  Atomic bosons and fermions in an optical lattice can realize a variety of
interesting condensed matter states that support equilibrium current patterns
in the presence of synthetic magnetic fields or non-abelian gauge fields. As a
route to probing such mass currents, we propose a nonequilibrium quantum quench
of the Hamiltonian that dynamically converts the current patterns into
experimentally measurable real-space density patterns. We illustrate how a
specific such "unidirectional" quench of the optical lattice can be used to
uncover checkerboard and stripe current orders in lattice Bose superfluids and
Fermi gases, as well as chiral edge currents in an integer quantum Hall state.
