  Topological insulators insulate in the bulk but exhibit robust conducting
edge states protected by the topology of the bulk material. Here, we design a
colloidal topological insulator and demonstrate experimentally the occurrence
of edge states in a classical particle system. Magnetic colloidal particles
travel along the edge of two distinct magnetic lattices. We drive the colloids
with a uniform external magnetic field that performs a topologically
non-trivial modulation loop. The loop induces closed orbits in the bulk of the
magnetic lattices. At the edge, where both lattices merge, the colloids perform
skipping orbits trajectories and hence edge-transport. We also observe
paramagnetic and diamagnetic colloids moving in opposite directions along the
edge between two inverted patterns; the analogue of a quantum spin Hall effect
in topological insulators. We present a new, robust, and versatile way of
transporting colloidal particles, enabling new pathways towards lab on a chip
applications.
