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arXiv · 1902.06132

Emission-frequency separated high quality single-photon sources enabled by phonons

Michael Cosacchi·Florian Ungar·Moritz Cygorek·Alexei Vagov·Vollrath Martin Axt
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Abstract

We demonstrate theoretically that the single-photon purity of photons emitted from a quantum dot exciton prepared by phonon-assisted off-resonant excitation can be significantly higher in a wide range of parameters than that obtained by resonant preparation for otherwise identical conditions. Despite the off-resonant excitation the brightness stays on a high level. These surprising findings exploit that the phonon-assisted preparation is a two-step process where phonons first lead to a relaxation between laser-dressed states while high exciton occupations are reached only with a delay to the laser pulse maximum by adiabatically undressing the dot states. Due to this delay, possible subsequent processes, in particular multi-photon excitations, appear at a time when the laser pulse is almost gone. The resulting suppression of reexcitation processes increases the single-photon purity. Due to the spectral separation of the signal photons from the laser frequencies this enables the emission of high quality single photons not disturbed by a laser background while taking advantage of the robustness of the phonon assisted scheme.

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Michael Cosacchi, Florian Ungar, Moritz Cygorek, Alexei Vagov, Vollrath Martin Axt. 2019-07-05. Emission-frequency separated high quality single-photon sources enabled by phonons. https://doi.org/10.1103/physrevlett.123.017403

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