arXiv subjects

O. Morsch

Publications and source records attributed to O. Morsch.

41 records · Page 3Linked to original sources

arXiv2001

Bloch oscillations and mean-field effects of Bose-Einstein condensates in 1-D optical lattices

We have loaded Bose-Einstein condensates into one-dimensional, off-resonant optical lattices and accelerated them by chirping the frequency difference between the two lattice beams. For small values of the lattice well-depth, Bloch oscillations were observed. Reducing the potential depth further, Landau-Zener tunneling out of the lowest lattice band, leading to a breakdown of the oscillations, was also studied and used as a probe for the effective potential resulting from mean-field interactions as predicted by Choi and Niu [Phys. Rev. Lett. {\bf 82}, 2022 (1999)]. The effective potential was measured for various condensate densities and trap geometries, yielding good qualitative agreement with theoretical calculations.

cond-mat.soft↗

arXiv2001

Coherent acceleration and Landau-Zener tunneling of Bose-Einstein condensates in 1-D optical lattices

We have loaded Bose-Einstein condensates into one-dimensional, off-resonant optical lattices and accelerated them by chirping the frequency difference between the two lattice beams. For small values of the lattice well-depth, Bloch oscillations were observed. Landau-Zener tunneling out of the lowest lattice band, leading to a breakdown of the oscillations, was also studied. In order to allow in-trap measurements of these phenomena, we dynamically compensated for the intrinsic micromotion of the atoms in our time-orbiting potential trap.

cond-mat↗

arXiv2000

Atomic micromotion and geometric forces in a triaxial magnetic trap

Non-adiabatic motion of Bose-Einstein condensates of rubidium atoms arising from the dynamical nature of a time-orbiting-potential (TOP) trap was observed experimentally. The orbital micromotion of the condensate in velocity space at the frequency of the rotating bias field of the TOP was detected by a time-of-flight method. A dependence of the equilibrium position of the atoms on the sense of rotation of the bias field was observed. We have compared our experimental findings with numerical simulations. The nonadiabatic following of the atomic spin in the trap rotating magnetic field produces geometric forces acting on the trapped atoms.

physics.atom-ph↗

arXiv2000

Coherent transients in optical lattices

We use a method based on optical coherent transients to study the vibrational coherence lifetimes of atoms trapped in the potential wells of a near-resonant optical lattice in the oscillating regime. The dependence of the positions and widths of the vibrational Raman resonances of the coherent transient spectra on the intensity, detuning, and geometry of the lattice beams is investigated and the results are compared with theoretical predictions. It is shown that the principal source of broadening of the vibrational Raman resonances is the anharmonicity of the light-shift potential wells. We also perform time-resolved measurements of the vibrational excitation of atoms equilibrating in an optical lattice.

physics.atom-ph↗

arXiv2000

Bose-Einstein condensation of rubidium atoms in a triaxial TOP-trap

We report the results of experiments with Bose-Einstein condensates of rubidium atoms in a triaxial TOP-trap, presenting measurements of the condensate fraction and the free expansion of a condensate released from the trap. The experimental apparatus and the methods used to calibrate the magnetic trapping fields are discussed in detail. Furthermore, we compare the performance of our apparatus with other TOP-traps and discuss possible limiting factors for the sizes of condensates achievable in such traps.

cond-mat.soft↗