2,732 research outputs found
Dissipation in Open Two-Level Systems: Perturbation Theory and Polaron Transformation
We compare standard perturbation theory with the polaron transformation for
non-linear transport of electrons through a two-level system. For weak
electron-phonon coupling and large bias, there is good agreement between both
approaches. This regime has recently been explored in experiments in double
quantum dots.Comment: 4 pages, 1 figure, to appear in proceedings of MB1
Dynamics of a large-spin-boson system in the strong coupling regime
We investigate collective effects of an ensemble of biased two level systems
interacting with a bosonic bath in the strong coupling regime. The two level
systems are described by a large pseudo-spin J. An equation for the expectation
value M(t) of the z-component of the pseudo spin is derived and solved
numerically for an ohmic bath at T=0. In case of a large cut-off frequency of
the spectral function, a Markov approximation is justified and an analytical
solution is presented. We find that M(t) relaxes towards a highly correlated
state with maximum value for large times. However, this relaxation is
extremely slow for most parameter values so as if the system was "frozen in" by
interaction with the bosonic bath.Comment: 4 pages, 2 figures, to be published in proceedings of MB1
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