Abstract
Zero-photon subtraction (ZPS) is a conditional measurement process that can reduce the mean photon number of quantum optical states without physically removing any photons. Here we show that ZPS can also be used to transform certain super-Poissonian states into sub-Poissonian states, and vice versa. Combined with a well-known "no-go" theorem on conditional measurements, this effect leads to a new set of non-classicality criteria that can be experimentally tested through ZPS measurements.