Overcoming power broadening of the quantum dot emission in a pure wurtzite nanowire

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DOIResolve DOI: http://doi.org/10.1103/PhysRevB.93.195316
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TypeArticle
Journal titlePhysical Review B
ISSN2469-9950
2469-9969
Volume93
Issue19
Article number195316
Pages19
AbstractOne of the key challenges in developing quantum networks is to generate single photons with high brightness, purity, and long temporal coherence. Semiconductor quantum dots potentially satisfy these requirements; however, due to imperfections in the surrounding material, the coherence generally degrades with increasing excitation power yielding a broader emission spectrum. Here we overcome this power-broadening regime and demonstrate an enhanced coherence at exciton saturation where the detected count rates are highest. We detect single-photon count rates of 460 000 counts per second under pulsed laser excitation while maintaining a single-photon purity greater than 99%. Importantly, the enhanced coherence is attained with quantum dots in ultraclean wurtzite InP nanowires, where the surrounding charge traps are filled by exciting above the wurtzite InP nanowire band gap. By raising the excitation intensity, the number of possible charge configurations in the quantum dot environment is reduced, resulting in a narrower emission spectrum. Via Monte Carlo simulations we explain the observed narrowing of the emission spectrum with increasing power. Cooling down the sample to 300 mK, we further enhance the single-photon coherence twofold as compared to operation at 4.5 K, resulting in a homogeneous coherence time, T₂, of 1.2 ns, and two-photon interference visibility as high as 83% under strong temporal postselection (∼5% without temporal postselection).
Publication date
PublisherAmerican Physical Society
LanguageEnglish
AffiliationInformation and Communication Technologies; National Research Council Canada
Peer reviewedYes
NPARC number23000390
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Record identifiera5c48e82-c78d-49ca-9896-6e8aaf981dd1
Record created2016-07-12
Record modified2016-07-12
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