Light and photons have a special place in the Quantum Hall of Fame. Most principles of Quantum Mechanics, from the very existence of quanta to entanglement (the “spooky action at a distance”), were first tested with quantum states of light. Besides investigating the foundations of Quantum Mechanics, we also exploit the quantum properties of light for the development of novel technologies. We achieve this by the accurate generation and manipulation of quantum light states. LENS researchers were the first to implement the bosonic creation operator by the experimental realization of single photon addition. Then, by combining it with photon subtraction, we realized physics textbook experiments, such as the verification of quantum commutation relations. Besides their fundamental interest, these basic tools can now be used for proof-of-principle demonstrations of novel quantum protocols and technologies. True single photons are also essential for such purposes and may be obtained from the spontaneous emission of single organic molecules in the solid state. Researchers at LENS have achieved record-high collection efficiencies by integrating such molecules in photonic structures, such as silicon nitride/polymeric chips or planar antennas. Besides their possible use as nanoscale sensors, these integrated quantum emitters can become important ingredients of new technologies for information processing and communication. In particular, LENS researchers are actively working on practical schemes of Quantum Key Distribution, the only technology currently able to guarantee unconditionally secure communications by relying on the physical laws of Quantum Mechanics, whose validity is unaffected by the increasing power of future computers. Moreover, quantum algorithms able to solve classically intractable problems may be realized with quantum logic gates made of complex optical networks that can be efficiently implemented with integrated photonic platforms.