  We present a method that can simultaneously locate positions of overlapped
multi-emitters at the theoretical-limit precision. We derive a set of simple
equations whose solution gives the maximum likelihood estimator of
multi-emitter positions. We compare the performance of our simultaneous
localization analysis with the conventional single-molecule analysis for
simulated images and show that our method can improve the time-resolution of
superresolution microscopy an order of magnitude. In particular, we derive the
information-theoretical bound on time resolution of localization-based
superresolution microscopy and demonstrate that the bound can be closely
attained by our analysis.
