Perfect Quantum Privacy Implies Nonlocality

TL;DR

This paper proves that all quantum states capable of providing perfect privacy in cryptography inherently exhibit nonlocality by violating Bell inequalities, linking privacy and nonlocal quantum correlations.

Contribution

It establishes a fundamental connection between perfect quantum privacy and nonlocality, showing that private states always violate Bell inequalities, which was previously unknown.

Findings

All private states violate Bell inequalities.

Perfect privacy implies quantum nonlocality.

The result links quantum cryptography and nonlocality.

Abstract

Private states are those quantum states from which a perfectly secure cryptographic key can be extracted. They represent the basic unit of quantum privacy. In this work we show that all states belonging to this class violate a Bell inequality. This result establishes a connection between perfect privacy and nonlocality in the quantum domain.