title: Lower and upper bounds on the fidelity susceptibility.
abstract: We derive upper and lower bounds on the fidelity susceptibility in terms of macroscopic thermodynamical quantities, such as the susceptibilities and thermal average values. The quality of the bounds is checked against the exact expressions for a single spin in an external magnetic field. Their usefulness is illustrated by two examples of many-particle models which are exactly solved in the thermodynamic limit: the Dicke superradiance model and the single-impurity Kondo model. It is shown that, when divergent behavior is considered, the fidelity susceptibility and the thermodynamic susceptibility are equivalent for a large class of models exhibiting critical behavior.
authors.affiliation: Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russian Federation.
authors.forename: J G
authors.initials: JG
authors.lastname: Brankov
authors.forename: N S
authors.initials: NS
authors.lastname: Tonchev
mesh_terms: D003198:Computer Simulation; D004735:Energy Transfer / Q000528:radiation effects*; D060526:Magnetic Fields; D008956:Models, Chemical; D013816:Thermodynamics