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

• Published in: Scientific reports 2018-11, Vol.8 (1), p.17237-12, Article 17237
• Main Authors: Bhattacharyya, Biplab, Awana, V. P. S., Senguttuvan, T. D., Ojha, V. N., Husale, Sudhir
• Format: Article
• Language: English
• Subjects: 639/301/119/1003; 639/301/357/1016; Fabrication; Humanities and Social Sciences; Magnetic fields; multidisciplinary; Nanotechnology; Nanowires; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-35424-1

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 (Bi 2 Se 3 ) 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 I c R N product in long Bi 2 Se 3 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 I c R N product on the width of the nanowire junction was also observed.