  We study coupled transport in the nonequilibrium stationary state of a model
consisting of independent random walkers, moving along a one-dimensional
channel, which carry a conserved energy-like quantity, with density and
temperature gradients imposed by reservoirs at the ends of the channel. In our
model, walkers interact with other walkers at the same site by sharing energy
at each time step, but the amount of energy carried does not affect the motion
of the walkers. We find that already in this simple model long-range
correlations arise in the nonequilibrium stationary state which are similar to
those observed in more realistic models of coupled transport.

Statistical Mechanics