Institut für Experimentalphysik und Zentrum für Quantenphysik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
Faraday Discuss. 2009;142:283-95; discussion 319-34. doi: 10.1039/b820542f.
One possibility for the creation of ultracold, high phase space density quantum gases of molecules in the rovibronic ground state relies on first associating weakly-bound molecules from quantum-degenerate atomic gases on a Feshbach resonance and then transferring the molecules via several steps of coherent two-photon stimulated Raman adiabatic passage (STIRAP) into the rovibronic ground state. Here, in ultracold samples of Cs2 Feshbach molecules produced out of ultracold samples of Cs atoms, we observe several optical transitions to deeply-bound rovibrational levels of the excited 0(u)+ molecular potentials with high resolution. At least one of these transitions, although rather weak, allows efficient STIRAP transfer into the deeply-bound vibrational level (see text for symbols)v = 73 > of the singlet X1 sigma(g)+ ground state potential, as recently demonstrated (J. G. Danzl, E. Haller, M. Gustavsson, M. J. Mark, R. Hart, N. Bouloufa, O. Dulieu, H. Ritsch, and H.-C. Nägerl, Science, 2008, 321, 1062). From this level, the rovibrational ground state (see text for symbols)v = 0, J = 0 > can be reached with one more transfer step. In total, our results show that coherent ground state transfer for Cs2 is possible using a maximum of two successive two-photon STIRAP processes or one single four-photon STIRAP process.
一种在旋转振动基态下产生超冷、高相空间密度的分子量子气体的可能性，依赖于首先在费什巴赫共振上将弱束缚分子从量子简并的原子气体中结合起来，然后通过几个相干双光子受激拉曼绝热通道（STIRAP）步骤将分子转移到旋转振动基态。在这里，我们在由超冷铯原子产生的超冷 Cs2 费什巴赫分子样本中，以高分辨率观察到几个到激发 0(u)+分子势能深束缚旋转振动能级的光学跃迁。这些跃迁中至少有一个虽然较弱，但允许高效地将分子转移到单重态 X1 sigma(g)+基态势能的深束缚振动能级（见正文符号）v = 73 >中，最近已经证明了这一点（J. G. Danzl、E. Haller、M. Gustavsson、M. J. Mark、R. Hart、N. Bouloufa、O. Dulieu、H. Ritsch 和 H.-C. Nägerl，Science，2008，321，1062）。从这个能级，通过再一次转移步骤，可以达到旋转振动基态（见正文符号）v = 0，J = 0 >。总的来说，我们的结果表明，使用最多两个连续的双光子 STIRAP 过程或一个单四光子 STIRAP 过程，就可以实现 Cs2 的相干基态转移。
