论文标题
强大的casimir样力在蜂拥而至的活性物质中
Strong Casimir-like Forces in Flocking Active Matter
论文作者
论文摘要
局限于空间中具有远距离相关性的统计系统的平衡波动会导致边界上的有效力。在这里，我们证明了Casimir样力的发生在通过蜂拥而至的活动物质提供的非平衡环境中。特别是，我们考虑了一个在两个空间维度中对齐自构粒子的系统，这些系统在横向上被反射或部分反射壁限制。我们表明，在有序的植入阶段，这种狭窄的活性矢量流体的特征是广泛的边界层，而不是在受限的标量活动物质中通常观察到的有限层。此外，有限大小的波动引起的对壁压力的贡献出现，在增加壁之间的距离时，该壁的衰减缓慢而代数。我们在密度和速度场的流体动力描述中解释了我们的发现，这些发现显示了一定程度的普遍性。
Confining in space the equilibrium fluctuations of statistical systems with long-range correlations is known to result into effective forces on the boundaries. Here we demonstrate the occurrence of Casimir-like forces in the non-equilibrium context provided by flocking active matter. In particular, we consider a system of aligning self-propelled particles in two spatial dimensions, which are transversally confined by reflecting or partially reflecting walls. We show that in the ordered flocking phase this confined active vectorial fluid is characterized by extensive boundary layers, as opposed to the finite ones usually observed in confined scalar active matter. Moreover, a finite-size,fluctuation-induced contribution to the pressure on the wall emerges, which decays slowly and algebraically upon increasing the distance between the walls. We explain our findings, which display a certain degree of universality, within a hydrodynamic description of the density and velocity fields.
