Sudarshan-Glauber representation

The Sudarshan-Glauber representation is a way physicists describe light in quantum optics by expressing its quantum state as a superposition of many classical-like states called coherent states. Think of it as a map showing how much of each "classical" light pattern contributes to the overall quantum light. This approach helps us understand and analyze quantum properties of light—like entanglement or squeezing—using familiar classical concepts, bridging the gap between quantum and classical descriptions in a structured, visually intuitive manner.