  In this work we study One Axis Twisting (OAT) spin squeezing for metrology in
the presence of decoherence. We study Linbladian evolution in the presence of
both T_1 and T_2 (longitudinal and transverse relaxation processes). We show
that spin squeezing can be an effective way to improve metrological accuracy
even in the presence of decoherence for OAT squeezing. We show our results are
not sensitive to inhomogeneity of the squeezing strength of the many spin OAT
Hamiltonian and that very general squeezed states do not have entanglement
enhanced decoherence. We also extend the Kitagawa-Ueda OAT squeezing formula to
finite polarization.
