78 research outputs found
Low and high intensity velocity selective coherent population trapping in a two-level system
An experimental investigation is made of sub-recoil cooling by velocity
selective coherent population trapping in a two-level system in Sr. The
experiment is carried out using the narrow linewidth intercombination line at
689 nm. Here, the ratio between the recoil shift and the linewidth is as high
as 0.64. We show that, on top of a broader momentum profile, subrecoil features
develop, whose amplitude is strongly dependent on the detuning from resonance.
We attribute this structure to a velocity selective coherent population
trapping mechanism. We also show that the population trapping phenomenon leads
to complex momentum profiles in the case of highly saturated transitions,
displaying a multitude of subrecoil features at integer multiples of the recoil
momentum.Comment: 6 pages and 7 figure
Coherent flash of light emitted by a cold atomic cloud
When a resonant laser sent on an optically thick cold atomic cloud is
abruptly switched off, a coherent flash of light is emitted in the forward
direction. This transient phenomenon is observed due to the highly resonant
character of the atomic scatterers. We analyze quantitatively its
spatio-temporal properties and show very good agreement with theoretical
predictions. Based on complementary experiments, the phase of the coherent
field is reconstructed without interferometric tools.Comment: Submitted to Phys. Rev. Let
Wigner crystal versus Fermionization for one-dimensional Hubbard models with and without long-range interactions
The ground state properties of Hubbard model with or without long-range
interactions in the regime with strongly repulsive on-site interaction are
investigated by means of the exact diagonalization method. We show that the
appearance of -crests in the density profile of a trapped N-fermion system
is a natural result of "fermionization" between antiparallel-spin fermions in
the strongly repulsive limit and can not be taken as the only signature of
Wigner crystal phase, as the static structure factor does not show any
signature of crystallization. On the contrary, both the density distribution
and static structure factor of Hubbard model with strong long-range
interactions display clear signature of Wigner crystal. Our results indicate
the important role of long-range interaction in the formation of Wigner
crystal.Comment: 7 pages, 7 figure
Doppler cooling to the Quantum limit
Doppler cooling on a narrow transition is limited by the noise of single
scattering events. It shows novel features, which are in sharp contrast with
cooling on a broad transition, such as a non-Gaussian momentum distribution,
and divergence of its mean square value close to the resonance. We have
observed those features using 1D cooling on an intercombination transition in
strontium, and compared the measurements with theoretical predictions and Monte
Carlo simulations. We also find that for a very narrow transition, cooling can
be improved using a dipole trap, where the clock shift is canceled.Comment: DOI: 10.1103/PhysRevLett.107.24300
Long-range gravitational-like interaction in a neutral atomic cold gas
A quasi-resonant laser induces a long-range attractive force within a cloud
of cold atoms. We take advantage of this force to build in the laboratory a
system of particles with a one-dimensional gravitational-like interaction, at a
fluid level of modeling. We give experimental evidences of such an interaction
in a cold Strontium gas, studying the density profile of the cloud, its size as
a function of the number of atoms, and its breathing oscillations.Comment: 4 pages, 4 figures. Published in PRA 87, 013401 (2013
Effectiveness of Machine Learning in Assessing QoT Impairments of Photonics Integrated Circuits to Reduce System Margin
We propose machine learning technique for assessment of QoT impairments of integrated circuits. We consider margin reduction problem applied to a switching component. Overall results and data sets for machine-learning training are obtained by leveraging the integrated software environment of the Synopsys Photonic Design Suite
SiC-based/EBC Coating systems investigated by LASAT (LAser Shock Adhesion Test)
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Machine-learning-aided abstraction of photonic integrated circuits in software-defined optical transport
International round-robin experiment for angle-resolved light scattering measurement
International audienc
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