发表机构
Department of Physics, Harvard University（哈佛大学物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出对超冷CaNH$_2$不对称陀螺分子施加静电场，利用其K双重态分裂诱导偶极相互作用，使弹性碰撞比损失碰撞高三个数量级，从而为蒸发冷却实现量子简并气体提供可行途径。
AI 中文摘要
我们提出，对反应性CaNH$_2$分子施加静电场可以在超冷温度下产生大的弹性碰撞与损失碰撞之比。在第一转动激发流形中，CaNH$_2$的不对称陀螺结构导致相反宇称的$K$双重态能级产生约226 MHz的分裂。这种适度的分裂使得低于每厘米千伏的电场能够极化分子并诱导长程偶极-偶极相互作用。通过增加电场，我们发现偶极-偶极吸引力可以变得足够大，从而诱导形成[CaNH$_2$]$_2$的弱束缚八原子场连接态。在不存在这些场连接态的情况下，我们确定了特定的分子态，其中偶极相互作用使得弹性碰撞能够比损失碰撞占据主导地位，优势高达三个数量级，同时将损失速率系数维持在$10^{-14}$ cm$^3$s$^{-1}$的水平。这些结果表明，蒸发冷却是实现激光可冷却不对称陀螺分子量子简并气体的可行途径。获得这种低熵的不对称陀螺分子系综有望推动量子模拟、态分辨化学以及超越标准模型物理的探索前沿。
英文摘要
We propose that the application of static electric fields to reactive CaNH$_2$ molecules can result in large ratios of elastic to lossy collisions at ultracold temperatures. In the first rotationally excited manifold, the asymmetric top structure of CaNH$_2$ results in a $\approx 226$ MHz splitting of the opposite parity $K$-doublet states. This modest splitting allows electric fields below a kilovolt per centimeter to polarize the molecules and induce long-range dipole-dipole interactions. By increasing the electric field, we find that dipole-dipole attraction can become sufficiently large to induce weakly bound octatomic field-linked states of [CaNH$_2$]$_2$. In the absence of these field-linked states, we identify select molecular states where dipolar interactions allow elastic collisions to dominate over lossy collisions by up to three orders of magnitude, while maintaining loss rate coefficients at the $10^{-14}$ cm$^3$s$^{-1}$ level. These results establish that evaporative cooling is a viable route to quantum degenerate gases of laser coolable asymmetric top molecules. Access to such low entropy ensembles of asymmetric top molecules holds promise to push the frontiers of quantum simulation, state-resolved chemistry, and searches for beyond the Standard Model physics.
Comments12 pages, 7 figures
