scholarly journals Twin-Field Quantum Key Distribution over 511 km Optical Fiber Linking two Distant Metropolitans

Author(s):  
Jiu-Peng Chen ◽  
Chi Zhang ◽  
Yang Liu ◽  
Cong Jiang ◽  
Weijun Zhang ◽  
...  

Abstract The basic principle of quantum mechanics guarantee the unconditional security of quantum key distribution (QKD) at the cost of inability of amplification of quantum state. As a result, despite remarkable progress in worldwide metropolitan QKD networks over the past decades, long haul fiber QKD network without trustful relay has not been achieved yet. Here, through sending-or-not-sending (SNS) protocol, we complete a twin field QKD (TF-QKD) and distribute secure keys without any trusted repeater over a 511 km long haul fiber trunk linking two distant metropolitans. Our secure key rate is around 3 orders of magnitudes greater than what is expected if the previous QKD field test system over the same length were applied. The efficient quantum-state transmission and stable single-photon interference over such a long distance deployed fiber paves the way to large-scale fiber quantum networks.

2021 ◽  
Vol 2086 (1) ◽  
pp. 012137
Author(s):  
A V Khmelev ◽  
A V Duplinsky ◽  
V L Kurochkin ◽  
Y V Kurochkin

Abstract Satellite quantum communication is the technology that allows to deploy large-scale quantum networks with a communication range of thousands kilometres We report the ground receiver for downlink quantum key distribution (QKD) with satellite. An optical part of this system including an active tracking loop is mounted on a 600-mm Ritchey-Chretien telescope and permits to distinguish polarization states to perform QKD between ground and satellite. Moreover, a procedure of calibration the receiver using stars with known brightness is presented. Measurements of the photon count rate of stars in the spectral range of 845 nm - 855 nm are performed and compared with an estimate.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Wei Li ◽  
Le Wang ◽  
Shengmei Zhao

Abstract Two time-reversal quantum key distribution (QKD) schemes are the quantum entanglement based device-independent (DI)-QKD and measurement-device-independent (MDI)-QKD. The recently proposed twin field (TF)-QKD, also known as phase-matching (PM)-QKD, has improved the key rate bound from O(η) to O$$(\sqrt{{\boldsymbol{\eta }}})$$ ( η ) with η the channel transmittance. In fact, TF-QKD is a kind of MDI-QKD but based on single-photon detection. In this paper, we propose a different PM-QKD based on single-photon entanglement, referred to as single-photon entanglement-based phase-matching (SEPM)-QKD, which can be viewed as a time-reversed version of the TF-QKD. Detection loopholes of the standard Bell test, which often occur in DI-QKD over long transmission distances, are not present in this protocol because the measurement settings and key information are the same quantity which is encoded in the local weak coherent state. We give a security proof of SEPM-QKD and demonstrate in theory that it is secure against all collective attacks and beam-splitting attacks. The simulation results show that the key rate enjoys a bound of O$$(\sqrt{{\boldsymbol{\eta }}})$$ ( η ) with respect to the transmittance. SEPM-QKD not only helps us understand TF-QKD more deeply, but also hints at a feasible approach to eliminate detection loopholes in DI-QKD for long-distance communications.


Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 1010
Author(s):  
Guoqi Huang ◽  
Qin Dong ◽  
Wei Cui ◽  
Rongzhen Jiao

Measurement-device-independent quantum key distribution (MDI-QKD) protocol has high practical value. Satellite-based links are useful to build long-distance quantum communication network. The model of satellite-based links for MDI-QKD was proposed but it lacks practicality. This work further analyzes the performance of it. First, MDI-QKD and satellite-based links model are introduced. Then considering the operation of the satellite the performance of their combination is studied under different weather conditions. The results may provide important references for combination of optical-fiber-based links on the ground and satellite-based links in space, which is helpful for large-scale quantum communication network.


2007 ◽  
Vol 1 (6) ◽  
pp. 343-348 ◽  
Author(s):  
Hiroki Takesue ◽  
Sae Woo Nam ◽  
Qiang Zhang ◽  
Robert H. Hadfield ◽  
Toshimori Honjo ◽  
...  

2020 ◽  
Vol 125 (26) ◽  
Author(s):  
Yuan Cao ◽  
Yu-Huai Li ◽  
Kui-Xing Yang ◽  
Yang-Fan Jiang ◽  
Shuang-Lin Li ◽  
...  

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