Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 41: Focus Session: Quantum Light Sources Based on Solid State Systems: Status and Visions I (organized by HL)

TT 41.4: Talk

Tuesday, April 1, 2014, 10:30–10:45, POT 251

Emission of polarization-entangled photons from biexcitons: two-photon processes and phonon-assisted cavity feeding — •Dirk Heinze, Artur Zrenner, and Stefan Schumacher — Department of Physics and CeOPP, University of Paderborn, Warburger Str. 100, 33098 Paderborn

Semiconductor quantum dots are promising sources for generation of pairs of polarization-entangled photons. In [1] we have shown theoretically that using a direct two-photon emission process inside a high-quality optical microcavity, the degree of achievable polarization-entanglement can be rendered insensitive to exciton fine-structure splitting (in contrast to the usual cascaded emission). The results in [1] were obtained for realistic quantum-dot and cavity parameters but neglecting the influence of phonon-assisted cavity feeding. Here we extend our previous study and include the interaction with a bath of acoustic phonons in a Born-Markov approximation in the master-equation for the system density operator. Our analysis shows the detrimental influence of phonons on the polarization entanglement with increasing temperature. However, it also demonstrates that at low temperature the influence of phonons on the scheme proposed in [1] is strongly suppressed such that high degrees of entanglement can be achieved.

[1] S. Schumacher, J. Förstner, A. Zrenner, M. Florian, C. Gies, P. Gartner, and F. Jahnke. Cavity-assisted emission of polarization-entangled photons from biexcitons in quantum dots with fine-structure splitting. Optics Express, 20, 5335 (2012).