%0 Journal Article
%A Viyuela, O.
%A Rivas, A.
%A Martín-Delgado Alcántara, Miguel Ángel
%T Uhlmann phase as a topological measure for one-dimensional fermion systems
%D 2014
%@ 0031-9007
%U https://hdl.handle.net/20.500.14352/35600
%X We introduce the Uhlmann geometric phase as a tool to characterize symmetry-protected topological phases in one-dimensional fermion systems, such as topological insulators and superconductors. Since this phase is formulated for general mixed quantum states, it provides a way to extend topological properties to finite temperature situations. We illustrate these ideas with some paradigmatic models and find that there exists a critical temperature Tc at which the Uhlmann phase goes discontinuously and abruptly to zero. This stands as a borderline between two different topological phases as a function of the temperature. Furthermore, at small temperatures we recover the usual notion of topological phase in fermion systems.
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