1207.2036 (Zhihai Wang et al.)

Disappearance of equilibrium with thermal spin bath induced by
non-Markov process    [PDF]

Zhihai Wang, Yu Guo, D. L. Zhou

In most cases, a small system weakly interacting with a thermal bath will finally reach the thermal state with the temperature of the bath. We show that this intuitive picture is not always true by a spin star model where non-Markov effect predominates in the whole dynamical process. The spin star system consists a central spin homogeneously interacting with an ensemble of identical noninteracting spins. We find that the correlation time of the bath is infinite, which implies that the bath has a perfect memory, and that the dynamical evolution of the central spin must be non- Markovian. A direct consequence is that the final state of the central spin is not the thermal state equilibrium with the bath, but a steady state which depends on its initial state.

View original: http://arxiv.org/abs/1207.2036