Information capacity of continuous variable measurement channel

The present paper is devoted to investigation of the classical capacity of infinite-dimensional continuous variable quantum measurement channels. A number of usable conditions are introduced that enable us to apply previously obtained general results to specific models, in particular, to the multi-mode bosonic Gaussian measurement channels. An explicit formula for the classical capacity of the Gaussian measurement channel is obtained in this paper without assuming the global gauge symmetry, solely under certain 'threshold condition'. The result is illustrated by the capacity computation for a one-mode squeezed-noise heterodyne measurement channel. (paper)