论文标题
手性活性流体中的非肾脏和奇粘度
Nonreciprocity and odd viscosity in chiral active fluids
论文作者
论文摘要
奇数粘度伴侣以耗散方式压力应力。它已经在磁场下的等离子体中进行了研究，超级流体$ {\ rm he}^3 $，量子助大的流体，以及最近在手性活性物质的背景下进行了研究。在大多数这些研究中，粘度中的奇数词遵守Onsager的相互关系。尽管在平衡系统中预期这是预期的，但显而易见的是，Onsager关系在活性材料中持有。通过直接使用泊松托架形式主义和动力学理论推导，可以直接粗糙的动能，并独立地独立使用，我们发现非呈现角度动量密度的出现是手性活性材料的标志，必然会破坏Onsager的互惠关系。这导致了总流体动力动量以及奇数粘度和其他对粘度的其他非动态贡献的非热动力基质。此外，通过考虑角动量密度和导致奇数粘度的相互作用，我们在参数空间中找到了区域，其中3D奇数机械波传播的区域和它们在机械上不稳定的区域。将这些区域分开的线是特殊点的连续线，表明可能的非转向相变。
Odd viscosity couples stress to strain rate in a dissipationless way. It has been studied in plasmas under magnetic fields, superfluid ${\rm He}^3$, quantum-Hall fluids, and recently in the context of chiral active matter. In most of these studies, odd terms in the viscosity obey Onsager reciprocal relations. Although this is expected in equilibrium systems, it is not obvious that Onsager relations hold in active materials. By directly coarse graining the kinetic energy and independently using both the Poisson-bracket formalism and a kinetic theory derivation, we find that the appearance of a non-vanishing angular momentum density, which is a hallmark of chiral active materials, necessarily breaks Onsager reciprocal relations. This leads to a non-Hermitian dynamical matrix for the total hydrodynamic momentum and to the appearance of odd viscosity and other non-dissipative contributions to the viscosity. Furthermore, by accounting for both the angular momentum density and interactions that lead to odd viscosity, we find regions in the parameter space in which 3D odd mechanical waves propagate and regions in which they are mechanically unstable. The lines separating these regions are continuous lines of exceptional points, suggesting a possible non-reciprocal phase transition.
