Ahsan Nazir, Dara P. S. McCutcheon, Alex W. Chin
We propose a ground-state ansatz for the Ohmic spin-boson model that improves
upon the variational treatment of Silbey and Harris for biased systems in the
scaling limit. In particular, it correctly captures the smooth crossover
behaviour expected for the ground-state magnetisation when moving between the
delocalised and localised regimes of the model, a feature that the variational
treatment is unable to properly reproduce, while it also provides a lower
ground-state energy estimate in the crossover region. We further demonstrate
the validity of our intuitive ground-state by showing that it leads to
predictions in excellent agreement with those derived from a non-perturbative
Bethe-ansatz technique. Finally, recasting our ansatz in the form of a
generalised polaron transformation, we are able to explore the dissipative
two-state dynamics beyond weak system-environment coupling within an efficient
time-local master equation formalism.
View original:
http://arxiv.org/abs/1201.5650
No comments:
Post a Comment