Sub-Poissonian twin beams

Abstract

Using the method of photon addition into both beams of a multi-mode twin beam, a new kind of highly nonclassical states is obtained. As these states exhibit tight photon-number cross-correlations and are endowed with marginal sub-Poissonian photon-number distributions, we suggest to call them sub-Poissonian twin beams. We reveal their properties in the model as well as experimentally using mesoscopic twin beams. An intensified CCD camera as a photon-number resolving detector is applied to prepare as well as characterize the states with up to three photons added into each beam and containing from 2.8 to 7.5 photons in average in each beam. Their nonclassicality as well as non-Gaussianity are determined to demonstrate their prominent features. Spatial correlations of photons in the beams are exploited to improve the properties of the generated states. The beams are promising as the quantum light source for virtual-state entangled-photon spectroscopy. Their properties are prospective for monitoring and manipulating two-photon light–matter interactions.