Nonreciprocal robotic active matter

Nonreciprocity in biological and synthetic active matter gives rise to distinctive material properties, such as odd material moduli, sustained wave propagation, and transverse responses. A key challenge is translating these phenomena into macroscopic systems with robust, programmable functionality. To address this, we have developed a Magnetically-Augmented Spinning Robotic Swarm (MASbotS) platform that operates at the air-water interface, with programmable magnetic and hydrodynamic interactions. In addition to breaking time-reversal and chiral symmetry, individual MASbot can further disrupt n-fold symmetry via programmable magnetic interactions. Preliminary experiments demonstrate that tuning the interaction strength can transition the system from a solid-like state with directed boundary flows to a fluid-like regime with flowing dynamics reminiscent of topological mixing. Strikingly, robot pairs exhibit emergent oscillatory dynamics and synchronization in rotation phase, both crucial ingredients to drive robust wave propagation in many-body collectives. Our MASbotS platform provides a new avenue to explore how the interplay of nonlinear dynamics—such as synchronization—and nonreciprocal interactions can define novel emergent states of matter with programmable functionality.