SEAQUE: a polarization-entanglement quantum payload*

Future quantum networks will rely on high-rate entanglement distribution across global scales. An alternative to fiber networks, which are limited in size due to exponential loss in fiber, would be to use free-space satellite nodes. Developing compact space-grade quantum payloads is a necessary step towards realizing a quantum network that could have application in not only entanglement distribution, quantum telescopy, and quantum key distribution, but also in deep space experiments that could explore fundamental physics. The Space Entanglement and Annealing QUantum Experiment (SEAQUE) aims to launch such a compact polarization-entanglement source robust enough to withstand the space environment. With payload design components such as an integrated waveguide source and single liquid crystal (LC) tomography system, SEAQUE will pave the road towards implementing robust quantum space nodes within low size, weight, and power (SWaP) constraints. The experiment will utilize well known verification methods such as Bell inequality violations and state tomographies to monitor the status of the quantum optical system throughout the payload’s lifetime. Through a laser annealing technique that has not previously been demonstrated in a space environment, SEAQUE will showcase self-healing capabilities to combat radiation damage on single-photon avalanche photodiodes (APDs), a key to extending future mission lifetimes. SEAQUE is planned to launch in 2024 to the International Space Station (ISS).