A Crystal of Light and Atoms

Helmut Ritsch

Markus K Oberthaler, Roland Abfalterer, Stefan Bernet +3 more

Atoms in light crystals formed by a standing light wave are a model system to study the propagation of matter waves in periodic potentials. The encountered phenomena can be described by dynamical diffraction theory which has been extensively studied for x-ray, electron, and neutron scattering from solid state crystals. In this paper we show that an atomic de Broglie wave traversing a standing light wave allows investigation of predictions of dynamical diffraction theory which were previously experimentally not accessible. We present standard diffraction efficiency characterizations for pure absorptive and pure refractive crystals. Additionally we were able to measure directly the total atomic wave field formed inside a refractive and an absorptive crystal and to confirm the predicted absolute position of the atomic wave field with respect to the lattice planes. By superposing two standing light waves of different frequency we tailored a new kind of crystal potential where Friedel's law about usual diffraction symmetries is maximally violated.

Markus K. Oberthaler, Roland Abfalterer, Stefan Bernet +2 more

We present experiments studying the coherent motion of atoms in crystals made from on and off resonant light. The experiments confirm that inside the light-field atoms fulfilling the Bragg condition form a standing matter wave pattern. As a consequence we observed anomalous transmission of atoms through resonant light fields.

Amit Goswami

Andrew S. Milman

S. Meneghini, Igor Jex, K. A. H. van Leeuwen +3 more

We study the dynamics of atomic waves in longitudinally modulated light crystals using an effective complex potential with time (space) dependent detuning. In the weak coupling regime we predict a sharp asymmetry of the scattering probability near the Bragg angle. In the strong coupling case we introduce the concept of a light crystal with "complex kick." We have found that the initially blue detuned crystal is much more transparent for atomic waves. Moreover, the probability distribution of the outgoing wave shows carpetlike interference structure.