Entangled photon source gearing up for International Space Station

A single-photon detector and counting module (SPODECT) recently designed and built by Waterloo’s Quantum Photonics Lab for the International Space Station (ISS) will be used to verify quantum entanglement and test its survivability in space. The research is part of the Space Entanglement and Annealing QUantum Experiment (SEAQUE) mission, in collaboration with researchers at the University of Illinois Urbana-Champaign, the Jet Propulsion Laboratory, ADVR Inc, and the National University of Singapore.

Waterloo’s SPODECT module is unique in that it will include four single-photon detectors, an onboard coincidence counting logic as well as a microcontroller for managing its operation, all in a very compact format. The Waterloo project is headed by Prof. Thomas Jennewein from the Department of Physics and Astronomy and member of the Institute for Quantum Computing, and is led by research associate Joanna Krynski. The work is a partnership of the Quantum Photonics Lab (QPL) with Excelitas Inc. (Canada) who provided the Silicon-APD devices, and Dotfast Consulting (Austria) who provided the internal coincidence detection solution.

Serving as a continuation of the Cool Annealing Payload Satellite (CAPSat) project that performs in-orbit measurements and annealing of silicon single-photon detectors, SEAQUE is the first ever space-based quantum experiment that integrates a source of entangled photon pairs using an optical waveguide crystal, which achieves about two orders of magnitude larger photon pair production rates than regular bulk crystals. SEAQUE’s pioneering design will also use a bright laser to regularly heal damage resulting from radiation exposure in between rounds of detecting photons generated from the entanglement source. This process, known as optical annealing, will help mitigate the increase of radiation-induced detector noise without the method of extreme cooling as used previously. 

“This new detector module design is a step towards building a quantum communication technology at lower cost and lower complexity systems than conventional designs,” said Krynski. “Our experiment will determine the viability of this new approach and whether it can be useful for future quantum information satellite networks.”

“The SEAQUE mission will demonstrate a novel and efficient photon pair source, a custom single-photon detector system, which could be a part of future quantum entanglement network nodes in space,” said Jennewein. "The main benefit of his space-based entanglement distribution will be that it can offer a tenfold greater quantum information transfer distance than for ground based signals, as the signals avoid the limitations of obstacles or absorptive media.”

One of the most exciting challenges for this project was to fit all of the required hardware for the SEAQUE system into the specifications laid out by commercial partner Nanoracks — a  box that is only 30 cm by 20 cm by 10 cm — of which Waterloo’s detector module SPODECT can only occupy a small fraction. Additionally, the chosen components must survive the turbulent launch, extreme temperature limits and exposure to space radiation.

SEAQUE will deploy early next year, arriving at the ISS and then will permanently reside in the the Bishop Airlock. View the recording of CAPSAT’s launch from October 2021.

The Waterloo team acknowledges dedicated support by the Canadian Space Agency (FAST program).

Read more: Space Station to Host ‘Self-Healing’ Quantum Communications Tech Demo, Jet Propulsion Laboratory at the California Institute of Technology.