Nagai Ken H, Sumino Yutaka, Montagne Raul, Aranson Igor S, Chaté Hugues
School of Materials Science, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan.
Department of Applied Physics, Tokyo University of Science, Tokyo 125-8585, Japan.
Phys Rev Lett. 2015 Apr 24;114(16):168001. doi: 10.1103/PhysRevLett.114.168001.
We show that memory, in the form of underdamped angular dynamics, is a crucial ingredient for the collective properties of self-propelled particles. Using Vicsek-style models with an Ornstein-Uhlenbeck process acting on angular velocity, we uncover a rich variety of collective phases not observed in usual overdamped systems, including vortex lattices and active foams. In a model with strictly nematic interactions the smectic arrangement of Vicsek waves giving rise to global polar order is observed. We also provide a calculation of the effective interaction between vortices in the case where a telegraphic noise process is at play, explaining thus the emergence and structure of the vortex lattices observed here and in motility assay experiments.
我们表明，以欠阻尼角动力学形式存在的记忆，是自驱动粒子集体特性的关键要素。通过使用维克斯克风格的模型，其中奥恩斯坦-乌伦贝克过程作用于角速度，我们发现了在通常的过阻尼系统中未观察到的丰富多样的集体相，包括涡旋晶格和活性泡沫。在具有严格向列相互作用的模型中，观察到维克斯克波的近晶排列产生了全局极性序。我们还对存在电报噪声过程时涡旋之间的有效相互作用进行了计算，从而解释了在此处和运动测定实验中观察到的涡旋晶格的出现和结构。
