Experimental Violation of the Leggett-Garg Inequality Using the Polarization of Classical Light

TL;DR

This paper demonstrates that the Leggett-Garg inequality, which tests temporal correlations in a single system, can be violated using classical light polarization, challenging the notion that such violations are exclusive to quantum systems.

Contribution

The study provides the first experimental violation of the Leggett-Garg inequality with a classical optical system, using polarization of laser light, highlighting the boundary between classical and quantum correlations.

Findings

Maximal violation of the Leggett-Garg inequality observed.

Classical light polarization can exhibit quantum-like temporal correlations.

Challenges the assumption that Leggett-Garg violations are purely quantum phenomena.

Abstract

In contrast to Bell's inequalities which test the correlations between multiple spatially separated systems, the Leggett-Garg inequalities test the temporal correlations between measurements of a single system. We experimentally demonstrate the violation of the Leggett-Garg inequality in a classical optical system using only the polarization degree-of-freedom of a laser beam. Our results show maximal violations of the Leggett-Garg inequality.