Triggered polarization-entangled photon pairs from a single quantum dot up to 30 K

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Date
2007
Volume
9
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Title
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Publisher
College Park, MD : Institute of Physics Publishing
Abstract

The radiative biexciton-exciton decay in a semiconductor quantum dot (QD) has the potential of being a source of triggered polarization-entangled photon pairs. However, in most cases the anisotropy-induced exciton fine structure splitting destroys this entanglement. Here, we present measurements on improved QD 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 QDs 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 polarization-entanglement for elevated temperatures up to 30 K. The fidelity of the maximally entangled state decreases only a little from 72% at 4 K to 68% at 30 K. This is especially encouraging for future implementations in practical devices. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

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Keywords
Electromagnetic wave polarization, Measurement theory, Photoluminescence, Quantum theory, Tomography, Inhomogeneous emission linewidths, Polarization-entanglement, Semiconductor quantum dots
Citation
Hafenbrak, R., Ulrich, S. M., Michler, P., Wang, L., Rastelli, A., & Schmidt, O. G. (2007). Triggered polarization-entangled photon pairs from a single quantum dot up to 30 K. 9. https://doi.org//10.1088/1367-2630/9/9/315
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License
CC BY-NC-SA 3.0 Unported