  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 $\pm J$ 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.
