Rate-selective synchronization in switching networks: when timing meets structure

Abstract

Switching networks arise across physics, biology, and engineering, where interactions turn on and off due to communication limits, control protocols, failures, or scheduling. Most synchronization theory for switching networks of continuous-time oscillators relies on the fast-switching approximation, yet many systems operate outside this regime, where switching can produce unexpected and counterintuitive collective dynamics. We develop the first analytical framework for synchronization in non-fast-switching networks of saddle-focus continuous-time oscillators. Using Rössler and piecewise-smooth systems as canonical examples, we leverage a structural property of saddle-focus oscillators to reduce the variational dynamics to a linear system with constant coefficients, enabling a Floquet-theoretic stability characterization under periodic switching. The analysis identifies explicit switching intervals that stabilize synchronization even when neither switching mode nor the corresponding average system supports synchronization in isolation, thereby revealing the mechanism underlying the emergence of "windows of opportunity" at intermediate switching rates. We further derive a switching-dependent master stability function linking the network Laplacian spectrum to the switching rate. The master stability function provides two complementary routes to inducing or preserving synchronization: adjusting the switching schedule for a fixed network or adapting the network spectrum to a prescribed schedule through our constructive edge-pruning or edge-augmentation algorithms. These results provide a rigorous basis for understanding and leveraging intermediate-rate switching in the design and control of evolving networks.