Glauber states

Glauber states, also known as coherent states, are special quantum states of light that most closely resemble classical light waves, like those from a laser. Unlike other quantum states, they have well-defined amplitude and phase, making their behavior predictable and stable over time. These states exhibit minimal quantum noise and fluctuations, allowing them to act similarly to classical electromagnetic waves, yet they retain quantum properties. Glauber states are fundamental in quantum optics and are important for applications where quantum effects of light are harnessed alongside classical behavior, such as in precision measurements and quantum communication.