Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 18: Quantum dots and wires I
HL 18.5: Talk
Monday, March 16, 2020, 16:15–16:30, POT 151
Preparation of the dark exciton in a semiconductor quantum dot using spatially structured light — •Doris E. Reiter1, Matthias Holtkemper1, Guillermo F. Quinteiro2, and Tilmann Kuhn1 — 1Institut für Festkörpertheorie, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany — 2IMIT and Departamento de Física, FaCENA, Universidad Nacional del Nordeste, Corrientes, Argentina
The ground state manifold of a semiconductor quantum dot hosts optically bright excitons which can be used for single photon generation. However, there are also two optically dark excitons in the ground state manifold, which are potentially interesting for storage. To access these dark excitons, we here propose the excitation of the quantum dot with the longitudinal component of a spatially structured light field. This light field component excites a light hole exciton in an excited state, also called a hot exciton state. In typical quantum dots, the hot exciton states are strongly mixed. We calculate the electronic structure of the quantum dot using a configuration interaction method accounting for Coulomb interaction and valence band mixing. We find a strong mixing between the excited light hole exciton and a hot dark heavy hole exciton. The latter is composed of an electron in the s-shell and a hole in the d-shell, which can relax quickly to its ground state (i.e., the s-shell). In this way we can prepare the dark exciton in the ground state manifold, which due to its optically inactivity exhibits a very long lifetime.