  We propose an experimental scheme to probe the contribution of a single Dirac
cone to the Hall conductivity as half-odd topological number sequence. In our
scheme, the quantum anomalous Hall effect as in graphene is simulated with cold
atoms trapped in an optical lattice and subjected to a laser-induced
non-Abelian gauge field. By tuning the laser intensity to change the gauge
flux, the energies of the four Dirac points in the first Brillouin zone are
shifted with each other and the contribution of the single Dirac cone to the
total atomic Hall conductivity is manifested. We also show such manifestation
can be experimentally probed with atomic density profile measurements.
