Optical Implementation of Non-locality with Coherent Light Fields for Quantum Communication

TL;DR

This paper demonstrates a method to observe polarization correlations using coherent light fields and beam splitter transformations, enabling nonlocality tests and potential quantum key distribution without post-selection.

Contribution

It introduces an optical scheme using coherent light and interference to realize nonlocal correlations, facilitating quantum communication protocols like Ekert's.

Findings

Polarization correlations observed with coherent light fields.

Nonlocal correlations established without post-selection.

Potential application in quantum key distribution.

Abstract

Polarization correlations of two distant observers are observed by using coherent light fields based on Stapp's formulation of nonlocality. Using a 50/50 beam splitter transformation, a vertically polarized coherent light field is found to be entangled with a horizontally polarized coherent noise field. The superposed light fields at each output port of the beam splitter are sent to two distant observers, where the fields are interfered and manipulated at each observer by using a quarter wave plate and an analyzer. The interference signal contains information of the projection angle of the analyzer, which is hidden by the phase noises. The nonlocal correlations between the projection angles of two distant observers are established by analyzing their data through analog signal multiplication without any post-selection technique. This scheme can be used to implement Ekert's protocol for quantum key distribution.