Photon-Assisted Average Current Through a Quantum Dot Coupled to Majorana Bound States

Abstract

We investigate the properties of photon-assisted current through a quantum dot (QD) coupled to two leads and Majorana bound states (MBSs) formed at two ends of a topological superconductor nanowire. Our numerical results show that the peak’s height of the average current is reduced to half by the half fermionic character of MBSs. When a microwave (MW) field is applied on one of the leads, the negative current is converted into positive by the MBSs. This abnormal phenomenon may serve as a detection method for MBSs. Moreover, the photon-assisted tunneling sideband peak appears while a MW field is applied on the QD. Turning on the coupling between the QD and MBSs, the magnitude of the average current decreases monotonously because that the MBSs now is changed to the non-zero energy mode by emitting (absorbing) photons from the MW field. Correspondingly, the energy level in the QD is split into two by the non-zero energy mode MBSs, and then the photon-assisted tunneling occurs with the help of the MBSs.