51 research outputs found
Exploring the van der Waals Atom-Surface attraction in the nanometric range
The van der Waals atom-surface attraction, scaling as C3 z-3 for z the
atom-surface distance, is expected to be valid in the distance range 1-1000 nm,
covering 8-10 orders of magnitudes in the interaction energy. A Cs vapour
nanocell allows us to analyze the spectroscopic modifications induced by the
atom-surface attraction on the 6P3/2->6D5/2 transition. The measured C3 value
is found to be independent of the thickness in the explored range 40-130 nm,
and is in agreement with an elementary theoretical prediction. We also discuss
the specific interest of exploring short distances and large interaction
energy.Comment: to appear in Europhysics Letter
Progress in atom chips and the integration of optical microcavities
We review recent progress at the Centre for Cold Matter in developing atom
chips. An important advantage of miniaturizing atom traps on a chip is the
possibility of obtaining very tight trapping structures with the capability of
manipulating atoms on the micron length scale. We recall some of the pros and
cons of bringing atoms close to the chip surface, as is required in order to
make small static structures, and we discuss the relative merits of metallic,
dielectric and superconducting chip surfaces. We point out that the addition of
integrated optical devices on the chip can enhance its capability through
single atom detection and controlled photon production. Finally, we review the
status of integrated microcavities that have recently been demonstrated at our
Centre and discuss their prospects for future development.Comment: 12 pages, 6 figures, proceedings of the ICOLS07 conferenc
Anisotropic Atom-Surface Interactions in the Casimir-Polder Regime
The distance-dependence of the anisotropic atom-wall interaction is studied.
The central result is the 1/z^6 quadrupolar anisotropy decay in the retarded
Casimir-Polder regime. Analysis of the transition region between non-retarded
van der Waals regime (in 1/z^3) and Casimir-Polder regime shows that the
anisotropy cross-over occurs at very short distances from the surface, on the
order of 0.03 Lambda, where Lambda is the atom characteristic wavelength.
Possible experimental verifications of this distance dependence are discussed.Comment: 5 pages, 2 figure
Negative-index media for matter-wave optics
We consider the extension of optical meta-materials to matter waves. We show
that the generic property of pulsed comoving magnetic fields allows us to
fashion the wave-number dependence of the atomic phase shift. It can be used to
produce a transient negative group velocity of an atomic wave packet, which
results into a negative refraction of the matter wave. Application to slow
metastable argon atoms Ar*(3P2) shows that the device is able to operate either
as an efficient beam splitter or an atomic meta-lens. Implications of
"meta-media" in atom optics are considered.Comment: 4 pages, 4 figures, submitted at PRL 4 November 200
Atom detection and photon production in a scalable, open, optical microcavity
A microfabricated Fabry-Perot optical resonator has been used for atom
detection and photon production with less than 1 atom on average in the cavity
mode. Our cavity design combines the intrinsic scalability of microfabrication
processes with direct coupling of the cavity field to single-mode optical
waveguides or fibers. The presence of the atom is seen through changes in both
the intensity and the noise characteristics of probe light reflected from the
cavity input mirror. An excitation laser passing transversely through the
cavity triggers photon emission into the cavity mode and hence into the
single-mode fiber. These are first steps towards building an optical
microcavity network on an atom chip for applications in quantum information
processing.Comment: 4 pages, 4 figures. A typographical error in the published paper has
been corrected (equation of the corrected normalized variance, page 3, 2nd
paragraph
Quadrupole transitions near interface: general theory and application to atom inside a planar cavity
Quadrupole radiation of an atom in an arbitrary environment is investigated
within classical as well as quantum electrodynamical approaches. Analytical
expressions for decay rates are obtained in terms of Green function of Maxwell
equations. The equivalence of both approaches is shown. General expressions are
applied to analyze the quadrupole decay rate of an atom placed between two half
spaces with arbitrary dielectric constant. It is shown that in the case when
the atom is close to the surface, the total decay rate is inversely
proportional to the fifth power of distance between an atom and a plane
interface.Comment: 18 pages, 7 figure
Dynamics of evanescent matter waves in negative-index media
International audiencenumbers: 03.75.-b Matter Waves 03.75.Be Atom and Neutron Optics 37.10.Gh Atom Traps and Guides 42.25.-p Wave Optics ABSTRACT Semi-evanescent and evanescent matter-waves produced by an atom wave packet impinging a repulsive barrier can be back-refracted and reconstructed by the application of negative-index " comoving " potential pulses. One shows that those collapses and revivals generate a matter wave confined on both sides of the barrier border (" surface matter wave ") and should be observable via the retardation of atom reflection from the barrier interface. This property, joined to the possibility recently demonstrated of inducing negative refraction of atom waves, makes such potentials a matter-wave counterpart of negative-index materials or " meta materials " well-known in light optics
Saturation effects in the sub-Doppler spectroscopy of Cesium vapor confined in an Extremely Thin Cell
Saturation effects affecting absorption and fluorescence spectra of an atomic
vapor confined in an Extremely Thin Cell (cell thickness ) are
investigated experimentally and theoretically. The study is performed on the
line ( of and concentrates on the two
situations and , the most contrasted ones with
respect to the length dependence of the coherent Dicke narrowing. For , the Dicke-narrowed absorption profile simply broadens and
saturates in amplitude when increasing the light intensity, while for , sub-Doppler dips of reduced absorption at line-center appear on the
broad absorption profile. For a fluorescence detection at ,
saturation induces narrow dips, but only for hyperfine components undergoing a
population loss through optical pumping. These experimental results are
interpreted with the help of the various existing models, and are compared with
numerical calculations based upon a two-level modelling that considers both a
closed and an open system.Comment: 11 pages, 12 figure
High contrast D line electromagnetically induced transparency in nanometric-thin rubidium vapor cell
Electromagnetically induced transparency (EIT) on atomic D line of
rubidium is studied using a nanometric-thin cell with atomic vapor column
length in the range of L= 400 - 800 nm. It is shown that the reduction of the
cell thickness by 4 orders as compared with an ordinary cm-size cell still
allows to form an EIT resonance for ( nm) with the
contrast of up to 40%. Remarkable distinctions of EIT formation in
nanometric-thin and ordinary cells are demonstrated. Despite the Dicke effect
of strong spectral narrowing and increase of the absorption for , EIT resonance is observed both in the absorption and the fluorescence
spectra for relatively low intensity of the coupling laser. Well resolved
splitting of the EIT resonance in moderate magnetic field for
can be used for magnetometry with nanometric spatial resolution. The presented
theoretical model well describes the observed results.Comment: Submitted to Applied Physics B: Lasers and Optics, 9 pages, 10
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