87 research outputs found
Tailoring optical metamaterials to tune the atom-surface Casimir-Polder interaction
Metamaterials are fascinating tools that can structure not only surface
plasmons and electromagnetic waves but also electromagnetic vacuum
fluctuations. The possibility of shaping the quantum vacuum is a powerful
concept that ultimately allows engineering the interaction between macroscopic
surfaces and quantum emitters such as atoms, molecules or quantum dots. The
long-range atom-surface interaction, known as Casimir-Polder interaction, is of
fundamental importance in quantum electrodynamics but also attracts a
significant interest for platforms that interface atoms with nanophotonic
devices. Here we perform a spectroscopic selective reflection measurement of
the Casimir-Polder interaction between a Cs(6P_{3/2}) atom and a nanostructured
metallic planar metamaterial. We show that by engineering the near-field
plasmonic resonances of the metamaterial, we can successfully tune the
Casimir-Polder interaction, demonstrating both a strong enhancement and
reduction with respect to its non-resonant value. We also show an enhancement
of the atomic spontaneous emission rate due to its coupling with the evanescent
modes of the nanostructure. Probing excited state atoms next to nontrivial
tailored surfaces is a rigorous test of quantum electrodynamics. Engineering
Casimir-Polder interactions represents a significant step towards atom trapping
in the extreme near field, possibly without the use of external fields.Comment: 21 pages, 9 figure
Optics of an opal modeled with a stratified effective index and the effect of the interface
Reflection and transmission for an artificial opal are described through a
model of stratified medium based upon a one-dimensional variation of an
effective index. The model is notably applicable to a Langmuir-Blodgett type
disordered opal. Light scattering is accounted for by a phenomenological
absorption. The interface region between the opal and the substrate -or the
vacuum- induces a periodicity break in the photonic crystal arrangement, which
exhibits a prominent influence on the reflection, notably away from the Bragg
reflection peak. Experimental results are compared to our model. The model is
extendable to inverse opals, stacked cylinders, or irradiation by evanescent
wavesComment: arXiv admin note: substantial text overlap with arXiv:1407.577
Integrated magneto-optical traps on a chip using silicon pyramid structures
International audienceWe have integrated magneto-optical traps (MOTs) into an atom chip by etching pyramids into a silicon wafer. These have been used to trap atoms on the chip, directly from a room temperature vapor of rubidium. This new atom trapping method provides a simple way to integrate several atom sources on the same chip. It represents a substantial advance in atom chip technology and offers new possibilities for atom chip applications such as integrated single atom or photon sources and molecules on a chip
Sub-Doppler optical resolution by confining a vapour in a nanostructure
We show that a thermal vapor confined in a nanostructure is of spectroscopic
interest. We perform reflection spectroscopy on a Cs vapour cell whose window
is covered with a thin opal film (typically, 10 or 20 layers of ~ 1{\mu}m
diameter spheres). Sub-Doppler structures appear in the optical spectrum in a
purely linear regime of optical excitation and the signal is shown to originate
from the interstitial regions of the opal. These narrow spectral structures,
observable for a large range of oblique incidence angles (~ 30-50°), are an
original feature associated to the 3-D vapor confinement. It remembers a Dicke
narrowing, i.e. a Doppler broadening suppression when the atomic motion is
sub-wavelength confined. This narrowing, commonly observed in the r.f. domain
when a buffer gas ensures a collision confinement effect, had remained elusive
in the optical frequency. Also, we describe preliminary experiments performed
in a pump-probe technique, intended to elucidate the spatial origin of the
narrow contribution. We finally discuss how our results allow envisioning
micron-size references for optical frequency clocks, and high resolution
spectroscopy of weak and hard-to-saturate molecular lines
Characteristics of integrated magneto-optical traps for atom chips
International audienceWe investigate the operation of pyramidal magneto-optical traps (MOTs) microfabricated in silicon. Measurements of the loading and loss rates give insight into the role of the nearby surface in the MOT dynamics. Studies of the fluorescence versus laser frequency and intensity allow us to develop a simple theory of operation. The number of 85Rb atoms trapped in the pyramid is approximately L6, where L . 6 is the size in mm. This follows quite naturally from the relation between capture velocity and size and differs from the L3.6 often used to describe larger MOTs. Our results constitute substantial progress towards fully integrated atomic physics experiments and devices
Rb otical resonance inside a random porous medium
International audienceWe studied resonant laser interaction with Rb atoms confined to the interstitial cavities of a random porous glass. Due to diffusive light propagation, the effect of atomic absorption on the light scattered by the sample is almost entirely compensated by atomic fluorescence at low atomic densities. For higher densities, radiation trapping increases the probability of non-radiative decay via atom-wall collisions. A simple connection of the fluorescence/absorption yield to the sample porosity is given
Infiltrating a thin or single layer opal with an atomic vapour: sub-doppler signals and crystal optics
Artificial thin glass opals can be infiltrated with a resonant alkali-metal
vapour, providing novel types of hybrid systems. The reflection at the
interface between the substrate and the opal yields a resonant signal, which
exhibits sub-Doppler structures in linear spectroscopy for a range of oblique
incidences. This result is suspected to originate in an effect of the
three-dimensional confinement of the vapour in the opal interstices. It is here
extended to a situation where the opal is limited to a few or even a single
layer opal film, which is a kind of bidimensional grating. We have developed a
flexible one-dimensional layered optical model, well suited for a
Langmuir-Blodgett opal. Once extended to the case of a resonant infiltration,
the model reproduces quick variations of the lineshape with incidence angle or
polarization. Alternately, for an opal limited to a single layer of identical
spheres, a three-dimensional numerical calculation was developed. It predicts
crystalline anisotropy, which is demonstrated through diffraction on an empty
opal made of a single-layer of polystyrene spheres.Comment: to appear in Europhysics Letters, Special Issue (Proceedings of META
14-Singapore May 2014
EXTRA SUB-DOPPLER LINES IN THE VICINITY OF THE THIRD RESONANCE 6S-8P OF ATOMIC Cs ATTRIBUTED TO OPTICALLY INDUCED Cs DIMERS
International audienceWe report on the observation of extra sub-Doppler lines in a saturated absorption experiment when exploring the vicinity of the 6S1/2 8P3/2 transition of Cs ( = 388 nm). These extra lines are observed only under a relatively strong irradiation of both the pump and the probe beams. Extra narrow lines are also observed in co-propagating nonlinear spectroscopy, and around the lines of the V-type three-level system 8P3/2 - 6S1/2 - 8P1/2 (1 = 388 nm, 2 = 389 nm). We attribute theses extra-lines to a probing of high-lying molecular caesium, produced as a result of the optical excitation of Cs atoms, as the low Cs atom density ( 1012cm-3) is unable to populate significantly the dimer states in the condition of thermal equilibrium
Three-dimensional confinement of vapor in nanostructures for sub-Doppler optical resolution
International audienceWe confine a Cs thermal vapor in the interstitial regions of a glass opal. We perform linear reflection spectroscopy on a cell whose window is covered with a thin film (10 or 20 layers) of 1000 nm (or 400 nm) diameter glass spheres and observe sub-Doppler structures in the optical spectrum for a large range of oblique incidences. This original feature associated with the inner (3-dimensional) confinement of the vapor in the interstitial regions of the opal evokes a Dicke narrowing. We finally consider possible micron-size references for optical frequency clocks based on weak, hard to saturate, molecular line
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