Fidelity, susceptibility and critical exponents in the Dicke model

36th Symposium on Nuclear Physics

Bastarrachea-Magnani, M.A.^1 ; Castaños, O.^1 ; Nahmad-Achar, E.^1 ; López-Peña, R.^1 ; Hirsch, J.G.^1

Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, C.P. 04510 México, Mexico^1

关键词: Critical coupling;    Critical exponent;    Critical value;    Dicke model;    Finite number;    Ground state wavefunctions;    Quantum phase;    Universal curve;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/492/1/012012/pdf
DOI  :  10.1088/1742-6596/492/1/012012

来源: IOP

【 摘 要 】

We calculate numerically the fidelity and its susceptibility for the ground state of the Dicke model. A minimum in the fidelity identifies the critical value of the interaction where a quantum phase crossover, the precursor of a phase transition for finite number of atoms N, takes place. The evolution of these observables is studied as a function of N, and their critical exponents evaluated. Using the critical exponents the universal curve for the specific susceptibility is recovered. An estimate to the precision to which the ground state wave function is numerically calculated is given, and found to have its lowest value, for a fixed truncation, in a vicinity of the critical coupling.