Pure Quantum Correlations Between Bright Optical Beams

TL;DR

This paper experimentally demonstrates that quantum correlations between bright optical beams can exist independently of classical coherence, challenging traditional views on the relationship between quantum and classical properties of light.

Contribution

It provides the first experimental evidence that quantum correlations can be completely independent of classical interference and coherence in bright optical beams.

Findings

Quantum correlations persist despite loss of classical interference.

Classical coherence and quantum correlations are shown to be independent.

Quantum correlations are unaffected by classical interference degradation.

Abstract

The pure quantum correlations totally independent of the classical coherence of light have been experimentally demonstrated. By measuring the visibility of the interference fringes and the correlation variances of amplitude and phase quadratures between a pair of bright twin optical beams with different frequencies produced from a non-degenerate optical parametric oscillator, we found that when classical interference became worse even vanished, the quadrature quantum correlations were not influenced, completely. The presented experiment obviously shows the quantum correlations of light do not necessarily imply the classical coherence.