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.
Highlights
Quantum key distribution (QKD) [1, 2, 3] enables an unconditionally secure means of distributing secret keys between two spatially separated parties, Alice and Bob
We find that in a polarizationencoding measurement-device-independent quantum key distribution (MDI-QKD) system [14, 28, 29], polarization misalignment is the major source contributing to the quantum bit error rate (QBER) and mode mismatch, does not appear to be a major problem
Its photon number follows a Poisson distribution of mean μ. This list does not consider the state-preparation error [19, 22], because a strict discussion about this problem is related to the security proof of MDI-QKD, which will be considered in future publications
Summary
Quantum key distribution (QKD) [1, 2, 3] enables an unconditionally secure means of distributing secret keys between two spatially separated parties, Alice and Bob. The second question is: how can one design a practical finite decoy-state protocol and perform a finite-key analysis in MDI-QKD? This model is a useful tool for analyzing experimental results and performing the optimization of parameters This model is proposed to study MDI-QKD, it is useful for other non-QKD experiments involving quantum interference, such as entanglement swapping [35] and linear optics quantum computing [36]. (iii) By combining the system model, the finite decoy-state protocol, and the finite-key analysis of [34], we offer a general framework to determine the optimal intensities of the signal and decoy states Notice that this framework has already been adopted and verified in the experimental demonstration reported in [29].
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