Classical model of quantum interferometry tests of macrorealism

TL;DR

This paper presents a classical model that can replicate the results of a quantum interferometry experiment testing macrorealism, challenging the interpretation that such results definitively reject macrorealist views.

Contribution

It introduces a classical model of heralded photon detection in an interferometer that aligns with experimental data, questioning the quantum interpretation of macrorealism tests.

Findings

Classical model reproduces experimental results

Model aligns with local realism

Challenges the interpretation of macrorealism rejection

Abstract

Macrorealism is a characteristic feature of many, but not all, classical systems. It is known, for example, that classical light can violate a Leggett-Garg inequality and, hence, reject a macrorealist interpretation. A recent experiment has used entangled light and negative measurements to demonstrate a loophole-free test of macrorealism [PRX Quantum $\mathbf{3}$, 010307 (2022)]. This paper shows that such an experiment, while soundly rejecting macrorealism, may nevertheless be open to a classical interpretation. This is done by offering an explicit classical model of heralded photon detection in an optical interferometer with beam blockers. A numerical analysis of the model shows good agreement with experimental observations and consistency with both local realism and a rejection of macrorealism.