Single-Photon Detectors for Satellite and CubeSat Quantum Key Distribution: A Systematic Evidence Map

Area of Science:

• Quantum communication
• Optical engineering
• Space technology

Background:

• Advancing satellite and CubeSat quantum key distribution (QKD) necessitates receiver-level engineering trade studies.
• Secure-key feasibility in space is constrained by single-photon detectors (SPDs) facing Size, Weight, and Power (SWaP), thermal, and radiation challenges.

Purpose of the Study:

• To systematically map recent literature connecting various single-photon detector (SPD) variants to CubeSat QKD and space-based quantum communication.
• To assess the consistency of reported performance data for guiding detector selection in space QKD applications.

Main Methods:

• A systematic evidence map was created using a concept-token methodology.
• Keywords and key phrases identified mission contexts and detector families (SNSPDs, Si SPAD/APD, InGaAs SPAD/APD, NFADs).
• Structured extraction focused on detection efficiency (η), dark count rate (DCR), timing jitter, receiver timing window (Δt), operating mode, temperature, and radiation evidence.

Main Results:

• Publication trends show a significant increase, particularly in the last two years.
• Superconducting Nanowire Single-Photon Detectors (SNSPDs) and Avalanche Photodiode/Single-Photon Avalanche Diode (APD/SPAD) families are most frequently discussed.
• Key parameters like detection efficiency (η), jitter, and timing window (Δt) are reported inconsistently, hindering cross-study comparisons.

Conclusions:

• CubeSat-focused studies highlight APD/SPAD feasibility and radiation effects on DCR, while SNSPDs offer high performance but require cryogenics.
• Standardized reporting of η, DCR, jitter, Δt, temperature, and radiation conditions is essential for accelerating the development of deployable space-QKD receivers.