2022 Fiscal Year Final Research Report
Dynamical property of topological physics in multi-dimensional space of superconducting phase at multi-terminal Josephson junction
| Project/Area Number |
18K13484
|
|---|
| Research Category |
Grant-in-Aid for Early-Career Scientists
|
| Allocation Type | Multi-year Fund |
|---|
| Review Section |
Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
|
|---|
| Project Period (FY) |
2018-04-01 – 2023-03-31
|
| Keywords | ジョセフソン効果 / 多端子系 / トポロジカル物性 / ワイル特異点 / 異常ジョセフソン効果 / ジョセフソンダイオード効果 |
|---|
| Outline of Final Research Achievements |
We have proposed extensions of the Josephson effect in multi-terminal Josephson junctions. Owing to the addition of supoerconducting phases, we have obtained qualitatively different properties from two-terminal junctions.
In the case of four-terminal junctions, topologically protected Weyl singular points are emerged. In this study, by tuning the structure electrically, the Weyl points move continuously. They are pari-created and pari-annihilated accompanying with the topological phase transition. The Weyl points draw open and closed trajectories, which indicates a dynamical classification of topological phase transitions. For three-terminal case, we have obtained an asymmetric current-phase relation, hence a controllable Josephson diode effect is acheived.
These results indicates an emergent physics without spin-orbit interaction or paticular materials, which open an aspect of artifical quantum physics.
|
| Free Research Field |
メゾスコピック物理
|
| Academic Significance and Societal Importance of the Research Achievements |
本研究では超伝導体の数を３つ以上に拡張した多端子ジョセフソン接合における創発物性を解明した。多端子化によって、トポロジカル相、異常ジョセフソン効果、ジョセフソンダイオード効果などが創発されている。これらは多端子ジョセフソン接合ではなくとも現れるが、スピン軌道相互作用などの物質パラメータを必要とする。本成果は物質パラメータを必要とせず、純粋にナノ構造化による物性創発であり、さらに自在な制御を可能としている。これらは物質探索では不可能な特性をナノテクノロジーによって到達できることを示唆しており、学術的意義に加えて科学技術的・社会的意義も非常に大きい成果である。
|
