Visualizing nonclassical effects in phase space

TL;DR

This paper introduces and analyzes nonclassicality filters for visualizing quantum states of light, optimizing experimental detection of nonclassical effects through negativities in the phase space quasiprobability distributions.

Contribution

It presents a new analytic filter that preserves full quantum state information and discusses its application to various quantum optical states and multimode correlations.

Findings

The analytic filter effectively visualizes nonclassicality in different quantum states.

Optimized data analysis reduces the number of measurements needed for certification.

The method extends to multimode quantum correlations.

Abstract

Nonclassicality filters provide a universal method to visualize the nonclassicality of arbitrary quantum states of light through negativities of a regularized Glauber-Sudarshan $P$ function, also denoted as nonclassicality quasiprobability. Such filters are introduced and analyzed for optimizing the experimental certification of nonclassical effects. An analytic filter is constructed which preserves the full information on the quantum state. For balanced homodyne detection, the number of data points is analyzed to get the negativities of the nonclassicality quasiprobability with high statistical significance. The method is applied to different scenarios, such as phase randomized squeezed vacuum states, single-photon-added thermal states, and heralded state engineering with array detectors. The generalization to visualize quantum correlations of multimode radiation fields is also considered.