  Detecting topological order in cold-atom experiments is an ongoing challenge,
the resolution of which offers novel perspectives on topological matter. In
material systems, unambiguous signatures of topological order exist for
topological insulators and quantum Hall devices. In quantum Hall systems, the
quantized conductivity and the associated robust propagating edge modes -
guaranteed by the existence of non-trivial topological invariants - have been
observed through transport and spectroscopy measurements. Here, we show that
optical-lattice-based experiments can be tailored to directly visualize the
propagation of topological edge modes. Our method is rooted in the unique
capability for initially shaping the atomic gas, and imaging its time-evolution
after suddenly removing the shaping potentials. Our scheme, applicable to an
assortment of atomic topological phases, provides a method for imaging the
dynamics of topological edge modes, directly revealing their angular velocity
and spin structure.
