Experimental detection of quantum coherent evolution through the violation of Leggett-Garg-type inequalities

TL;DR

This paper demonstrates an experimental method to detect quantum coherence by violating Leggett-Garg-type inequalities, confirming quantum behavior in complex light-matter systems.

Contribution

It presents the first experimental violation of LGtI using a light-matter system and introduces a method to benchmark quantumness independent of memory effects.

Findings

Violation of LGtI observed in a light-matter system

Quantum coherence persists in complex systems

Method to certify quantumness without memory effects

Abstract

We discuss the use of inequalities of the Leggett-Garg type (LGtI) to witness quantum coherence and present the first experimental violation of this type of inequalities using a light-matter interfaced system. By separately benchmarking the Markovian character of the evolution and the translational invariance of the conditional probabilities, the observed violation of a LGtI is attributed to the quantum coherent character of the process. These results provide a general method to benchmark `quantumness' when the absence of memory effects can be independently certified and confirm the persistence of quantum coherent features within systems of increasing complexity.