Easier coordination by less influence

Theoretical physicists from the Max Planck Institute for Dynamics and Self-Organization study the optimal synchronization of complex systems

Whether it is people, fireflies or power plants: synchronization is a vital aspect of many social, biological and technical systems. Reaching a compromise requires 'synchronizing' different opinions. Similarly, fireflies coordinate their blinking and generators in the power grid need to be synchronous for stable operation. However, achieving synchronization of the individual units in complex networked systems can be difficult. In order to solve this problem theoretical physicists from the Göttingen Max Planck Institute for Dynamics and Self-Organization in collaboration with Indian scientists invented and tested a new method. Instead of permanently coupling the individual units the new method occasionally switches interactions off. For many systems this implies larger synchronizability.

Synchronization requires interactions

Coordinating different units, i.e., individual people, fireflies or power generators, obviously requires interactions. Synchrony, the coordinated operation of several units in a system, should be easier to achieve with more interactions. While this seems intuitive, in several chaotic systems stronger coupling can destabilize the synchronous state. Since in many experimental and technical systems the interaction strength cannot be arbitrarily modified the question arises how to synchronize such systems.

Less interaction yields better sychronizability

Mostly, the overall influence of interactions depends on the current state of the system. This led the researchers to restrict the coupling. “Instead of permanently coupling the individual units we allow interaction only occasionally”, explains Professor Dr. Marc Timme, Head of the Research Group Network Dynamics. “In a similar rough analogy, fireflies would not adjust their blinking rhythm continuously but only when observing the blinking of another firefly.”

To describe the effects of this 'uncoupling' in detail the researchers studied the new method in numerical simulations. “ Our results show that the new method makes synchronization more stable and therefore more often possible”, Malte Schröder, PhD student of Marc Timme, points out. In particular, the new method allows synchronization for arbitrarily large interaction strengths, even though this is often not possible for standard coupling. With these results it is feasible to achieve more stable synchrony in certain systems. Potential applications could include self-organized communication networks, wireless sensor networks or possibly even synthetic biological systems such as coupled heart cells.

The work is published in “Physical Review Letters”.
Link to the article: Physical Review Letters 115 (2015) 054101