Proximity-induced supercurrent through topological insulator based nanowires for quantum computation studies

Abstract

Proximity-induced superconducting energy gap in the surface states of topological insulators has been predicted to host the much wanted Majorana fermions for fault-tolerant quantum computation. Recent theoretically proposed architectures for topological quantum computation via Majoranas are based on large networks of Kitaev’s one-dimensional quantum wires, which pose a huge experimental challenge in terms of scalability of the current single nanowire based devices. Here, we address this problem by realizing robust superconductivity in junctions of fabricated topological insulator (Bi2Se3) nanowires proximity-coupled to conventional s-wave superconducting (W) electrodes. Milling technique possesses great potential in fabrication of any desired shapes and structures at nanoscale level, and therefore can be effectively utilized to scale-up the existing single nanowire based design into nanowire based network architectures. We demonstrate the dominant role of ballistic topological surface states in propagating the long-range proximity induced superconducting order with high IcRN product in long Bi2Se3 junctions. Large upper critical magnetic fields exceeding the Chandrasekhar-Clogston limit suggests the existence of robust superconducting order with spin-triplet cooper pairing. An unconventional inverse dependence of IcRN product on the width of the nanowire junction was also observed.

Nanoscale direct-write fabrication of superconducting devices for application in quantum technologies

“…Interestingly, W-C deposits have been applied to the editing of superconducting circuits based on other superconductors [94]. • W-C FIBID deposits have been frequently used to induce superconductivity by proximity effect on other materials such as graphene [95], bismuth [96,97], copper and cobalt [98], gold [99] and Bi 2 Se 3 [100]. In the last case, topological superconductivity was searched for Majorana-based quantum computing applications.…”

2D Bi2Se3 materials for optoelectronics

“…Topological surface states of Bi 2 Se 3 possess helical Dirac dispersion with spin locked to momentum, which makes it potentially promising for quantum computing spintronics applications ( Bhattacharyya et al., 2018a , 2018b ; He et al., 2019 ; Khokhriakov et al., 2020 ). Numerous studies have demonstrated that topological surface states of topological insulators exhibit novel electronic responses and fascinating optoelectronic effects to polarized light ( Besbas et al, 2016 ; Kastl et al., 2015 ; Wang et al., 2019a , 2019b , 2019c ; Zhuang et al., 2021 ).…”

“…In addition, Bi 2 Se 3 demonstrates attractive optoelectronic properties such as broadband optical absorption ( Guo et al., 2013 ; Peng et al., 2012 ; Yao et al., 2014 ), thickness-dependent surface bandgap ( He et al., 2010 ; Post et al., 2013 ) and polarization-sensitive photocurrent ( Besbas et al, 2016 ; Duan et al., 2014 ; Yan et al., 2014 ). These intriguing properties are favorable for Bi 2 Se 3 as a promising candidate for optoelectronic devices ( Bhattacharyya et al., 2018a , 2018b ; Sharma et al., 2016 ; Wang et al., 2019a , 2019b , 2019c ; Zhang et al., 2010 ). Up to now, a large amount of efforts have been devoted and significant progress have been made in the study of 2D Bi 2 Se 3 from materials preparation to optoelectronic applications.…”

Evolution of Measurement System and SI Units in India

“…The closure of QMT experiment in principle needed the measurement of current with an uncertainty better than 1 part in 10 8 . CSIR-NPL maintains primary quantum standards of voltage and resistance through programmable Josephson voltage standard and quantum Hall resistance standard, and efforts are targeted for development of the quantum current standard [88,89].…”