Sensitivity to perturbations and quantum phase transition

• Autores: Wisniacki, Diego Ariel; Roncaglia, Augusto Jose
• Año de publicación: 2013
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: quantum phase transitions; quantum chaos
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

The local density of states or its Fourier transform, usually called fidelity amplitude, are important measures of quantum irreversibility due to imperfect evolution. In this Rapid Communication we study both quantities in a paradigmatic many body system, the Dicke Hamiltonian, where a single-mode bosonic field interacts with an ensemble of N two-level atoms. This model exhibits a quantum phase transition in the thermodynamic limit, while for finite instances the system undergoes a transition from quasi-integrability to quantum chaotic. We show that the width of the local density of states clearly points out the imprints of the transition from integrability to chaos but no trace remains of the quantum phase transition. The connection with the decay of the fidelity amplitude is also established.
Fil: Wisniacki, Diego Ariel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisica; Argentina;
Fil: Roncaglia, Augusto Jose. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisica; Argentina;