Observation of induced subcritical bifurcation by near-resonant perturbations

We present the first experimental evidence that near-resonant perturbations produce a destabilizing shift of a subcritical bifurcation. This is in direct contrast to supercritical bifurcations, where near-resonant perturbations always suppress the instability. Using a normal form analysis we derive a generic scaling law relating the magnitude of the destabilizing shift {μ} to the perturbation amplitude {ε} and detuning frequency {δ}. The predictions are in excellent agreement with our experiments. In the limit of very small {δ} the shift obeys a pure scaling law, {μ}{∝}({ε})2/3.