Device-independent secret-key-rate analysis for quantum repeaters

TL;DR

This paper analyzes the secret key rates achievable in device-independent quantum key distribution using quantum repeaters, comparing different protocols and optimizing parameters to enhance security under untrusted device assumptions.

Contribution

It introduces a systematic analysis of device-independent secret key rates for quantum repeaters, comparing protocols and optimizing parameters for improved security.

Findings

Device-independent key rates depend on gate quality and detector efficiency.

Comparison of original and hybrid quantum repeater protocols.

Optimized strategies improve security in untrusted device scenarios.

Abstract

The device-independent approach to quantum key distribution (QKD) aims to establish a secret key between two or more parties with untrusted devices, potentially under full control of a quantum adversary. The performance of a QKD protocol can be quantified by the secret key rate, which can be lower bounded via the violation of an appropriate Bell inequality in a setup with untrusted devices. We study secret key rates in the device-independent scenario for different quantum repeater setups and compare them to their device-dependent analogon. The quantum repeater setups under consideration are the original protocol by Briegel et al. and the hybrid quantum repeater protocol by van Loock et al.. For a given repeater scheme and a given QKD protocol, the secret key rate depends on a variety of parameters, such as the gate quality or the detector efficiency. We systematically analyze the impact of these parameters and suggest optimized strategies.