55 research outputs found
Atom interferometry in an optical cavity
We propose and demonstrate a new scheme for atom interferometry, using light
pulses inside an optical cavity as matter wave beamsplitters. The cavity
provides power enhancement, spatial filtering, and a precise beam geometry,
enabling new techniques such as low power beamsplitters (), large momentum transfer beamsplitters with modest power, or new
self-aligned interferometer geometries utilizing the transverse modes of the
optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with
contrast and measure the acceleration due to gravity, , to
resolution in a Mach-Zehnder geometry.
We use cesium atoms in the compact mode volume (
waist) of the cavity and show trapping of atoms in higher transverse
modes. This work paves the way toward compact, high sensitivity, multi-axis
interferometry.Comment: 5 pages, 6 figure
New determination of the fine structure constant and test of the quantum electrodynamics
We report a new measurement of the ratio between the
Planck constant and the mass of atom. A new value of the
fine structure constant is deduced, with
a relative uncertainty of . Using this determination, we
obtain a theoretical value of the electron anomaly
which is in agreement with the
experimental measurement of Gabrielse
(). The comparison of these values
provides the most stringent test of the QED. Moreover, the precision is large
enough to verify for the first time the muonic and hadronic contributions to
this anomaly
Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy
In this paper, we present significant progress performed on an experiment
dedicated to the determination of the Boltzmann constant, k, by accurately
measuring the Doppler absorption profile of a line in a gas of ammonia at
thermal equilibrium. This optical method based on the first principles of
statistical mechanics is an alternative to the acoustical method which has led
to the unique determination of k published by the CODATA with a relative
accuracy of 1.7 ppm. We report on the first measurement of the Boltzmann
constant by laser spectroscopy with a statistical uncertainty below 10 ppm,
more specifically 6.4 ppm. This progress results from improvements in the
detection method and in the statistical treatment of the data. In addition, we
have recorded the hyperfine structure of the probed saQ(6,3) rovibrational line
of ammonia by saturation spectroscopy and thus determine very precisely the
induced 4.36 (2) ppm broadening of the absorption linewidth. We also show that,
in our well chosen experimental conditions, saturation effects have a
negligible impact on the linewidth. Finally, we draw the route to future
developments for an absolute determination of with an accuracy of a few ppm.Comment: 22 pages, 11 figure
Testing new physics with the electron g-2
We argue that the anomalous magnetic moment of the electron (a_e) can be used
to probe new physics. We show that the present bound on new-physics
contributions to a_e is 8*10^-13, but the sensitivity can be improved by about
an order of magnitude with new measurements of a_e and more refined
determinations of alpha in atomic-physics experiments. Tests on new-physics
effects in a_e can play a crucial role in the interpretation of the observed
discrepancy in the anomalous magnetic moment of the muon (a_mu). In a large
class of models, new contributions to magnetic moments scale with the square of
lepton masses and thus the anomaly in a_mu suggests a new-physics effect in a_e
of (0.7 +- 0.2)*10^-13. We also present examples of new-physics theories in
which this scaling is violated and larger effects in a_e are expected. In such
models the value of a_e is correlated with specific predictions for processes
with violation of lepton number or lepton universality, and with the electric
dipole moment of the electron.Comment: 34 pages, 7 figures. Minor changes and references adde
Atom lasers: production, properties and prospects for precision inertial measurement
We review experimental progress on atom lasers out-coupled from Bose-Einstein
condensates, and consider the properties of such beams in the context of
precision inertial sensing. The atom laser is the matter-wave analog of the
optical laser. Both devices rely on Bose-enhanced scattering to produce a
macroscopically populated trapped mode that is output-coupled to produce an
intense beam. In both cases, the beams often display highly desirable
properties such as low divergence, high spectral flux and a simple spatial mode
that make them useful in practical applications, as well as the potential to
perform measurements at or below the quantum projection noise limit. Both
devices display similar second-order correlations that differ from thermal
sources. Because of these properties, atom lasers are a promising source for
application to precision inertial measurements.Comment: This is a review paper. It contains 40 pages, including references
and figure
New Physics Searches Using Precision Spectroscopy
The exceptional precision attainable using modern spectroscopic techniques
provides a promising avenue to search for signatures of physics beyond the
Standard Model in tiny shifts of the energy levels of atoms and molecules. We
briefly review three categories of new-physics searches based in precision
measurements: tests of QED using measurements of the anomalous magnetic moment
of the electron and the value of the fine-structure constant, searches for time
variation of the fundamental constants, and searches for a permanent electric
dipole moment of an electron or atomic nucleus.Comment: Prepared for Advances in Atomic, Molecular, and Optical Physics vol
6
Precision tau physics
Precise measurements of the lepton properties provide stringent tests of the Standard Model and accurate determinations of its parameters. We overview the present status of tau physics, highlighting the most recent developments, and discuss the prospects for future improvements. The leptonic decays of the tau lepton probe the structure of the weak currents and the universality of their couplings to the W boson. The universality of the leptonic Z couplings has also been tested through Z -> l(+)l(-) decays. The hadronic tau decay modes constitute an ideal tool for studying low-energy effects of the strong interaction in very clean conditions. Accurate determinations of the QCD coupling and the Cabibbo mixing V-us have been obtained with tau data. The large mass of the tau opens the possibility to study many kinematically-allowed exclusive decay modes and extract relevant dynamical information. Violations of flavour and CP conservation laws can also be searched for with tau decays. Related subjects such as μdecays, the electron and muon anomalous magnetic moments, neutrino mixing and B-meson decays into tau leptons are briefly covered. Being one the fermions most strongly coupled to the scalar sector, the tau lepton is playing now a very important role at the LHC as a tool to test the Higgs properties and search for new physics at higher scales
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