2018 Fiscal Year Annual Research Report
Protecting a single solid-state spin from a spin bath in diamond for quantum sensing
| Project/Area Number |
18F18023
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| Research Institution | Institute of Physical and Chemical Research |
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Principal Investigator |
NORI FRANCO 国立研究開発法人理化学研究所, 開拓研究本部, 主任研究員 (50415262)
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| Co-Investigator(Kenkyū-buntansha) |
LIU TAO 国立研究開発法人理化学研究所, 開拓研究本部, 外国人特別研究員
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| Project Period (FY) |
2018-04-25 – 2020-03-31
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| Keywords | Topological insulator / Non-Hermitian / Topological SC / Topological protection / Quantum information |
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| Outline of Annual Research Achievements |
In FY2018, my research is mainly focused on the following two topics:
(1) Majorana corner states in a 2D magnetic topological insulator on a high-temperature superconductor. A d-dimensional second-order topological superconductor (TSC) is characterized by topologically protected gapless (d -2)dimensional states with the usual gapped (d - 1) boundaries. In this work, we studied a second-order TSC with a 2D magnetic topological insulator proximity coupled to a high-temperature superconductor, where Majorana bound states (MBSs) are localized at the corners of a square sample with gapped edge modes. A detailed analysis, based on edge theory, revealed the origin of the existence of MBSs at the corners of the 2D sample, which results from the sign change of the Dirac mass emerging at the intersection of any two adjacent edges due to pairing symmetry. Our proposal offers a promising platform for realizing MBSs in 2D systems.
(2) Second-order topological phases in non-Hermitian systems. A d-dimensional second-order topological insulator (SOTI) can host topologically protected (d-2)-dimensional gapless boundary modes. In this work, we showed that a 2D non-Hermitian SOTI can host zero-energy modes localized only at one corner. A 3D non-Hermitian SOTI is shown to support second-order boundary modes, which are localized not along hinges but anomalously at a corner. The usual bulk-corner (hinge) correspondence in the second-order 2D (3D) non-Hermitian system breaks down. Our work lays the cornerstone for exploring higher-order topological phenomena in non-Hermitian systems.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
This because we obtained results that were positively evaluated by referees of top journals (e.g., Physical Review B and Physical Review Letters). The evaluations of the referees were more positively than we originally expected. Thus, the progress has been more than initially expected.
The actual topic of research has evolved into a different direction (e.g., topological phases and non-Hermitian physics), because we recently got new ideas, and we felt that it was better to focus on a very recent hot topic, which is attracting considerable attention. This change of research problem, and the new ideas we proposed, has provided surprisingly insightful results, which have been published to very good journals (e.g., Physical Review B and Physical Review Letters).
This recent focus on a more timely and hotter topic will also help me to secure a better academic position at the end of this Fellowship, because this topic is attracting considerable attention from the community.
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| Strategy for Future Research Activity |
I plan to work in the field of higher-order topological phases and non-Hermitian physics. The studies will be mainly focused on: (1). We will explore how the interplay between non-Hermiticity and crystalline symmetries change the topological properties of non-Hermitian higher-order topological insulators, as compared to the Hermitian cases. (2). We will study the non-equilibrium topological phases in higher-order topological insulators, especially Floquet topological insulators and quenched dynamics. (3). We will investigate the higher-order topological phases in the presence of many-body interactions. (4). We will study how the interplay between non-Hermiticity and many-body interactions influences the system dynamics. These studies will enrich our understanding of non-Hermitian higher-order topological phases and non-Hermitian phenomena.
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Research Products
(3 results)
