  We study the dynamics of impurity bound electrons interacting with a bath of
conduction band electrons in a semiconductor. Only the exchange interaction is
considered. We derive master equations for the density matrices of single and
two qubit systems under the usual Born and Markov approximations. The bath
mediated RKKY interaction in the two qubit case arises naturally. It leads to
an energy shift significant only when the ratio ($R_{T}$) of the inter-qubit
distance to the thermal deBroglie wavelength of the bath electrons is small.
This bath mediated interaction also has a profound impact on the decoherence
times; the effect decreases monotonically with $R_{T}$.
