20 research outputs found
High contrast Mach-Zehnder lithium atom interferometer in the Bragg regime
We have constructed an atom interferometer of the Mach-Zehnder type,
operating with a supersonic beam of lithium. Atom diffraction uses Bragg
diffraction on laser standing waves. With first order diffraction, our
apparatus has given a large signal and a very good fringe contrast (74%), which
we believe to be the highest ever observed with atom interferometers. This
apparatus will be applied to high sensitivity measurementsComment: 6 pages, 3 figures, accepted by Appl. Phys.
Optimization of a Langmuir-Taylor detector for lithium
This paper describes the construction and optimization of a Langmuir-Taylor
detector for lithium, using a rhenium ribbon. The absolute detection
probability of this very sensitive detector is measured and the dependence of
this probability with oxygen pressure and surface temperature is studied.
Sources of background signal and their minimization are also discussed in
details. And a comparison between our data concerning the response time of the
detector and literature values is given. A theoretical analysis has been made:
this analysis supports the validity of the Saha-Langmuir law to relate the
ionization probability to the work function. Finally, the rapid variations of
the work function with oxygen pressure and temperature are explained by a
chemical equilibrium model.Comment: 11 pages, 7 figures, to appear in Rev. Sci. Instru
Planck's scale dissipative effects in atom interferometry
Atom interferometers can be used to study phenomena leading to
irreversibility and dissipation, induced by the dynamics of fundamental objects
(strings and branes) at a large mass scale. Using an effective, but physically
consistent description in terms of a master equation of Lindblad form, the
modifications of the interferometric pattern induced by the new phenomena are
analyzed in detail. We find that present experimental devices can in principle
provide stringent bounds on the new effects.Comment: 12 pages, plain-Te
Atomic diffraction by a laser standing wave: Analysis using Bloch states
Atomic diffraction by a laser stationary wave is
commonly used to build mirrors and beam splitters for atomic
interferometers. Many aspects of this diffraction process are
well understood but it is difficult to get an unified view of
this process because it is commonly described in several
approximate ways. We want to show here that a description
inspired by optics and using the exact Bloch description of the
atomic wave inside the laser standing wave is a tutorial way of
describing the various regimes by a single formalism. In order to
get simple analytic expressions of the diffraction amplitudes, we
consider a standing wave intensity with a flat transverse
profile. The resulting general expression of the diffraction
intensities is then compared to available analytical formulae in
the Raman-Nath limit and in the Bragg regime. We think that this
formalism can be fruitfully extended to study many important
questions
Diffraction phases in atom interferometry
Using Bloch states to describe atomic motion, we show how to calculate the phase shifts associated to atomic diffraction by a laser standing wave and we illustrate our calculation by the evaluation of the phase shifts in the contrast interferometer developed by D. Pritchard and co-workers [Phys. Rev. Lett. 89, 140401 (2002)]
An atom interferometer using thermal lithium atoms
We have built an atom interferometer of the Mach-Zehnder type, operating with thermal lithium atoms [1]. Its design is largely inspired by previous works done by the groups of D. Pritchard [2], A. Zeilinger [3] and S.A. Lee [4]. In our apparatus, the atomic wave is diffracted in the Bragg regime by three laser sanding waves to achieve a Mach-Zehnder configuration. This paper briefly recalls the diffraction process and shows the experimental results obtained in our group. Our apparatus is able to achieve a high fringe contrast of 74 % with a large mean detected atom flux of s. Finally, the paper ends with the measurement of the velocity distribution of our lithium beam using a light induced fluorescence technique