The effect of fluctuations in the classical control parameters on the Berry phase of a spin 1/2 interacting with a adiabatically cyclically varying magnetic field is analyzed. It is explicitly shown that in the adiabatic limit dephasing is due to fluctuations of the dynamical phase.
@article{arxiv.quant-ph/0303155,
title = {Berry phase for a spin 1/2 in a classical fluctuating field},
author = {Gabriele De Chiara and G. Massimo Palma},
journal= {arXiv preprint arXiv:quant-ph/0303155},
year = {2009}
}