J. Phys. IV France 08 (1998) Pr6-203-Pr6-207
Chaos in effective classical and quantum dynamics of nonlinear oscillatorsL. Casetti1, 2, R. Gatto1 and M. Modugno1, 3
1 Département de Physique Théorique, Université de Genève, 24 quai Ernest-Ansermet, 1211 Genève, Switzerland
2 INFM, Unità di Ricerca del Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
3 Dipartimento di Fisica, Università di Firenze, Largo Enrico Fermi 2, 50125 Firenze, Italy
We investigate the dynamics of classical and quantum N-component Φ4 oscillators in presence of an external field. In the large N limit the effective dynamics is described by two-degree-of-freedom classical Hamiltonian systems. In the classical model we observe chaotic orbits for any value of the external field, while in the quantum case chaos is strongly suppressed. A simple explanation of this behaviour is found in the change in the structure of the orbits induced by quantum corrections. Consistently with Heisenberg's principle, quantum fluctuations are forced away from zero, removing in the effective quantum dynamics a hyperbolic fixed point that is a major source of chaos in the classical model.
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