In many active matter systems, particle trajectories have a well-defined handedness or chirality. Whether such chiral activity can introduce stereoselective interactions between particles is not known. Here, we developed a strategy to tune the nature of chiral activity of three-dimensionally printed granular ellipsoids without altering their shape or size. In vertically agitated monolayers of these particles, we observed two types of dimers form depending on the chirality of the pairing monomers. Heterochiral dimers moved collectively as a single achiral active unit, while homochiral ones formed a translationally immobile spinner. In active racemic mixtures, the former was more abundant than the latter, indicating that interactions were stereoselective. Through dimer lifetime measurements, we further provide evidence for chiral self-recognition in mixtures of particles with different chiral activities. We lastly show that, at fixed particle number density, changing the net chirality of a dense active liquid fundamentally alters the nature of collective relaxation.

在许多活性物质系统中，粒子轨迹具有明确的惯性或手性。这种手性是否能在颗粒之间引入立体选择性相互作用尚不清楚。在这里，我们开发了一种策略，可在不改变其形状或大小的情况下调整三维打印的粒状椭球体的手性活性。在这些颗粒的垂直搅动的单层中，我们观察到两种类型的二聚体形成，这取决于配对单体的手性。异源二聚体作为一个非手性活性单元共同移动，而同手性二聚体形成一个平移固定的旋转器。在活性外消旋混合物中，前者比后者更丰富，表明相互作用是立体选择性的。通过二聚体寿命测量，我们进一步为具有不同手性活性的颗粒混合物中的手性自我识别提供了证据。我们最后表明，在固定的粒子数密度下，改变稠密活性液体的净手性从根本上改变了集体弛豫的性质。