Photon-assisted mesoscopic transport through a toroidal carbon nanotube coupled to normal metal leads

Abstract

The mesoscopic transport through a toroidal carbon nanotube (TCN) system applied with ac fields to the electrodes has been investigated by employing the nonequilibrium Green's function (NGF) technique. The Landauer–Büttiker-like formula is presented for numerical calculations of differential conductance and tunneling current. The conductance resonance takes place due to the electrons resonating in the quantum levels of TCN and side-band caused by the external ac fields. The photon-assisted transport can be observed both in conductance oscillation and current oscillation with respect to the magnetic flux. The side peaks and current suppressions are the main effect of photon absorption and emission in the transport procedure. The stair-like current–voltage characteristics are resulted from the quantum nature of TCN and applied microwave fields. The photon–electron pumping effect can be obtained by applying the microwave fields to the leads.