Fig. 3: Experimental frequency dependence of the effective second-order nonlinear susceptibility as a function of twist angle in bilayer WSe2 at 5 K.

The dashed circle highlights the region where the 21° twisted bilayer exceeds the 1° sample in \(\chi ^{(2)}\) due to the shift of the excitonic resonances. The black arrows mark the suppression of \(\chi ^{(2)}\) due to the quantum interference.