Photon-assisted transport in a carbon nanotube calculated using Green's function techniques

We investigate the quantum transport through a single-walled carbon nanotube connected to leads in the presence of an external radiation field. We analyze the conductance spectrum as a function of the frequency and strength of the field. We found that above a critical value of the field intensity, an enhancement of the conductance, or suppressed resistance, as a function of the field strength occurs. The conductance increases displaying oscillations which amplitude shows a strong dependence on the field frequency. For low radiation energies in comparison with the lead\char21{}carbon-nanotube coupling energies, the oscillations evolve toward a structure of well defined steps in the conductance. We have shown that in this range of frequencies, the field intensity dependence of the conductance can give direct information of single-walled carbon nanotube energy spectra.