Classification of Mixed State Topology in One Dimension
  We show how to generalize the concepts of identifying and classifying symmetry protected topological phases in 1D to the case of an arbitrary mixed state. The pure state concepts are reviewed using a concrete spin-1 model. For the mixed state setup we demonstrate our findings numerically using matrix product state algorithms. Starting from the ground state and applying various types of noise sources we find a transient regime where the system is driven out of equilibrium while retaining its topological properties. 
Evert P. L. van Nieuwenburg and Sebastian D. Huber
cond-mat.str-el cond-mat.stat-mech