode. For a certain measurement time, we observe that the conventional dispersive readout yields close to 100% higher average measurement error than our protocol. Finally, we use an additional resonator drive to leave the resonator state to vacuum if the qubit is in the ground state during the measurement protocol. This suggests that the proposed measurement technique may become useful in unconditionally resetting the resonator to a vacuum state after the measurement pulse.