Atomic nonclassicality quasiprobabilities

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.

5 pages, 2 figures

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• Nonclassicality Phase-Space Functions: More Insight with Fewer Detectors
• Continuous sampling of the squeezed state nonclassicality
• Towards quantum state tomography of a single polariton state of an atomic ensemble
• Visualizing nonclassical effects in phase space
• Tracking quantum coherence in polariton condensates with time-resolved tomography
• Quantum correlations in composite systems
• Preparation of arbitrary quantum states with regular $P$~functions
• Revealing hidden physical nonclassicality with nonnegative polynomials
• Strictly nonclassical behavior of a mesoscopic system
• Filter functions for the Glauber-Sudarshan $P$-function regularization