Arbitrary superpositions of quantum operators demonstrated: first direct quantitative test of quantum commutation rules. We designed a scheme for conditionally generating arbitrary coherent superpositions of quantum operators. The general scheme was later applied to an experiment for implementing the commutator of the creation and annihilation operators. We quantitatively verified the well-known commutation rules in a direct experiment for the first time.

We implemented a reliable scheme for single photon subtraction and tested its effects on paradigmatic light states: Fock, thermal, and coherent. When applied to coherent states, the annihilation operator does not modify the state itself. Experimentally verified that coherent states are eigenstates of the photon annihilation operator.

We use a pulsed pump enhancement cavity to produce highly-nonclassical states of light at high repetition rates. The frequency comb structure of the pump laser may be transferred to the produced quantum light.

We performed the first reconstruction of a non-classical P-function for a photon-added thermal light state. This is the first demonstration of non-classicality according to the original definition by R. Glauber.