Xu Liujun, Dai Gaole, Wang Gang, Huang Jiping
Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (MOE), Fudan University, Shanghai 200438, China.
School of Sciences, Nantong University, Nantong 226019, China.
Phys Rev E. 2020 Sep;102(3-1):032140. doi: 10.1103/PhysRevE.102.032140.
Particle diffusion is a fundamental process in various systems, so its effective manipulation is crucially important. For this purpose, here we design a basic structure composed of two moving rings with equal-but-opposite velocities and a stationary intermediate layer, which can realize multiple functions to control particle diffusion. On the one hand, the intermediate layer allows particle exchange between the two moving rings, which gives birth to an exceptional point of velocity. As a result, a geometric phase appears for a loop evolution of velocity containing the exceptional point. On the other hand, the two moving rings also enhance the effective diffusivity of the intermediate layer, which helps design a bilayer particle-diffusion cloak. The present cloak only requires homogeneous parameters and simple structures, and meanwhile, its on and off can be flexibly controlled by velocity. These results broaden the scope of geometric phase and provide hints for designing particle-diffusion metamaterials.
粒子扩散是各种系统中的一个基本过程，因此对其进行有效操控至关重要。为此，我们在此设计了一种基本结构，它由两个速度大小相等但方向相反的移动环和一个静止的中间层组成，该结构可实现多种控制粒子扩散的功能。一方面，中间层允许粒子在两个移动环之间交换，这产生了一个特殊的速度点。结果，对于包含该特殊点的速度循环演化会出现一个几何相位。另一方面，两个移动环还增强了中间层的有效扩散率，这有助于设计双层粒子扩散隐身衣。这种隐身衣仅需要均匀的参数和简单的结构，同时，其开启和关闭可通过速度灵活控制。这些结果拓宽了几何相位的范围，并为设计粒子扩散超材料提供了思路。
