English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We study the fidelity approach to quantum phase transitions (QPTs) and applyit to general thermal phase transitions (PTs). We analyze two particular cases:the Stoner-Hubbard itinerant electron model of magnetism and the BCS theory ofsuperconductivity. In both cases we show that the sudden drop of the mixedstate fidelity marks the line of the phase transition. We conduct a detailedanalysis of the general case of systems given by mutually commutingHamiltonians, where the non-analyticity of the fidelity is directly related tothe non-analyticity of the relevant response functions (susceptibility and heatcapacity), for the case of symmetry-breaking transitions. Further, on the caseof BCS theory of superconductivity, given by mutually non-commutingHamiltonians, we analyze the structure of the system's eigenvectors in thevicinity of the line of the phase transition showing that their sudden changeis quantified by the emergence of a generically non-trivial Uhlmann mixed stategeometric phase.

Macroscopic Distinguishability Between Quantum States Defining Different Phases of Matter: Fidelity and the Uhlmann Geometric Phase