Rapid production of many-body entanglement in spin-1 atoms via cavity output photon counting

TL;DR

This paper introduces a straightforward method to generate highly entangled spin-1 atom states using cavity photon counting, achieving Heisenberg-limited sensitivity for quantum metrology.

Contribution

It presents a novel scheme combining spin-1 atoms, cavity interactions, and photon counting to produce metrologically useful entanglement with Heisenberg scaling.

Findings

Photon counting projects the collective spin state into highly entangled states.

The method achieves Heisenberg-limited sensitivity scaling with atom number N.

The scheme is efficient and relies on simple initial state preparation.

Abstract

We propose a simple and efficient method for generating metrologically useful quantum entanglement in an ensemble of spin-1 atoms that interacts with a high-finesse optical cavity mode. It requires straightforward preparation of $N$ atoms in the $m_F=0$ sublevel, tailoring of the atom-field interaction to give an effective Tavis-Cummings model for the collective spin-1 ensemble, and a photon counting measurement on the cavity output field. The photon number provides a projective measurement of the collective spin length $S$, which, for the chosen initial state, is heavily weighted around values $S\simeq\sqrt{N}$, for which the corresponding spin states are strongly entangled and exhibit Heisenberg scaling of the metrological sensitivity with $N$, as quantified by the quantum Fisher information.