中国物理B ›› 2016, Vol. 25 ›› Issue (6): 67302-067302.doi: 10.1088/1674-1056/25/6/067302

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Quantum transport through a multi-quantum-dot-pair chain side-coupled with Majorana bound states

Zhao-Tan Jiang(江兆潭), Cheng-Cheng Zhong(仲成成)   

  1. School of Physics, Beijing Institute of Technology, Beijing 100081, China
  • 收稿日期:2015-11-06 修回日期:2016-02-27 出版日期:2016-06-05 发布日期:2016-06-05
  • 通讯作者: Zhao-Tan Jiang E-mail:jiangzhaotan@hotmail.com
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11274040 and 10974015) and the Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0044).

Quantum transport through a multi-quantum-dot-pair chain side-coupled with Majorana bound states

Zhao-Tan Jiang(江兆潭), Cheng-Cheng Zhong(仲成成)   

  1. School of Physics, Beijing Institute of Technology, Beijing 100081, China
  • Received:2015-11-06 Revised:2016-02-27 Online:2016-06-05 Published:2016-06-05
  • Contact: Zhao-Tan Jiang E-mail:jiangzhaotan@hotmail.com
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 11274040 and 10974015) and the Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0044).

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摘要：

We investigate the quantum transport properties through a special kind of quantum dot (QD) system composed of a serially coupled multi-QD-pair (multi-QDP) chain and side-coupled Majorana bound states (MBSs) by using the Green functions method, where the conductance can be classified into two kinds: the electron tunneling (ET) conductance and the Andreev reflection (AR) one. First we find that for the nonzero MBS-QDP coupling a sharp AR-induced zero-bias conductance peak with the height of e2/h is present (or absent) when the MBS is coupled to the far left (or the other) QDP. Moreover, the MBS-QDP coupling can suppress the ET conductance and strengthen the AR one, and further split into two sub-peaks each of the total conductance peaks of the isolated multi-QDPs, indicating that the MBS will make obvious influences on the competition between the ET and AR processes. Then we find that the tunneling rate ΓL is able to affect the conductances of leads L and R in different ways, demonstrating that there exists a ΓL-related competition between the AR and ET processes. Finally we consider the effect of the inter-MBS coupling on the conductances of the multi-QDP chains and it is shown that the inter-MBS coupling will split the zero-bias conductance peak with the height of e2/h into two sub-peaks. As the inter-MBS coupling becomes stronger, the two sub-peaks are pushed away from each other and simultaneously become lower, which is opposite to that of the single QDP chain where the two sub-peaks with the height of about e2/2h become higher. Also, the decay of the conductance sub-peaks with the increase of the MBS-QDP coupling becomes slower as the number of the QDPs becomes larger. This research should be an important extension in studying the transport properties in the kind of QD systems coupled with the side MBSs, which is helpful for understanding the nature of the MBSs, as well as the MBS-related QD transport properties.

关键词: electron transport, quantum dot, Andreev reflection

Abstract:

We investigate the quantum transport properties through a special kind of quantum dot (QD) system composed of a serially coupled multi-QD-pair (multi-QDP) chain and side-coupled Majorana bound states (MBSs) by using the Green functions method, where the conductance can be classified into two kinds: the electron tunneling (ET) conductance and the Andreev reflection (AR) one. First we find that for the nonzero MBS-QDP coupling a sharp AR-induced zero-bias conductance peak with the height of e2/h is present (or absent) when the MBS is coupled to the far left (or the other) QDP. Moreover, the MBS-QDP coupling can suppress the ET conductance and strengthen the AR one, and further split into two sub-peaks each of the total conductance peaks of the isolated multi-QDPs, indicating that the MBS will make obvious influences on the competition between the ET and AR processes. Then we find that the tunneling rate ΓL is able to affect the conductances of leads L and R in different ways, demonstrating that there exists a ΓL-related competition between the AR and ET processes. Finally we consider the effect of the inter-MBS coupling on the conductances of the multi-QDP chains and it is shown that the inter-MBS coupling will split the zero-bias conductance peak with the height of e2/h into two sub-peaks. As the inter-MBS coupling becomes stronger, the two sub-peaks are pushed away from each other and simultaneously become lower, which is opposite to that of the single QDP chain where the two sub-peaks with the height of about e2/2h become higher. Also, the decay of the conductance sub-peaks with the increase of the MBS-QDP coupling becomes slower as the number of the QDPs becomes larger. This research should be an important extension in studying the transport properties in the kind of QD systems coupled with the side MBSs, which is helpful for understanding the nature of the MBSs, as well as the MBS-related QD transport properties.

Key words: electron transport, quantum dot, Andreev reflection

中图分类号:  (Electronic transport in mesoscopic systems)

  • 73.23.-b
73.21.La (Quantum dots) 74.45.+c (Proximity effects; Andreev reflection; SN and SNS junctions)