Stroboscopic qubit measurement with squeezed illumination

TL;DR

This paper introduces a stroboscopic measurement technique compatible with microwave squeezing, significantly enhancing superconducting qubit readout sensitivity and reducing measurement backaction.

Contribution

The authors develop a stroboscopic coupling method that allows microwave squeezing to improve qubit measurement without signal pollution, demonstrating practical advantages.

Findings

24% increase in room-temperature SNR

Slowed dephasing by a factor of 1.8

Enhanced measurement sensitivity with microwave squeezing

Abstract

Microwave squeezing represents the ultimate sensitivity frontier for superconducting qubit measurement. However, observation of enhancement has remained elusive, in part because integration with conventional dispersive readout pollutes the signal channel with antisqueezed vacuum. Here we induce a stroboscopic light-matter coupling with superior squeezing compatibility, and observe an increase in the room-temperature signal-to-noise ratio of 24%. Squeezing the orthogonal phase controls measurement backaction, slowing dephasing by a factor of 1.8. This protocol enables the practical use of microwave squeezing for qubit state measurement.