# Anomalous Quantum Correlations of Squeezed Light

## TL;DR

This paper demonstrates a novel measurement technique for squeezed light that reveals quantum correlations through classical physics analysis, showing violation of classical inequalities.

## Contribution

It introduces a homodyne cross-correlation measurement method that uncovers quantum correlations without relying on quantum theory assumptions.

## Key findings

- Violation of classical inequalities for almost all signal phases
- Detection method insensitive to quantum efficiencies and dark noise
- Reveals quantum correlations through classical analysis

## Abstract

Three different noise moments of field strength, intensity, and their correlations are simultaneously measured. For this purpose a homodyne cross-correlation measurement [W. Vogel, Phys. Rev. A 51, 4160 (1995)] is implemented by superimposing the signal field and a weak local oscillator on an unbalanced beam splitter. The relevant information is obtained via the intensity noise correlation of the output modes. Detection details like quantum efficiencies or uncorrelated dark noise are meaningless for our technique. Yet unknown insight in the quantumness of a squeezed signal field is retrieved from the anomalous moment, correlating field strength with intensity noise. A classical inequality including this moment is violated for almost all signal phases. Precognition on quantum theory is superfluous, as our analysis is solely based on classical physics.