Photon-Assisted Transport Through a Quantum Dot Side-Coupled to Majorana Bound States

Feng Chi,Zhen-Guo Fu,Ping Liu,Jing Wang,Ping Zhang,Li-Ming Liu,Tian-Yu He

doi:10.3389/fphy.2020.00254

Abstract

Transmission function of a system composing of a quantum dot (QD) subjected to a photon field and side-coupled to a topological superconductor nanowire hosting a pair of Majorana bound states (MBSs) is calculated by using the nonequilibrium Green's function technique. We find that a series of photon-induced peaks emerge and are split by the coupling between the QD and the MBSs. Moreover, the peaks' height are suppressed to zero because the MBSs absorb (emit) the photon energy. Under this condition, the MBSs may be shifted to the non-zero energy mode, and thus provide another detection scheme for its existence which is quite different from the currently adopted ones depending on the zero-energy mode of the MBSs. In the presence of MBS-MBS overlaping, the central photon-assisted peaks in the transmission function reappear due to the fact that the photon absorbed (emitted) by one mode of the MBSs are subsequently emitted (absorbed) by another MBSs' mode. We also find that the positions of the additional peaks induced by the MBS-MBS overlaping in the presence of the photon field are quite different from the case of zero photon field.

Highlights

In recent years, there is much interest in the newly emerged issue of how to prepare and detect Majorana bound states (MBSs) in solid platforms
If there is no coupling between the quantum dot (QD) and MBSs existed at the ends of the topological nanowire λ = 0, the transmission function T in Figure 2A shows the typical resonant tunneling feature, i.e., it develops a Lorentzian peak with height of 1 at zero energy state [27], T(ε −→ 0) = 1
Turning on the coupling between the QD and MBSs at the ends of topological superconductor nanowire λ = 0, we find that value of the zero-energy transmission function is reduced to half of its quantum value 1, i.e., T(0) = 1/2, showing the half-fermionic character of the MBSs

Summary

INTRODUCTION

There is much interest in the newly emerged issue of how to prepare and detect Majorana bound states (MBSs) in solid platforms. In [21], the authors found that the MBSs will absorb(emit) photons and result in photon-assisted tunneling side band peaks This process can split the MBSs and induces non-zero MBSs mode, providing another detection scheme for the existence of MBSs which is quite different the currently adopted ones concerning zero-energy MBSs mode. They found that the height of the photon-assisted tunneling side band peaks is related to the intensity of the microwave field, and the time-varying conductance induced by the MBSs shows negative values for a certain period of time. The positions of the peaks induced by the MBSMBS overlaping in the presence of the photon field are quite different from those without photon field

MODEL AND METHODS

RESULTS AND DISCUSSION

SUMMARY

DATA AVAILABILITY STATEMENT