Quantum Optics 2 - Two photons and more

Quantum Optics 1, single photons" introduced learners to light quantization and the Standard Formalism of Quantum Optics. The examples in "Quantum Optics 1, Single photons" allowed learners to be introduced to the basic principles of light quantization and to the standard formalism of Quantum Optics. This will enable them to employ the Quantum Optics formalism for the description and application to entangled photos, an unusual feature that is at the heart the second quantum revolution. The Quantum Optics approach allows for the description of classical light. It can be coherent, such as with laser light, as well as incoherent, such as with thermal radiation. It is possible to use a description of many photons to determine the Standard Quantum Limit (SQL) for classical light. Also, to see how new types of quantum states, like squeezed states, of light can be used to defeat the SQL, which is one of the greatest achievements in quantum metrology. Quantum Technologies that are based upon entangled photons, will be shown in several examples, including Quantum Teleportation, Quantum Cryptography, and Quantum Communication. Quantum Computing, Quantum Simulation, and some insight into recently proposed Noisy Intermediate Scale Quantum computing (NISQ), will be also presented. This is a real hope that we can demonstrate in the near future the active searched quantum advantage. It is the ability to perform calculations exponentially more quickly than classical computers.