Photon-assisted mesoscopic transport in a toroidal carbon nanotube coupled with Majorana bound states

The armchair metallic and semiconducting toroidal carbon nanotubes (TCNs) coupled with Majorana bound states (MBSs) under the perturbation of microwave fields (MWFs) have been investigated, and the photon-assisted features relating to tunneling current, differential conductance, and shot noise have been evaluated numerically. For the semiconducting TCN system, the photon-induced resonant peaks emerge at the conductance valley around zero-bias voltage, and the semiconducting energy gap can be closed by MBSs and MWFs. For the metallic TCN system, normal tunneling and Andreev reflections cooperate to generate a hybridized zero-bias conductance. The periodic behavior of conductance versus magnetic flux is intimately dependent on the metallic and semiconducting TCN structures. Applying MWFs on the TCN system coupled with MBSs can enhance the shot noise largely compared with the case without MBSs. The Fano factor appears two kinds of triple-peak oscillation structure when MBSs are connected to the semiconducting TCN, and the application of MWFs enhances the maximum value of Fano factor. The shot noise jumps at zero bias, and the steps are smeared by the photon absorption and emission. The Fano factor is enhanced by MBSs, and it increases rapidly to exhibit a giant value around zero bias. (C) 2020 Elsevier Inc. All rights reserved.