https://doi.org/10.1140/epjd/e2013-40099-0
Regular Article
Non-Markovian dynamics in a spin star system: the failure of thermalisation
1 Beijing National Laboratory for
condensed matter physics, Institute of Physics, Chinese Academy of Sciences,
Beijing
100190, P.R.
China
2 School of Physics and Electronic
Science, Changsha University of Science and Technology, Changsha
410114, P.R.
China
a
e-mail: zhoudl72@aphy.iphy.ac.cn
Received:
25
February
2013
Received in final form:
29
May
2013
Published online:
1
November
2013
In most cases, a small system weakly interacting with a thermal bath will eventually reach a thermal state with the temperature of the bath. We show that this intuitive picture is not always true, by using a spin star model where the non-Markov effect dominates the dynamical process. The spin star system consists of 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 of this is that the final state of the central spin is not the thermal state in equilibrium with the bath, but a steady state which depends on the initial state of the spin.
Key words: Quantum Optics
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2013