科学家观测到偶极超固体中的涡旋
近日，奥地利科学院量子光学与量子信息研究所的Francesca Ferlaino及其研究团队取得一项新进展。经过不懈努力，他们观测到偶极超固体中的涡旋。相关研究成果已于2024年11月6日在国际权威学术期刊《自然》上发表。
在已有条件下，即一种在偶极气体和具有二维晶体有序性的超固体中生成涡旋的方法，该研究团队报道了对超固体相（SSP）中涡旋的理论研究和实验观测。这项研究工作揭示了未调制和调制量子流体之间，在涡旋形成动力学上的根本差异。这为研究量子晶体和中子星等不同领域中，具有众多自发破缺对称性的奇异量子系统的，流体动力学特性打开了大门。
据悉，超固体是一种自发破缺两种连续对称性的物质状态：一种是由于晶体结构的出现而破缺的平移不变性，另一种是由于单粒子波函数的相位锁定而破缺的相位不变性，后者是产生超流现象的原因。
虽然超固体最初被预测存在于固态氦中，但超冷量子气体为观察超固体提供了首个平台，尤其是偶极原子在这方面取得了显著成果。人们已经通过测量相位相干性和无间隙的戈德斯通模式等方法，研究了偶极超固体中的相位锁定，但尚未观察到量化涡旋——这是超流体的一个流体动力学特征。
附：英文原文
Title: Observation of vortices in a dipolar supersolid
Author: Casotti, Eva, Poli, Elena, Klaus, Lauritz, Litvinov, Andrea, Ulm, Clemens, Politi, Claudia, Mark, Manfred J., Bland, Thomas, Ferlaino, Francesca
Issue&Volume: 2024-11-06
Abstract: Supersolids are states of matter that spontaneously break two continuous symmetries: translational invariance owing to the appearance of a crystal structure and phase invariance owing to phase locking of single-particle wavefunctions, responsible for superfluid phenomena. Although originally predicted to be present in solid helium, ultracold quantum gases provided a first platform to observe supersolids, with particular success coming from dipolar atoms. Phase locking in dipolar supersolids has been investigated through, for example, measurements of the phase coherence and gapless Goldstone modes, but quantized vortices, a hydrodynamic fingerprint of superfluidity, have not yet been observed. Here, with the prerequisite pieces at our disposal, namely a method to generate vortices in dipolar gases and supersolids with two-dimensional crystalline order, we report on the theoretical investigation and experimental observation of vortices in the supersolid phase (SSP). Our work reveals a fundamental difference in vortex seeding dynamics between unmodulated and modulated quantum fluids. This opens the door to study the hydrodynamic properties of exotic quantum systems with numerous spontaneously broken symmetries, in disparate domains such as quantum crystals and neutron stars.
DOI: 10.1038/s41586-024-08149-7
Source: https://www.nature.com/articles/s41586-024-08149-7
