Experimental quantum key distribution based on a Bell test

TL;DR

This paper presents a real-world free-space quantum key distribution experiment using entangled photons and Bell tests to ensure security against eavesdroppers, demonstrating a practical implementation of quantum cryptography.

Contribution

It introduces a complete field implementation of a modified Ekert91 protocol utilizing Bell inequality violations for secure quantum key distribution.

Findings

Successful free-space quantum key distribution with Bell test verification

Effective detection of eavesdropper's knowledge through Bell inequality violation

Practical demonstration of quantum cryptography in real-world conditions

Abstract

We report on a complete free-space field implementation of a modified Ekert91 protocol for quantum key distribution using entangled photon pairs. For each photon pair we perform a random choice between key generation and a Bell inequality. The amount of violation is used to determine the possible knowledge of an eavesdropper to ensure security of the distributed final key.