Satellite-to-Ground Entanglement-Based Quantum Key Distribution

Abstract

We report on entanglement-based quantum key distribution between a low-Earth-orbit satellite equipped with a space borne entangled-photon source and a ground observatory. One of the entangled photons is measured locally at the satellite, and the other one is sent via a down link to the receiver in the Delingha ground station. The link attenuation is measured to vary from 29 dB at 530 km to 36 dB at 1000 km. We observe that the two-photon entanglement survives after being distributed between the satellite and the ground, with a measured state fidelity of ≥0.86. We then perform the entanglement-based quantum key distribution protocol and obtain an average final key rate of 3.5 bits/s at the distance range of 530-1000 km.

Satellite-based links for quantum key distribution: beam effects and weather dependence

“…We chose D sat =30 cm for the orbiting one, D grnd =1 m for the ground station telescope and λ=800 nm. These are demanding values, consistent with the Chinese mission Micius (see [12][13][14][15] for details). Further analysis are reported in section 5.…”

“…They can take advantage of the satellite technology and the optical communication methods developed in the last decades in the classical case. Various feasibility studies had addressed this topic in the last twenty years [8][9][10][11] and several experiments have definitely proved that the technology involved is ready for deployment [12][13][14][15][16].…”

“…They can take advantage of the satellite technology and the optical communication methods developed in the last decades in the classical case. Various feasibility studies had addressed this topic in the last twenty years [8][9][10][11] and several experiments have definitely proved that the technology involved is ready for deployment [12][13][14][15][16].Optical satellite-based links have the important drawback of being strongly dependent on the weather conditions [17][18][19][20]. The presence of turbulent eddies and scattering particles like haze or fog generates random fluctuations of the relative permittivity of the air, on different length-and time-scales.…”

Practical reference-frame-independent quantum key distribution systems against the worst relative rotation of reference frames

“…Simulation results show that RFI-QKD can achieve quite good performance against the worst relative rotation of reference frames, which clearly demonstrates the possibility of practical QKD systems with free drifting reference frames. We believe practical QKD systems with free drifting reference frames will easily find a place in the satellite-to-ground QKD scenario [11,12] or other scenarios where it is difficult to calibrate the reference frames. Furthermore, we propose a universal estimation method of the secret key rate in practical RFI-QKD systems, which conforms to the nature of RFI-QKD more well than the usual estimation method.…”

“…Based on the theory of quantum physics, quantum key distribution (QKD) [1] provides a way of generating information-theoretic secure keys between two distant parties Alice and Bob, even in the presence of a malicious eavesdropper Eve. Since the first Bennett-Brassard-1984 (BB84) protocol was proposed in 1984, a series of works have been made to improve the practical performance of QKD systems [2][3][4][5][6][7][8][9][10][11][12][13][14]. Generally, in most of these systems, the complicated and real-time operation of calibrating reference frames is indispensable to assure the regular running of practical QKD systems [4,[11][12][13][14].…”