"Topological Quantization in Units of the Fine Structure Constant"

Joseph Maciejko: Xiao-Liang Qi, H. Dennis Drew, and Shou-Cheng Zhang; Phys. Rev. Lett. , 12/12/10.

Additional Authors: Xiao-Liang Qi, H. Dennis Drew, and Shou-Cheng Zhang


Fundamental topological phenomena in condensed matter physics are associated with a quantized electromagnetic response in units of fundamental constants. Recently, it has been predicted theoretically that the time-reversal invariant topological insulator in three dimensions exhibits a topological magnetoelectric effect quantized in units of the fine structure constant α=e2/ℏc. In this Letter, we propose an optical experiment to directly measure this topological quantization phenomenon, independent of material details. Our proposal also provides a way to measure the half-quantized Hall conductances on the two surfaces of the topological insulator independently of each other.