Article (Scientific journals)
Uhlmann fidelity and fidelity susceptibility for integrable spin chains at finite temperature: exact results
Białończyk, Michał; Gomez-Ruiz, Fernando Javier; Del Campo Echevarria, Adolfo
2021In New Journal of Physics
Peer reviewed
 

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Abstract :
[en] We derive the exact expression for the Uhlmann fidelity between arbitrary thermal Gibbs states of the quantum XY model in a transverse field with finite system size. Using it, we conduct a thorough analysis of the fidelity susceptibility of thermal states for the Ising model in a transverse field.We compare the exact results with a common approximation that considers only the positive-parity subspace, which is shown to be valid only at high temperatures. The proper inclusion of the odd parity subspace leads to the enhancement of maximal fidelity susceptibility in the intermediate range of temperatures. We show that this enhancement persists in the thermodynamic limit and scales quadratically with the system size. The correct low-temperature behavior is captured by an approximation involving the two lowest many-body energy eigenstates, from which simple expressions are obtained for the thermal susceptibility and specific heat.
Disciplines :
Physics
Author, co-author :
Białończyk, Michał;  Institute of Theoretical Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krak´ow, Poland
Gomez-Ruiz, Fernando Javier;  Donostia International Physics Center, E-20018 San Sebastián, Spain ; Departamento de Física, Universidad de los Andes, A.A. 4976, Bogotá D. C., Colombia ; Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg, Luxembourg
Del Campo Echevarria, Adolfo  ;  University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)
External co-authors :
yes
Language :
English
Title :
Uhlmann fidelity and fidelity susceptibility for integrable spin chains at finite temperature: exact results
Publication date :
23 September 2021
Journal title :
New Journal of Physics
Peer reviewed :
Peer reviewed
Focus Area :
Physics and Materials Science
Available on ORBilu :
since 11 November 2021

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