Nathalie Westbrook

Specular reflection of matter waves from a rough mirror.

We present a high resolution study of the specularity of the atomic reflection from an evanescent wave mirror using velocity selective Raman transitions. We observed a double structure in the velocity distribution after reflection: a peak consistent with specular reflection and a diffuse reflection pedestal whose contribution decreases rapidly with increasing detuning. The diffuse reflection is due to two distinct effects: spontaneous emission in the evanescent wave and roughness in the evanescent wave potential whose amplitude is smaller than the de Broglie wavelength of the reflected atoms.

PROPERTIES OF MICROELECTROMAGNET MIRRORS AS REFLECTORS OF COLD RB ATOMS

Cryogenically cooled microelectromagnet mirrors were used to reflect a cloud of free-falling laser-cooled

Theory of atomic diffraction from evanescent waves

{}^{85}\mathrm{Rb}

Optical detection of cold atoms without spontaneous emission

atoms at normal incidence. The mirrors consisted of microfabricated current-carrying Au wires in a periodic serpentine pattern on a sapphire substrate. The fluorescence from the atomic cloud was imaged after it had bounced off a mirror. The transverse width of the cloud reached a local minimum at an optimal current corresponding to minimum mirror roughness. A distinct increase in roughness was found for mirror configurations with an even versus odd number of lines. These observations confirm theoretical predictions.

Resolved diffraction patterns from a reflection grating for atoms

Abstract.We review recent theoretical models and experiments dealing with the diffraction of neutral atoms by a reflection grating, formed by a standing evanescent wave. We analyze diffraction mechanisms proposed for normal and grazing incidence, point out their scopes and confront the theory with experiment.

An atom interferometer for measuring loss of coherence from an atom mirror

We have demonstrated nondestructive detection of cold atoms with a probe laser by a frequency-modulation spectroscopy technique. We were able to tune the probe laser and its sidebands far from atomic resonance to reduce the spontaneous emission to less than 0.2 photon per atom during detection.

Bouncing atoms: A coherent nano-probe

We have studied atomic diffraction at normal incidence from an evanescent standing wave with high resolution using velocity-selective Raman transitions. We have observed up to three resolved orders of diffraction, which are well accounted for using scalar diffraction theory. In our experiment the transverse coherence length of the source is greater than the period of the diffraction grating.

Using atomic interference to probe atom-surface interactions

Abstract.We describe an atom interferometer to study the coherence of atoms reflected from an evanescent wave mirror. The interferometer is sensitive to the loss of phase coherence induced by the defects in the mirror. The results are consistent with and complementary to recent measurements of specular reflection.

ATOMIC INTERFERENCE IN GRAZING INCIDENCE DIFFRACTION FROM AN EVANESCENT WAVE MIRROR

We describe experiments with atoms reflecting from atomic mirrors. We show that the Zeeman structure of the atoms permits the realization of an nano scale interferometer which can be used to probe the van der Waals interaction between an atom an a dielectric surface. We also discuss preliminary results on an experiment to observe sub-angstrom surface roughness using stimulated Raman transitions to achieve velocity selection of 0.3 times the single photon recoil velocity. This resolution corresponds to a 1.5 mrad maximum deviation in the effective reflecting surface.