123 research outputs found
Slow light in degenerate Fermi gases
We investigate the effect of slow light propagating in a degenerate atomic
Fermi gas. In particular we use slow light with an orbital angular momentum. We
present a microscopic theory for the interplay between light and matter and
show how the slow light can provide an effective magnetic field acting on the
electrically neutral fermions, a direct analogy of the free electron gas in an
uniform magnetic field. As an example we illustrate how the corresponding de
Haas-van Alphen effect can be seen in a neutral gas of fermions.Comment: Slightly updated. Phys. Rev. Lett. 93, 033602 (2004
Enhancing capacity of coherent optical information storage and transfer in a Bose-Einstein condensate
Coherent optical information storage capacity of an atomic Bose-Einstein
condensate is examined. Theory of slow light propagation in atomic clouds is
generalized to short pulse regime by taking into account group velocity
dispersion. It is shown that the number of stored pulses in the condensate can
be optimized for a particular coupling laser power, temperature and interatomic
interaction strength. Analytical results are derived for semi-ideal model of
the condensate using effective uniform density zone approximation. Detailed
numerical simulations are also performed. It is found that axial density
profile of the condensate protects the pulse against the group velocity
dispersion. Furthermore, taking into account finite radial size of the
condensate, multi-mode light propagation in atomic Bose-Einstein condensate is
investigated. The number of modes that can be supported by a condensate is
found. Single mode condition is determined as a function of experimentally
accessible parameters including trap size, temperature, condensate number
density and scattering length. Quantum coherent atom-light interaction schemes
are proposed for enhancing multi-mode light propagation effects.Comment: 12pages. Laser Physics, in pres
Electromagnetically-induced transparency and light storing of a pair of pulses
Electromagnetically-induced transparency and light storing are studied in the
case of a medium of atoms in a double Lambda configuration, both in terms of
dark- and bright-state polatitons and atomic susceptibility. It is proven that
the medium can be made transparent simultaneously for two pulses following
their self-adjusting so that a condition for an adiabatic evolution has become
fulfilled. Analytic formulas are given for the shapes and phases of the
transmitted/stored pulses. The level of transparency can be regulated by
adjusting the heights and phases of the control fields.Comment: text +6 figure
Observation of light dragging in rubidium vapor cell
We report on the experimental demonstration of light dragging effect due to
atomic motion in a rubidium vapor cell. We found that the minimum group
velocity is achieved for light red-shifted from the center of the atomic
resonance, and that the value of this shift increases with decreasing group
velocity, in agreement with the theoretical predictions by Kocharovskaya,
Rostovtsev, and Scully [Phys. Rev. Lett. {\bf 86}, 628 (2001)].Comment: 4 pages 4 figures, submitted to PR
Polarization phase gate with a tripod atomic system
We analyze the nonlinear optical response of a four-level atomic system
driven into a tripod configuration. The large cross-Kerr nonlinearities that
occurr in such a system are shown to produce nonlinear phase shift of order
. Such a substantial shift may be observed in a cold atomic gas in a
magneto-optical trap where it coupl be fasibly exploited towards the
realization of a polarization quantum phase gate. The experimental feasibility
of such a gate is here examined in detail.Comment: Corrected versio
Effective magnetic fields in degenerate atomic gases induced by light beams with orbital angular momenta
We investigate the influence of two resonant laser beams on the mechanical
properties of degenerate atomic gases. The control and probe beams of light are
considered to have Orbital Angular Momenta (OAM) and act on the three-level
atoms in the Electromagnetically Induced Transparency (EIT) configuration. The
theory is based on the explicit analysis of the quantum dynamics of cold atoms
coupled with two laser beams. Using the adiabatic approximation, we obtain an
effective equation of motion for the atoms driven to the dark state. The
equation contains a vector potential type interaction as well as an effective
trapping potential. The effective magnetic field is shown to be oriented along
the propagation direction of the control and probe beams containing OAM. Its
spatial profile can be controlled by choosing proper laser beams. We
demonstrate how to generate a constant effective magnetic field, as well as a
field exhibiting a radial distance dependence. The resulting effective magnetic
field can be concentrated within a region where the effective trapping
potential holds the atoms. The estimated magnetic length can be considerably
smaller than the size of the atomic cloud.Comment: 11 pages, 5 figures Corrected some mistakes in equation
Selective addressing of high-rank atomic polarization moments
We describe a method of selective generation and study of polarization
moments of up to the highest rank possible for a quantum state with
total angular momentum . The technique is based on nonlinear magneto-optical
rotation with frequency-modulated light. Various polarization moments are
distinguished by the periodicity of light-polarization rotation induced by the
atoms during Larmor precession and exhibit distinct light-intensity and
frequency dependences. We apply the method to study polarization moments of
Rb atoms contained in a vapor cell with antirelaxation coating. Distinct
ultra-narrow (1-Hz wide) resonances, corresponding to different multipoles,
appear in the magnetic-field dependence of the optical rotation. The use of the
highest-multipole resonances has important applications in quantum and
nonlinear optics and in magnetometry.Comment: 5 pages, 6 figure
Trace formula for dielectric cavities II: Regular, pseudo-integrable, and chaotic examples
Dielectric resonators are open systems particularly interesting due to their
wide range of applications in optics and photonics. In a recent paper [PRE,
vol. 78, 056202 (2008)] the trace formula for both the smooth and the
oscillating parts of the resonance density was proposed and checked for the
circular cavity. The present paper deals with numerous shapes which would be
integrable (square, rectangle, and ellipse), pseudo-integrable (pentagon) and
chaotic (stadium), if the cavities were closed (billiard case). A good
agreement is found between the theoretical predictions, the numerical
simulations, and experiments based on organic micro-lasers.Comment: 18 pages, 32 figure
Slow Light Propagation in a Thin Optical Fiber via Electromagnetically Induced Transparency
We propose a novel configuration that utilizes electromagnetically induced
transparency (EIT) to tailor a fiber mode propagating inside a thin optical
fiber and coherently control its dispersion properties to drastically reduce
the group velocity of the fiber mode. The key to this proposal is: the
evanescent-like field of the thin fiber strongly couples with the surrounding
active medium, so that the EIT condition is met by the medium. We show how the
properties of the fiber mode is modified due to the EIT medium, both
numerically and analytically. We demonstrate that the group velocity of the new
modified fiber mode can be drastically reduced (approximately 44 m/sec) using
the coherently prepared orthohydrogen doped in a matrix of parahydrogen crystal
as the EIT medium.Comment: 10 pages in two column RevTex4, 6 Figure
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