Heidelberg 2015 – scientific programme

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SYEP: Symposium Efimov Physics

SYEP 2: Symposium Efimov Physics II

SYEP 2.4: Talk

Monday, March 23, 2015, 15:45–16:00, C/gHS

An optically trapped mixture of metastable helium and rubidium — •Adonis Flores, Hari Prasad Mishra, Wim Vassen, and Steven Knoop — LaserLaB, Department of Physics and Astronomy, VU University Amsterdam, The Netherlands

We report on our efforts to realize an ultracold mixture of metastable triplet ⁴He and ⁸⁷Rb in an optical dipole trap (ODT). This extreme mass-imbalanced mixture is interesting for investigating the Efimov trimer spectrum, in particular to test its scale invariance [1]. Recently, we have realized a BEC of ⁸⁷Rb in the F=2, m_F=2 hyperfine substate in a hybrid trap [2], consisting of a quadrupole magnetic field and a single beam ODT. 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 are currently exploring the application of the hybrid trap for metastable He. Previously, we have studied interspecies thermalization in the quadrupole magnetic trap, from which we have obtained a value of the interspecies quartet scattering length, in agreement with ab initio quantum chemistry calculations [3]. Once we have obtained an ultracold mixture in the ODT we will study interspecies Penning ionization for different spin mixtures and search for interspecies Feshbach resonances.

[1] R. Pires et al., Phys. Rev. Lett. 112, 250404 (2014)

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

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