Yan Zhenjie, Patel Parth B, Mukherjee Biswaroop, Vale Chris J, Fletcher Richard J, Zwierlein Martin W
MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Optical Science Centre and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Swinburne University of Technology, Melbourne 3122, Australia.
Science. 2024 Feb 9;383(6683):629-633. doi: 10.1126/science.adg3430. Epub 2024 Feb 8.
Heat transport can serve as a fingerprint identifying different states of matter. In a normal liquid, a hotspot diffuses, whereas in a superfluid, heat propagates as a wave called "second sound." Direct imaging of heat transport is challenging, and one usually resorts to detecting secondary effects. In this study, we establish thermography of a strongly interacting atomic Fermi gas, whose radio-frequency spectrum provides spatially resolved thermometry with subnanokelvin resolution. The superfluid phase transition was directly observed as the sudden change from thermal diffusion to second-sound propagation and is accompanied by a peak in the second-sound diffusivity. This method yields the full heat and density response of the strongly interacting Fermi gas and therefore all defining properties of Landau's two-fluid hydrodynamics.
热输运可作为识别不同物质状态的一种特征。在正常液体中，热点会扩散，而在超流体中，热量以一种称为“第二声”的波的形式传播。对热输运进行直接成像具有挑战性，人们通常诉诸于检测次要效应。在本研究中，我们建立了强相互作用原子费米气体的热成像，其射频光谱提供了具有亚纳开尔文分辨率的空间分辨温度测量。超流相变被直接观测为从热扩散到第二声传播的突然变化，并伴随着第二声扩散率的峰值。这种方法产生了强相互作用费米气体的完整热响应和密度响应，从而得到了朗道双流体动力学的所有定义性质。
