Observation of the Predicted Behavior of Nonlinear Pulse Propagation in Disordered Media

A fundamental question concerning systems which are both disordered and nonlinear is whether or not Anderson localization is weakened by the nonlinearity. Theory predicts that localized eigenstates will survive nonlinearity, whereas nonlinear pulses may or may not experience the effects of localization depending on the relative magnitude of the Anderson localization length and a characteristic ``nonlinearity'' length for the pulse. We have used nonlinear surface waves on a superfluid helium film to obtain results in agreement with theoretical predictions.