Selective scattering between Floquet Bloch and Volkov states in a topological insulator Journal Article

Author(s): Mahmood, Fahad; Chan, Ching-Kit; Alpichshev, Zhanybek; Gardner, Dillon; Lee, Young; Lee, Patrick A; Gedik, Nuh
Article Title: Selective scattering between Floquet Bloch and Volkov states in a topological insulator
Abstract: The coherent optical manipulation of solids is emerging as a promising way to engineer novel quantum states of matter. The strong time-periodic potential of intense laser light can be used to generate hybrid photon-electron states. Interaction of light with Bloch states leads to Floquet-Bloch states, which are essential in realizing new photo-induced quantum phases. Similarly, dressing of free-electron states near the surface of a solid generates Volkov states, which are used to study nonlinear optics in atoms and semiconductors. The interaction of these two dynamic states with each other remains an open experimental problem. Here we use time- and angle-resolved photoemission spectroscopy (Tr-ARPES) to selectively study the transition between these two states on the surface of the topological insulator Bi2Se3. We find that the coupling between the two strongly depends on the electron momentum, providing a route to enhance or inhibit it. Moreover, by controlling the light polarization we can negate Volkov states to generate pure Floquet-Bloch states. This work establishes a systematic path for the coherent manipulation of solids via light-matter interaction.
Journal Title: Nature Physics
Volume: 12
Issue 4
ISSN: 1745-2473
Publisher: Nature Publishing Group  
Date Published: 2016-04-01
Start Page: 306
End Page: 310
DOI: 10.1038/nphys3609
Notes: The authors would like to thank C. Lee for useful discussions. This work is supported by US Department of Energy (DOE), Basic Energy Sciences, Division of Materials Sciences and Engineering (experimental set-up, data acquisition and theory), Army Research Office (electron spectrometer) and by the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4540 (data analysis).
Open access: yes (repository)