We develope a model to describe the transmission coefficient and tunneling
current in the presence of photon-electron coupling in a resonant diode. Our
model takes into account multiphoton processes as well as the transitions
between electronic states with different wave numbers. This is crutial to
explain the experimental features observed in the tunneling current through a
double barrier which cannot be reproduced with more simplified established
models. According to our results, what experiments show in the current density
are quantum photon-assisted features coming from multiphoton transitions which
are not related with sample heating.Comment: 8 pages,2 Postscript Figure
