Unbounded Sharing of Nonlocality Using Projective Measurements

TL;DR

This paper introduces a novel measurement protocol that allows unlimited sequential sharing of quantum nonlocality between multiple observers and a single party, challenging previous limitations caused by measurement sharpness.

Contribution

It presents a local randomness-assisted projective measurement method enabling unbounded sharing of nonlocality, revealing new insights into measurement incompatibility and quantum nonlocality.

Findings

Unbounded sharing of nonlocality demonstrated with sequential observers.

New measurement protocol preserves nonlocality despite sharp projective measurements.

Highlights the role of measurement incompatibility in quantum nonlocality.

Abstract

It is a common perception that a sharp projective measurement in one side of the Bell experiment destroys the entanglement of the shared state, thereby preventing the demonstration of sequential sharing of nonlocality. In contrast, we introduce a local randomness-assisted projective measurement protocol, enabling the sharing of nonlocality by an arbitrary number of sequential observers (Bobs) with a single spatially separated party Alice. Subsequently, a crucial feature of the interplay between the degrees of incompatibility of observables of both parties is revealed, enabling the unbounded sharing of nonlocality. Our findings, not only offer a new paradigm for understanding the fundamental nature of incompatibility in demonstrating quantum nonlocality but also pave a new path for various information processing tasks based on local randomness-assisted projective measurement.