Nonclassicality Quasiprobability of Single-Photon Added Thermal States

TL;DR

This paper demonstrates an experimental method to reconstruct a nonclassicality quasiprobability for single-photon added thermal states, revealing negativities that confirm nonclassicality without needing prior assumptions or being limited by quantum efficiency.

Contribution

The authors introduce a novel, assumption-free method for reconstructing nonclassicality quasiprobabilities that is robust against low quantum efficiencies.

Findings

Significant negativities in the quasiprobability confirm nonclassicality.

The method regularizes quasiprobabilities and their uncertainties without prior assumptions.

The approach is theoretically not limited by small quantum efficiencies.

Abstract

We report the experimental reconstruction of a nonclassicality quasiprobability for a single-photon added thermal state. This quantity has significant negativities, which is necessary and sufficient for the nonclassicality of the quantum state. Our method presents several advantages compared to the reconstruction of the P function, since the nonclassicality filters used in this case can regularize the quasiprobabilities as well as their statistical uncertainties. A-priori assumptions about the quantum state are therefore not necessary. We also demonstrate that, in principle, our method is not limited by small quantum efficiencies.