Xu Guoqiang, Zhou Xue, Chen Weijin, Hu Guangwei, Yan Zhiyuan, Li Zhipeng, Yang Shuihua, Qiu Cheng-Wei
Department of Electrical and Computer Engineering, National University of Singapore, Kent Ridge, Singapore, Republic of Singapore.
School of Computer Science and Information Engineering, Chongqing Technology and Business University, Chongqing, China.
Science. 2024 Dec 20;386(6728):1377-1383. doi: 10.1126/science.adq2329. Epub 2024 Dec 19.
The structural periodicity in photonic crystals guarantees the crystal's effective energy band structure, which is the fundamental cornerstone of topological and moiré physics. However, the shear modulus in most fluids is close to zero, which makes it challenging for fluids to maintain spatial periodicity akin to photonic crystals. We realized periodic vortices in hydrodynamic metamaterials and created a bilayer moiré superlattice by stacking and twisting two such vortex fluids. We observed energy delocalization and localization when the twist angles, respectively, result in the Pythagorean and non-Pythagorean triples in the fluidic moiré superlattice. Anomalous localization was found even in commensurate moiré fluids with large lattice constants that satisfy Pythagorean triples. Our work reports the moiré phenomena in fluids and opens an unexpected door to controlling the energy transfer, mass transport, and particle navigation through the elaborate dynamics of vortices in fluidic moiré superlattices.
光子晶体中的结构周期性保证了晶体的有效能带结构，这是拓扑物理和莫尔物理的基本基石。然而，大多数流体的剪切模量接近于零，这使得流体难以维持类似于光子晶体的空间周期性。我们在流体动力学超材料中实现了周期性涡旋，并通过堆叠和扭转两种这样的涡旋流体创建了双层莫尔超晶格。当扭转角分别在流体莫尔超晶格中产生勾股数和非勾股数三元组时，我们观察到了能量离域和定域现象。即使在具有满足勾股数三元组的大晶格常数的相称莫尔流体中也发现了反常定域。我们的工作报道了流体中的莫尔现象，并通过流体莫尔超晶格中涡旋的精细动力学为控制能量转移、质量输运和粒子导航打开了一扇意想不到的大门。
