Experimental Observation of Intermittency in Coupled Chaotic Pendulums

We have experimentally realized on–off intermittency in a pair of mutually coupled damped driven pendula. The pendula interacted bidirectionally via a torque which was proportional to the difference in their angular velocities. Experimental data show that the intervals of synchronized chaotic motion are distributed in agreement with the theory for on–off intermittency: The conditional probability of short laminar times is found to follow a power law whilst the conditional probability of long laminar times follows the expected exponential law. The experimental data also reveal that the intermittent properties vary with the coupling strength, and that the average laminar time inferred from the results depends on the choice of threshold level.