Phase self-aligned continuous-variable measurement-device-independent quantum key distribution

Hua-Lei Yin,Wei Zhu,Yao Fu

doi:10.1038/s41598-018-36366-4

Hua-Lei Yin, Wei Zhu + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-36366-4

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Abstract

Continuous-variable measurement-independent-device quantum key distribution (CV-MDI-QKD) can offer high secure key rate at metropolitan distance and remove all side channel loopholes of detection as well. However, there is no in-field experimental demonstration of CV-MDI-QKD due to the remote distance phase-locking techniques challenge. Here, we present a new optical scheme to overcome this difficulty and also removes the requirement of two identical independent lasers. Furthermore, we give an alternate but detailed proof of the minimized key rate condition to extract the secure key rate. We anticipate that our new scheme can be used to demonstrate the in-field CV-MDI-QKD experiment and build the CV-MDI-QKD network with untrusted source.

Highlights

Quantum key distribution (QKD) allows remote parties to establish a string of secure key even at the presence of an eavesdropper[1,2,3]
(2) The quantum states are transmitted through insecure quantum links to the untrusted relay for Continuous variable (CV) Bell state measurement (BSM). (3) The incoming quantum states from two parties are coupled to interfere through a balanced beam splitter
After a polarization maintaining optical circulator, the laser pulse directly goes through a balanced PMF beam splitter (PMF-BS) and be splitted into two identical laser pulses that each will be transmitted to Alice and Bob for CV encoding

Summary

Introduction

Quantum key distribution (QKD) allows remote parties (usually referred as Alice and Bob) to establish a string of secure key even at the presence of an eavesdropper (referred as Eve)[1,2,3]. The experimental demonstration of DV-MDI-QKD has been successfully performed over 404 km optical fiber[23], while the secure key rate is relatively low even at metropolitan distance due to the single photon encoding. In order to be immune to all detector loopholes and achieve high secure key rate at metropolitan distance, the CV-MDI-QKD is proposed recently[49,50,51,52] with a proof-of-principle experimental demonstration performed on the free space optical platform by sharing a highly stable laser[49]. The main challenge is that remote distance phase-locking technique is necessary to achieve correct CV BSM This requirement is not needed in DV-MDI-QKD due to the fact that the two-photon Hong-Ou-Mandel interference is phase unrelated[55]. We give an alternate but detailed proof of the minimized key rate condition to extract the secure key rate, which has been used and first proved in ref. 49

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