State Diagram of the Non-Reciprocal Cahn-Hilliard Model and the Effects of Symmetry (2503.07579v2)

Abstract: Interactions between active particles may be non-reciprocal, breaking action-reaction symmetry and leading to novel physics not seen in equilibrium systems. In this work, we study the state diagram for the non-reciprocal Cahn-Hilliard (NRCH) model with different types of symmetry -- discrete and continuous -- and examine the effects of non-reciprocity on phase separation. The models are analyzed by drawing the full linear stability diagrams, indicating the onset of phase separation, allowing us to demonstrate how non-reciprocity gives rise to out-of-equilibrium steady states with non-zero currents. These observations remain valid in a large part of parameter space, and with the addition of weak noise. By describing the effects of symmetry on conserved, non-reciprocal models, this work adds to our understanding of the rich behavior of such models.