Nonreciprocity as a generic route to traveling states
Nonreciprocity as a generic route to traveling states
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DOI：
10.1073/pnas.2010318117
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
Zhihong You;A. Baskaran;M. Marchetti
中科院分区：
文献类型：
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作者：
Zhihong You;A. Baskaran;M. Marchetti
意义 在非平衡环境介导相互作用的系统中，打破作用-反应对称性的有效相互作用是普遍存在的。它们也是生活世界的常态。通过检查扩散二元混合物的动力学，我们证明了对抗性交叉扩散可以驱动从静态到移动空间模式的转变。在分析易处理模型的背景下，我们阐明了转变的本质，并证明移动或振荡模式的出现是标量场描述的多物种系统中非互易性的一般结果。我们的工作与理解和控制化学相互作用胶体混合物中的非平衡组装直接相关。我们研究了两种扩散物质混合物的非互易耦合动力学模型。我们证明，通过对抗性交叉扩散性在模型中编码的非互易性，为具有保守动力学的纯扩散系统中旅行模式的出现提供了一种通用机制。在不存在非互易性的情况下，二元流体混合物经历从均匀混合状态到分层状态的相变，其中空间分离的区域富含两种组分之一。在参数调整非互易性的临界值以上，静态去混合图案获得有限速度，从而产生破坏空间和时间反转对称性以及静态图案的反射奇偶性的状态。我们使用可分析研究的最小模型阐明了向旅行模式过渡的一般性质。我们的工作与已知表现出非互易有效相互作用的化学相互作用胶体混合物中的非平衡组装直接相关，也与主动剂和被动剂的混合物直接相关，其中在模拟中观察到了此处预测类型的移动状态。它还提供了关于在具有非保守动力学的广泛非互易系统中看到的旅行和振荡状态的转变的见解，从反应扩散和猎物捕食者模型到具有拮抗相互作用的微生物的多物种混合物。
Significance Effective interactions that break action–reaction symmetry are ubiquitous in systems where interactions are mediated by a nonequilibrium environment. They are also the norm in the living world. By examining the dynamics of a diffusing binary mixture, we demonstrate that antagonistic cross-diffusivities can drive the transition from static to traveling spatial patterns. In the context of an analytically tractable model, we elucidate the nature of the transition and demonstrate that the emergence of traveling or oscillating patterns is a generic consequence of nonreciprocity in multispecies systems described by scalar fields. Our work is directly relevant to the understanding and control of nonequilibrium assembly in mixtures of chemically interacting colloids. We examine a nonreciprocally coupled dynamical model of a mixture of two diffusing species. We demonstrate that nonreciprocity, which is encoded in the model via antagonistic cross-diffusivities, provides a generic mechanism for the emergence of traveling patterns in purely diffusive systems with conservative dynamics. In the absence of nonreciprocity, the binary fluid mixture undergoes a phase transition from a homogeneous mixed state to a demixed state with spatially separated regions rich in one of the two components. Above a critical value of the parameter tuning nonreciprocity, the static demixed pattern acquires a finite velocity, resulting in a state that breaks both spatial and time-reversal symmetry, as well as the reflection parity of the static pattern. We elucidate the generic nature of the transition to traveling patterns using a minimal model that can be studied analytically. Our work has direct relevance to nonequilibrium assembly in mixtures of chemically interacting colloids that are known to exhibit nonreciprocal effective interactions, as well as to mixtures of active and passive agents where traveling states of the type predicted here have been observed in simulations. It also provides insight on transitions to traveling and oscillatory states seen in a broad range of nonreciprocal systems with nonconservative dynamics, from reaction–diffusion and prey–predators models to multispecies mixtures of microorganisms with antagonistic interactions.