Stability and multistability of synchronization in networks of coupled phase oscillators

Coupled phase oscillators usually achieve synchronization as the coupling strength among oscillators is increased beyond a critical value.The stability of synchronous state remains an open issue.In this paper,we study the stability of the synchronous state in coupled phase oscillators.It is found that numerical integration of differential equations of coupled phase oscillators with a finite time step may induce desynchronization at strong couplings.The mechanism behind this instability is that numerical accumulated errors in simulations may trigger the loss of stability of the synchronous state.Desynchronization critical couplings are found to increase and diverge as a power law with decreasing the integral time step.Theoretical analysis supports the local stability of the synchronized state.Globally the emergence of synchronous state depends on the initial conditions.Other metastable ordered states such as twisted states can coexist with the synchronous mode.These twisted states keep locally stable on a sparse network but lose their stability when the network becomes dense.