Multimode photon addition

We review our recent experimental results concerning the conditional implementation of coherent superpositions of single-photon additions onto distinct field modes. On the cover of Entropy.

Such a basic operation can give rise to a wealth of interesting and useful effects, from the generation of a tunable degree of entanglement to the birth of peculiar correlations in the photon numbers and the quadratures of multimode, multiphoton, states of light. The experimental investigation of these properties will have an impact both on fundamental studies concerning, for example, the quantumness and entanglement of macroscopic states, and for possible applications in the realm of quantum-enhanced technologies.