Experimental test of strongly non-classical character of a noisy squeezed single-photon state

TL;DR

This paper experimentally demonstrates the non-Gaussian quantum nature of a noisy squeezed single-photon state, even with a positive Wigner function, using an optimized witness based on homodyne detection data.

Contribution

The study provides the first experimental verification of the quantum non-Gaussian character of a noisy squeezed single-photon state with positive Wigner function.

Findings

Confirmed non-Gaussian character of the state

Used an optimized witness based on homodyne data

Results agree with theoretical model

Abstract

We experimentally verify the quantum non-Gaussian character of a conditionally generated noisy squeezed single-photon state with positive Wigner function. Employing an optimized witness based on probabilities of squeezed vacuum and squeezed single-photon states we prove that the state cannot be expressed as a mixture of Gaussian states. In our experiment, the non-Gaussian state is generated by conditional subtraction of a single photon from squeezed vacuum state. The state is probed with a homodyne detector and the witness is determined by averaging a suitable pattern function over the measured homodyne data. Our experimental results are in good agreement with a theoretical fit obtained from a simple yet realistic model of the experimental setup.