Projected Entangled Pair States at Finite Temperature: Imaginary Time   Evolution with Ancillas
  A projected entangled pair state (PEPS) with ancillas is evolved in imaginary time. This tensor network represents a thermal state of a 2D lattice quantum system. A finite temperature phase diagram of the 2D quantum Ising model in a transverse field is obtained as a benchmark application. 
Piotr Czarnik, Lukasz Cincio, Jacek Dziarmaga
cond-mat.str-el cond-mat.quant-gas cond-mat.stat-mech quant-ph