Spin-squeezing and Dicke state preparation by heterodyne measurement

TL;DR

This paper explores how heterodyne measurement can be used as a quantum non-demolition technique to generate spin-squeezed and Dicke states in atomic ensembles, with analytical and simulation results supporting the approach.

Contribution

It introduces a heterodyne detection scheme for QND measurement that enables the preparation of specific quantum states, with analytical formulas and experimental considerations.

Findings

Analytical formulas match Monte-Carlo simulations.

Spontaneous emission impacts the squeezing process.

The scheme is feasible for experimental implementation.

Abstract

We investigate the quantum non-demolition (QND) measurement of an atomic population based on a heterodyne detection and show that the induced back-action allows to prepare both spin-squeezed and Dicke states. We use a wavevector formalism to describe the stochastic process of the measurement and the associated atomic evolution. Analytical formulas of the atomic distribution momenta are derived in the weak coupling regime both for short and long time behavior, and they are in good agreement with those obtained by a Monte-Carlo simulation. The experimental implementation of the proposed heterodyne detection scheme is discussed. The role played in the squeezing process by the spontaneous emission is considered.