Programmable structural control of a type of bistable spiral waves via engineered pulses.

Abstract

Spiral waves, self-organized patterns prevalent in diverse nonequilibrium systems from cardiac tissue to chemical reactions, exhibit complex dynamics influenced by medium properties such as bistability. A type of structure, the bistable Yin-Yang (BYY) spiral waves, characterized by a dynamic line defect separating two regions oscillating with distinct wave crests, emerges uniquely in oscillatory bistable media. Controlling such intricate spiral structures-particularly modifying their internal features like line defects-remains challenging and underexplored. Here we establish a methodology for the structural control of the BYY spiral waves. Through targeted pulse application, we demonstrate three fundamental operations: elimination of the line defect in the BYY spiral wave, driving the system to a homogeneous wave crest state; programmable addition of line defects whose evolution depends critically on their spatial placement; and induction of persistent spatiotemporal oscillations, where wave crests rhythmically alternate during wave propagation. Phase space analysis reveals that these controlled states emerge from symmetric limit cycles with intertwined basins of attraction, with pulse thresholds dictated by geometric relationships between these basins. This work provides a method for manipulating complex spiral wave architectures and reveals elimination, addition, and modulation of line defects.