Practical aspects of measurement-device-independent quantum key distribution

TL;DR

This paper analyzes practical implementation aspects of measurement-device-independent quantum key distribution (MDI-QKD), demonstrating its feasibility with standard optical devices and providing analytical tools for optimizing its performance in real-world scenarios.

Contribution

It introduces a simple analytical method for finite decoy-state analysis and a framework for optimizing signal and decoy intensities in MDI-QKD, including asymmetric channel considerations.

Findings

MDI-QKD is highly practical with standard optical devices.

A simple two-decoy-state method for finite decoy-state analysis is proposed.

Optimization strategies for asymmetric channels are discussed.

Abstract

A novel protocol - measurement-device-independent quantum key distribution (MDI-QKD) - removes all attacks from the detection system, the most vulnerable part in QKD implementations. In this paper, we present an analysis for practical aspects of MDI-QKD. To evaluate its performance, we study various error sources by developing a general system model. We find that MDI-QKD is highly practical and thus can be easily implemented with standard optical devices. Moreover, we present a simple analytical method with only two (general) decoy states for the finite decoy-state analysis. This method can be used directly by experimentalists to demonstrate MDI-QKD. By combining the system model with the finite decoy-state method, we present a general framework for the optimal choice of the intensities of the signal and decoy states. Furthermore, we consider a common situation, namely asymmetric MDI-QKD, in which the two quantum channels have different transmittances. We investigate its properties and discuss how to optimize its performance. Our work is of interest not only to experiments demonstrating MDI-QKD but also to other non-QKD experiments involving quantum interference.