Universität zu Köln

Huang, Ze-Min ORCID: 0000-0002-2369-6245 and Diehl, Sebastian ORCID: 0009-0009-5631-9882 (2025). Mixed-state topological order parameters for symmetry-protected fermion matter. Physical Review Research, 7 (3). pp. 1-17. American Physical Society (APS). ISSN 2643-1564

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Abstract

[Artikel-Nr. 033028] 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

Item Type:	Article
Creators:	Creators Email ORCID ORCID Put Code Huang, Ze-Min UNSPECIFIED https://orcid.org/0000-0002-2369-6245 UNSPECIFIED Diehl, Sebastian UNSPECIFIED https://orcid.org/0009-0009-5631-9882 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-798245
Identification Number:	10.1103/h1qg-96kw
Journal or Publication Title:	Physical Review Research
Volume:	7
Number:	3
Page Range:	pp. 1-17
Date:	7 July 2025
Publisher:	American Physical Society (APS)
ISSN:	2643-1564
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute for Theoretical Physics
Subjects:	Natural sciences and mathematics Physics
['eprint_fieldname_oa_funders' not defined]:	Publikationsfonds UzK
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/79824