  Here we provide a general methodology to directly measure the topological
currents emerging in the optical lattice implementation of the Haldane model.
Alongside the edge currents supported by gapless edge states, transverse
currents can emerge in the bulk of the system whenever the local potential is
varied in space, even if it does not cause a phase transition. In optical
lattice implementations the overall harmonic potential that traps the atoms
provides the boundaries of the topological phase that supports the edge
currents, as well as providing the potential gradient across the topological
phase that gives rise to the bulk current. Both the edge and bulk currents are
resilient to several experimental parameters such as trapping potential,
temperature and disorder. We propose to investigate the properties of these
currents directly from time-of-flight images with both short-time and long-time
expansions.
