Quantum theory of spontaneous and stimulated resonant transition radiation

Resonant transition radiation generated by high-energy electron beams traversing a periodic medium has been considered by many researchers as a potential source of both spontaneous and stimulated emission at short wavelengths. To our knowledge, this problem has only been treated classically. This paper presents a quantum-mechanical theory that leads to a unified description of both spontaneous and stimulated emission and agrees closely with the classical results.