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N. Syassen, T. Volz, D. Bauer, E. Hansis, S. Dürr, and G. Rempe
Feshbach molecules from bosonic atomic species have proven to be very unstable with respect to inelastic collisions [1]. As a result the typical lifetime observed for a cloud of ultracold 87Rb_2 molecules stored in an optical dipole trap is limited to a few milliseconds. Here, we report on the observation of long-lived Feshbach molecules in an optical lattice. A BEC of 87Rb atoms is loaded into the lowest Bloch band of a 3D optical lattice operated at a wavelength of 830 nm. By ramping up the lattice depth, the atomic gas enters the Mott insulator regime. A magnetic-field ramp through the Feshbach resonance at 1007 G creates molecules [2]. Lattice sites initially occupied with more than 2 atoms experience fast inelastic collisional losses. The observed lifetime of the remaining molecules is ~100 ms, which is much longer than for a pure molecular sample in an optical dipole trap. Similar results have recently been reported in Ref. [3]. The increased lifetime is an important step on the route to a BEC of molecules in the vibrational ground state [4]. [1] T. Mukaiyama et al., Phys. Rev. Lett. 92, 180402 (2004) [2] S. Dürr et al., Phys. Rev. Lett. 92, 020406 (2004) [3] G. Thalhammer et al., cond-mat/0510755} [4] D. Jaksch et al., Phys. Rev. Lett. 89, 040402 (2002) |
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