Quantification and observation of genuine three-party coherence: A solution based on classical optics

TL;DR

This paper introduces a method to quantify genuine three-party coherence in wave fields, using classical optics concepts, and demonstrates experimental validation with potential applications to quantum coherence analysis.

Contribution

It develops a classical optics-based framework to quantify and observe three-party coherence, linking classical and quantum coherence measures with experimental validation.

Findings

Established a classical optics-based measure of three-party coherence.

Derived geometric constraint relations among two-party coherences.

Validated the approach through experimental tests and measurements.

Abstract

We introduce a quantification of genuine three-party pure-state coherence for wave fields, classical and quantum, by borrowing concepts from classical optics. The tensor structure of a classical paraxial light beam composed of three principle degrees of freedom is shown to be equivalent to that of a three-qubit quantum state. The traditional basis-independent optical coherence quantity called degree of polarization is then determined to be the desired quantitative two-party coherence measure. When appropriately generalized, a set of fundamental constraint relations is derived among three two-party coherences. The constraint relations can be geometrically interpreted and visualized as tetrahedra nested within a coherence cube. A measure of three-party coherence is defined based on the constraints. We are reporting completed experimental tests and confirmations of the constraints as well as measurement of three-party coherence in the optical context. Our approach based on classical optics also opens an alternative way to analyze quantum coherence.