Squeezing Towards the Heisenberg Limit with Locally Interacting Spins

TL;DR

This paper introduces a robust method for spin squeezing using local interactions that nearly reaches the Heisenberg limit, applicable to various physical systems and resilient to disorder.

Contribution

It generalizes the two-axis countertwisting Hamiltonian to systems with power-law interactions, enabling near-Heisenberg-limited phase sensitivity with practical robustness.

Findings

Time to reach Heisenberg limit scales sublinearly with particle number in 2D and 3D systems.

Protocol is robust against disorder and density fluctuations.

Applicable to molecules, Rydberg atoms, and solid-state spins in near-term experiments.

Abstract

We propose a robust approach to spin squeezing with local interactions that approaches the Heisenberg limit of phase sensitivity. To generate the requisite entanglement, we generalize the paradigmatic two-axis countertwisting Hamiltonian -- akin to squeezing by parametric amplification -- to systems with power-law interactions, incorporating a Heisenberg coupling that aids in spreading correlations and protects the collective spin coherence. The resulting time to approach the Heisenberg limit scales sublinearly with particle number in 2D dipolar and 3D van der Waals interacting systems. Our protocol is robust to disorder and density fluctuations, and can be implemented in near-term experiments with molecules, Rydberg atoms, and solid-state spins.