Coherence of an entangled exciton-photon state

We study the effect of the exciton fine-structure splitting on the polarization entanglement of photon pairs produced by the biexciton cascade in a quantum dot. Entanglement persists despite separations between the intermediate energy levels of up to 4 microeV. Measurements show that entanglement of...

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Bibliographic Details
Published in:Physical review letters 2007-12, Vol.99 (26), p.266802, Article 266802
Main Authors: Hudson, A J, Stevenson, R M, Bennett, A J, Young, R J, Nicoll, C A, Atkinson, P, Cooper, K, Ritchie, D A, Shields, A J
Format: Article
Language:English
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Summary:We study the effect of the exciton fine-structure splitting on the polarization entanglement of photon pairs produced by the biexciton cascade in a quantum dot. Entanglement persists despite separations between the intermediate energy levels of up to 4 microeV. Measurements show that entanglement of the photon pair is robust to the dephasing of the intermediate exciton state responsible for the first-order coherence time of either single photon. We present a theoretical framework incorporating the effects of spin scattering, background light, and dephasing. We distinguish between the first-order coherence time, and a parameter which we measure for the first time and define as the cross-coherence time.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.99.266802