  Conventional topological insulators exhibit exotic gapless edge or surface
states, as a result of non-trivial bulk topological properties. In
periodically-driven systems the bulk-boundary correspondence is fundamentally
modified and knowledge about conventional bulk topological invariants is
insufficient. While ultracold atoms provide excellent settings for clean
realizations of Floquet protocols, the observation of real-space edge modes has
so far remained elusive. Here we demonstrate an experimental protocol for
realizing chiral edge modes in optical lattices, by creating a topological
interface using a potential step that is generated with a programmable optical
potential. We show how to efficiently prepare particles in these edge modes in
three distinct Floquet topological regimes that are realized in a
periodically-driven honeycomb lattice. Controlling the height and sharpness of
the potential step, we study how edge modes emerge at the interface and how the
group velocity of the particles is modified as the sharpness of the potential
step is varied.
