Manipulating photons in a cavity and raising Schrödinger cats of light

From QCLab

Experiments involving Rydberg atoms interacting with photons in cavities are modern versions of the thought experiments imagined by the founding fathers of quantum physics. They illustrate the concepts of state superpositions, complementarity and entanglement which are at the heart of the theory. These concepts are essential to understand what Schrödinger had in mind when he conceived the famous thought experiment in which a cat would be at the same time alive and dead. I will show how this provocative situation is translated in a real experiment involving several photons in a superposition of states having simultaneously two different phases. The study of these "photonic Schrödinger cat states » shed light on the phenomenon of decoherence, which is essential to describe the transition from the quantum to the classical worlds. I will conclude by saying a few words about possible applications of these studies to quantum information science.