Laser-dressing of electronic quantum states in graded semiconductor nanostructures

It is known that a non-resonant laser field will modify the electronic states in a low-dimensional semiconductor very similarly to the laser-dressing of electrons in isolate atoms. Under intense laser field, the energy levels are functions of the laser parameter which depends on the intensity and frequency of the laser but also on the effective mass of the carriers. This aspect is qualitatively different as compared with the laser-dressing of atoms and it was poorly addressed in the literature until now. This work will demonstrate that in compositionally graded quantum wells the gradient of the effective mass will affect the laser dressing of electronic states in a non-trivial manner. The operatorial nature of the laser parameter leads to a surprising result: the electrons in different subbands will feel different laser-dressed confinement potentials. In particular, for a non-graded quantum well the expectation value of the laser parameter will depend on the effective masses of the electron in all distinct layers of the heterostructure.