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arXiv physics/0610214physics.atom-phphysics.atm-clusphysics.chem-ph
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磁场中超冷原子-分子碰撞和束缚态：He-NH（3 Sigma-）中零能费什巴赫共振的调谐

Ultracold atom-molecule collisions and bound states in magnetic fields: tuning zero-energy Feshbach resonances in He-NH (3Sigma-)

Maykel Leonardo Gonzalez-Martinez, Jeremy M. Hutson

备注：
14 pages, 13 figures Version 2 has clarified (slightly extended) discussion in sections 2C and 2D, exact forms of Eqs. 23 and 24 (new numbering) and some extra references. A few minor typographical errors have also been corrected
发表信息：
Phys. Rev. A 75, 022702 (2007)
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摘要：

我们推广了BOUND和MOLSCAT软件包，允许在单体哈密顿量非对角的基组中进行计算，并使用新的能力对3 He-NH和4 He-NH进行束缚态和散射计算，作为磁场的函数。跟踪束缚态能量到它们穿过阈值的点，可以非常精确地预测零能费什巴赫共振发生的磁场。我们已经用它来定位和表征两个非常窄的费什巴赫共振在3 He-NH。这样的共振可以用来调整弹性和非弹性碰撞的截面，而扫过它们的磁场将允许一种形式的量子控制，其中分离的原子和分子结合在一起形成复合物。对于第一个共振，其中只有弹性散射是可能的，散射长度示出了作为磁场的函数的极点，并且在弹性截面中存在非常大的峰值。然而，对于第二共振，非弹性散射也是可能的。在这种情况下，散射长度中的极点被显著抑制，并且截面示出相对小的峰值。在具有较强非弹性的系统中，预期峰值抑制甚至更大。结果表明，超冷分子非弹性碰撞的计算可能是更不敏感的细节的势能面比已经相信。

英文摘要：

We have generalized the BOUND and MOLSCAT packages to allow calculations in basis sets where the monomer Hamiltonians are off-diagonal and used the new capability to carry out bound-state and scattering calculations on 3He-NH and 4He-NH as a function of magnetic field. Following the bound-state energies to the point where they cross thresholds gives very precise predictions of the magnetic fields at which zero-energy Feshbach resonances occur. We have used this to locate and characterize two very narrow Feshbach resonances in 3He-NH. Such resonances can be used to tune elastic and inelastic collision cross sections, and sweeping the magnetic field across them will allow a form of quantum control in which separated atoms and molecules are associated to form complexes. For the first resonance, where only elastic scattering is possible, the scattering length shows a pole as a function of magnetic field and there is a very large peak in the elastic cross section. For the second resonance, however, inelastic scattering is also possible. In this case the pole in the scattering length is dramatically suppressed and the cross sections show relatively small peaks. The peak suppression is expected to be even larger in systems with stronger inelasticity. The results suggest that calculations on ultracold molecular inelastic collisions may be much less sensitive to details of the potential energy surface than has been believed.

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