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Conference on Lasers and Electro-Optics

Entangled photons on-demand from a single quantum dot

Robert James Young, R. M. Stevenson, P. Atkinson, K. Cooper, D. A. Ritchie, Andrew J. Shields

Published Jan 1, 2006• 2 citations
Publisher

Abstract

Polarisation-entangled photon pairs are generated from single InAs quantum dots. This is achieved by restoring the degeneracy of the exciton level with an in-plane magnetic field or by careful selection of the dot.
DOI
10.1109/cleo.2006.4628585

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We propose a scheme to generate hyper-entangled photon pairs from single quantum dots (SQDs). Single photons emitted by SQD are manipulated to be entangled after post-selection. Crucially, exciton fine-structure splitting, which was previously deemed undesirable in similar schemes, is used here to produce photon pairs entangled in both frequency and polarization degrees of freedom. This hyper-entangled two-photon state is potentially more powerful than a normal entangled state for quantum state engineering and quantum information processing.
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Polarization correlation in a linear basis, but not entanglement, is observed between the biexciton and single-exciton photons emitted by a single InAs quantum dot in a two-photon cascade. The results are well described quantitatively by a probabilistic model that includes two decay paths for a biexciton through a nondegenerate pair of one-exciton states, with the polarization of the emitted photons depending on the decay path. The results show that spin nondegeneracy due to quantum-dot asymmetry is a significant obstacle to the realization of an entangled-photon generation device.