title: Delocalization and quantum chaos in atom-field systems.
abstract: Employing efficient diagonalization techniques, we perform a detailed quantitative study of the regular and chaotic regions in phase space in the simplest nonintegrable atom-field system, the Dicke model. A close correlation between the classical Lyapunov exponents and the quantum Participation Ratio of coherent states on the eigenenergy basis is exhibited for different points in the phase space. It is also shown that the Participation Ratio scales linearly with the number of atoms in chaotic regions and with its square root in the regular ones.
authors.affiliation: Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, México D. F., C.P. 04510, México.
authors.forename: M A
authors.initials: MA
authors.lastname: Bastarrachea-Magnani
authors.affiliation: Facultad de Física, Universidad Veracruzana, Circuito Aguirre Beltrán s/n, Xalapa, Veracruz, C.P. 91000, México.
authors.forename: B
authors.initials: B
authors.lastname: López-del-Carpio
authors.affiliation: Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, México D. F., C.P. 04510, México.
authors.forename: J
authors.initials: J
authors.lastname: Chávez-Carlos
authors.affiliation: Facultad de Física, Universidad Veracruzana, Circuito Aguirre Beltrán s/n, Xalapa, Veracruz, C.P. 91000, México.
authors.forename: S
authors.initials: S
authors.lastname: Lerma-Hernández
authors.affiliation: Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apdo. Postal 70-543, México D. F., C.P. 04510, México.
authors.forename: J G
authors.initials: JG
authors.lastname: Hirsch