Controlled dynamics of interfaces in a vibrated granular layer

We present an experimental study of a topological excitation, interface, in a vertically vibrated layer of granular material. We show that these interfaces, which separate regions of granular material oscillating with opposite phases, can be shifted and controlled by a very small amount of additional subharmonic driving mixed with the harmonic driving signal. The speed and the direction of the interface motion depends sensitively on the phase and the amplitude of the subharmonic driving.