Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.42: Poster

Monday, March 26, 2007, 15:00–17:30, Poster A

Entanglement decay in semiconductor quantum dots — •Katarzyna Roszak^1,2, Pawel Machnikowski², and Tilmann Kuhn¹ — ¹Institut für Festkörpertheorie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany — ²Institute of Physics, Wroclaw University of Technology, Wybrzerze Wyspianskiego 27, 50-370 Wroclaw, Poland

Entanglement is a vital component in all quantum computing schemes; for maintaining entanglement coherence must be sustained in multi-partite systems. We study the evolution of entanglement in initially completely entangled states of two excitons confined in one or two semiconductor quantum dots under partial pure dephasing induced by a phonon bath. The decay of entanglement (measured by the entanglement of formation) shows two qualitatively different scenarios for different initial states; in some cases the state may become separable (completely disentangled) at a finite time (the pure dephasing is still only partial). It turns out that these states can be easily characterized. The appearance of the effect additionally depends on the coupling strength (as does pure dephasing) and subsequently on temperature. The effect of separation between the dots is also studied; it reflects the crossover from a common-reservoir regime (a biexciton state in one quantum dot) to separate reservoirs (two, well separated dots).