Light Sources for Quantum Communication in the 1300 nm Spectral Range

• Applicant: Professor Dr. Stephan Reitzenstein
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 429588372

The realization of novel and telecom-compatible optoelectronic devices for long-distance fiber-based quantum communication is the central goal of this project. The key technologies address single-QD-based single-photon sources (SPSs) for both electrical and optical excitation and advanced vertical-cavity surface-emitting lasers (VCSELs) in the ~1300 nm wavelength range. The overarching goal of the project is the combination of both key technologies, namely the realization of a highly-efficient single-photon source with indistinguishable photon emission in the telecom O-band (1.3 µm) that is resonantly driven by an electrically-pumped VCSEL. This paves the way for compact and practical SPSs based solely on semiconductor technology.The QD structures will be grown on top of distributed Bragg reflectors (DBRs) and dielectric multilayer structure will be deposited on top to form a microcavity. The dielectric structure will be further laterally patterned to allow for simple and highly-efficient coupling (>80%) of single photons into single-mode waveguides or standard single-mode fibers. Unique In-situ low-temperature electron-beam lithography will be applied to define the microcavitys’ base-mesas to properly align them to single pre-selected QDs for optimal device performance. For the resonant high-speed excitation of the single QDs high-speed VCSELs in the 1300 nm wavelength range will be realized. Therefore, both GaAs-based monolithic and InP-based wafer-fusion VCSEL-technologies will be utilized and tested for superior performance. The fabricated structures will be investigated and evaluated by quantum-optical experiments to determine the most important properties with respect to the envisaged applications like emission dynamics/rates, photon-extraction efficiency, purity of single-photon emission, and indistinguishability of the single photons.The synergy of the complementary long-standing expertise of both partners from Germany and Russia provides the necessary basis to succeed in this ambitious approach to foster real applications in quantum information processing in the telecom wavelength regime.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research, until 3/2022
• Cooperation Partner: Dr. Sergey Blokhin, until 3/2022