Determination of weak squeezed vacuum state through photon statistics measurement

TL;DR

This paper introduces a photon statistics measurement method to accurately determine weak squeezed vacuum states, overcoming limitations of homodyne detection, and applicable to various quantum states with weak non-classical features.

Contribution

The paper presents a novel photon statistics approach that reliably measures weak squeezing in vacuum states, independent of detection efficiency, with theoretical and experimental validation.

Findings

The method accurately determines weak squeezing levels.

It is independent of detection efficiency.

The approach is applicable to other quantum states with weak non-classicality.

Abstract

Weak squeezed vacuum light, especially resonant to the atomic transition, plays an important role in quantum storage and generation of various quantum sources. However, the general homodyne detection (HD) cannot determine weak squeezing due to the low signal to noise ratio and the limited resolution of the HD system. Here we provide an alternative method based on photon statistics measurement to determine the weak squeezing of the squeezed vacuum light generated from an optical parametric oscillator working far below the threshold. The approach is established the relationship between the squeezing parameter and the second-order degree of coherence. The theoretical analysis agrees well with the experiment results. The advantage of this method is that it provides a feasible and reliable experimental measure to determine the weak squeezing with high precision and the measurement is independent on the detection efficiency. This method can be used to measure other quantum features for various quantum states with extremely weak non-classicality.