Fiber-integrated Quantum Frequency Conversion for Long-distance Quantum Networking

• URL: http://arxiv.org/abs/2604.23444v1
• Date: Sat, 25 Apr 2026 21:04:40 GMT
• Title: Fiber-integrated Quantum Frequency Conversion for Long-distance Quantum Networking
• Abstract summary: Quantum frequency conversion (QFC) offers an effective optical interface that bridges quantum nodes with telecom-band channels.<n>We demonstrate a compact, fiber-integrated QFC system with low noise and a high signal-to-noise ratio (SNR)<n>These findings highlight the potential of our QFC system for scalable, long-distance quantum networking.
• Score: 6.1909047271409925
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Signal photons emitted by quantum nodes typically fall outside the low-loss telecom window of optical fibers, leading to severe transmission losses. Quantum frequency conversion (QFC) offers an effective optical interface that bridges quantum nodes with telecom-band channels, enabling long-distance quantum communication. In this work, we demonstrate a compact, fiber-integrated QFC system with low noise and a high signal-to-noise ratio (SNR). Using a periodically poled lithium niobate (PPLN) waveguide, input photons at 637.2 nm are down-converted to telecom photons at 1588.3 nm. Our system achieves a total conversion efficiency of approximately 9%, with pump-induced noise suppressed to 154 Hz. For input photon rates of 32.7, 118.0, and 327.7 kHz, the corresponding SNRs are 12.3, 43.9, and 117.8, respectively. We further develop a theoretical model to simulate the entanglement fidelity between nitrogen-vacancy (NV) center spins and the frequency-converted telecom photons. At the emission rate of an NV center, our QFC system maintains an expected fidelity exceeding 52% over a transmission distance of 100 km. These findings highlight the potential of our QFC system for scalable, long-distance quantum networking.

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