674 research outputs found
Three level atom optics via the tunneling interaction
Three level atom optics (TLAO) is introduced as a simple, efficient and
robust method to coherently manipulate and transport neutral atoms. The
tunneling interaction among three trapped states allows to realize the spatial
analog of the stimulated Raman adiabatic passage (STIRAP), coherent population
trapping (CPT), and electromagnetically induced transparency (EIT) techniques.
We investigate a particular implementation in optical microtrap arrays and show
that under realistic parameters the coherent manipulation and transfer of
neutral atoms among dipole traps could be realized in the millisecond range.Comment: 5 pages, 6 figure
On Galilean invariance and nonlinearity in electrodynamics and quantum mechanics
Recent experimental results on slow light heighten interest in nonlinear
Maxwell theories. We obtain Galilei covariant equations for electromagnetism by
allowing special nonlinearities in the constitutive equations only, keeping
Maxwell's equations unchanged. Combining these with linear or nonlinear
Schroedinger equations, e.g. as proposed by Doebner and Goldin, yields a
Galilean quantum electrodynamics.Comment: 12 pages, added e-mail addresses of the authors, and corrected a
misprint in formula (2.10
Coherent Patterning of Matter Waves with Subwavelength Localization
We propose the Subwavelength Localization via Adiabatic Passage (SLAP)
technique to coherently achieve state-selective patterning of matter waves well
beyond the diffraction limit. The SLAP technique consists in coupling two
partially overlapping and spatially structured laser fields to three internal
levels of the matter wave yielding state-selective localization at those
positions where the adiabatic passage process does not occur. We show that by
means of this technique matter wave localization down to the single nanometer
scale can be achieved. We analyze in detail the potential implementation of the
SLAP technique for nano-lithography with an atomic beam of metastable Ne* and
for coherent patterning of a two-component 87Rb Bose-Einstein condensate.Comment: 6 pages, 5 figure
The response of a neutral atom to a strong laser field probed by transient absorption near the ionisation threshold
We present transient absorption spectra of an extreme ultraviolet attosecond pulse train in helium dressed by an 800 nm laser field with intensity ranging from W/cm to W/cm. The energy range probed spans 16-42 eV, straddling the first ionisation energy of helium (24.59 eV). By changing the relative polarisation of the dressing field with respect to the attosecond pulse train polarisation we observe a large change in the modulation of the absorption reflecting the vectorial response to the dressing field. With parallel polarized dressing and probing fields, we observe significant modulations with periods of one half and one quarter of the dressing field period. With perpendicularly polarized dressing and probing fields, the modulations of the harmonics above the ionisation threshold are significantly suppressed. A full-dimensionality solution of the single-atom time-dependent Schr odinger equation obtained using the recently developed ab-initio time-dependent B-spline ADC method reproduce some of our observations
Dark States and Coherent Control of Spin States in Molecular Magnets
We propose a scheme to realize coherent control of spin states of molecule
magnet, Ni. We introduce transverse magnetic fields with special
frequencies. When the frequencies of transverse magnetic fields match in some
conditions, we obtain dark states in Ni molecules. Through adjusting the
magnitude of magnetic fields, we can obtain any arbitrary superposition of the
two ground spin states of Ni molecules.Comment: 7 pages, 4 figures. To appear in Physical Review
Enhancement of Kerr nonlinearity via multi-photon coherence
We propose a new method of resonant enhancement of optical Kerr nonlinearity
using multi-level atomic coherence. The enhancement is accompanied by
suppression of the other linear and nonlinear susceptibility terms of the
medium. We show that the effect results in a modification of the nonlinear
Faraday rotation of light propagating in an Rb87 vapor cell by changing the
ellipticity of the light.Comment: 4 pages, 3 figures Submitted to Optics Letter
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