  The quantum theory of electromagnetic radiation predicts characteristic
statistical fluctuations for light sources as diverse as sunlight, laser
radiation and molecule fluorescence. Indeed, these underlying statistical
fluctuations of light are associated with the fundamental physical processes
behind their generation. In this contribution, we demonstrate that the
manipulation of the quantum electromagnetic fluctuations of a pair of vacuum
states leads to a novel family of quantum-correlated multiphoton states with
tunable mean photon numbers and degree of correlation. Our technique relies on
the use of conditional measurements to engineer the excitation mode of the
field through the simultaneous subtraction of photons from two-mode squeezed
vacuum states. The experimental generation of multiphoton states with quantum
correlations by means of photon subtraction unveils novel mechanisms to control
fundamental properties of light. As a remarkable example, we demonstrate the
engineering of a quantum correlated state of light, with nearly Poissonian
photon statistics, that constitutes the first step towards the generation of
entangled lasers. Our technique enables a robust protocol to prepare quantum
states with multiple photons in high-dimensional spaces and, as such, it
constitutes a novel platform for exploring quantum phenomena in mesoscopic
systems.
