Optimal estimation of Gaussian states and channels

We will discuss the problem of Gaussian state and channel
estimation from a general viewpoint. By providing an analytic form for
the elusive Fisher information matrix in the Gaussian case, we proceed
to analyze the optimal estimation rates of Gaussian channels. We pay
special attention to the physical limits on energy/squeezing and
derive optimal states and measurements for the task. Our results put
in perspective previously known results.