Nonequilibrium Quantum Phase Transitions in the XY model: comparison of unitary time evolution and reduced density matrix approaches

Shigeru Ajisaka, Felipe Barra, Bojan Žunkovič

We study nonequilibrium quantum phase transitions in XY spin 1/2 chain using the $C^{\ast }$ algebra. We show that the well-known quantum phase transition at magnetic field $h=1$ persi…