Does "quantum nonlocality without entanglement" have quantum origin?

TL;DR

This paper investigates whether the phenomenon of quantum nonlocality without entanglement is fundamentally quantum or can be explained classically, by analyzing a task involving state discrimination and entanglement preservation.

Contribution

It demonstrates that the observed gap between separable operations and LOCC in a specific task has a classical analogue, suggesting quantum properties are not essential for this nonlocality.

Findings

The gap between separable operations and LOCC can be replicated in a classical context.

Quantum nonlocality without entanglement may have a classical explanation.

The quantum properties are not necessary for the existence of the nonlocality gap.

Abstract

Quantum separable operations are defined as those that cannot produce entanglement from separable states, and it is known that they strictly surpass local operations and classical communication (LOCC) in a number of tasks, which is sometimes referred to as "quantum nonlocality without entanglement." Here we consider a task with such a gap regarding the trade-off between state discrimination and preservation of entanglement. We show that this task along with the gap has an analogue in a purely classical setup, indicating that the quantum properties are not essential in the existence of a nonzero gap between the separable operations and LOCC.