As a summary, all measured states presented in the preceding sections are presented here again, depicted by the contour of their experimentally determined Wigner function in phase space. Shown are a vacuum state, a coherent state, a squeezed vacuum state, three bright squeezed states with different phase angles, two phase-diffused states, an amplitude-diffused state and a thermal state.
How could the analyzing methods presented above be used to gain new information about the physics of the light field? One possibility is the generation of so far unkown states of the light field, which could be detected by these tomographical methods. An example for such a state is the star state, which should evolve during the process of 3-photon downconversion (instead of 2 photons used for the generation of squeezed states shown above). Although frequency tripling is a widely used process, the opposite, splitting one photon of high energy into three has not been observed so far. Perhaps the methods outlined above could provide first insights into this new area of optics. A simulation (T. Felbinger, see ref. 13) of the quantum statistics of the light field yields the following result:
Another interesting family of states of the light field is the
one-photon Fock state and states derived from it
(see also ref 14).