Strong and weak single particle nonlocality induced by time-dependent boundary conditions

TL;DR

This paper explores how time-dependent boundary conditions affect single particle nonlocality, demonstrating the absence of strong nonlocality and the presence of a weak, measurable nonlocal effect in extended states.

Contribution

It clarifies the nature of nonlocality in quantum systems with moving boundaries, distinguishing between strong and weak forms and proposing a measurement method for the latter.

Findings

No strong nonlocality for localized states

Existence of weak nonlocality in extended states

Weak current density can be measured via weak measurements

Abstract

We investigate the issue of single particle nonlocality in a quantum system subjected to time-dependent boundary conditions. We first prove that contrary to earlier claims, there is no strong nonlocality: a quantum state localized at the center of a well with infinitely high moving walls is not modified by the wall's motion. We then show the existence of a weak form of nonlocality: when a quantum state is extended over the well, the wall's motion induces a current density all over the box instantaneously. We indicate how this current density can in principle be measured by performing weak measurements of the particle's momentum.