Transport through the T-shaped double-quantum-dot structure with side-coupled Majorana bound states

Abstract

We perform theoretical investigation of the transport properties in the T-shaped double-quantum-dot structure, by considering Majorana bound states (MBSs) to be coupled to the dot in the main channel. Calculation results show that in the linear transport regime, the side-coupled dot covers the influence of the MBS on the transport behaviors, independent of the Coulomb interaction in the QDs. In the absence of superconducting pairing potential in the QDs, tuning the side-coupled dot level to the Fermi energy can erase the contribution of MBS to the conductance, due to the occurrence of antiresonance. Otherwise, the linear conductance exhibits two distinct results determined by the inter-MBS coupling manners. In the case of Majorana zero mode, the linear conductance value keeps equal to e 2 2 h when the side-coupled dot departs from the Fermi energy. Alternatively in the case of Majorana nonzero mode, the linear conductance is always analogous to the MBS-absent case. On the other hand, when the superconducting pairing potential is incorporated, the linear conductance is also independent of the QD-MBS coupling. Especially in the case of Majorana nonzero mode, the MBSs are decoupled from the QDs. These findings provide new information for understanding the interplay between the MBSs and the quantum dots. • We study transport in T-shaped double quantum dots, by considering MBSs to be coupled to the main dot. • Tuning the side-coupled dot level to the Fermi level can erase the contribution of MBS to the conductance. • For Majorana zero mode, the linear conductance is equal to e 2 /2h when the side-coupled dot departs from the Fermi level. • For Majorana nonzero mode, the linear conductance is always analogous to the MBS-absent case. • If superconducting pairing potential exists in QDs, MBSs are decoupled from QDs for Majorana nonzero mode.