Tuning of dipolar interactions and evaporative cooling in a three-dimensional molecular quantum gas
Tuning of dipolar interactions and evaporative cooling in a three-dimensional molecular quantum gas
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DOI：
10.1038/s41567-021-01329-6
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发表时间：
2021-09-02
期刊：
影响因子：
19.6
通讯作者：
Ye, Jun
中科院分区：
文献类型：
--
作者：
Li, Jun-Ru;Tobias, William G.;Ye, Jun
超冷极性分子具有长程、各向异性和可调的偶极相互作用，为探测现有冷气平台无法实现的量子现象提供了机会。然而，实验进展一直受到两体损失超过弹性相互作用的主导地位，这阻碍了有效的蒸发冷却。虽然最近的工作已经证明了通过将分子限制在二维几何形状中来控制相互作用，但是一直缺乏在三维稳定系统中调节分子相互作用的一般方法。在这里，我们展示了可调弹性偶极相互作用的超冷（KRb）-K-40-Rb-87分子在三维空间中的散装气体，促进了电场诱导的屏蔽共振，抑制反应性损失的一个因素为30。这种弹性碰撞与非弹性碰撞之比的提高使直接热化成为可能。热化速率取决于碰撞轴和偶极取向之间的角度，偶极取向由外部电场控制，是各向异性偶极相互作用的直接表现。我们在三维空间中实现了由偶极相互作用介导的蒸发冷却。这项工作展示了对具有可调远程相互作用的长寿命体量子气体系统的完全控制，为集体量子多体物理学的研究铺平了道路。
Ultracold polar molecules possess long-range, anisotropic and tunable dipolar interactions, providing opportunities to probe quantum phenomena that are inaccessible with existing cold gas platforms. However, experimental progress has been hindered by the dominance of two-body loss over elastic interactions, which prevents efficient evaporative cooling. Although recent work has demonstrated controlled interactions by confining molecules to a two-dimensional geometry, a general approach for tuning molecular interactions in a three-dimensional stable system has been lacking. Here we demonstrate tunable elastic dipolar interactions in a bulk gas of ultracold (KRb)-K-40-Rb-87 molecules in three dimensions, facilitated by an electric field-induced shielding resonance that suppresses the reactive loss by a factor of 30. This improvement in the ratio of elastic to inelastic collisions enables direct thermalization. The thermalization rate depends on the angle between the collisional axis and the dipole orientation controlled by an external electric field, a direct manifestation of the anisotropic dipolar interaction. We achieve evaporative cooling mediated by the dipolar interactions in three dimensions. This work demonstrates full control of a long-lived bulk quantum gas system with tunable long-range interactions, paving the way for the study of collective quantum many-body physics.