Electronic transport in a quantum wire under external terahertz electromagnetic irradiation

We theoretically study the electronic transport of a straight quantum wire partly irradiated under an external terahertz electromagnetic field at low temperature. Using the free-electron model and the scattering matrix approach, we demonstrate that although the electrons in a ballistic quantum wire only suffer from lateral collisions with photons, the reflection of electrons also takes place. Interestingly, when the frequency of the electromagnetic field is resonant with the separation of lateral energy levels of the wire, there is a sharp step structure in the electronic transmission probability as a function of the total energy of the electron or the strength of the field. The physical origin of this phenomena is the electron intersubband transition when a finite-range transversely polarized electromagnetic field irradiates a quantum wire. The interference pattern also appears in the electronic transmission probability as a function of the field-irradiated length.