Feasibility of satellite-to-ground continuous-variable quantum key distribution

Abstract

Establishing secure communication links at a global scale is a major potential application of quantum information science but also extremely challenging for the underlying technology. Although milestone experiments using satellite-to-ground links and exploiting singe-photon encoding for implementing quantum key distribution have shown recently that this goal is achievable, it is still necessary to further investigate practical solutions compatible with classical optical communication systems. Here, we examine the feasibility of establishing secret keys in a satellite-to-ground downlink configuration using continuous-variable encoding, which can be implemented using standard telecommunication components certified for space environment and able to operate at high symbol rates. Considering a realistic channel model and state-of-the-art technology, and exploiting an orbit subdivision technique for mitigating fluctuations in the transmission efficiency, we find positive secret key rates for a low-Earth-orbit scenario, whereas finite-size effects can be a limiting factor for higher orbits. Our analysis determines regions of values for important experimental parameters where secret key exchange is possible and can be used as a guideline for experimental efforts in this direction.

Enhanced Uplink Quantum Communication With Satellites via Downlink Channels

“…The mean fidelity for the direct transmission scheme is given by Eqs. (12) and (14). The results are illustrated in Fig.…”

“…This is largely due to the relatively technical simplicity (and maturity) of the CV-enabled devices required to send, receive, and measure quantum signals, robustness against background noise, and the potential of the enlarged Hilbert space associated with CV systems to lead to enhanced communication throughput in practical settings. 1 For these reasons, there is great interest in pursuing designs of CV-enabled quantum satellites, there have been many recent studies focusing on the more feasible satellite-to-ground (downlink) transmission of quantum signals, largely with a view to enable CV-QKD [11], [12]. As yet, there has not been any experimental realizations of satellite-based CV quantum communications.…”

GEOQKD: quantum key distribution from a geostationary satellite

“…photons sent by the two users on ground must arrive simultaneously and shall be indistinguishable in the beforementioned degrees of freedom) which makes this protocol less suited for a GEOQKD mission. Although developments in Continuous Variable (CV-)QKD protocols advance, their Technology Readiness Level (TRL) 9 seems to be too low to be suited for GEOQKD applications.…”

How to choose the best QKD network technology: three different satellite based scenarios compared

“…Recently, CV-QKD was considered for use in satellite-based QKD. [18][19][20] While academically interesting, we think it is practically not applicable in a satellite scenario for the following reasons: The expected total loss of satellite-based QKD networks is usually above 10dB. However, CV-QKD security proofs considering realistic implementation schemes † and an excess noise level of 0.01 shot-noise-units are secure only below 5dB total loss.…”