57 research outputs found
Test of the He-McKellar-Wilkens topological phase by atom interferometry. Part I: theoretical discussion
We have recently tested the topological phase predicted by He and McKellar
and by Wilkens: this phase appears when an electric dipole propagates in a
transverse magnetic field. In the present paper, we first recall the physical
origin of this phase and its relations to the Aharononov-Bohm and
Aharonov-Casher phases. We then explain possible detection schemes and we
briefly describe the lithium atom interferometer we have used for this purpose.
Finally, we analyze in great detail the phase shifts induced by electric and
magnetic fields acting on such an interferometer, taking into account
experimental defects. The experiment and its results are described in a
companion paper
Optical pumping of a lithium atomic beam for atom interferometry
We apply optical pumping to prepare the lithium beam of our atom
interferometer in a single hyperfine-Zeeman sublevel: we use two components of
the D1-line for pumping the 7Li atoms in a dark state F,mF=+2 (or -2) sublevel.
The optical pumping efficiency has been characterized by two techniques:
state-selective laser atom deflection or magnetic dephasing of the atom
interferometer signals. The first technique has not achieved a high
sensitivity, because of a limited signal to noise ratio, but magnetic dephasing
signals have shown that about 95% of the population has been transferred in the
aimed sublevel, with similar results for three mean velocities of the atomic
beam covering the range 744-1520m/s
Test of the He-McKellar-Wilkens topological phase by atom interferometry. Part II: the experiment and its results
In this paper, we describe an experimental test of the He-McKellar-Wilkens
(HMW) topological phase with our lithium atom interferometer. The expected
value of the HMW phase shift in our experiment is small and its measurement was
difficult because of stray phase shifts due to small experimental defects. We
start by describing our setup and we characterize the effects of the electric
and magnetic fields needed to observe the HMW effect. Then, we develop a model
of our interferometer signals including all the defects we have identified.
After various tests of this model, we use it to suppress the largest part of
the stray phase shifts. We thus obtain a series of measurements of the HMW
phase: the results are 31% larger than expected and this discrepancy is
probably due to some limitations of our model
Measurement of the Aharonov-Casher geometric phase with a separated-arm atom interferometer
In this letter, we report a measurement of the Aharonov-Casher (AC) geometric
phase with our lithium atom interferometer. The AC phase appears when a
particle carrying a magnetic dipole propagates in a transverse electric field.
The first measurement of the AC phase was done with a neutron interferometer in
1989 by A. Cimmino \textit{et al.} (Phys. Rev. Lett. \textbf{63}, 380, 1989)
and all the following experiments were done with Ramsey or Ramsey-Bord\'e
interferometers with molecules or atoms. In our experiment, we use lithium
atoms pumped in a single hyperfine-Zeeman sublevel and we measure the AC-phase
by applying opposite electric fields on the two interferometer arms. Our
measurements are in good agreement with the expected theoretical values and
they prove that this phase is independent of the atom velocity.Comment: 6 page
Measurement of the Boltzmann constant by the Doppler broadening technique at a 3,8x10-5 accuracy level
In this paper, we describe an experiment performed at the Laboratoire de
Physique des Lasers and dedicated to an optical measurement of the Boltzmann
constant. With the proposed innovative technique, determining comes down to an
ordinary frequency measurement. The method consists in measuring as accurately
as possible the Doppler absorption profile of a rovibrational line of ammonia
in thermal equilibrium. This profile is related to the Maxwell-Boltzmann
molecular velocity distribution along the laser beam. A fit of the absorption
line shape leads to a determination of the Doppler width proportional to
sqrt(kT) and thus to a determination of the Boltzmann constant. The laser
source is an ultra-stable CO2 laser with a wavelength . The absorption cell is
placed in a thermostat keeping the temperature at 273.15 K within 1.4 mK. We
were able to measure with a relative uncertainty as small as 3.8x10-5, which
represents an improvement of an order of magnitude for an integration time
comparable to our previous measurement published in 2007 [1
Measurement of the sensitivity function in time-domain atomic interferometer
submitted to IEEE Trans. Instrum. Meas.We present here an analysis of the sensitivity of a time-domain atomic interferometer to the phase noise of the lasers used to manipulate the atomic wave-packets. The sensitivity function is calculated in the case of a three pulse Mach-Zehnder interferometer, which is the configuration of the two inertial sensors we are building at BNM-SYRTE. We successfully compare this calculation to experimental measurements. The sensitivity of the interferometer is limited by the phase noise of the lasers, as well as by residual vibrations. We evaluate the performance that could be obtained with state of the art quartz oscillators, as well as the impact of the residual phase noise of the phase-lock loop. Requirements on the level of vibrations is derived from the same formalism
Off-resonant Raman transitions impact in an atom interferometer
International audienceWe study the influence of off-resonant two photon transitions on high precision measurements with atom interferometers based on stimulated Raman transitions. These resonances induce a two photon light shift on the resonant Raman condition. The impact of this effect is investigated in two highly sensitive experiments: a gravimeter and a gyroscope-accelerometer. We show that it can lead to significant systematic phase shifts, which have to be taken into account in order to achieve best performances in term of accuracy and stability
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