Tomographic Approach to Squeezing

In this chapter we illustrate the procedure to quantify, directly from optical tomograms, the extent of squeezing displayed by various states of light. To begin with, we briefly discuss the salient features of quadratic and higher-order squeezing, as well as entropic squeezing. We then outline an elegant procedure, reported in the literature, for calculating normal-ordered moments from optical tomograms. From these expressions it is straightforward to compute variances and entropic squeezing properties of various quantum states. This is illustrated for single-mode and two-mode states of light. We illustrate how the tomograms of ‘Janus-faced’ partner pairs of states such as the even coherent state and the squeezed vacuum are related to each other. We demonstrate that, as a consequence, the squeezing properties of such partner states are also related to each other.