Mixed state topological order parameters for symmetry protected fermion matter

• URL: http://arxiv.org/abs/2401.10993v1
• Date: Fri, 19 Jan 2024 19:21:25 GMT
• Title: Mixed state topological order parameters for symmetry protected fermion matter
• Authors: Ze-Min Huang, Sebastian Diehl
• Abstract summary: We construct an observable mixed state topological order parameter for symmetry-protected free fermion matter. It provides a robust, quantized signal not only for pure ground states, but also for mixed states in- or out of thermal equilibrium.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We construct an observable mixed state topological order parameter for symmetry-protected free fermion matter. It resolves the entire table of topological insulators and superconductors, relying exclusively on the symmetry class, but not on unitary symmetries. It provides a robust, quantized signal not only for pure ground states, but also for mixed states in- or out of thermal equilibrium. Key ingredient is a unitary probe operator, whose phase can be related to spectral asymmetry, in turn revealing the topological properties of the underlying state. This is demonstrated analytically in the continuum limit, and validated numerically on the lattice. The order parameter is experimentally accessible via either interferometry or full counting statistics, for example, in cold atom experiments.

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