Phase-correlation-free quantum key distribution source operating at gigahertz rates

• URL: http://arxiv.org/abs/2606.04947v1
• Date: Wed, 03 Jun 2026 14:35:59 GMT
• Title: Phase-correlation-free quantum key distribution source operating at gigahertz rates
• Abstract summary: We present a 1.25 GHz phase-randomized QKD source based on a super-luminescent light emitting diode (SLED) operating in the C-band.<n>The source generates $sim100$ ps optical pulses with $400$ ps pulse-to-pulse separation, compatible with high-speed time-bin encoding.<n>This work establishes a scalable SLED-based platform for high-speed prepare-and-measure QKD systems.
• Score: 30.080390530541084
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Phase randomization is essential for the security of practical decoy-state quantum key distribution (QKD) systems. Commonly, implementations rely on laser sources which are either actively phase-randomized, or gain-switched. However, at high repetition rates these show correlations, which can ultimately compromise security and performance. We present a 1.25 GHz phase-randomized QKD source based on a super-luminescent light emitting diode (SLED) operating in the C-band as a compact and cost-effective alternative. The source generates $\sim100$ ps optical pulses with $400$ ps pulse-to-pulse separation, compatible with high-speed time-bin encoding. Interferometric measurements demonstrate $>99\%$ visibility between adjacent time bins, confirming strong first-order coherence within the same quantum signals, while the spontaneous-emission-driven nature of the SLED ensures intrinsic global phase randomization between adjacent signals. This work establishes a scalable SLED-based platform for high-speed prepare-and-measure QKD systems.

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