Europhys. Lett, 47 (3), pp. 285-291 (1999)
Quantum tunneling and the semiclassical real time
of the density matrix
J. Ankerhold 1,2 and H. Grabert 2
1 Department of Chemistry, Columbia University - New York,
NY 10027, USA
2 Fakultät für Physik, Albert-Ludwigs-Universität Freiburg
Hermann-Herder-Straße 3, D-79104 Freiburg, Germany
(received 12 February 1999; accepted in final form 2 June 1999)
PACS. 03.65Sq - Semiclassical theories and applications.
PACS. 82.20Db - Statistical theories (including transition states).
PACS. 05.60Gg - Quantum transport.
The time evolution of the density matrix of a system with potential barrier is determined using path integrals. Describing the quantum dynamics in terms of the semiclassical motion in the complex coordinate plane, a detailed picture of barrier penetration in the time domain and the change-over from thermal activation to quantum tunneling is gained. Deep tunneling is shown to arise from specific fluctuations about the semiclassical real time trajectories.
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