708 research outputs found
Non‐Blinking Single‐Photon Generation with Anisotropic Colloidal Nanocrystals: Towards Room‐Temperature, Efficient, Colloidal Quantum Sources
Blinking and single-photon emission can be tailored in CdSe/CdS core/shell colloidal dot-in-rods. By increasing the shell thickness it is possible to obtain almost non-blinking nanocrystals, while the shell length can be used to control single-photon emission probability
Investigating the fast spectral diffusion of a quantum emitter in hBN using resonant excitation and photon correlations
The ability to identify and characterize homogeneous and inhomogeneous
dephasing processes is crucial in solid-state quantum optics. In particular,
spectral diffusion leading to line broadening is difficult to evidence when the
associated timescale is shorter than the inverse of the photon detection rate.
Here, we show that a combination of resonant laser excitation and second-order
photon correlations allows to access such fast dynamics. The resonant laser
drive converts spectral diffusion into intensity fluctuations, leaving a
signature in the second-order coherence function of the
scattered light that can be characterized using two-photon coincidences --
which simultaneously provides the homogeneous dephasing time. We experimentally
implement this method to investigate the fast spectral diffusion of a color
center generated by an electron beam in the two-dimensional material hexagonal
boron nitride. The function of the quantum emitter measured
over more than ten orders of magnitude of delay times, at various laser powers,
establishes that the color center experiences spectral diffusion at a
characteristic timescale of a few tens of microseconds, while emitting
Fourier-limited single photons () between spectral jumps
Room temperature single-photon sources based on single colloidal nanocrystals in microcavities
Abstract Direct lithography of resist blends, embedding semiconductor colloidal nanocrystals (NCs) is an innovative way to achieve nanopositioning of NCs in quantum-confined optical resonators. In this work, we show a new appealing approach for the fabrication of single-photon sources operating at room temperature by localizing semiconductor colloidal NCs into vertical planar microcavities with lithographic techniques
First direct determination of the Boltzmann constant by an optical method
International audienceWe have recorded the Doppler profile of a well-isolated rovibrational line in the ν2 band of 14NH3. Ammonia gas was placed in an absorption cell thermalized by a water-ice bath. By extrapolating to zero pressure, we have deduced the Doppler width which gives a first measurement of the Boltzmann constant, kB, by laser spectroscopy. A relative uncertainty of 2x10-4 has been obtained. The present determination should be significantly improved in the near future and contribute to a new definition of the kelvin
Effects of the lipase inhibitors, Triton WR-1339 and tetrahydrolipstatin on the synthesis and secretion of lipids by rat hepatocytes
AbstractThe lipase inhibitors, Triton WR-1339 and tetrahydrolipstatin, were incubated with rat hepatocytes. Triton WR-1339 increased the recovery of triacylglycerol in the hepatocytes and incubation medium by 31% and 38%, respectively. Tetrahydrolipstatin decreased the accumulation of newly synthesized, and of total triacylglycerol in the medium. This compound might be useful in determining mechanisms involved in intracellular triacylglycerol metabolism and the secretion of very low density lipoproteins
Strong Purcell effect observed in single thick shell CdSe/CdS nanocrystals coupled to localized surface plasmons
High quality factor dielectric cavities designed to a nanoscale accuracy are
mostly used to increase the spontaneous emission rate of a single emitter. Here
we show that the coupling, at room temperature, between thick shell CdSe/CdS
nanocrystals and random metallic films offers a very promising alternative
approach. Optical modes confined at the nanoscale induce strong Purcell factors
reaching values as high as 60. Moreover the quantum emission properties can be
tailored: strong antibunching or radiative biexcitonic cascades can be obtained
with high photon collection efficiency and extremely reduced blinking.Comment: 16 pages, 7 figure
Consequences of PPARα Invalidation on Glutathione Synthesis: Interactions with Dietary Fatty Acids
Glutathione (GSH) derives from cysteine and plays a key role in redox status. GSH synthesis is determined mainly by cysteine availability and γ-glutamate cysteine ligase (γGCL) activity. Because PPARα activation is known to control the metabolism of certain amino acids, GSH synthesis from cysteine and related metabolisms were explored in wild-type (WT) and PPARα-null (KO) mice, fed diets containing either saturated (COCO diet) or 18 : 3 n-3, LIN diet. In mice fed the COCO diet, but not in those fed the LIN diet, PPARα deficiency enhanced hepatic GSH content and γGCL activity, superoxide dismutase 2 mRNA levels, and plasma uric acid concentration, suggesting an oxidative stress. In addition, in WT mice, the LIN diet increased the hepatic GSH pool, without effect on γGCL activity, or change in target gene expression, which rules out a direct effect of PPARα. This suggests that dietary 18 : 3 n-3 may regulate GSH metabolism and thus mitigate the deleterious effects of PPARα deficiency on redox status, without direct PPARα activation
Photon correlations in the collective emission of hybrid gold-(CdSe/CdS/CdZnS) nanocrystal supraparticles
We investigate the photon statistics of the light emitted by single
self-assembled hybrid gold-CdSe/CdS/CdZnS colloidal nanocrystal supraparticles
through the detailed analysis of the intensity autocorrelation function
. We first reveal that, despite the large number of nanocrystals
involved in the supraparticle emission, antibunching can be observed. We then
present a model based on non-coherent F\"orster energy transfer and Auger
recombination that well captures photon antibunching. Finally, we demonstrate
that some supraparticles exhibit a bunching effect at short time scales
corresponding to coherent collective emission
Polarized single photon emission for quantum cryptography based on colloidal nanocrystals
In this paper, the evidence of a polarized and room temperature single photon emission from wet-chemically synthesized colloidal dot-in-a-rod is reported. The time and polarization resolved measurements clearly indicate a high degree of linear polarization and a lifetime of ∼11 ns. We report also about a viable strategy to develop single photon sources with polarization control for quantum cryptography
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