Secure device-independent quantum key distribution with causally independent measurement devices

TL;DR

This paper proves the security of device-independent quantum key distribution protocols that rely on causally independent measurement devices, enabling secure quantum communication without assumptions about device internals.

Contribution

It provides a general security proof for DI-QKD protocols under causal independence of measurement devices, broadening practical implementation possibilities.

Findings

Security is achievable with causally independent measurement devices.

Key rates comparable to standard QKD schemes.

Applicable to implementations with multiple separate device pairs.

Abstract

Device-independent quantum key distribution aims to provide key distribution schemes whose security is based on the laws of quantum physics but which does not require any assumptions about the internal working of the quantum devices used in the protocol. This strong form of security, unattainable with standard schemes, is possible only when using correlations that violate a Bell inequality. We provide a general security proof valid for a large class of device-independent quantum key distribution protocols in a model in which the raw key elements are generated by causally independent measurement processes. The validity of this independence condition may be justifiable in a variety of implementations and is necessarily satisfied in a physical realization where the raw key is generated by N separate pairs of devices. Our work shows that device-independent quantum key distribution is possible with key rates comparable to those of standard schemes.