Measurement-device-independent quantum key distribution: from idea towards application

TL;DR

This paper evaluates the performance of a measurement-device-independent quantum key distribution system using various components, demonstrating its potential for secure communication over long distances and practical deployment.

Contribution

It experimentally demonstrates high-performance MDI-QKD over significant distances and shows FPGA integration does not impair system performance, advancing practical quantum communication.

Findings

QKD over 60 dB loss with superconducting detectors

Over 600 bits/sec secret key rate over 16 dB loss

System operable outside laboratory conditions

Abstract

We assess the overall performance of our quantum key distribution (QKD) system implementing the measurement-device-independent (MDI) protocol using components with varying capabilities such as different single photon detectors and qubit preparation hardware. We experimentally show that superconducting nanowire single photon detectors allow QKD over a channel featuring 60 dB loss, and QKD with more than 600 bits of secret key per second (not considering finite key effects) over a 16 dB loss channel. This corresponds to 300 km and 80 km of standard telecommunication fiber, respectively. We also demonstrate that the integration of our QKD system into FPGA-based hardware (instead of state-of-the-art arbitrary waveform generators) does not impact on its performance. Our investigation allows us to acquire an improved understanding of the trade-offs between complexity, cost and system performance, which is required for future customization of MDI-QKD. Given that our system can be operated outside the laboratory over deployed fiber, we conclude that MDI-QKD is a promising approach to information-theoretic secure key distribution.