Proposal for spin squeezing in rare-earth ion-doped crystals with a four-color scheme

TL;DR

This paper proposes a four-color scheme for generating spin squeezing in rare-earth ion-doped crystals, demonstrating up to 8 dB of squeezing, which enhances their potential for quantum sensing and entanglement applications.

Contribution

It introduces an interferometer-free method based on a Tavis-Cummings model for spin squeezing in rare-earth crystals, with practical experimental feasibility.

Findings

Up to 8 dB of spin squeezing achievable with current resources.

Analytic derivation provides microscopic understanding of squeezing generation.

Signatures of spin squeezing observed in light intensity variance.

Abstract

Achieving spin squeezing within solid-state devices is a long standing research goal, due to the promise of their particularities, for instance their long coherence times, the possibility of low-temperature experiments or integration of entanglement-assisted sensors on-chip. In this work, we investigate an interferometer-free four-color scheme to achieve spin squeezing of rare-earth ion-doped crystals. The proposal relies on an analytic derivation that starts from a Tavis-Cummings model for light-matter interaction, providing microscopic insights onto spin-squeezing generation. We evidence spin squeezing signature in the light intensity variance. We consider the two particular cases of europium- and praseodymium-doped yttrium orthosilicates, workhorses of quantum technology developments. We show that up to 8 dB of spin squeezing can be obtained with readily accessible experimental resources, including noise due to photon scattering. Our results for rare-earth ion-doped crystals add to promising properties of these platforms for manipulating many-body entangled states and for high-precision measurements.