The 2-level Rydberg Atom: The Electron of Cavity Quantum Electrodynamics

摘要

Cavity quantum electrodynamics (cavity q.e.d.) studies Rydberg atoms, (i.e. atoms in 'high Rydberg' states such as ~(85)Rb in the 63 P_(3/2) state) in microwave or other cavities. For example the 'micromaser' is a one-atom-one-cavity-mode system operating at the Max Planck Institute at Garching, Germany. This uses a succession of single ~(85)Rb atoms entering the maser cavity in 63 P_(3/2) and making transitions to 61 D_(5/2) at 21.5 GHz. The relevance of the system to this conference is that high Rydberg atoms (like ~(85)Rb in 63 P_(3/2)) act like '2-level' atoms coupled to a single cavity mode. This can be seen as the, fundamentally non-linear, fermion-boson coupling of cavity q.e.d. analogous to the fermion-boson coupling of 'ordinary' q.e.d. Of course, the 2-level atom is itself based on the 'loose' optical electron of the ~(85)Rb atom in 63 P_(3/2). This state is a relatively simple Bohr-like orbit state with principal quantum number n = 63. The theme of the 2-level atom acting as the 'electron' in cavity q.e.d. is developed in terms of a string of theoretical results obtained in cavity q.e.d. theory since 1979, some of which have already been confirmed in (rather spectacular) experiments e.g. on the micromaser and in heavily damped microwave cavities at finite temperatures.