Entanglement-based quantum key distribution with biased basis choice via free space.
We report a free-space entanglement-based quantum key distribution experiment, implementing the biased basis protocol between two sites which are 15.3 km apart. Photon pairs from a polarization-entangled source are distributed through two 7.8-km free-space optical links. An optimal bias 20:80 between the X and Z basis is used. A post-processing scheme with finite-key analysis is applied to extract the final secure key. After three-hour continuous operation at night, a 4293-bit secure key is obtained, with a final key rate of 0.124 bit per raw key bit which increases the final key rate by 14.8% comparing to the standard BB84 case. Our results experimentally demonstrate that the efficient BB84 protocol, which increases key generation efficiency by biasing Alice and Bob's basis choices, is potentially useful for the ground-satellite quantum communication.
Yuan
Y
Cao
Hao
H
Liang
Juan
J
Yin
Hai-Lin
HL
Yong
Fei
F
Zhou
Yu-Ping
YP
Wu
Ji-Gang
JG
Ren
Yu-Huai
YH
Li
Ge-Sheng
GS
Pan
Tao
T
Yang
Xiongfeng
X
Ma
Cheng-Zhi
CZ
Peng
Jian-Wei
JW
Pan