Compact and efficient quantum frequency conversion of a fiber-pigtailed single-photon source
Mathis Cohen, Anthony Martin, Romain Dalidet, Florian Pastier, Marie Billard, Aristide Lemaître, Valérian Giesz, Niccolò Somaschi, Sarah E. Thomas, P. Senellart, Sébastien Tanzilli, Laurent Labonté
Quantum frequency converters are key enabling technologies in photonic quantum information science to bridge the gap between quantum emitters and telecom photons. Here, we report a coherent frequency converter scheme combining a fiber-coupled nonlinear optical lithium niobate waveguide with a fiber-pigtailed single-photon source based on semiconductor quantum dots. Single and indistinguishable photons are converted from 925.7 nm to the telecommunication C-band, with a 48.4% end-to-end efficiency and full preservation of single-photon purity and indistinguishability. The integration of the two fiber-based modules achieving top-level performance represents an important step toward the practical interconnection of future quantum information processing systems operating at different wavelengths.
Quantum frequency converters are key enabling technologies in photonic quantum information science to bridge the gap between quantum emitters and telecom photons. Here, we report a coherent frequency converter scheme combining a fiber-coupled nonlinear optical lithium niobate waveguide with a fiber-pigtailed single-photon source based on semiconductor quantum dots. Single and indistinguishable photons are converted from 925.7 nm to the telecommunication C-band, with a 48.4% end-to-end efficiency and full preservation of single-photon purity and indistinguishability. The integration of the two fiber-based modules achieving top-level performance represents an important step toward the practical interconnection of future quantum information processing systems operating at different wavelengths.
Quantum frequency converters are key enabling technologies in photonic quantum information science to bridge the gap between quantum emitters and telecom photons. Here, we report a coherent frequency converter scheme combining a fiber-coupled nonlinear optical Lithium Niobate waveguide with a fiber-pigtailed single-photon source based on semiconductor quantum dots. Single and indistinguishable photons are converted from 925.7 nm to the telecommunication C-band, with a 48.4% end-to-end efficiency and full preservation of single-photon purity and indistinguishability. The integration of the two fiber-based modules achieving top-level performance represents an important step toward the practical interconnection of future quantum information processing systems operating at different wavelengths.
On-demand indistinguishable single-photon sources are essential for quantum networking and communication. Semiconductor quantum dots are among the most promising candidates, but their typical emission wavelength renders them unsuitable for use in fiber networks. Here, we present quantum frequency conversion of near-infrared photons from a bright quantum dot to the telecommunication C-band, allowing integration with existing fiber architectures. We use a custom-built, tunable 2400 nm seed laser to convert single photons from 942 nm to 1550 nm in a difference-frequency generation process. We achieve an end-to-end conversion efficiency of ≃35%, demonstrate count rates approaching 1 MHz at 1550 nm with g(2)(0)=0.043(1), and achieve Hong-Ou-Mandel (HOM) visibilities of 60%. We expect this scheme to be preferable to quantum dot sources directly emitting at telecom wavelengths for fiber-based quantum networking.
Quantum frequency conversion (QFC), which involves the exchange of frequency modes of photons, is a prerequisite for quantum interconnects among various quantum systems, primarily those based on telecom photonic network infrastructures. Compact and fiber-closed QFC modules are in high demand for such applications. In this paper, we report such a QFC module based on a fiber-coupled 4-port frequency converter with a periodically poled lithium niobate (PPLN) waveguide. The demonstrated QFC shifted the wavelength of a single photon from 780 to 1541 nm. The single photon was prepared via spontaneous parametric down-conversion (SPDC) with heralding photon detection, for which the cross-correlation function was 40.45 ± 0.09. The observed cross-correlation function of the photon pairs had a nonclassical value of 13.7 ± 0.4 after QFC at the maximum device efficiency of 0.73, which preserved the quantum statistical property. Such an efficient QFC module is useful for interfacing atomic systems and fiber-optic communication.
We demonstrate a quantum interface that simultaneously converts the wavelength, bandwidth, and duration of single-photon-level pulses, enabling compatibility between disparate quantum systems. Using difference frequency generation in a lithium niobate waveguide driven by a highly chirped pump, we transform pulses from 798 nm, 5 GHz, 150 ps (quantum dot-like) to 1300 nm, 35 GHz, < 25 ps (telecom standard). This nonlinear optical time lens achieves over 80% internal conversion efficiency and compresses output pulses below detector resolution. The device offers a compact solution for integrating quantum emitters, memories, and telecom networks, with potential for further pulse shape control.
Abstract On‐demand single‐photon sources emitting pure and indistinguishable photons at the telecommunication wavelength are critical assets toward the deployment of fiber‐based quantum networks. Indeed, single photons may serve as flying qubits, allowing communication of quantum information over long distances. Self‐assembled InAs quantum dots embedded in GaAs constitute an excellent nearly deterministic source of high‐quality single photons, but the vast majority of sources operate in the 900–950 nm wavelength range, precluding their adoption in a quantum network. A quantum frequency conversion scheme is presented here for converting single photons from quantum dots to the telecommunication C band, around 1550 nm, achieving 40.8% end‐to‐end efficiency, while maintaining both high purity and a high degree of indistinguishability during conversion with measured values of and , respectively.
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.