In this talk I will consider two fermionic chains at
different densities joined together and evolved unitarily. I will
present many exact results concerning the large-time limit of
correlation functions and the Loschmidt echo. I will show that this
type of quench is deeply related, via analytic continuation in
imaginary time, to the arctic curve phenomena in statistical
mechanics: interfaces separating fluctuating and frozen regions, a
celebrated example of which is the arctic circle in the six-vertex
model.
