605 research outputs found
Coherent spin mixing dynamics in a spin-1 atomic condensate
We study the coherent off-equilibrium spin mixing inside an atomic
condensate. Using mean field theory and adopting the single spatial mode
approximation (SMA), the condensate spin dynamics is found to be well described
by that of a nonrigid pendulum, and displays a variety of periodic oscillations
in an external magnetic field. Our results illuminate several recent
experimental observations and provide critical insights into the observation of
coherent interaction-driven oscillations in a spin-1 condensate.Comment: 6 pages, 5 eps figures, update the discussion of the experimental
result
Pseudoresonance mechanism of all-optical frequency standard operation
We propose a novel approach to all-optical frequency standard design, based
on a counterintuitive combination of the coherent population trapping effect
and signal discrimination at the maximum of absorption for the probe radiation.
The short-term stability of such a standard can achieve the level of
10^-14/(\tau)^1/2. The physics beyond this approach is dark resonance splitting
caused by interaction of the nuclear magnetic moment with the external magnetic
field.Comment: revtex4, references adde
Measurement of the Blackbody Radiation Shift of the 133Cs Hyperfine Transition in an Atomic Fountain
We used a Cs atomic fountain frequency standard to measure the Stark shift on
the ground state hyperfine transiton frequency in cesium (9.2 GHz) due to the
electric field generated by the blackbody radiation. The measures relative
shift at 300 K is -1.43(11)e-14 and agrees with our theoretical evaluation
-1.49(07)e-14. This value differs from the currently accepted one
-1.69(04)e-14. The difference has a significant implication on the accuracy of
frequency standards, in clocks comparison, and in a variety of high precision
physics tests such as the time stability of fundamental constants.Comment: 4 pages, 2 figures, 2 table
Pulsed beams as field probes for precision measurement
We describe a technique for mapping the spatial variation of static electric,
static magnetic, and rf magnetic fields using a pulsed atomic or molecular
beam. The method is demonstrated using a beam designed to measure the electric
dipole moment of the electron. We present maps of the interaction region,
showing sensitivity to (i) electric field variation of 1.5 V/cm at 3.3 kV/cm
with a spatial resolution of 15 mm; (ii) magnetic field variation of 5 nT with
25 mm resolution; (iii) radio-frequency magnetic field amplitude with 15 mm
resolution. This new diagnostic technique is very powerful in the context of
high-precision atomic and molecular physics experiments, where pulsed beams
have not hitherto found widespread application.Comment: 6 pages, 12 figures. Figures heavily compressed to comply with
arxiv's antediluvian file-size polic
Investigation of microwave transitions and nonlinear magneto-optical rotation in anti-relaxation-coated cells
Using laser optical pumping, widths and frequency shifts are determined for
microwave transitions between ground-state hyperfine components of Rb
and Rb atoms contained in vapor cells with alkane anti-relaxation
coatings. The results are compared with data on Zeeman relaxation obtained in
nonlinear magneto-optical rotation (NMOR) experiments, a comparison important
for quantitative understanding of spin-relaxation mechanisms in coated cells.
By comparing cells manufactured over a forty-year period we demonstrate the
long-term stability of coated cells, an important property for atomic clocks
and magnetometers
Non-Destructive Probing of Rabi Oscillations on the Cesium Clock Transition near the Standard Quantum Limit
We report on non-destructive observation of Rabi oscillations on the Cs clock
transition. The internal atomic state evolution of a dipole-trapped ensemble of
cold atoms is inferred from the phase shift of a probe laser beam as measured
using a Mach-Zehnder interferometer. We describe a single color as well as a
two-color probing scheme. Using the latter, measurements of the collective
pseudo-spin projection of atoms in a superposition of the clock states are
performed and the observed spin fluctuations are shown to be close to the
standard quantum limit.Comment: 4 pages, 4 figures, accepted for publication in Physical Review
Letter
Parity nonconservation in Atomic Zeeman Transitions
We discuss the possibility of measuring nuclear anapole moments in atomic
Zeeman transitions and perform the necessary calculations. Advantages of using
Zeeman transitions include variable transition frequencies and the possibility
of enhancement of parity nonconservation effects
Metrological characterization of the pulsed Rb clock with optical detection
We report on the implementation and the metrological characterization of a
vapor-cell Rb frequency standard working in pulsed regime. The three main parts
that compose the clock, physics package, optics and electronics, are described
in detail in the paper. The prototype is designed and optimized to detect the
clock transition in the optical domain. Specifically, the reference atomic
transition, excited with a Ramsey scheme, is detected by observing the
interference pattern on a laser absorption signal.
\ The metrological analysis includes the observation and characterization of
the clock signal and the measurement of frequency stability and drift. In terms
of Allan deviation, the measured frequency stability results as low as
, being the averaging time, and
reaches the value of few units of for s, an
unprecedent achievement for a vapor cell clock. We discuss in the paper the
physical effects leading to this result with particular care to laser and
microwave noises transferred to the clock signal. The frequency drift, probably
related to the temperature, stays below per day, and no evidence of
flicker floor is observed.
\ We also mention some possible improvements that in principle would lead to
a clock stability below the level at 1 s and to a drift of few units
of per day
Buffer-gas induced absorption resonances in Rb vapor
We observe transformation of the electromagnetically induced transparency
(EIT) resonance into the absorption resonance in a interaction
configuration in a cell filled with Rb and a buffer gas. This
transformation occurs as a one-photon detuning of the coupling fields is varied
from the atomic transition. No such absorption resonance is found in the
absence of a buffer gas. The width of the absorption resonance is several times
smaller than the width of the EIT resonance, and the changes of absorption near
these resonances are about the same. Similar absorption resonances are detected
in the Hanle configuration in a buffered cell.Comment: 11 pages, 15 figures; 13 pages, 17 figures, added numerical
simulatio
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