Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 109: Quantum dots and wires: Quantum communication and quantum information science

HL 109.5: Talk

Friday, March 20, 2015, 12:15–12:30, ER 164

A quantum dot single-photon source with on-the-fly all-optical polarization control — •Dirk Heinze, Dominik Breddermann, Artur Zrenner, and Stefan Schumacher — Physics Department and Center for Optoelectronics and Photonics Paderborn (CeOPP), University of Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany

Semiconductor quantum dots have been highlighted as efficient on demand sources for single photons. In contrast to the usual cascaded biexciton-exciton emission, here we study the direct two-photon emission from the biexciton. We show that emission through this higher-order transition is a promising and in certain ways superior alternative to generate a single photon. In the scheme we propose, the two-photon emission from the biexciton is enabled by a laser field (or laser pulse) driving the system into a virtual state inside the band gap. From this intermediate virtual state, the single photon of interest is then spontaneously emitted as the quantum dot relaxes to its electronic ground state. The big advantage of this scheme lies in the fact that the properties of the emitted photon (such as polarization state, time of emission, frequency) can be controlled all-optically by the classical laser field enabling the emission. This gives our scheme great potential to be used in the next generation of flexible semiconductor single-photon sources.