Emergent phenomena in chiral active matter

In recent years, there has been growing interest in the study of chiral active materials, which consist of building blocks that show active dynamics featuring chiral symmetry breaking, e.g., particles that rotate in a common direction. These materials exhibit fascinating phenomena such as odd viscosity, odd diffusivity, active turbulence in fluids, vivid dislocation dynamics or odd elasticity in crystals or elastic materials, and hyperuniform states. The systematic study of soft chiral active matter systems is relatively new, starting around 2017, but has already shown promising applications in robust cargo transport,segregation and mixing dynamics, or manipulation of metamaterials. In this review, we summarize recent experimental and theoretical advances in this field, highlighting the emergence of anti-symmetric and odd stresses and ensuring effects such as odd viscosity or topologically protected edge modes. We further discuss the underlying mechanisms and provide insights into the potential of chiral active matter for various applications.