Experiments with atomics

Otto Robert Frisch

J P Connerade, G Droungas, Roger Elliott +6 more

We present a report on experiments performed at Imperial College on diamagnetic effects in many-electron atoms. These include both atomic-beam experiments with DC fields, for which the measurement technique involves detecting Rydberg atoms after laser excitation, and experiments on columns of atomic vapour, in which case we have studied Faraday rotation induced by a pulsed magnetic field. In the atomic-beam experiments, interesting differences between the sigma + and sigma - spectra have been observed. We also describe theoretical work related to the interpretation of the data for both sets of experiments.

Alexander D. Cronin, John D. Perreault

Four atom optics experiments that each serve to measure atom-surface interactions near nanofabricated gratings are presented here. In these experiments atoms in a beam travel within 25 nm of a material grating bar, and the analysis incorporates phase shifts for the atomic de Broglie waves due to interactions betwen Na atoms and silicon nitride surfaces. One atom diffraction experiment determines the van der Waals coeficient C 3 = 2.7 ± 0.8 meV nm 3 , and one atom interferometer experiment determines C 3 = 4 ± 1 meV nm 3 . The results of all four experiments are consistent with the Lifshitz prediction that is explicitly calculated here for Nasilicon nitride to be C 3 = 3.25 meV nm 3 . The four atom optics experiments and review of van der Waals theory are complemented by similar experiments using electron beams and analysis of image-charge effects.

Oskar J. Painter

Christoph Ira Westbrook, M. Schellekens, A. Perrin +12 more

We discuss experiments to produce and detect atom correlations in a degenerate or nearly degenerate gas of neutral atoms. First we treat the atomic analog of the celebrated Hanbury Brown Twiss experiment, in which atom correlations result simply from interference effects without any atom interactions. We have performed this experiment for both bosons and fermions. Next we show how atom interactions produce correlated atoms using the atomic analog of spontaneous four‐wave mixing. Finally, we briefly mention experiments on a one dimensional gas on an atom chip in which correlation effects due to both interference and interactions have been observed.