Luca Magazzù - Università di Palermo #
Dissipative quantum dynamics of a multi-state system #
We consider the dissipative dynamics of a multi-state quantum system
interacting with an environment modeled as a bosonic thermal bath. The
system is a particle in a double well potential, characterized by a
metastable state.
We calculate the time evolution of the populations in a spatially
localized representation (discrete variable representation, DVR),
starting form a non-equilibrium initial condition. Unlike the
Born-Markov approximated master equation, the approach used, which is
based on a real time path integral technique, is non-perturbative in the
system-bath coupling and therefore is suited also for the strong
coupling regime.
The resulting non-Markovian dynamics is given in terms of a set of
coupled integro-differential equations (generalized master equation,
GME) for the populations in the DVR. The kernels of the GME are derived
in different approximation schemes, depending on the damping regime and
bath temperature. Under appropriate conditions, a Markovian master
equation can be derived from the GME.
Various physical systems, ranging from single-molecule magnets to
superconducting devices with Josephson junctions, display dissipative
tunneling and are effectively described by the model considered.
In collaboration with: Davide Valenti and Bernardo Spagnolo
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