Robustness of travelling states in generic non-reciprocal mixtures

Abstract

Emergent non-reciprocal interactions violating Newton's third law are widespread in out-of-equilibrium systems. Phase separating mixtures with such interactions exhibit travelling states with no equilibrium counterpart. Using extensive Brownian dynamics simulations, we investigate the existence and stability of such travelling states in a generic non-reciprocal particle system. By varying a broad range of parameters including aggregate state of mixture components, diffusivity, degree of non-reciprocity, effective spatial dimension and density, we determine that travelling states do exist below the predator-prey regime, but nonetheless are only found in a narrow region of the parameter space. Our work also sheds light on the physical mechanisms for the disappearance of travelling states when relevant parameters are being varied, and has implications for a range of non-equilibrium systems including non-reciprocal phase separating mixtures, non-equilibrium pattern formation and predator-prey models.