Chip-to-chip entanglement distribution over 80-km multicore fiber link

• URL: http://arxiv.org/abs/2604.26791v1
• Date: Wed, 29 Apr 2026 15:24:22 GMT
• Title: Chip-to-chip entanglement distribution over 80-km multicore fiber link
• Abstract summary: We report chip-to-chip distribution of path-encoded entangled states over 80 km between fully integrated silicon photonic transmitter and receiver chips.<n>These results establish silicon photonic chips as a viable platform for long-distance path-encoded entanglement-based quantum key distribution.
• Score: 0.032769173057785206
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Long-range quantum entanglement is essential for building large-scale quantum networks and unconditionally secure cryptographic systems based on quantum key distribution (QKD). While photonic integrated circuits offer a highly scalable platform, the fragility of phase coherence between spatial modes has prevented the distribution of path-encoded entanglement over long distances. Here, we report chip-to-chip distribution of path-encoded entangled states over 80 km between fully integrated silicon photonic transmitter and receiver chips. Telecom-band entangled photon pairs are generated via spontaneous four-wave mixing in on-chip spiral waveguides and distributed between chips over a dual-core, actively stabilized fiber link. Upon distribution, we measure a Bell state fidelity of $85.7 \pm 0.2 \%$. Implementing the BBM92 protocol with the same source, we obtain a secure key rate of 2.03 bit/s in the infinite-key regime. These results establish silicon photonic chips as a viable platform for long-distance path-encoded entanglement-based quantum key distribution, paving the way toward scalable, device-independent quantum networks.

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