Spaceborne, low-noise, single-photon detection for satellite-based quantum communications.

Area of Science:

• Space instrumentation
• Quantum optics
• Photonics

Background:

• Single-photon detectors (SPDs) are crucial for sensitive applications but degrade in space due to radiation and vacuum.
• Commercial off-the-shelf (COTS) silicon avalanche photodiodes (APDs) are susceptible to noise and reliability issues in space environments.

Purpose of the Study:

• To develop spaceborne, low-noise, high-reliability SPDs using COTS APDs.
• To mitigate the impact of space radiation and thermal vacuum on SPD performance.
• To enable reliable quantum communication and other space-based applications.

Main Methods:

• Developed specialized shielding structures for COTS APDs.
• Implemented multistage cooling technologies to manage thermal conditions.
• Designed configurable driver electronics to enhance reliability and mitigate noise sensitivity.

Main Results:

• Reduced the expected radiation-induced dark count rate (DCR) increment from ~219 cps/day to ~0.76 cps/day.
• Maintained SPD DCR below 1000 cps over 1029 days of operation, with an actual increment rate of ~0.54 cps/day.
• Achieved a photon detection efficiency greater than 45%.

Conclusions:

• Demonstrated a feasible satellite-based quantum communication link using the developed SPDs.
• The novel SPD design offers two orders of magnitude lower radiation-induced DCR compared to previous technologies.
• These SPDs open new avenues for deep-space optical communications, single-photon laser ranging, and fundamental physics research in space.