# Spin squeezing via one- and two-axis twisting induced by a single off-resonance stimulated Raman scattering in a cavity

## TL;DR

This paper demonstrates a simplified method to generate spin squeezing using a single off-resonance stimulated Raman scattering in a cavity, achieving near-Heisenberg limited noise reduction and practical implementation with current technology.

## Contribution

It introduces a new approach to produce spin squeezing via a single Raman process and transforms it into a two-axis interaction for enhanced squeezing, simplifying experimental realization.

## Key findings

- Single Raman scattering can produce spin squeezing with appropriate initial states.
- Transforming one-axis to two-axis twisting enhances noise reduction to Heisenberg limit.
- Significant squeezing remains achievable despite atomic and cavity noise effects.

## Abstract

Squeezed spin states have important applications in quantum metrology and sensing. It has been shown by S{\o}rensen and M{\o}lmer [Phys. Rev. A 66, 022314(2002)] that an effective one-axis-twisting interaction can be realized in a cavity setup via a double off-resonance stimulated Raman scattering, resulting in a noise reduction scaling $\propto 1/N^{2/3}$ with $N$ being the atom number. Here, we show that, by making an appropriate change of the initial input spin state, it is possible to produce a one-axis-twisting spin squeezing via a \emph{single} off-resonance stimulated Raman scattering, which thus can greatly simplify the realistic implementation. We also show that the one-axis-twisting interaction can be transformed into a more efficient two-axis-twisting interaction by rotating the collective spin while coupling to the cavity, yielding a Heisenberg limited noise reduction $\propto1/N$. Considering the noise effects due to atomic decoherence and cavity decay, we find that substantial squeezing is still attainable with current laboratory techniques.