Symmetry protected topological phases under decoherence

We investigate mixed states exhibiting nontrivial topological features, focusing on symmetry-protected topological (SPT) phases under various types of decoherence. Our findings demonstrate that these systems can retain topological information from the SPT ground state despite decoherence. In the ''doubled Hilbert space,'' we define symmetry-protected topological ensembles (SPT ensembles) and examine boundary anomalies in this space. We generalize the concept of the strange correlator, initially used to diagnose SPT ground states, to identify anomalies in mixed-state density matrices. Through exact calculations of stabilizer Hamiltonians and field theory evaluations, we show…

• NS
  National Science Foundation

  Awards: 2238360, 1920434, DMR-1920434, 1748958, DMR-2238360
• GA
  Gordon and Betty Moore Foundation

  Awards: PHY-1748958, GBMF8690
• UO
  University of California, San Diego
• DO
  Division of Materials Research

  Award: DMR-2238360
• KI
  Kavli Institute for Theoretical Physics, University of California, Santa Barbara

  Awards: 1748958, PHY-1748958