  I analyze a metrological strategy for improving the precision of frequency
estimation via Ramsey interferometry with strings of atoms in the presence of
correlated dephasing. This strategy does not employ entangled states, but
rather a product state which evolves into a stationary state under the
influence of correlated dephasing. It is shown that by using this state an
improvement in precision compared to standard Ramsey interferometry can be
gained. This improvement is not an improvement in scaling, i.e. the estimation
precision has the same scaling with the number of atoms as the standard quantum
limit, but an improvement proportional to the free evolution time in the Ramsey
interferometer. Since a stationary state is used, this evolution time can be
substantially larger than in standard Ramsey interferometry which is limited by
the coherence time of the atoms.
