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applscia/6981/10.1490/369869.0236appscia/On-demand Generation of Indistinguishable Photons in the Telecom C-Band using Quantum Dot Devices

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On-demand Generation of Indistinguishable Photons in the Telecom C-Band using Quantum Dot Devices

Daniel A. Vajner,1 Paweł Holewa,2, 3, 4 Emilia Zięba-Ostój,2 Maja Wasiluk,2 Martin von Helversen,1 Aurimas Sakanas,3 Alexander Huck,5 Kresten Yvind,3, 4 Niels Gregersen,3 Anna Musiał,2 Marcin Syperek,2 Elizaveta Semenova,3, 4 Tobias Heindel1 ------ 1)Institute of Solid State Physics, Technical University of Berlin, 10623 Berlin, Germany 2)Department of Experimental Physics, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Wyb. Wyspia´nskiego 27, 50-370 Wrocław, Poland 3)DTU Electro, Department of Electrical and Photonics Engineering, Technical University of Denmark, Kongens Lyngby 2800, Denmark 4)NanoPhoton-Center for Nanophotonics, Technical University of Denmark, 2800 Kongens Lyngby, Denmark 5)Center for Macroscopic Quantum States (bigQ), Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
Applied Science Letters

2023 ° 17(06) ° 1685-9937

DOI: 10.1490/369869.7359appscia


Semiconductor quantum dots (QDs) enable the generation of single and entangled photons for applications in quantum information and quantum communication. While QDs emitting in the 780nm to 950nm spectral range feature closeto-ideal single-photon purities and indistinguishabilities, they are not the best choice for applications in fiber-optical networks, due to the high optical losses in this wavelength regime. The preferable choice here are QDs operating in the lowest-loss spectral window around 1550 nm (telecom C-band). In this work, we demonstrate the coherent ondemand generation of indistinguishable photons in the telecom C-band from single QD devices consisting of InAs/InP QD-mesa structures heterogeneously integrated with a metallic reflector on a silicon wafer. Using pulsed two-photon resonant excitation of the biexciton-exciton radiative cascade, we observe Rabi rotations up to pulse areas of 4π and a high single-photon purity in terms of g (2) (0) = 0.005(1) and 0.015(1) for exciton and biexciton photons, respectively. We obtain two-photon interference visibilities of up to 35(3)% in Hong-Ou-Mandel-type experiments by comparing co- and cross-polarized coincidences. This represents a significant advancement in the photon-indistinguishability of single photons emitted directly in the telecom C-band without wavelength conversion.


Single indistinguishable photons are a key resource for many applications in quantum information ranging from quantum communication to distributed quantum computing. They are an essential requirement for quantum networks and the quantum internet1 . While a plethora of quantum emitters enable the generation of single photons2,3, epitaxial semiconductor quantum dots (QD) turned out to be advantageous in many regards4–7. Over the last decades, photons generated on-demand using QDs demonstrated unprecedented quantum optical properties in terms of high purity, brightness and indistinguishability and have been repeatedly employed in implementations of quantum communication8 . So far, such closeto-ideal single-photon sources have only been demonstrated at wavelengths around 780nm for GaAs/AlGaAs QDs9,10 and 930nm for InGaAs/GaAs QDs11–15. For long-distance quantum information transfer via optical fibers, however, wavelengths around 1550nm, i.e. in the telecom C-band, are required to benefit from lowest losses in optical fibers. To shift the emission of QDs to C-band wavelength, quantum frequency conversion of QD-photons emitted at shorter wavelengths can be used16–18, which introduces

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