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arXiv:2411.16490 · Physical Review Applied

C-band plug-and-play all-fiber single-photon source based on In As / In P quantum dots integrated via microtransfer printing

Marek G. Mikulicz, Paweł Mrowiński, Paweł Holewa, Kresten Yvind, M. Syperek, Elizaveta S. Semenova

Published Jun 5, 2025• 3 citations
arXivHTMLPDF

Abstract

Fiber-based long-haul quantum communication would greatly benefit from a robust and deterministically integrated source of quantum states. Here, we report the design, fabrication, and optical characterization of In As / In P quantum dots in the In P H1 point-defect 2D photonic crystal cavity, integrated with a standard single-mode fiber employing microtransfer printing. The device is placed in a compact cryocooler maintaining a cryogenic temperature of 15 K, and it exhibits a low multiphoton contribution to emission, with g ( 2 ) ( 0 ) = 0.14 ( 14 ) in the all-fiber-based optical link between two laboratory nodes. In this way, we demonstrate a plug-and-play all-fiber single-photon source operating in the third telecom window, where standard telecommunication fiber networks can be used as a low-loss medium.

DOI
10.1103/128x-4731

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Fiber-based long-haul quantum communication would greatly benefit from a robust and deterministically integrated source of quantum states. Here, we report the design, fabrication, and optical characterization of In As / In P quantum dots in the In P H1 point-defect 2D photonic crystal cavity, integrated with a standard single-mode fiber employing microtransfer printing. The device is placed in a compact cryocooler maintaining a cryogenic temperature of 15 K, and it exhibits a low multiphoton contribution to emission, with g ( 2 ) ( 0 ) = 0.14 ( 14 ) in the all-fiber-based optical link between two laboratory nodes. In this way, we demonstrate a plug-and-play all-fiber single-photon source operating in the third telecom window, where standard telecommunication fiber networks can be used as a low-loss medium.
Abstract In this work, we present a stand-alone and fiber-coupled quantum-light source. The plug-and-play device is based on an optically driven quantum dot delivering single photons via an optical fiber. The quantum dot is deterministically integrated in a monolithic microlens which is precisely coupled to the core of an optical fiber via active optical alignment and epoxide adhesive bonding. The rigidly coupled fiber-emitter assembly is integrated in a compact Stirling cryocooler with a base temperature of 35 K. We benchmark our practical quantum device via photon auto-correlation measurements revealing g(2)(0) = 0.07 ± 0.05 under continuous-wave excitation and we demonstrate triggered non-classical light at a repetition rate of 80 MHz. The long-term stability of our quantum light source is evaluated by endurance tests showing that the fiber-coupled quantum dot emission is stable within 4% over several successive cool-down/warm-up cycles. Additionally, we demonstrate non-classical photon emission for a user-intervention-free 100-hour test run and stable single-photon count rates up to 11.7 kHz with a standard deviation of 4%.
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Single-photon sources are essential building blocks for for all aspects of quantum information technologies and more specifically for quantum communications. However, their widespread adoption is hindered by impractical constraints, such as cryogenic operation and emission wavelengths outside telecom windows. Leveraging telecom technology and point defects in GaN crystals, we present the first fully fibre-integrated single photon source operating at room temperature in the telecom O-band, meeting telecom photonics standards. We characterise an emitter producing single photons at 1292 nm, with a spectral broadening of 13 nm and a brightness of 25 kcps per mW of pump power and a purity of g(2)(0) = (5.9±0.5)×10−2at room temperature, demonstrating strong potential for integration into transportable quantum cryptography devices.
For quantum light sources in everyday telecommunication networks, quantum science needs to be fully transformed into quantum technology. The first necessary step to move outside a well-controlled lab environment requires the use of quantum light sources operating in the technologically relevant telecom O- and C-band. This can be provided using epitaxial quantum dots as deterministic sources of quantum light. Particularly intriguing is that emitters operating at telecom wavelengths are rapidly catching up with their short wavelength counterparts in terms of performances. Here, we make a decisive step forward in the development of quantum communication networks: a state-of-the-art source of quantum light, a semiconductor quantum dot (QD), with record coincidence rate for entangled photon emission in the telecom C-band, is operated inside an optimized rack-based setup. This setup includes a tunable pulsed laser for the QD excitation (from quasi- to fully resonant excitation), all optics for the excitation filtering, and QD signal coupling into single-mode fibers. Overall, the setup allows for above 50%50\%50% transmission for both exciton and biexciton photons. These results show that quantum dots-based telecom light sources can now be transported and integrated into existing fiber infrastructures, an important step to demonstrate the feasibility of the upcoming quantum internet.
High Resolution Image Download MS PowerPoint Slide A key resource in quantum-secured communication protocols are single photon emitters. For long-haul optical networks, it is imperative to use photons at wavelengths compatible with telecom single mode fibers. We demonstrate high purity single photon emission at 1.31 μm using deterministically positioned InP photonic waveguide nanowires containing single InAsP quantum dot-in-a-rod structures. At excitation rates that saturate the emission, we obtain a single photon collection efficiency at first lens of 27.6% and a probability of multiphoton emission of g (2) (0) = 0.021. We have also evaluated the performance of the source as a function of temperature. Multiphoton emission probability increases with temperature with values of 0.11, 0.34, and 0.57 at 77, 220 and 300 K, respectively, which is attributed to an overlap of temperature-broadened excitonic emission lines. These results are a promising step toward scalably fabricating telecom single photon emitters that operate under relaxed cooling requirements.
Single photon sources are essential building blocks for fundamental quantum optics, and quantum information networks. Their widespread use is currently hindered by impractical features, such as the need for operation at cryogenic temperatures and emission wavelengths lying outside telecom windows. Taking advantage of telecom technology and point defects in GaN crystals, we present, for the first time, the development of a fully-fibered source of single photons operating at room temperature, emitting photons in the telecom O-band and fulfilling the standards of telecom photonics. We characterise an emitter producting single photons at the wavelength of 1292 nm, a spectral broadening compatible with CWDM channels of 13 nm, and a brightness of 25 kcps per mW of pump power. The source shows a signal-to-noise ratio of 16.5 and a purity g(2)(0) = (5.9 ± 0.5) × 10−2 at room temperature, showing high potential for being integrated transportable quantum cryptography devices.