Strong Spin Squeezing Induced by Weak Squeezing of Light inside a Cavity

TL;DR

This paper introduces a novel method for generating strong spin squeezing in atomic ensembles using weak light squeezing inside a cavity, leveraging anti-Stokes scattering and Floquet sidebands, with improved experimental feasibility.

Contribution

It presents a new mechanism for Heisenberg-limited spin squeezing that requires no multiple classical or cavity drivings, simplifying experimental implementation.

Findings

Weak light squeezing can induce strong spin squeezing.

The method achieves Heisenberg-limited spin squeezing.

Implementation with superconducting resonator and NV centers is feasible.

Abstract

We propose a simple method for generating spin squeezing of atomic ensembles in a Floquet cavity subject to a weak, detuned two-photon driving. We demonstrate that {\it the weak squeezing of light inside the cavity can, counterintuitively, induce strong spin squeezing}. This is achieved by exploiting the anti-Stokes scattering process of a photon pair interacting with an atom. Specifically, {\it one photon of the photon pair is scattered into the cavity resonance by absorbing partially the energy of the other photon whose remaining energy excites the atom}. The scattering, combined with a Floquet sideband, provides an alternative mechanism to implement Heisenberg-limited spin squeezing. Our proposal does {\it not} need multiple classical and cavity-photon drivings applied to atoms in ensembles, and therefore its experimental feasibility is greatly improved compared to other cavity-based schemes. As an example, we demonstrate a possible implementation with a superconducting resonator coupled to a nitrogen-vacancy electronic-spin ensemble.