Quantum Optics

Quantum optics is a branch of atomic, molecular, and optical physics dealing with how individual quanta of light, known as photons, interact with atoms and molecules. It studies the nature and effects of light by considering the quantization of atomic systems and the corpuscular nature of light, overcoming classical theories that held it to be only an electromagnetic wave. 

Through quantum optics, it is also possible to study the statistics of photons, an analysis that has led to the development of instruments for direct photon detection based on the photoelectric or photovoltaic effect.

The development of ultrashort pulse lasers, generated by Q-switch and mode-locking techniques, enabled the creation of a branch of quantum optics, the study of ultrafast processes.