Quantum Transport Through Systems Of Multiple Quantum Dots With Side-coupled Majorana Bound States

Majorana fermions, whose antiparticles are themselves, have attracted lots of attention due to their development in the field of solid state physics in recent years. Their characteristics of non-Abelian statistics make possible their potential application in quantum computation. It has been reported that Majorana bound states can be realized at each end of a semiconductor nanowire with strong spin-orbit coupling and Zeeman splitting when the nanowire is placed in proximity to an s-wave superconductor. It means that Majorana fermions can be realized in solid state.However, how to detect and verify the existence of Majorana bound states is still a difficult question. There are several innovative ideas has been proposed. Among those, quantum-dot structures are more promising candidates due to their simple structure and special phenomena. In this paper, we provide two special kinds of muiti-quantum-dot structures coupled with Majorana bound states. One of them is a special quadruple-quantum-dot system with side coupled Majorana bound states. It is found that different results are obtained depending on which quantum dot is coupled with the Majorana bound state. When the Majorana bound stateis coupled to the quantum dots in connection with the leads, the zero-bias conductance will change obviously. However, the zero-bias conductance will remain unchanged when the MBSs are coupled to the central quantum dot. The other system is composed of a serially coupled muiti-quantum-dot-pair chain and side-coupled Majorana bound states. It is shown that the existence of Majorana bound state will induce a sharp zero-bias conductance peak when the Majorana bound state is coupled the far left quantum dot pair, which is abcent when the Majorana bound state is coupled the the other quantum dot pairs. Based on the peculiar effects of the two special quantum-dot systems coupled with Majorana bound state, we believe that these researches should be helpful for understanding the nature of Majorana bound states. Besides, the two quantum-dot systems can be considered as candidates for detecting the existence of Majorana bound states.