Simulating quantum repeater strategies for multiple satellites

Abstract

A global quantum repeater network involving satellite-based links is likely to have advantages over fiberbased networks in terms of long-distance communication, since the photon losses in free space scale only polynomially with the distance -compared to the exponential losses in optical fibers. To simulate the performance of such networks, we have introduced a scheme of large-scale event-based Monte Carlo simulation of quantum repeaters with multiple memories that can faithfully represent loss and imperfections in these memories. In this work, we identify the quantum key distribution rates achievable in various satellite and ground station geometries for feasible experimental parameters. The power and flexibility of the simulation toolbox allows us to explore various strategies and parameters, some of which only arise in these more complex, multi-satellite repeater scenarios. As a primary result, we conclude that key rates in the kHz range are reasonably attainable for intercontinental quantum communication with three satellites, only one of which carries a quantum memory.

Quantum memories for fundamental science in space

“…Hence, it can be concluded that employing quantum memories at memory-assisted ground nodes in conjunction with multiple satellites is a next step to increase the range of entanglement distribution even further. Finally, intermediary nodes may be moved onto satellites, improving fidelity by avoiding unnecessary light paths through the atmosphere altogether [28,29]. Building space-based quantum networks in this manner not only aids the establishment of future global quantum communication, but may also be utilized in fundamental science studies in space.…”

Topical White Paper: A Case for Quantum Memories in Space

“…In such a network, entanglement could be distributed over continental distances (up to a few thousand km) using ground fiber-based quantum repeaters [5,19], while longer distances could be reached using satellites, e.g. by performing entanglement swapping between quantum memories placed in LEO satellites [1,2,20], or by entangling quantum memories located in separate ground stations with entangled photon sources located on LEO satellites [16]. As is well established, optical fibers are commonly used to establish metropolitan quantum networks [21,22].…”

Finite resource performance of small satellite-based quantum key distribution missions

“…The emergence of terrestrial quantum networks in large metropolitan areas demonstrates an increasing maturity of quantum technologies. A networked infrastructure enables increased capabilities for distributed applications in delegated quantum computing [1,2], quantum communications [3,4], and quantum sensing [5]. However, extending these applications over global scales is currently not possible owing to exponential losses in optical fibres.…”