Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.
Phys Rev Lett. 2013 Feb 1;110(5):055305. doi: 10.1103/PhysRevLett.110.055305. Epub 2013 Jan 30.
We present a high-precision determination of the universal contact parameter in a strongly interacting Fermi gas. In a trapped gas at unitarity, we find the contact to be 3.06±0.08 at a temperature of 0.08 of the Fermi temperature in a harmonic trap. The contact governs the high-momentum (short-range) properties of these systems, and this low-temperature measurement provides a new benchmark for the zero-temperature homogeneous contact. The experimental measurement utilizes Bragg spectroscopy to obtain the dynamic and static structure factors of ultracold Fermi gases at high momentum in the unitarity and molecular Bose-Einstein condensate regimes. We have also performed quantum Monte Carlo calculations of the static properties, extending from the weakly coupled BCS regime to the strongly coupled Bose-Einstein condensate case, that show agreement with experiment at the level of a few percent.
我们提出了一种高精度的强相互作用费米气体普适接触参数的确定方法。在单位制下的囚禁气体中，我们在温度为费米温度的 0.08 时，在一个谐振子陷阱中发现接触参数为 3.06±0.08。接触参数控制着这些系统的高动量（短程）性质，这种低温测量为零温均匀接触提供了一个新的基准。实验测量利用布拉格光谱法在单位制和分子玻色-爱因斯坦凝聚态范围内获得了超高动量下的冷费米气体的动态和静态结构因子。我们还对静态性质进行了量子蒙特卡罗计算，从弱耦合 BCS 区域扩展到强耦合玻色-爱因斯坦凝聚区域，在百分之几的水平上与实验结果一致。
