Quantum phases of matter in open systems
Date:
In this talk, I plan to introduce our recent works on quantum phases in open systems. I will begin with briefly introducing the basic concepts and classification scheme for quantum phases of matter in closed systems, especially the classification of symmetry protected topological (SPT) phases with matrix product state (MPS). Secondly, I will discuss the generalization of symmetry properties to open systems, which are represented by the local symmetry transformation of locally purified density operator (LPDO). Next, the general classification of average SPT (ASPT) phases in open systems will be discussed, accompanied by their tensor construction and physical realization in decohered and disordered systems. Then I will proceed to our new framework to understand the quantum phase transitions in open systems, namely imaginary-time Lindbladian evolution. Using this formalism, a new phase named double ASPT phase is demonstrated, which exhibits both properties of SPT and spontaneous symmetry breaking (SSB). Finally, I will display a complete phase diagram of Z2×Z2 symmetry that contains all interesting phases above, with two topologically distinct triple points and three different realizations of gapless ASPT phases.