**Adding and subtracting single photons to/from light fields and some other new results in manipulating the quantum states of light** - Alessandro Zavatta

I will discuss some of the recent results obtained by the Quantum Optics Group of the Italian Institute for Applied Optics in Florence. In particular, I will discuss the experimental schemes to implement the action of single photon creation and annihilation operators on different kinds of basic quantum light states. The obtained states are then retrieved by means of quantum homodyne tomography which can reveal the density matrix, Wigner function and, in some particular cases, the Glauber P-function of the analyzed state. In addiction, I will show that when alternated sequences of the creation and annihilation operators are applied to a thermal state the resulting states depend on the order in which the two quantum operators are applied. In this way we can provide the most direct experimental verification of the non-commutation of bosonic operators.