High-contrast interference in a thermal cloud of atoms (4 pages)

X.-H. Chen, Yanhua Zhai

Daniel E. Miller, J. R. Anglin, J. R. Abo-Shaeer +3 more

The coherence properties of a gas of bosonic atoms above the Bose-Einstein-condensation transition temperature were studied. Bragg diffraction was used to create two spatially separated wave packets, which interfere during expansion. Given sufficient expansion time, high fringe contrast could be observed in a cloud of arbitrary temperature. Fringe visibility greater than 90% was observed, which decreased with increasing temperature, in agreement with a simple model. When the sample was ``filtered'' in momentum space using long, velocity-selective Bragg pulses, the contrast was significantly enhanced in contrast to predictions.

Mikhail Vladimirovich Fedorov, Н. П. Полуэктов

Rachel Sapiro, R. Zhang, Georg A. Raithel

We demonstrate two atom interferometric schemes based on Kapitza-Dirac scattering in a magnetic trap. In the first method, two Kapitza-Dirac scattering pulses are applied with a small time delay between them. High contrast interference is observed both using a thermal cloud and a Bose-Einstein condensate (BEC). In the second method, two Kapitza-Dirac scattering pulses are applied to a BEC with a time separation sufficiently large that the interfering orders complete half an oscillation in the magnetic trap; this enables interferometry between spatially separated paths.

G. Labeyrie, Dominique Delande, Robin Kaiser +1 more

We use the coherent backscattering interference effect to investigate experimentally and theoretically how coherent transport of light inside a cold atomic vapor is affected by the residual motion of atomic scatterers. As the temperature of the atomic cloud increases, the interference contrast decreases dramatically. This emphasizes the role of motion-induced decoherence for resonant scatterers even in the sub-Doppler regime of temperature. We derive analytical expressions for the corresponding coherence time.

Veniamin P. Chebotayev, B. Dubetsky, A. P. Kazantsev +1 more