Erlangen 2018 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 70: Ultracold Atoms II (joint session Q/A)
Q 70.8: Vortrag
Freitag, 9. März 2018, 12:15–12:30, K 1.022
Survival probability of coherent states in regular regimes — •Miguel A. Bastarrachea-Magnani1, Sergio A. Lerma-Hernández2, Jorge Chávez-Carlos3, Lea F. Santos4, and Jorge G. Hirsch3 — 1Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Germany — 2Facultad de Física, Universidad Veracruzana, Xalapa, México — 3Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México — 4Department of Physics, Yeshiva University, New York, USA
We study the behavior of coherent states under unitary quantum dynamics in systems with one and two degrees of freedom. To this end, we employ the Dicke Hamiltonian, a paradigmatic model of quantum optics. Within the regular regime of the spectrum, the distribution of the coherent states in the eigenstate basis consists of quasi-harmonic sub-sequences of energies with gaussian weights. This allows to derive analytical expressions for the survival probability of the coherent states. The analytical expressions describe the time evolution in agreement with numerical results up to the decay of the survival probability oscillations. We explore how this decay rate is related to the anharmonicity of the spectrum, and, for the chaotic regime of the Dicke model, to interference terms due to the contributions of different sub-sequences of eigenstates to the coherent states. Moreover, we correlate the dynamics of the coherent states with the classical limit of the model, to elucidate how these interference terms are related to the onset of chaos in the spectrum. Since most bounded Hamiltonians have a regular regime at low energies, the approach has broad applicability.