The micromaser as a quantum clock

The interaction of light and matter provides a 'clock' which allows us to extract characteristic timescales of quantum motion. Two-level atoms temporarily subjected to a radiation held will undergo Rabi oscillations, and the rotation angle of the corresponding Bloch vector serves as a measure of the interaction time. The approach is closely related to proposed 'Larmor clock' experiments exploiting particle spin precession in a magnetic field and gives some insight into how the usual notion of time emerges from quantum mechanics in its classical limit. The usage of the micromaser device for an experimental determination of quantum reflection, transmission, and dwell times is discussed.