Quantum Interference and the Limits of Separability

TL;DR

This paper explores the fundamental limits of quantum interference, revealing a principle that constrains how multiple spacelike separated events can influence each other, highlighting the non-separable nature of quantum correlations.

Contribution

It introduces a universal principle governing statistical correlations of spacetime events, linking quantum interference limits to a broader causality constraint.

Findings

Quantum interference is limited to second-order, preventing higher-order interference.

A principle is proposed that bounds how multiple spacelike events influence each other.

The non-separable influence among events has a quantifiable limit based on mediating events.

Abstract

Quantum theory implies, and empirical evidence confirms, that while particles $\textit{can}$ exhibit wave-like behavior in interferometric experiments, this behavior is so limited as $\textit{not}$ to allow for third- and higher-order interference. The article at hand shows that this possibility-impossibility structure suggests the universal validity of a principle that regulates statistical correlations between spatiotemporally localized events, $\textit{independently}$ of the nature of the objects that may or may not partake in these events. Roughly, the said principle mandates that $\textit{any}$ joint influence of $m$ mutually spacelike separated events on $\textit{another}$ event, be such, that it can be separated by $\textit{at least}$ $\lceil \frac{m}{2} \rceil$ mediating events, and in some cases, by $\textit{no more}$ than $\lceil \frac{m}{2} \rceil$ mediating events. The structure of quantum interference thus teaches us that events can influence each other in a non-separable fashion, but that this non-separability has a certain exactly quantifiable limit.