Coherence properties of a spin in a squeezed resonator

TL;DR

This paper investigates how preparing a resonator in a squeezed state affects the coherence of an impurity spin, revealing both potential enhancements and significant decoherence challenges.

Contribution

It introduces an analytic Schrieffer-Wolf transformation approach to predict spin-resonator coupling and decoherence in squeezed states, supported by numerical validation.

Findings

Squeezing can increase spin-resonator coupling.

Squeezing amplifies photon noise and spin decoherence.

Using squeezing poses challenges for strong coupling.

Abstract

A promising venue for hybrid quantum computation involves the strong coupling between impurity spins and superconducting resonators. One strategy to control and enhance this coupling is to prepare the resonator in a non-classical state, such as a squeezed state. In this work, we theoretically study the effects of these states on the coherence properties of the spin. We develop an analytic approach based on the Schrieffer-Wolf transformation that allows us to quantitatively predict the coupling and the dephasing rate of the spin, and we numerically confirm its validity. We find that squeezing can enhance the coupling between the resonator and the spin. However, at the same time, it amplifies the photon noise and enhances the spin decoherence. Our work demonstrates a major impediment in using squeezing to reach the strong-coupling limit.