We study the interplay between an inhomogeneous quantum quench of the
external potential in a system of relativistic fermions in one dimension and
the well-known Klein tunneling. We find that the large time evolution is
characterized by particle production at a constant rate which we derive
analytically. The produced particles can be physically interpreted according to
a semiclassical picture and the state reached in the long time limit can be
classified as a non-equilibrium-steady-state. Such a quantum quench can be used
in order to observe macroscopic effects of Klein tunneling in transport,
raising the possibility of an experimental implementation.Comment: 15 pages, 8 figure