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

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DOI	Resolve DOI: https://doi.org/10.1103/PhysRevB.93.195316
Author	Search for: Reimer, M. E.; Search for: Bulgarini, G.; Search for: Fognini, A.; Search for: Heeres, R. W.; Search for: Witek, B. J.; Search for: Versteegh, M. A. M.; Search for: Rubino, A.; Search for: Braun, T.; Search for: Kamp, M.; Search for: Höfling, S.; Search for: Dalacu, D.¹; Search for: Lapointe, J.¹; Search for: Poole, P. J.¹; Search for: Zwiller, V.
Name affiliation	National Research Council of Canada. Information and Communication Technologies
Format	Text, Article
Journal title	Physical Review B
ISSN	2469-9950 2469-9969
Volume	93
Issue	19
Article number	195316
Pages	1–9
Abstract	One 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	2016-05-25
Publisher	American Physical Society
Language	English
Peer reviewed	Yes
NPARC number	23000390
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Record identifier	a5c48e82-c78d-49ca-9896-6e8aaf981dd1
Record created	2016-07-12
Record modified	2020-06-02

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Date modified:: 2020-07-15