1,274 research outputs found
High-Spatial-Resolution Monitoring of Strong Magnetic Field using Rb vapor Nanometric-Thin Cell
We have implemented the so-called -Zeeman technique (LZT) to
investigate individual hyperfine transitions between Zeeman sublevels of the Rb
atoms in a strong external magnetic field in the range of G
(recently it was established that LZT is very convenient for the range of G). Atoms are confined in a nanometric thin cell (NTC) with the thickness
, where is the resonant wavelength 794 nm for Rb
line. Narrow velocity selective optical pumping (VSOP) resonances in the
transmission spectrum of the NTC are split into several components in a
magnetic field with the frequency positions and transition probabilities
depending on the -field. Possible applications are described, such as
magnetometers with nanometric local spatial resolution and tunable atomic
frequency references.Comment: 12 page
Dual coherent particle emission as generalized two-component Cherenkov-like effect
In this Letter we introduce a new kind of coherent particle production
mechanism called dual coherent particle emission (DCPE) as generalized
two-component Cherenkov-like effect, which takes place when the phase velocity
of emitted particle v_{Mph} and the particle source phase velocity v_{B_1ph}
satisfy a specific DCPE condition: v_{Mph} <= v_{B_1ph}^{-1}. The general
signatures of the DCPE in dielectric, nuclear and hadronic media are
established and some experimental evidences are presented.Comment: 12 pages, 4 fig
Dual coherent particle emission as generalised Cherenkov-like effect in high energy particle collisions
In this paper we introduce a new kind of nuclear/hadronic coherent particle
production mechanism in high-energy collisions called \emph{dual coherent
particle emission (DCPE)} which takes place when the phase velocities of the
emitted particle v_{Mph} and that of particle source v_{B_1ph} satisfy the dual
coherence condition: v_{Mph} <= v_{B_1ph}^-1. The general signatures of the
DCPE in the nuclear and hadronic media are established and some experimental
evidences are given.Comment: 5 pages, 5 eps figs., revtex4 styl
An Alkali-Vapor Cell with Metal Coated Windows for Efficient Application of an Electric Field
We describe the implementation of a cylindrical T-shaped alkali-vapor cell
for laser spectroscopy in the presence of a longitudinal electric field. The
two windows are used as two electrodes of the high-voltage assembly, which is
made possible by a metallic coating which entirely covers the inner and outer
sides of the windows except for a central area to let the laser beams in and
out of the cell. This allows very efficient application of the electric field,
up to 2 kV/cm in a rather dense superheated vapor, even when significant
photoemission takes place at the windows during pulsed laser irradiation. The
body of the cell is made of sapphire or alumina ceramic to prevent large
currents resulting from surface conduction observed in cesiated glass cells.
The technique used to attach the monocrystalline sapphire windows to the cell
body causes minimal stress birefringence in the windows. In addition,
reflection losses at the windows can be made very small. The vapor cell
operates with no buffer gas and has no magnetic part. The use of this kind of
cell has resulted in an improvement of the signal-to-noise ratio in the
measurement of Parity Violation in cesium vapor underway at ENS, Paris. The
technique can be applied to other situations where a brazed assembly would give
rise to unacceptably large birefringence in the windows
Complete hyperfine Paschen-Back regime at relatively small magnetic fields realized in Potassium nano-cell
A one-dimensional nano-metric-thin cell (NC) filled with potassium metal has
been built and used to study optical atomic transitions in external magnetic
fields. These studies benefit from the remarkable features of the NC allowing
one to use - and -methods for effective investigations of
individual transitions of the K D_1 line. The methods are based on strong
narrowing of the absorption spectrum of the atomic column of thickness L equal
to and to (with \lambda = 770\un{nm} being the resonant
laser radiation wavelength). In particular, for a -polarized radiation
excitation the -method allows us to resolve eight atomic transitions
(in two groups of four atomic transitions) and to reveal two remarkable
transitions that we call Guiding Transitions (GT). The probabilities of all
other transitions inside the group (as well as the frequency slope versus
magnetic field) tend to the probability and to the slope of GT. Note that for
circular polarization there is one group of four transitions and GT do not
exist. Among eight transitions there are also two transitions (forbidden for
= 0) with the probabilities undergoing strong modification under the
influence of magnetic fields. Practically the complete hyperfine Paschen-Back
regime is observed at relatively low (\sim 1\un{kG}) magnetic fields. Note
that for K line GT are absent. Theoretical models describe the experiment
very well.Comment: 6 page
Nonlinear magneto-optical resonances at D1 excitation of 85Rb and 87Rb in an extremely thin cell
Nonlinear magneto-optical resonances have been measured in an extremely thin
cell (ETC) for the D1 transition of rubidium in an atomic vapor of natural
isotopic composition. All hyperfine transitions of both isotopes have been
studied for a wide range of laser power densities, laser detunings, and ETC
wall separations. Dark resonances in the laser induced fluorescence (LIF) were
observed as expected when the ground state total angular momentum F_g was
greater than or equal to the excited state total angular momentum F_e. Unlike
the case of ordinary cells, the width and contrast of dark resonances formed in
the ETC dramatically depended on the detuning of the laser from the exact
atomic transition. A theoretical model based on the optical Bloch equations was
applied to calculate the shapes of the resonance curves. The model averaged
over the contributions from different atomic velocity groups, considered all
neighboring hyperfine transitions, took into account the splitting and mixing
of magnetic sublevels in an external magnetic field, and included a detailed
treatment of the coherence properties of the laser radiation. Such a
theoretical approach had successfully described nonlinear magneto-optical
resonances in ordinary vapor cells. Although the values of certain model
parameters in the ETC differed significantly from the case of ordinary cells,
the same physical processes were used to model both cases. However, to describe
the resonances in the ETC, key parameters such as the transit relaxation rate
and Doppler width had to be modified in accordance with the ETC's unique
features. Agreement between the measured and calculated resonance curves was
satisfactory for the ETC, though not as good as in the case of ordinary cells.Comment: v2: substantial changes and expanded theoretical model; 13 pages, 10
figures; accepted for publication in Physical Review
Magnetic field--induced modification of selection rules for Rb D line monitored by selective reflection from a vapor nanocell
Magnetic field-induced giant modification of the probabilities of five
transitions of of Rb and
three transitions of of Rb
forbidden by selection rules for zero magnetic field has been observed
experimentally and described theoretically for the first time. For the case of
excitation with circularly-polarized () laser radiation, the
probability of transition becomes
the largest among the seventeen transitions of Rb group, and the probability of transition becomes the largest among the nine transitions of
Rb group, in a wide range of magnetic
field 200 -- 1000 G. Complete frequency separation of individual Zeeman
components was obtained by implementation of derivative selective reflection
technique with a 300 nm-thick nanocell filled with Rb, allowing formation of
narrow optical resonances. Possible applications are addressed. The theoretical
model is perfectly consistent with the experimental results.Comment: 6 pages, 5 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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