Coaxing quantumness in a molecular gas A dilute atomic gas cooled down to very cold temperatures can enter the so-called quantum degenerate regime, where quantum properties of the gas come to the fore. This regime has been achieved for both bosonic and fermionic atoms, but molecules, with their many internal states, present a special challenge. De Marco et al. cooled a bulk gas of fermionic potassium-rubidium molecules to quantum degeneracy (see the Perspective by Zelevinsky). The authors first cooled atomic potassium and rubidium gases separately, then bound them together into potassium-rubidium molecules, and finally brought the molecules down to their ground state. The density profile of the molecular gas revealed the system's quantum nature, which in turn kept the gas stable by suppressing chemical reactions. Science, this issue p. 853; see also p. 820 A bulk gas of fermionic potassium-rubidium molecules is cooled down to below a third of the Fermi temperature. Experimental realization of a quantum degenerate gas of molecules would provide access to a wide range of phenomena in molecular and quantum sciences. However, the very complexity that makes ultracold molecules so enticing has made reaching degeneracy an outstanding experimental challenge over the past decade. We now report the production of a degenerate Fermi gas of ultracold polar molecules of potassium-rubidium. Through coherent adiabatic association in a deeply degenerate mixture of a rubidium Bose-Einstein condensate and a potassium Fermi gas, we produce molecules at temperatures below 0.3 times the Fermi temperature. We explore the properties of this reactive gas and demonstrate how degeneracy suppresses chemical reactions, making a long-lived degenerate gas of polar molecules a reality.

中文翻译：

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极性分子的简并费米气体

诱导分子气体中的量子性 冷却到非常冷的温度的稀释原子气体可以进入所谓的量子简并状态，在这种状态下，气体的量子特性脱颖而出。玻色子和费米子原子都实现了这种机制，但分子具有许多内部状态，这是一个特殊的挑战。德马可等人。将大量费米钾铷分子气体冷却至量子简并（见泽列文斯基的观点）。作者首先分别冷却原子钾和铷气体，然后将它们结合成钾铷分子，最后将分子降至基态。分子气体的密度分布揭示了系统的量子性质，从而通过抑制化学反应来保持气体稳定。科学，这个问题 p。853; 另见第。820 大量的费米钾铷分子气体被冷却到费米温度的三分之一以下。分子的量子简并气体的实验实现将提供对分子和量子科学中广泛现象的访问。然而，使超冷分子如此诱人的复杂性使得在过去十年中达到简并成为一项突出的实验挑战。我们现在报告了钾铷的超冷极性分子的简并费米气体的产生。通过铷玻色-爱因斯坦凝聚物和钾费米气体的深度简并混合物中的相干绝热缔合，我们在低于费米温度 0.3 倍的温度下产生分子。