Confinement-induced phase transitions of Living Chiral Crystal

Active crystal is a unique manifestation of active matter characterized by crystalline order. While recent studies have shown how the interplay between activity and elasticity can result in intriguing self-organized dynamical states in active crystals, how these nonequilibrium phases and their excitations are influenced by boundary conditions remains unexplored. Living Chiral Crystal (LCC), self-assembled by swimming starfish embryos, represents an active crystal distinguished by non-reciprocal (chiral) interactions. Here we explore the influence of boundary interactions on the structure and dynamics of LCC. We confine LCC within regular polygonal and circular boundaries, while controlling the density of LCC within the confinements. We observe various phases of LCC, ranging from localized fluctuations to robust rigid body rotations and chaotic mixing. These findings provide insights into how LCC serves as a model system for uncovering novel and diverse properties of non-reciprocal active matter.