  The position and motion of localized states of light in propagative
geometries can be controlled via an adequate parameter modulation. Here, we
show theoretically and experimentally that this process can be accurately
described as the phase locking of oscillators to an external forcing and that
non-reciprocal interactions between light bits can drastically modify this
picture. Interactions lead to the convective motion of defects and to unlocking
as a collective emerging phenomenon.
