Catch-Disperse-Release Readout for Superconducting Qubits

TL;DR

This paper proposes a novel superconducting qubit readout method using catch-dispersed-release of microwave fields, leveraging tunable couplers and nonlinear effects to improve speed and fidelity.

Contribution

It introduces a new readout scheme that reduces damping and enhances measurement accuracy through adiabatic qubit tuning and quadrature squeezing.

Findings

High-fidelity, fast qubit readout demonstrated

Quadrature squeezing reduces measurement error

Purcell effect is mitigated during dispersive interaction

Abstract

We analyze a single-shot readout for superconducting qubits via the controlled catch, dispersion, and release of a microwave field. A tunable coupler is used to decouple the microwave resonator from the transmission line during the dispersive qubit-resonator interaction, thus circumventing damping from the Purcell effect. We show that if the qubit frequency tuning is sufficiently adiabatic, a fast high-fidelity qubit readout is possible, even in the strongly nonlinear dispersive regime. Interestingly, the Jaynes-Cummings nonlinearity leads to the quadrature squeezing of the resonator field below the standard quantum limit, resulting in a significant decrease of the measurement error.