We have carried out bound-state and low-energy quantum scattering calculations on He + NH (triplet Sigma) in magnetic fields, with the NH molecule in its n=1 rotationally excited states. We have explored the pattern of levels as a function of magnetic field and identified the nearly good quantum numbers in different regimes. We have used the bound-state calculations to locate low-energy Feshbach resonances. When the magnetic field is used to tune across such a resonance, the real and imaginary part of the scattering length show asymmetric oscillations and peaks with amplitude between 1 and 3 Angstroms. The scattering length does not pass through a pole at resonance. The resonant behavior is characterized by a complex resonant scattering length a_res. The corresponding inelastic cross sections show troughs as well as peaks near resonance. This may be important for efforts to achieve evaporative and sympathetic cooling for molecules, because it offers the hope that inelastic trap losses can be reduced by tuning close to a Feshbach resonance.
Feshbach-optimized photoassociation of ultracold $^6$Li$^{87}$Rb molecules with short pulses
本文研究了在磁费什巴赫共振附近短脉冲作用下，基态$^6$ Li $^{87}$ Rb分子通过$\mathrm{B}^1Π$电子态的双色光缔合.施加近共振磁场以混合初始波函数的超精细单重态和三重态分量并增强光缔合速率，然后通过第二脉冲将群体转移到基态。我们表明，产生的分子的绝对数量的增加高达三个数量级是可以实现的深绑定的振动水平。这种技术可以推广到具有可接近的磁费什巴赫共振的其他分子。
Charge transfer in ultracold gases via Feshbach resonances
我们研究了在同元素原子和离子的异源同位素组合的超冷碰撞中控制电荷交换的前景。这种处理方法很容易应用于碱金属或链烷烃-土金属，如过程$^9$ Be $^{+}$ + $^{10}$ Be $\leftrightarrow$ $^{9}$ Be + $^{10}$ Be $^{+}$所示，它具有良好的电子、核和超精细结构。费什巴赫共振得到的量子散射计算在一个标准的耦合通道形式主义与非BO条款起源于核动力学运营商。在322 G处预测的窄共振附近，我们发现电荷交换速率系数从几乎为零上升到大于$10^{-12}$ cm $^3$ /s的值。我们的研究结果表明，可控的电荷交换反应之间的不同同位素的合适的原子-离子对与潜在的应用量子系统工程研究电荷扩散被困冷原子-离子混合物和模拟多体物理。
