Heidelberg 2015 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 15: Poster: Quantum Optics and Photonics I

Q 15.3: Poster

Montag, 23. März 2015, 17:00–19:00, C/Foyer

Bose-Einstein condensation of ⁸⁷Rb in the F=2, m_F=2 state in a hybrid trap — •Adonis Flores, Hari Prasad Mishra, Wim Vassen, and Steven Knoop — LaserLaB, Department of Physics and Astronomy, VU University Amsterdam, The Netherlands

We have realized BEC of ⁸⁷Rb in the F=2, m_F=2 state in a hybrid trap [1], consisting of a weak quadrupole magnetic trap (QMT) at 15 G/cm and a single beam optical dipole trap (ODT) at 1557 nm with a waist of 40 µm and a maximum power of 4 W. The symmetry axis of the quadrupole magnetic trap coincides with the optical beam axis, which gives stronger axial confinement than previous hybrid traps. After loading 2× 10⁶ atoms at 14 µK from the QMT into the hybrid trap, we efficiently perform forced evaporation and reach the onset of BEC at a temperature of 0.5 µK and 4×10⁵ atoms. We also obtain thermal clouds of 1×10⁶ atoms below 1 µK in a pure single beam ODT, by ramping down the magnetic field gradient after evaporative cooling in the hybrid trap. We do not observe atoms in the F=2, m_F=1 state after evaporative cooling in the hybrid trap, which suggests that unwanted repopulation of this state during MW-evaporative cooling in the QMT does not take place, in contrast to harmonic magnetic traps. This is in particular relevant for our experimental scheme to realize an ultracold mixture of metastable triplet ⁴He and ⁸⁷Rb [2]. Here we will also discuss the application of the hybrid trap for metastable He, and the preparation of the He+Rb mixture in an ODT.

[1] H. P. Mishra, A. S. Flores, W. Vassen, S. Knoop, arXiv:1411.7628

[2] S. Knoop et al., Phys. Rev. A 90, 022709 (2014)