Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 16: Quantum dots and wires: Optical properties I
HL 16.2: Vortrag
Montag, 25. Februar 2008, 14:15–14:30, ER 164
Triggered polarization-entangled photon pairs from a single quantum dot up to 30 K — •Robert Hafenbrak1, Sven M. Ulrich1, Peter Michler1, Lijuan Wang2, Armando Rastelli3, and Oliver G. Schmidt3 — 1Institut für Halbleiteroptik und Funktionelle Grenzflächen, Universität Stuttgart, Allmandring 3, 70569 Stuttgart — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstraße1, 70569 Stuttgart — 3Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, 01069 Dresden
The radiative biexciton-exciton decay in (In,Ga)As semiconductor quantum dots has the potential of being a source of triggered polarization-entangled photon pairs. However, this entanglement is in general reduced by the anisotropy-induced exciton fine structure splitting. Here we present measurements (1) on improved quantum dot structures, providing both significantly reduced inhomogeneous emission linewidths and near-zero fine structure splittings. A high-resolution detection technique is introduced which allows us to accurately determine the fine structure in the photoluminescence emission and therefore select appropriate quantum dots for quantum state tomography. We were able to verify the conditions of entangled or classically correlated photon pairs in full consistence with observed fine structure properties. Furthermore, we demonstrate reliable polarisation-entanglement for elevated temperatures up to 30 K. The fidelity of the maximally entangled state decreases only little from 72% at 4 K to 68% at 30 K.
(1) Hafenbrak et al., New J. Phys. 9 (2007) 315