Three-slit experiments and quantum nonlocality

TL;DR

This paper explores the connection between the absence of third-order interference in multi-slit experiments and the limits of quantum nonlocality, specifically Tsirelson's bound, revealing a fundamental link in quantum theory.

Contribution

It demonstrates that Tsirelson's bound applies broadly to probabilistic theories that exclude third-order interference, highlighting a key structural aspect of quantum mechanics.

Findings

Third-order interference is not possible in quantum mechanics.

Tsirelson's bound applies to theories without third-order interference.

The class of theories with Tsirelson's bound includes those with a consistent probability calculus.

Abstract

An interesting link between two very different physical aspects of quantum mechanics is revealed; these are the absence of third-order interference and Tsirelson's bound for the nonlocal correlations. Considering multiple-slit experiments - not only the traditional configuration with two slits, but also configurations with three and more slits - Sorkin detected that third-order (and higher-order) interference is not possible in quantum mechanics. The EPR experiments show that quantum mechanics involves nonlocal correlations which are demonstrated in a violation of the Bell or CHSH inequality, but are still limited by a bound discovered by Tsirelson. It now turns out that Tsirelson's bound holds in a broad class of probabilistic theories provided that they rule out third-order interference. A major characteristic of this class is the existence of a reasonable calculus of conditional probability or, phrased more physically, of a reasonable model for the quantum measurement process.