QKD optical ground terminal developments

Journal article (2021)

Authors

Niek J. Doelman TNO, Universiteit Leiden
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Adaptive Optics Quantum Key Distribution Free Space Optics Optical Ground Stations Opto-mechanics
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Published Date

2021

Language

English

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Abstract

Free space optical (FSO) satellite communications has very attractive properties for Quantum Key Distribution (QKD). The quantum channel loss and noise are major factors in setting the maximum achievable secure key rate of QKD systems. Primarily for a LEO satellite node and the BB84 protocol a number of technologies are proposed to reduce the quantum channel loss and noise. These technologies apply to the receiver side of the QKD link, the Optical Ground Terminal. It is shown that an optical beam shaper to optimize fiber mode matching, dedicated thermo-mechanical design to reduce misalignment induced by temperature gradients and an Adaptive Optics (AO) system to counteract optical turbulence effects can result in a significant reduction of loss and background noise. A breadboard verification experiment shows that using an medium-size AO system can maintain a fiber coupling efficiency up to 40%. The developed technologies have a general applicability with respect to satellite orbit and QKD protocol used.