Detector-optimized wavelength-hybrid entangled photon source for scalable fiber quantum key distribution
Abstract
Practical deployment of entanglement-based quantum key distribution (QKD) networks requires photon sources that simultaneously address fiber transmission loss, detector performance, and system cost–constraints that are individually well-understood but collectively unresolved in current source designs. Here we present a detector-optimized, wavelength-hybrid entangled photon source (EPS) that resolves this trilemma by design and show its performance in a QKD system. The source uses type-0 spontaneous parametric down-conversion in a crossed-crystal periodically poled KTiOPO 4 (ppKTP) configuration pumped at 473 nm, generating polarization-entangled photon pairs at 680 nm and 1550 nm. This highly nondegenerate wavelength combination is engineered to route the 680 nm photon to a high-efficiency, low-cost Si-SPAD detector while transmitting the 1550 nm photon through standard telecom fiber with minimum attenuation. The source achieves a spectral brightness of (1.9 × 10 ³ )s ⁻¹ mW ⁻¹ GHz ⁻¹ pairs over a 300 GHz phase-matching bandwidth, with polarization entanglement visibilities of (97.3 ± 1.0)% and (94.9 ± 1.6)% in the H/V and D/A bases, corresponding to a state fidelity of ≥ (96.1 ± 1.3)%. These results establish the wavelength-hybrid approach as a scalable and cost-effective building block for deployed entanglement-based QKD nodes and future quantum network infrastructure.
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BibTeX
@article{dosan2026detectoroptimized,
title = {{Detector-optimized wavelength-hybrid entangled photon source for scalable fiber quantum key distribution}},
author = {Vasile-Laurenţiu Dosan and Alek Lagarrigue and Alessandro Zannotti and Tushar Parab and Yannick Folwill and Fabian Steinlechner and Oliver de Vries},
journal = {Scientific Reports},
year = {2026},
month = nov,
doi = {10.1038/s41598-026-78321-8},
url = {https://www.nature.com/articles/s41598-026-78321-8},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Detector-optimized wavelength-hybrid entangled photon source for scalable fiber quantum key distribution
AU - Vasile-Laurenţiu Dosan
AU - Alek Lagarrigue
AU - Alessandro Zannotti
AU - Tushar Parab
AU - Yannick Folwill
AU - Fabian Steinlechner
AU - Oliver de Vries
PY - 2026
DA - 2026/11/05
JO - Scientific Reports
DO - 10.1038/s41598-026-78321-8
UR - https://www.nature.com/articles/s41598-026-78321-8
AB - Practical deployment of entanglement-based quantum key distribution (QKD) networks requires photon sources that simultaneously address fiber transmission loss, detector performance, and system cost–constraints that are individually well-understood but collectively unresolved in current source designs. Here we present a detector-optimized, wavelength-hybrid entangled photon source (EPS) that resolves this trilemma by design and show its performance in a QKD system. The source uses type-0 spontaneous parametric down-conversion in a crossed-crystal periodically poled KTiOPO _4 (ppKTP) configuration pumped at 473 nm, generating polarization-entangled photon pairs at 680 nm and 1550 nm. This highly nondegenerate wavelength combination is engineered to route the 680 nm photon to a high-efficiency, low-cost Si-SPAD detector while transmitting the 1550 nm photon through standard telecom fiber with minimum attenuation. The source achieves a spectral brightness of (1.9 × 10 ³ )s ⁻¹ mW ⁻¹ GHz ⁻¹ pairs over a 300 GHz phase-matching bandwidth, with polarization entanglement visibilities of (97.3 ± 1.0)% and (94.9 ± 1.6)% in the H/V and D/A bases, corresponding to a state fidelity of ≥ (96.1 ± 1.3)%. These results establish the wavelength-hybrid approach as a scalable and cost-effective building block for deployed entanglement-based QKD nodes and future quantum network infrastructure.
SN - 2045-2322
ER -