Magnetic Domain Wall And Superconducting Proximity-induced Effects On The Transport Of Majorana Bound States

The searching for physical realization of quantum computing system has received great attention during the last two decades.Recent progress in the topological superconductor material technology boosts this process by unveiling novel fermion quasi-particles.This kind of exotic quasi-particle has been reported to emerge in some low dimensional topological materials under certain conditions.These so-called Majorana bound states(MBSs)exhibit non-Abelian statistics and thus make a potential candidate for topologically protected quantum computing.Although seminal works have been done both in theories and in experiments,researchers are still pursuing the solid evidence for MBSs in the superconductor-based systems.One-dimensional superconducting semiconductor now stands out among various Majorana platforms due to its accessibility and flexibility.Motivated by a series of recent transport experiments in the superconducting-semiconducting Majorana nanowires,we incorporate domain wall(DW)into Majorana nanowires to manipulate single Majorana mode by applying a modulated magnetic field.Here we devise a one-dimensional tightbinding Hamiltonian to model the nanowire with DWs and follow the non-equilibrium Green function formalism to perform the numerical calculation of its transport properties.Furthermore,in order to account for the physics of impurities in Majorana nanowires,we put fluctuations of diverse system parameters such as proximity-superconducting pairing,chemical potential and hopping under a unified framework as system disorders and calculate the consequent transport properties.The results reveal that in the nanowire with DWs,you can manipulate the MBSs via tuning the position or width of DW and the transport signature can serve as an intuitive description for the hybridization of MBSs.For the disordered nanowire with suitable parameters,the conductance peaks can be lowered and broadened,the peak spacings can be suppressed,and a new zero-bias conductance peak can even to some extent be restored.Our numerical results of the disordered system can partially answer the question of decaying conductance peak spacings reported by recent Majorana experiments.It also provide a signature to discriminate between the zero-bias conductance peak of MBSs and that induced by disorder.