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Hartmut Wallis

Publications and source records attributed to Hartmut Wallis.

2 recordsLinked to original sources

Fully quantum mechanical moment of inertia of a mesoscopic ideal Bose gas

The superfluid fraction of an atomic cloud can be defined using the cloud's response to a rotation of the external potential, i.e. the moment of inertia. In this paper we derive analytical results for the moment of inertia of a small number of non-interacting Bosons using the canonical ensemble. The required symmetrized averages are obtained via a representation of the partition function by permutation cycles. Our results are useful to discriminate purely quantum statistical effects from interaction effects in studies of superfluidity and phase transitions in finite samples.

cond-mat.stat-mech

Theory of atomic diffraction from evanescent waves

We review recent theoretical models and experiments dealing with the diffraction of neutral atoms from 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.

quant-ph