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Hauptverfasser: Dosan, Vasile-Laurentiu, Lagarrigue, Alek, Zannotti, Alessandro, Parab, Tushar, Folwill, Yannick, Steinlechner, Fabian, de Vries, Oliver
Format: Preprint
Veröffentlicht: 2025
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Online-Zugang:https://arxiv.org/abs/2512.11630
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author Dosan, Vasile-Laurentiu
Lagarrigue, Alek
Zannotti, Alessandro
Parab, Tushar
Folwill, Yannick
Steinlechner, Fabian
de Vries, Oliver
author_facet Dosan, Vasile-Laurentiu
Lagarrigue, Alek
Zannotti, Alessandro
Parab, Tushar
Folwill, Yannick
Steinlechner, Fabian
de Vries, Oliver
contents Entangled photon sources (EPSs) are essential building blocks for scalable quantum communication and quantum key distribution (QKD). We present a stable, highly nondegenerate EPS based on type-0 spontaneous parametric down-conversion (SPDC) in a crossed-crystal configuration, generating photon pairs at 680~nm and 1550~nm when pumped by a 473~nm laser. This wavelength combination, reported here for the first time, simultaneously benefits from the peak detection efficiency of the most of the Si-SPADs in the visible/near-infrared spectral range and the low-loss fiber transmission of the telecom C-band. This configuration provides the most favorable balance between performance and cost for detection using Si-SPADs and InGaAs detectors. The source exhibits a measured spectral bandwidth of 300~GHz, corresponding to a spectral brightness of up to $1.9\times 10^3$~pairs~s$^{-1}$~mW$^{-1}$~GHz$^{-1}$. Heralding efficiencies reach 18~\% (signal) and 34~\% (idler) with Si-SPAD and superconducting nanowire single-photon detectors (SNSPD) detection. The entangled state achieves visibilities of $(97.3\pm 1.0)\,\%$ in the H/V basis and $(94.9\pm1.6)\,\%$ in the D/A basis, yielding a fidelity of $\geq(96.1\pm1.3)\,\%$. These results establish the presented EPS as a practical wavelength-hybrid platform for fiber-based QKD and emerging long-haul quantum network architectures.
format Preprint
id arxiv_https___arxiv_org_abs_2512_11630
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Highly Nondegenerate Entangled Photon Source for Fiber-Based Quantum Key Distribution
Dosan, Vasile-Laurentiu
Lagarrigue, Alek
Zannotti, Alessandro
Parab, Tushar
Folwill, Yannick
Steinlechner, Fabian
de Vries, Oliver
Quantum Physics
Entangled photon sources (EPSs) are essential building blocks for scalable quantum communication and quantum key distribution (QKD). We present a stable, highly nondegenerate EPS based on type-0 spontaneous parametric down-conversion (SPDC) in a crossed-crystal configuration, generating photon pairs at 680~nm and 1550~nm when pumped by a 473~nm laser. This wavelength combination, reported here for the first time, simultaneously benefits from the peak detection efficiency of the most of the Si-SPADs in the visible/near-infrared spectral range and the low-loss fiber transmission of the telecom C-band. This configuration provides the most favorable balance between performance and cost for detection using Si-SPADs and InGaAs detectors. The source exhibits a measured spectral bandwidth of 300~GHz, corresponding to a spectral brightness of up to $1.9\times 10^3$~pairs~s$^{-1}$~mW$^{-1}$~GHz$^{-1}$. Heralding efficiencies reach 18~\% (signal) and 34~\% (idler) with Si-SPAD and superconducting nanowire single-photon detectors (SNSPD) detection. The entangled state achieves visibilities of $(97.3\pm 1.0)\,\%$ in the H/V basis and $(94.9\pm1.6)\,\%$ in the D/A basis, yielding a fidelity of $\geq(96.1\pm1.3)\,\%$. These results establish the presented EPS as a practical wavelength-hybrid platform for fiber-based QKD and emerging long-haul quantum network architectures.
title Highly Nondegenerate Entangled Photon Source for Fiber-Based Quantum Key Distribution
topic Quantum Physics
url https://arxiv.org/abs/2512.11630