Braid description of few body dynamics

A few body system of magnetic holes set in motion by external ac magnetic f ields is studied both experimentally and numerically. Notions from braid th eory are used to describe the dynamics in a very compact manner. The time h istory of n magnetic holes moving in a plane is represented by an n-strand braid which enables us to extract periodic orbits and to map out phase port raits. The transitions between different periodic modes of motion are eithe r continuous or noncontinuous followed by strong hysteresis.