"Two quantized non-linear effects"

Who: Adolfo G Grushin, UC Berkeley / Néel Institute, University of California, USA

Place: Donostia International Physics Center

Date: Tuesday, 29 August 2017, 12:00

Quantized phenomena in solid state systems are typically linear responses of insulators. In this talk I will discuss two experiments that probe nonlinear responses that are quantized. The first probes the Chern number of a quantum Hall insulator by heating it and its related to the absorbed power. The second is the circular photogalvanic effect (CPGE): the part of the photocurrent which changes sign when the light's polarization flips. We find it is quantized to e^3/h^2 with no material-dependent parameters in mirror free Weyl semimetals (e.g. SrSi2) and three-dimensional Rashba materials (e.g. doped Te). Its magnitude is relatively large, which enables the direct detection of the monopole charge with current techniques.

Probing topology by "heating": Quantized circular dichroism in ultracold atoms
D. T. Tran, A. Dauphin, A. G. Grushin, P. Zoller, N. Goldman
Science Advances  3, no. 8, 1701207 (2017).

Quantized circular photogalvanic effect in Weyl semimetals
Fernando de Juan, Adolfo G. Grushin, Takahiro Morimoto, Joel E. Moore
Nature Communications 8, 15995 (2017)

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