Self-oscillating synchronematic colloids

Self-oscillators that sustain periodic dynamics under constant input are ubiquitous in natural and engineered systems, where their interactions enable spatiotemporal coordination among many individual units. New forms of organization can emerge when these self-oscillating units are free to move and rotate, linking their spatial arrangement and orientation with their oscillation frequencies and phases. Here, we report experiments and simulations on populations of Quincke colloids that behave as self-oscillating units characterized by position, orientation, frequency, and phase. Hydrodynamic interactions among these colloids drive temporal synchronization and spatial alignment of their phases and orientations, giving rise to a new form of collective order that we term synchronematic. Within finite-size crystalline clusters, these non-reciprocal interactions promote global synchronization and circular alignment, with a collective frequency that increases with cluster size. Using the theory of weakly coupled oscillators, we derive a reduced-order model that captures the coupled evolution of phase and orientation and explains how synchronematic order depends sensitively on the particle configuration. Our results establish Quincke colloids as a model system for active oscillatory matter and reveal fundamental principles by which synchronization, alignment, and structure co-emerge---offering a framework for designing adaptive, frequency-tunable materials.

在自然与工程系统中，可在恒定输入下维持周期性动力学的自激振子无处不在，这类振子间的相互作用可实现大量独立单元间的时空协调。当这些自激振子可自由移动与转动时，新的组织模式便会涌现，其空间排布与取向会与振荡频率、相位形成耦合关联。本研究针对以位置、取向、频率及相位为特征参数的自激振子型昆克胶体（Quincke colloids）群体开展了实验与模拟研究：这类胶体间的流体动力学相互作用会驱动其相位与取向实现时间同步与空间对齐，进而形成一种新型集体有序结构，我们将其命名为synchronematic。在有限尺寸晶体团簇中，这类非互易相互作用可促进全局同步与环形取向排布，且集体振荡频率随团簇尺寸增大而升高。本研究借助弱耦合振子理论，推导得到了可刻画相位与取向耦合演化的降阶模型，并阐明了synchronematic集体序对粒子构型的敏感依赖关系。本研究成果确立了昆克胶体作为活性振荡物质模型体系的地位，揭示了同步、取向对齐与结构共同涌现的底层物理机制，同时为自适应频率可调谐材料的设计提供了理论框架。