Photonic verification of device-independent quantum key distribution against collective attacks

TL;DR

This paper demonstrates a photonic implementation of device-independent quantum key distribution with enhanced loss tolerance and high detection efficiency, achieving positive key rates over 220 meters and advancing towards practical secure quantum communication.

Contribution

It combines theoretical improvements in loss tolerance with experimental realization of high-efficiency entangled photon sources for device-independent QKD.

Findings

Achieved a heralded detection efficiency of 87.5%.

Demonstrated positive key rate over 220 meters fiber.

Enhanced loss tolerance using combined theoretical approaches.

Abstract

In this paper, we employ theoretical and experimental efforts and realize a proof-of-principle verification of device-independent QKD based on the photonic setup. On the theoretical side, we enhance the loss tolerance for real device imperfections by combining different approaches, namely, random post-selection, noisy preprocessing, and developed numerical methods to estimate the key rate via the von Neumann entropy. On the experimental side, we develop a high-quality polarization-entangled photon source achieving a state-of-the-art (heralded) detection efficiency about 87.5%. This efficiency outperforms previous photonic experiments involving loophole-free Bell tests. Together, we show that the measured quantum correlations are strong enough to ensure a positive key rate under the fiber length up to 220 m. Our photonic platform can generate entangled photons at a high rate and in the telecom wavelength, which is desirable for high-speed generation over long distances. The results present an important step towards a full demonstration of photonic device-independent QKD.