JILA, National Institute of Standards and Technology, Department of Physics, University of Colorado, Boulder, CO 80309-0440, USA.
Faraday Discuss. 2009;142:351-9; discussion 429-61. doi: 10.1039/b821298h.
We report the creation and characterization of a near quantum-degenerate gas of polar 40K-87Rb molecules in their absolute rovibrational ground state. Starting from weakly bound heteronuclear KRb Feshbach molecules, we implement precise control of the molecular electronic, vibrational, and rotational degrees of freedom with phase-coherent laser fields. In particular, we coherently transfer these weakly bound molecules across a 125 THz frequency gap in a single step into the absolute rovibrational ground state of the electronic ground potential. Phase coherence between lasers involved in the transfer process is ensured by referencing the lasers to two single components of a phase-stabilized optical frequency comb. Using these methods, we prepare a dense gas of 4 x 10(4) polar molecules at a temperature below 400 nK. This fermionic molecular ensemble is close to quantum degeneracy and can be characterized by a degeneracy parameter of T/T(F) = 3. We have measured the molecular polarizability in an optical dipole trap where the trap lifetime gives clues to interesting decay mechanisms. Given the large measured dipole moment of the KRb molecules of 0.5 Debye, the study of quantum degenerate molecular gases interacting via strong dipolar interactions is now within experimental reach. PACS numbers: 37.10.Mn, 37.10.Pq.
我们报告了一种处于绝对转动基态的近简并极化 40K-87Rb 分子气体的产生和特性。从弱束缚的异核 KRb Feshbach 分子开始，我们利用相位相干激光场实现了对分子电子、振动和转动自由度的精确控制。特别是，我们将这些弱束缚分子在单次相干转移过程中跨越 125 THz 的频率间隙，转移到电子基态势能的绝对转动基态。参与转移过程的激光之间的相位相干性通过将激光参考到相稳定的光学频率梳的两个单分量来保证。使用这些方法，我们在低于 400 nK 的温度下制备了 4 x 10(4)个极化分子的稠密气体。这个费米子分子系综接近简并，可以用简并参数 T/T(F) = 3 来表征。我们已经在光学偶极阱中测量了分子的极化率，阱的寿命为有趣的衰减机制提供了线索。考虑到 KRb 分子的测量到的大偶极矩为 0.5 德拜，通过强偶极相互作用相互作用的量子简并分子气体的研究现在已经在实验范围内。 PACS 编号：37.10.Mn, 37.10.Pq。
