Development of deterministic quantum-light sources from InP-based quantum dots in the telecom c-band

• Applicants: Professor Dr. Mohamed Benyoucef; Professor Dr. Stephan Reitzenstein
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2019 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 418390659

This project focuses on generation of non-classical light at telecom wavelengths (1.55 μm) from self-assembled InP-based single quantum dots (QDs), which are deterministically integrated into photonic microstructures for enhanced photon outcoupling and emission control. Project addresses three main challenges: control of the electronic structure, enhancement of photon extraction efficiency for study on optically-generated quantum light states, i.e. bright single- and twin-photons (degenerate in energy and polarization) and electrically-driven single-photon emission. We will tackle these challenges by epitaxial growth, external tuning and deterministically integrating single QDs into microlenses using in-situ electron-beam lithography. The microlens design in combination with a lower mirror section is expected to result in broadband enhancement of photon extraction efficiency and will be the basis for efficient (quantum)-optical characterization of non-classical light at long wavelengths. We aim at exploring convenient external control of emission properties of QD-microlenses mainly in terms of the biexciton binding energy crucial for realization and systematic study of twin-photons emission. Regarding single-photon emission, we focus on electrical charge control and electrical carrier injection to study properties of different excitonic complexes. With respect to twin-photons we aim at using the degenerate biexciton-exciton (XX-X) cascade to generate time-correlated photon pairs. In order to study them in a systematic way, we will combine the QD-microlenses with a piezo-actuator, which allows for convenient tuning and reduction of biexciton binding energy towards fine structure splitting of the bright X as required for twin-photon emission. Our project combines leading expertise of the involved groups on the growth and optical characterization of high-quality telecom-wavelength InP-based QDs (UNIKASSEL), and the deterministic fabrication of quantum light sources and quantum- optical study of semiconductor quantum dots (TUB). The output of the proposed research will significantly advance the state of knowledge on quantum light emission at telecom wavelengths and will open up exciting prospects for single- and twin-photon sources for fiber-based quantum communication and nonlinear spectroscopy.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Professor Dr. Grzegorz Sek