拓扑绝缘体
物理
拓扑(电路)
高次谐波产生
准粒子
Berry连接和曲率
迪拉克费米子
几何相位
量子力学
凝聚态物理
费米子
超导电性
数学
激光器
组合数学
作者
Christoph Schmid,Leonard Weigl,P. Grössing,Vanessa Junk,Cosimo Gorini,S. Schlauderer,Suguru Ito,Manuel Meierhofer,Niklas Hofmann,D. Afanasiev,Jack Crewse,К. А. Кох,O. E. Tereshchenko,J. Güdde,Ferdinand Evers,Jan Wilhelm,Klaus Richter,U. Höfer,Rupert Huber
出处
期刊:Nature
[Springer Nature]
日期:2021-05-19
卷期号:593 (7859): 385-390
被引量:91
标识
DOI:10.1038/s41586-021-03466-7
摘要
When intense lightwaves accelerate electrons through a solid, the emerging high-order harmonic (HH) radiation offers key insights into the material1–11. Sub-optical-cycle dynamics—such as dynamical Bloch oscillations2–5, quasiparticle collisions6,12, valley pseudospin switching13 and heating of Dirac gases10—leave fingerprints in the HH spectra of conventional solids. Topologically non-trivial matter14,15 with invariants that are robust against imperfections has been predicted to support unconventional HH generation16–20. Here we experimentally demonstrate HH generation in a three-dimensional topological insulator—bismuth telluride. The frequency of the terahertz driving field sharply discriminates between HH generation from the bulk and from the topological surface, where the unique combination of long scattering times owing to spin–momentum locking17 and the quasi-relativistic dispersion enables unusually efficient HH generation. Intriguingly, all observed orders can be continuously shifted to arbitrary non-integer multiples of the driving frequency by varying the carrier-envelope phase of the driving field—in line with quantum theory. The anomalous Berry curvature warranted by the non-trivial topology enforces meandering ballistic trajectories of the Dirac fermions, causing a hallmark polarization pattern of the HH emission. Our study provides a platform to explore topology and relativistic quantum physics in strong-field control, and could lead to non-dissipative topological electronics at infrared frequencies. High-harmonic generation from the Dirac-like surface state of a topological insulator is separated from bulk contributions and continuously tuned by the carrier-envelope phase of the driving lightwave.
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