  The nonequilibrium steady state of an infinite-range Ising model is studied.
The steady state is obtained by dividing the spins into two groups and
attaching them to two heat baths generating spin flips at different
temperatures. In the thermodynamic limit, the resulting dynamics can be solved
exactly, and the probability flow in the phase space can be visualized. We can
calculate the steady state fluctuations far from equilibrium and, in
particular, we find the exact probability distribution of the energy current in
both the high- and low-temperature phase.
