Dynamical heterogeneity in chiral active jamming

Jamming transitions in granular materials occur when the density exceeds a certain threshold, leading to the emergence of mechanical rigidity, even in disordered media. While the characteristics of jamming transitions have been extensively studied, the role of nonequilibrium activity and chirality in modulating this transition remains poorly understood. In this work, we demonstrate that a 2D collective of self-propelling and chirally rotating starfish embryos undergoes a jamming transition as density increases. We observe intermittent bursts of displacement chains and dynamic rearrangement, reminiscent of the dynamical heterogeneity seen in glassy systems, but with chiral signatures. As embryos develop further, we find that short-range nematic ordering develops in the system, giving rise to distinct structural patterns and orientational ordering. We posit that non-reciprocal interactions between the embryos will lead to odd behavior in the jamming transition, which may be detected through geometric order parameters such as tension triangles.