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Four Photons Shared 750 Secret Bits Each Second

A four-arm, 20-kilometer fiber network supported composable protection against outside and participant attacks.

Published Updated Story ID: mp-2026-09-15-016
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Summary

A four-arm, 20-kilometer fiber network supported composable protection against outside and participant attacks.

Two engineered photon-pair sources generated four-qubit GHZ states at more than 5,000 fourfold events per second. Distributed across a four-arm star network totaling 20 km of fiber, the setup reached a maximum asymptotic secret-key rate of 750 ± 10 bits per second. From measured rates and errors, the authors infer an 8.7-megabit finite-key lower bound for an optimized 24-hour run if device statistics remain stationary.

Why it matters

A four-arm, 20-kilometer fiber network supported composable protection against outside and participant attacks.

Limits and context

  • From measured rates and errors, the authors infer an 8.7-megabit finite-key lower bound for an optimized 24-hour run if device statistics remain stationary.

Key claims

  1. A four-arm, 20-kilometer fiber network supported composable protection against outside and participant attacks.

    Qualification: From measured rates and errors, the authors infer an 8.7-megabit finite-key lower bound for an optimized 24-hour run if device statistics remain stationary.

    Evidence: source-2026-09-15-018

Sources

  1. arXiv preprint 2609.13367arXiv · primary research

Corrections

No corrections have been recorded for this story.