Dynamics and thermodynamics in artificial and natural active systems with delay

主动自我推进是赋予生物体进化优势的重要特征之一。尽管细菌和精细胞等单细胞生命的原始形式所利用的自我推进技术已经相当复杂了。它们跳动的鞭毛或动态的身体形状变化需要简化的模型来掌握它们集体运动的物理原理。另一方面，最近的实验和技术进步已经提供了大量的人造微型游泳器，它们可以被激活，甚至以一种很好理解和控制的方式操纵。我们现在可以赋予它们越来越复杂的物理和虚拟相互作用，使我们能够以自下而上的方式模仿在生活世界中观察到的新出现的复杂性。特别是，我们可以刻意设计理论上易于处理的实验系统，并且可以通过对有趣的集体行为进行理想化的理论预测来指导实验设计。这一策略是本提案的核心，旨在促进实验、分析理论和计算机模拟之间的密切合作。我们的重点将主要集中在有/没有约束的相互作用游泳者的自组织和动态尺度，构象熵和信息通量，以及主动物质环境中的被动探针。作为一个重要的创新方面，我们希望系统地研究延迟相互作用的作用。长期目标是为正在进行的日益普遍和统一的活性物质的粗粒度动态和热力学描述提供概念里程碑和范例模型系统。

Active self-propulsion is one of the important traits giving living organisms an evolutionary edge. Already the self-propulsion techniques harnessed by primitive forms of unicellular life, such as bacteria and sperm cells, are quite complicated, though. Their beating flagella or dynamic body shape changes call for simplified models to grasp the physical principles of their collective motion. On the other hand, recent experimental and technological progress has supplied a large arsenal of artificial microswimmers that can be activated and even steered in a well-understood and well-controlled way. We can now endow them with increasingly sophisticated physical and virtual mutual interactions that enable us to mimic the emerging complexity observed in the living world, within a bottom-up approach. In particular, we can deliberately design experimental systems that are theoretically tractable, and idealized theoretical predictions promising interesting collective behavior can guide the experimental design. This strategy is at the heart of the present proposal, which aims to foster a close collaboration between experiment, analytical theory and computer simulations. Our focus will mostly be on self-organization and dynamical scaling of interacting swimmers with/without confinement, conformational entropy and information fluxes, and passive probes in active-matter environments. As an important innovative aspect, we want to systematically investigate the role of time-delayed mutual interactions. The long-term goal is to contribute conceptual milestones and paradigmatic model systems for an ongoing increasingly general and unified coarse-grained dynamic and thermodynamic description of active matter.