Compound Twin Beams Without the Need of Genuine Photon-Number-Resolving Detection

A scheme for building stronger multimode twin beams from a greater number of identical twin beams sufficiently weak so that single-photon-sensitive on-off detectors suffice for their detection is studied. The statistical properties of these compound twin beams involving nonclassicality are analyzed for intensities up to hundreds of photon pairs. Their properties are compared with those of genuine twin beams that require photon-number-resolving detectors for their experimental investigation. The use of such compound twin beams for the generation of sub-Poissonian light and for the measurement of absorption with sub-shot-noise precision is analyzed. A suitable theoretical model for compound twin beams is developed to interpret the experimental data.