arXiv:1705.02425 · Physical Review A
Trapping of Bose-Einstein condensates in a three-dimensional dark focus generated by conical refraction
Dominik Pfeiffer, Ludwig Lind, J. Küber, F. Schmaltz, Alex Turpin, V. Ahufinger, J. Mompart, G. Birkl
Abstract
We present an efficient three-dimensional dark-focus optical trapping potential for neutral atoms and Bose-Einstein condensates. This ``optical bottle'' is created by a single blue-detuned light field exploiting the phenomenon of conical refraction occurring in biaxial crystals. The conversion of a Gaussian input beam to the bottle beam has an efficiency of close to 100% and the optical setup requires the addition of the biaxial crystal and a circular polarizer only. Based on the conical-refraction theory, we derive the general form of the potential, the trapping frequencies, and the potential barrier heights. We present experiments on confining a $^{87}\mathrm{Rb}$ Bose-Einstein condensate in three dimensions. We determine the trap shape, the vibrational frequencies along the weak axis, as well as the lifetime of ultracold atoms in this type of potential.