arXiv subjects
Publications and source records attributed to Jacques Vigue.
In this paper, we describe in detail the BMV (Biréfringence Magnétique du Vide) experiment, a novel apparatus to study the propagation of light in a transverse magnetic field. It is based on a very high finesse Fabry-Perot cavity and on pulsed magnets specially designed for this purpose. We justify our technical choices and we present the current status and perspectives.
We have built an atom interferometer and, by applying an electric field on one of the two interfering beams, we have measured the static electric polarizability of lithium with a 0.66 % uncertainty. Our experiment is similar to an experiment done on sodium in 1995 by D. Pritchard and co-workers, with several improvements: the electric field can be calculated analytically and our phase measurements are very accurate. This experiment illustrates the extreme sensitivity of atom interferometry: when the atom enters the electric field, its velocity increases and the fractional change, equal to 4 x 10^(-9) for our largest field, is measured with a 10^(-3) accuracy.
We have built and operated an atom interferometer of the Mach-Zehnder type. The atomic wave is a supersonic beam of lithium seeded in argon and the mirrors and beam-splitters for the atomic wave are based on elastic Bragg diffraction on laser standing waves at 671 nm. We give here a detailed description of our experimental setup and of the procedures used to align its components. We then present experimental signals, exhibiting atomic interference effects with a very high visibility, up to 84.5 %. We describe a series of experiments testing the sensitivity of the fringe visibility to the main alignment defects and to the magnetic field gradient.
We have found recently that, in a supersonic expansion of a mixture of two monoatomic gases, the parallel temperatures of the two gases can be very different. This effect is large if the seeded gas is highly diluted and if its atomic mass is considerably smaller than the one of the carrier gas. In the present paper, we present a complete derivation of our theoretical analysis of this effect. Our calculation is a natural extension of the existing theory of supersonic cooling to the case of a gas mixture, in the high dilution limit. Finally, we describe a set of temperature measurements made on a beam of lithium seeded in argon. Our experimental results are in very good agreement with the results of our calculation.
Diffraction of atoms by laser is a very important tool for matter wave optics. Although this process is well understood, the phase shifts induced by this diffraction process are not well known. In this paper, we make analytic calculations of these phase shifts in some simple cases and we use these results to model the contrast interferometer recently built by the group of D. Pritchard at MIT. We thus show that the values of the diffraction phases are large and that they probably contribute to the phase noise observed in this experiment.