3 years ago

Strain-tunable GaAs quantum dot: An on-demand source of nearly-maximally entangled photon pairs.

Saimon Filipe Covre da Silva, Giovanni Piredda, Johannes Edlinger, Daniel Huber, Rinaldo Trotta, Armando Rastelli, Marcus Reindl, Javier Martin-Sanchez, Christian Schimpf, Huiying Huang

Entangled photon generation from semiconductor quantum dots via the biexciton-exciton cascade underlies various decoherence mechanisms related to the solid-state nature of the quantum emitters. So far, this has prevented the demonstration of nearly-maximally entangled photons without the aid of inefficient and complex post-selection techniques that are hardly suitable for quantum communication technologies. Here, we tackle this challenge using strain-tunable GaAs quantum dots driven under two-photon resonant excitation and with strictly-degenerate exciton states. We demonstrate experimentally that our on-demand source generates polarization-entangled photons with fidelity of 0.978(5) and concurrence of 0.97(1) without resorting to post-selection techniques. Moreover, we show that the remaining decoherence mechanisms can be overcome using a modest Purcell enhancement so as to achieve a degree of entanglement >0.99. Our results highlight that GaAs quantum dots can be readily used in advanced communication protocols relying on the non-local properties of quantum entanglement.

Publisher URL: http://arxiv.org/abs/1801.06655

DOI: arXiv:1801.06655v2

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