Generalized sub-Poissonian states of two-beam fields

Two -beam states obtained by partial photon -number -resolving detection in one beam of a multi -mode twin beam are experimentally investigated using an intensified CCD camera. In these states, sub-Poissonian photon -number distributions in one beam are accompanied by subshot -noise fluctuations in the photon -number difference of both beams. Multi -mode character of the twin beam implying the beam nearly Poissonian statistics is critical for reaching sub-Poissonian photon -number distributions, which contrasts with the use of a two -mode squeezed vacuum state. Relative intensities of both nonclassical effects as they depend on the generation conditions are investigated both theoretically and experimentally using photon -number distributions of these fields. Fano factor, noise -reduction parameter, local and global nonclassicality depths, degree of photon -number coherence, mutual entropy as a non-Gaussianity quantifier, and negative quasidistributions of integrated intensities are used to characterize these fields. Spatial photon -pair correlations as means for improving the field properties are employed. These states are appealing for quantum metrology and imaging including the virtual -state entangled -photon spectroscopy.