26-260 Free space entanglement distribution for Quantum Information Networks

Mission

The Quantum Internet, currently under development, requires mastering entanglement distribution in optical fibers over short distances (<150 km) but also via satellite over longer distances.

On the ground, entanglement distribution is performed daily in various research laboratories in France, the USA, China, Austria, Germany, etc. The quantum optics Team at the INPHYNI laboratory, which will lead this thesis, has developed a quantum network "Quantum@UNiCA" that enables quasi-operational quantum cryptography based on an entanglement protocol (BBM92). Their recent developments have made it possible to connect this quantum network to an optical ground station (MéO telescope) to provide an entry point to space, with a view to connecting with a quantum satellite, such as Eagle-1 (currently developed by SES) or QINSAT (future French quantum satellite - phase A of CNES).

INPHYNI is currently carrying out very first tests with this MéO station to move towards sky tests with a satellite. To date, such tests have been carried out by the Chinese with the Micius satellite (Rev. Mod. Phys. 94, 035001 (2022), Science 356, 1140 (2017), Nature 549, 43 (2017), Phys. Rev. Lett. 120, 030501 (2018), Nature 589, 214–219 (2021), Nature 582, 501–505 (2020), Nature 549, 70 (2017)) and more recently with Jinan-1 (Nature 640, 47-54 (2025)). China has also conducted quantum cryptography tests with Russia (Vol. 32, Mar 2024, Optics Express 11964) and with South Africa (Nature 640, 47–54 (2025)).

Unfortunately, France is lagging far behind in these developments. However, the international community has mainly focused on non-entanglement-based quantum cryptography. This thesis will therefore be innovative, internationally, in its focus on effects involving entanglement to move towards the quantum Internet quantum information networks - QIN).

The student will work on various technologies: degenerate or non-degenerate entangled photon sources, quantum polarization and time-energy analyzers, time synchronization system, compatibility with quantum memories, etc.

The physical phenomena that can be addressed are multiple: decoherence of entanglement in noisy channels atmosphere), effects of atmospheric turbulence and mitigation in quantum communications, Raman effect involved in transmission of multiplexed quantum and classical fluxes in an optical fiber, Hong-Ou-Mandel effect and teleportation involving photons coming from space, storage of entanglement in quantum memories. An important criterion for the success of this thesis will be the demonstration of the control of quantum channels in free space.

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