2021/11/11(Thu)
10:30 -12:00
五樓第一會議室 5F, 1st Meeting Room
視訊演講 Video Seminar [ Meeting Link / ID: 2553 / Password: 123456 ]
Title
Majorana bound states in proximitized higher-order topological insulators
Speaker
Dr. Chen-Hsuan Hsu (RIKEN Center for Emergent Matter Science (CEMS), Japan)Abstract
Majorana bound states (MBS) have stimulated intensive experimental and theoretical studies, owing to their potential for realizing topological quantum computation. However, the most intensively studied setups based on nanowires with Rashba strong spin-orbit coupling in the presence of proximity-induced superconductivity require external magnetic fields, which are detrimental to the superconductivity and therefore MBS themselves. This situation motivates subsequent works on alternative setups which dispose the requirement of magnetic fields [1], including those involving double Rashba wires [2, 3] or isotope-enriched carbon nanotubes [4]. In this talk, I will present an alternative setup realizing Kramers pairs of MBS in a nanowire made of a higher-order topological insulator (HOTI). Specifically, we propose to use a second-order topological insulator, which are characterized by gapless helical hinge states. We demonstrate that, when two hinges of a HOTI nanowire are brought into the proximity of an s-wave superconductor, there arise two types of pairing, one being local (intrahinge) and the other being nonlocal (interhinge). Our renormalization-group analysis shows that moderate electron-electron interactions favor the interhinge pairing over the intrahinge one. It leads to band inversion and thus a topological phase transition. As a result, MBS are stabilized at the ends of the HOTI nanowire, providing building blocks for topological quantum computation [5].
References:
[1] C.-H. Hsu, P. Stano, J. Klinovaja, and D. Loss, Semicond. Sci. Technol. 36, 123003 (2021).
[2] C.-H. Hsu, P. Stano, Y. Sato, S. Matsuo, S. Tarucha, and D. Loss, Phys. Rev. B 100, 195423 (2019).
[3] Y. Sato, S. Matsuo, C.-H. Hsu et al., Phys. Rev. B 99, 155304 (2019).
[4] C.-H. Hsu, P. Stano, J. Klinovaja, and D. Loss, Phys. Rev. B 92, 235435 (2015).
[5] C.-H. Hsu, P. Stano, J. Klinovaja, and D. Loss, Phys. Rev. Lett. 121, 196801 (2018).
Language
演講語言 (Language): in English