Reduced quantum dynamics in condensed phase

Joachim Ankerhold

The phase space dynamics of dissipative quantum systems in strongly condensed phase is considered. Based on the exact path integral approach, it is shown that the Wigner transform of the reduced density matrix obeys a time evolution equation of Fokker-Planck type valid from high down to very low temperatures. The effect of quantum fluctuations is discussed and the accuracy of these findings is tested against exact data for a harmonic system.

Zvi Kotler

Joachim Ankerhold

The phase space dynamics of dissipative quantum systems in strongly condensed phase is considered. Based on the exact path integral approach it is shown that the Wigner transform of the reduced density matrix obeys a time evolution equation of Fokker-Planck type valid from high down to very low temperatures. The effect of quantum fluctuations is discussed and the accuracy of these findings is tested against exact data for a harmonic system. Typeset using REVTEX 1 Introduction–Dynamics in strongly condensed phase can be found almost everywhere in nature, e.g. for tunnel diodes in mesoscopic physics, for macromolecules in biological and soft matter systems, and for chemical reactions, to name but a few. Associated with this bunch of realizations is a rich phenomenology comprising prominent effects such as stochastic resonance [1], resonant activation [2], transport in ratchets [3], and adiabatic

L. Lanz, Luigi A. Lugiato, G. Ramella

M. Nigro, P. Capuzzi, Horacio M. Cataldo +1 more

We study the dynamics of three-dimensional weakly linked Bose-Einstein condensates using a multimode model with an effective interaction parameter. The system is confined by a ring-shaped four-well trapping potential. By constructing a two-mode Hamiltonian in a reduced highly symmetric phase space, we examine the periodic orbits and calculate their time periods both in the self-trapping and Josephson regimes. The dynamics in the vicinity of the reduced phase space is investigated by means of a Floquet multiplier analysis, finding regions of different linear stability and analyzing their implications on the exact dynamics. The numerical exploration in an extended region of the phase space demonstrates that two-mode tools can also be useful for performing a partition of the space in different regimes. Comparisons with Gross-Pitaevskii simulations confirm these findings and emphasize the importance of properly determining the effective on-site interaction parameter governing the multimode dynamics.

D. C. Hutcgings