関連する実験動画
Updated: Jan 31, 2026

05:57
Blood Flow Imaging with Ultrafast Doppler
Published on: October 14, 2020
8.5K
ウェイル半金属の超高速対称スイッチ
Edbert J Sie1,2, Clara M Nyby3, C D Pemmaraju2
1Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, USA.
Nature
|January 4, 2019
まとめ
研究者はテラヘルツの光パルスを使って WTe2に超高速の切断ストレスを誘導し,新しいトポロジックフェーズを作成しました. 未来の電子機器の トポロジカルプロパティの高速操作を可能にします
科学分野:
- 凝縮物質物理学
- 材料科学
- 量子現象について
背景:
- トポロジカルな量子材料は,高度な電子と量子コンピューティングに不可欠なユニークな性質を持っています.
- トポロジカル・インヴァリアントの制御は,トポロジカル・スイッチングアプリケーションの開発の鍵です.
- 格子ストレインは,トポロジカルインヴァリアントをチューニングするための主要な方法ですが,従来の方法はダイナミックコントロールが欠けている.
研究 の 目的:
- テラヘルツ (THz) の光パルスによる量子材料のトポロジ的性質の誘導および操作の可能性を調査する.
- 超高速のトポロジックスイッチングのための時間変動のストレスのプロトコルを作成する.
- THz周波数で動作するトポロジックスイッチの実現可能性を実証する.
主な方法:
- 結晶学的な測定のために相対性電子 difrraction を利用した.
- テラヘルツの光パルスを使って,WTe2の層間切断を誘導する.
- 非線形光学測定を行い,相変遷と対称性の変化を特徴づけました.
主要な成果:
- WTe2で大きな幅を持つTHz周波数インターレイヤのスイヤーストレスを実証した.
- THz誘導によるトポロジカルに異なったメタステーブル・フェーズ・トランジションを引き起こした.
- トポロジ的に微不足道な中心対称性への対称性変化を観測した.
- 反対のキラリティを持つウェイル点の超高速誘導または消去を証明した.
結論:
- THzの光パルスは,トポロジカルな材料で超高速で大きな幅の切断ストレスを引き起こすことができます.
- このストレンは,トポロジカル状態のダイナミックな操作を可能にし,異なるメタステーブルフェーズにつながります.
- この発見は,THz周波数で動作する超高速トポロジックスイッチの開発への道を開く.
関連する概念動画
Symmetry
205
The equation of an ellipse centered at the origin defines all points whose distances from the center maintain a constant ratio between the horizontal and vertical axes. This equation results in a smooth, closed curve that extends further along the x-axis than the y-axis, giving it a horizontal orientation. Such an ellipse demonstrates three kinds of symmetry: across the x-axis, across the y-axis, and about the origin. These symmetries are essential in understanding the graph's structure and...
205
Switching of BJT
857
Switching behavior in Bipolar Junction Transistors (BJTs) is a fundamental aspect utilized in various electronic circuits, particularly for digital logic applications like switches and amplifiers. In a typical switching circuit, a BJT alternates between cut-off and saturation modes, corresponding to the "off" and "on" states, respectively, thus behaving like an ideal switch.
Cut-off Mode ("Off" State): In this state, both the emitter-base and collector-base junctions are...
Cut-off Mode ("Off" State): In this state, both the emitter-base and collector-base junctions are...
857
Gauss's Law: Planar Symmetry
9.6K
A planar symmetry of charge density is obtained when charges are uniformly spread over a large flat surface. In planar symmetry, all points in a plane parallel to the plane of charge are identical with respect to the charges. Suppose the plane of the charge distribution is the xy-plane, and the electric field at a space point P with coordinates (x, y, z) is to be determined. Since the charge density is the same at all (x, y) - coordinates in the z = 0 plane, by symmetry, the electric field at P...
9.6K
Symmetry in Maxwell's Equations
4.2K
Once the fields have been calculated using Maxwell's four equations, the Lorentz force equation gives the force that the fields exert on a charged particle moving with a certain velocity. The Lorentz force equation combines the force of the electric field and of the magnetic field on the moving charge. Maxwell's equations and the Lorentz force law together encompass all the laws of electricity and magnetism. The symmetry that Maxwell introduced into his mathematical framework may not be...
4.2K
Gauss's Law: Spherical Symmetry
9.3K
A charge distribution has spherical symmetry if the density of charge depends only on the distance from a point in space and not on the direction. In other words, if the system is rotated, it doesn't look different. For instance, if a sphere of radius R is uniformly charged with charge density ρ0, then the distribution has spherical symmetry. On the other hand, if a sphere of radius R is charged so that the top half of the sphere has a uniform charge density ρ1 and the bottom half has a...
9.3K
Gauss's Law: Cylindrical Symmetry
9.5K
A charge distribution has cylindrical symmetry if the charge density depends only upon the distance from the axis of the cylinder and does not vary along the axis or with the direction about the axis. In other words, if a system varies if it is rotated around the axis or shifted along the axis, it does not have cylindrical symmetry. In real systems, we do not have infinite cylinders; however, if the cylindrical object is considerably longer than the radius from it that we are interested in,...
9.5K

