Majorana-free bound state in continuum in the double-channel Fano-Anderson structure

Abstract

We investigate the electron transport through a double-channel Fano-Anderson structure, by considering the side-coupling of Majorana bound states (MBSs). It is found that the bound state in continuum (BIC) phenomenon can be induced when inter-channel dot-lead couplings are identical to the intra-channel dot-lead couplings, whose signature is manifested as the halved quantum transmission ability. If the balance between the dot-lead couplings is broken, the BIC phenomenon will also be destroyed, leading to further suppression of the transmission ability. Next, when MBSs are introduced to this system, the BIC phenomenon can be modified efficiently. For the case of two MBSs side-coupled to the quantum dots in a symmetric way, level degeneracy causes new a BIC phenomenon. As only one MBS is incorporated, it suppresses the electron transmission by inducing new transmission dips. When the interdot Coulomb interaction is considered, the BIC phenomena are still robust despite the complicate changes of the transmission ability spectra. One can then understand the realization of BIC in coupled quantum dots and their variation due to the presence of side-coupled MBSs.