Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 44: Quantum Dots: Optical Properties II

HL 44.1: Talk

Tuesday, March 21, 2017, 14:45–15:00, POT 81

Quantum Light Sources based on Quantum-Dot Biexcitons — •Dirk Heinze, Dominik Breddermann, Artur Zrenner, and Stefan Schumacher — Department of Physics and CeOPP, Warburger Strasse 100, Paderborn, Germany

Quantum dot biexcitons show great potential as sources of quantum light. In this work we study the possibilities of two photon emission from a biexciton to generate both polarization-entangled photon pairs and all optically controllable single photons. Using a high-Q cavity we show theoretically that biexcitons can decay by simultaneously emitting two degenerate and polarization-entangled photons. The degree of entanglement is insensitive to the fine-structure splitting of the excitons due to the nature of the two-photon decay of the biexciton[1]. We demonstrate that this process is robust against phonon-assisted cavity feeding at low temperatures[2]. A partly stimulated partly spontaneous two photon emission from the biexciton can further be used to generate single photons with all optically tailored properties, such as polarization, frequency and time of emission [3],[4]. Here, the first photon is stimulated by a classical light field which drives the system into an intermediate virtual state from which the second single photon is emitted as the system relaxes into its ground state. This scheme does not rely on cavity enhancement, however the probability of emitting the single photon can be enhanced if the photon is emitted into a cavity. [1] S. Schumacher et al., Opt. Express 20, 5335-5342 (2012). [2] D. Heinze et al., arXiv:1611.04328 (2016). [3] D. Heinze et al., Nat. Commun. 6,8473 (2015). [4] D. Breddermann et al., Phys. Rev. B 94, 165310 (2016).