Atomic nonclassicality quasiprobabilities

TL;DR

This paper introduces a straightforward method to certify nonclassicality in atomic quantum states using collective quadrature measurements and quasiprobability sampling, demonstrated on a large ensemble of Cesium atoms with high significance.

Contribution

A new, accessible approach for detecting atomic nonclassicality without full state tomography, applicable to large atomic ensembles.

Findings

Successfully demonstrated nonclassicality in 2x10^5 Cesium atoms

Achieved a significance of up to 23 standard deviations

Method surpasses ground-state noise level analysis

Abstract

Although nonclassical quantum states are important both conceptually and as a resource for quantum technology, it is often difficult to test whether a given quantum system displays nonclassicality. A simple method to certify nonclassicality is introduced, based on easily accessible collective atomic quadrature measurements, without the need of full state tomography. The statistics is analyzed beyond the ground-state noise level, by direct sampling of a regularized atomic quadrature quasiprobability. Nonclassicality of a squeezed ensemble of 2x10^5 Cesium atoms is demonstrated, with a significance of up to 23 standard deviations.