Abstract:
Long-distance quantum communication relies on distribution of either single qubits or entangled photon pairs across large distances. However, the direct transmission distance is limited to around few hundred kilometres by exponential losses in optical fibres. Quantum repeaters that rely on heralded generation and storage of entanglement have been proposed to overcome this limit. Although they can surpass the direct transmission limit, they still fall short of providing a global coverage. On the other hand, distribution of entangled states from an orbiting satellite provides a significant improvement over the land-based fibre links [1]. Here, the communication range is mainly limited by the line-of-sight of the satellite which depends on its orbit (~2000 km for low Earth orbit, 1/3 of the globe for geostationary orbit).
In order to provide a truly global coverage, we propose to combine the above two solutions in a single architecture: a quantum repeater in space. The network would consist of two types of satellites: one carrying an entangled photon pair source and the other quantum memories and Bell state measurement stations. Our work shows that up to 3 orders of magnitude faster entanglement distribution rate can be achieved for distances ~20× 10^3 km [2] when compared to ground-space hybrid networks. After presenting the details of this work, I will focus on the optimizations performed with a three-satellite QR link [3]. I will finally summarize our experimental efforts towards creating quantum memory systems suitable for space applications for such global quantum communication architectures.
[1] J. S. Sidhu, S. Joshi, M. Gündoğan et. al. Advances in Space Quantum Communications, IET Quant. Comm. 2, 182 (2021)
[2] M. Gündoğan, J. S. Sidhu, V. Henderson, L. Mazzarella, J. Wolters, D.K.L Oi and M. Krutzik, Proposal for space-borne quantum memories for global quantum networking, npj Quant. Inf. 7, 128 (2021)
[3] J. Wallnöfer, F. Hahn, M. Gündoğan, J. S. Sidhu, F. Krüger, N. Walk, J. Eisert and J. Wolters, Simulating quantum repeater strategies for multiple satellites, under review, arXiv:211015806 (2021)
Biography:
Mustafa Gündoğan studied physics in Turkey, earning his BSc and MSc degrees from Bilkent (2008) and Koç Universities (2010) before moving to ICFO - The Institute of Photonic Sciences in Barcelona for his PhD. He graduated in 2015 with a thesis focused on the development of solid-state quantum memory devices for single photonic qubits. Afterwards he moved to the University of Cambridge where his work was centered on quantum optics with novel color centers in diamond. Currently, as a Marie Curie fellow, he has been leading the quantum optics and memory activities within the Joint Lab Integrated Quantum Sensors at the Humboldt University of Berlin.