Experimental demonstrations for randomness-based macroscopic Franson-type nonlocal correlation using coherently coupled photons

TL;DR

This paper experimentally demonstrates macroscopic nonlocal correlations based on coherence theory using coupled photons, highlighting the wave nature of quantum mechanics with nearly sub-Poisson photon pairs and polarization-based superposition.

Contribution

It introduces a novel experimental approach to observe macroscopic Franson-type nonlocal correlation using coherently coupled photons and polarization randomness.

Findings

Successful demonstration of coherence-based nonlocal correlation

Use of polarization basis-randomness to achieve quantum superposition

Confirmation of wave nature of quantum mechanics at macroscopic scale

Abstract

Franson-type nonlocal quantum correlation based on the particle nature of quantum mechanics has been intensively studied for both fundamental physics and potential applications of quantum key distribution between remotely separated parties over the last several decades. Recently, a coherence theory of deterministic quantum features has been applied for Franson-type nonlocal correlation [arXiv:2102.06463] to understand its quantumness in a purely classical manner, where the resulting features are deterministic and macroscopic. Here, nearly sub-Poisson distributed coherent photon pairs obtained from an attenuated laser are used for the experimental demonstrations of the coherence Franson-type nonlocal correlation. As an essential requirement of quantum mechanics, quantum superposition is macroscopically provided using polarization basis-randomness via a half-wave plate, satisfying fairness compared with the original scheme based on phase bases. The observed coherence quantum feature of the modified Franson correlation successfully demonstrates the proposed wave nature of quantum mechanics, where the unveiled nonlocal correlation is relied on a definite phase relation between the paired coherent photons.