Zero-bias conductance modification in the quantum-dot system with side-coupled Majorana bound states

We propose a closed quantum-dot system with one side-coupled Majorana bound state (MBS) to investigate the electron transport behavior. The closed mesoscopic circuit is formed by coupling two metallic leads to one QD, which is side-coupled to one MBS at the end of the topological-superconductor nanowire. We found that the leakage effect of the MBS induces the appearance of zero-bias conductance peak. However, its magnitude is adjustable, especially when the dot suffers from the superconducting proximity effect. The Zeeman splitting in the quantum dot can further modify the zero-bias conductance peak. These results are completely different from the Andreev reflection in the case of single metallic lead. We believe that our findings provide critical clues for further understanding the MBS-assisted transport behaviors in quantum-dot systems.