Long-distance device-independent quantum key distribution with standard optics tools

TL;DR

This paper introduces two practical long-distance device-independent quantum key distribution protocols using standard optics tools, achieving improved communication distances through heralding schemes and noisy preprocessing.

Contribution

It presents experimentally accessible DI-QKD protocols with enhanced robustness and longer distances by combining heralding, standard optics, and classical noisy preprocessing.

Findings

Protocols outperform existing methods in communication distance

Numerical optimization confirms positive key rates under realistic conditions

Use of standard optics tools makes implementation feasible

Abstract

Device-independent quantum key distribution (DI-QKD) enables information-theoretically secure key exchange between remote parties without any assumptions on the internal workings of the devices used for its implementation. However, its practical deployment remains severely constrained by the need for loophole-free Bell inequality violations, which are highly susceptible to losses and detection efficiencies. In this paper, we propose two long-distance DI-QKD protocols based on a heralding scheme using single-photon interference. Our protocols consist of only standard quantum optics tools such as two-mode squeezed states, displacement operations and on-off detectors, making them experimentally accessible. To further enhance robustness against realistic imperfections, we integrate a classical noisy preprocessing technique during post-processing. We calculate key rates of the protocols by numerical optimization and show the supremacy of this implementation over existing protocols in terms of communication distances.