On a recent proof of nonlocality without inequalities

TL;DR

This paper critically reexamines a recent claim of nonlocality without inequalities in a single-photon superposition, aiming to clarify the conceptual foundations and improve the presentation of the original results.

Contribution

It provides a clearer, more lucid derivation of the nonlocality proof, emphasizing the roles of locality and realism, and enhances understanding of the original findings.

Findings

Reaffirmation of nonlocality in single-photon superpositions

Clarification of the roles of locality and realism

Improved conceptual understanding of nonlocality proofs

Abstract

Recently a quite stimulating paper [1] dealing with the possibility of exploiting the nonlocal aspects of a superposition of states of a single photon appeared. We regard as greatly relevant the results which have been obtained. However we think that the presentation of the matter and the way to derive the conclusion are not fully satisfactory and do not put the necessary emphasis on some subtle basic aspects like locality and realism. In view of its interest we consider it useful to reconsider the line of reasoning of ref.[1] and to derive once more its results by following a procedure which seems to us more lucid and which makes fully clear the role of the various conceptual aspects of the treatment. We hope that our analysis will contribute to clarify and to deepen the interesting results of ref.[1].