QUARC: Quantum Research Cubesat—A Constellation for Quantum Communication

Abstract

Quantum key distribution (QKD) offers future proof security based on fundamental laws of physics. Long-distance QKD spanning regions such as the United Kingdom (UK) may employ a constellation of satellites. Small satellites, CubeSats in particular, in low Earth orbit are a relatively low-cost alternative to traditional, large platforms. They allow the deployment of a large number of spacecrafts, ensuring greater coverage and mitigating some of the risk associated with availability due to cloud cover. We present our mission analysis showing how a constellation comprising 15 low-cost 6U CubeSats can be used to form a secure communication backbone for ground-based and metropolitan networks across the UK. We have estimated the monthly key rates at 43 sites across the UK, incorporating local meteorological data, atmospheric channel modelling and orbital parameters. We have optimized the constellation topology for rapid revisit and thus low-latency key distribution.

Spooky action at a global distance: analysis of space-based entanglement distribution for the quantum internet

“…Including these extra elements would introduce extra attenuation factors (see, for e.g., section 2.1.1.4 of ref. 37 and refs 96,97 ), which would increase the overall satellite-to-ground transmission loss (see refs 78,98 for an analysis of satellite-to-ground quantum key distribution in a localized area that incorporates local weather conditions). We also point out that, especially in the daytime, background photons (e.g., from the sun) can reduce the fidelity of the distributed entangled pairs, because the receiver will collect those background photons in addition to the signal photons from the entanglement source.…”

“…constellations for entanglement distribution 69,78 , to our knowledge, the type of dynamic quantum network simulation with satellite constellations that we consider, along with optimization over different constellation configurations, has not been previously studied.…”

Proposal for space-borne quantum memories for global quantum networking

“…In satellite QKD (SatQKD) [22][23][24][25] , the transmission loss through the vacuum of space is dominated by diffraction that has an inverse square scaling instead of exponential. However, the connection distance for SatQKD is primarily limited by the line-of-sight between satellite and ground station, which in turn depends on its orbit unless the satellite acts as a trusted node [26][27][28][29][30] . To establish a global quantum network without trusted nodes will require overcoming the above limitations.…”

A low cost, short range quantum key distribution system

“…The majority of current research in the field of quantum key distribution (QKD) focuses on either commercializing high speed fibre systems in networks [1][2][3][4] or long distance free space links to satellites [5][6][7][8][9]. A combination of these services will form the backbone of a global "Quantum Internet" [10] but this does not address access to this network for end-users.…”