Device-independent quantum key distribution from generalized CHSH inequalities

TL;DR

This paper introduces a generalized CHSH inequality for device-independent quantum key distribution, enabling higher key rates by utilizing more detailed correlation information, thus enhancing security and efficiency in practical photonic systems.

Contribution

It develops a security proof based on a generalized CHSH score that incorporates individual correlation function values, improving key rates over traditional methods.

Findings

Higher key rates achieved with the generalized CHSH score.

Potential advantages demonstrated for photonic implementations.

Enhanced security guarantees with more detailed correlation data.

Abstract

Device-independent quantum key distribution aims at providing security guarantees even when using largely uncharacterised devices. In the simplest scenario, these guarantees are derived from the CHSH score, which is a simple linear combination of four correlation functions. We here derive a security proof from a generalisation of the CHSH score, which effectively takes into account the individual values of two correlation functions. We show that this additional information, which is anyway available in practice, allows one to get higher key rates than with the CHSH score. We discuss the potential advantage of this technique for realistic photonic implementations of device-independent quantum key distribution.