Peculiarities of Intersubband Transision Between Split Levels in Symmetrical Triple-Barrier Structures

For symmetric three-barrier resonance tunnel structures with thin high barriers resonant transitions between the split-levels in a weak non-uniform high-frequency field are investigated. It is shown, that in spite of transitions between usual levels both in two, and in three-barrier structures, the probability of transitions between the split levels depends essentially not only on parity of perturbation but also on its form. The investigated effect brings up a question on the top limit of high-frequency conductivity in such systems.