The "Forgotten" Process : the emission stimulated by matter waves
  In a famous paper where he introduces the A and B coefficients, Einstein considered that atomic decays of excited atoms can be stimulated by light waves. Here we consider that atomic decays can also be stimulated by atomic waves. It is however necessary to change the Maxwell-Boltzmann statistics of thermal equilibrium into Bose-Einstein statistics and to introduce a coefficient C which complements the list of the coefficients introduced by Einstein. Stimulated emission of light can be considered as the first step towards the laser. Similarly, stimulated production of matter waves can be considered as the basic phenomenon for an atom-laser. Most of the results that we obtain here are not new. However, the method that we use remains very close to elementary classical physics and emphasizes the symmetry between electromagnetic and matter waves from various points of view. 
Philippe Tourrenc (ERGA/LERMA), Marie-Christine Angonin (ERGA/LERMA),   Peter Wolf (BIPM, BNM-SYRTE)