 frequencies nicely agree with the dashed lines, confirming that they originate from the valley modulation of the X and Y valleys. (See Supplemental Material [00] for more details). In summary, our results demonstrate a novel technique to induce a periodic valley modulation for 0D electrons in a multivalley system. We remark in closing on a possible extension of our work to realize a device which could support one-dimensional, helical edge modes (Fig. 0 ) and therefore be of potential use in exploring Majorana fermion physics. Note that our choice of a negative electron-beam resist as the surface grating yields a valley modulation of ≃ 00 % in our samples (see Supplemental Material [00] ). This modulation may be enhanced to essentially 000% by using a grating material, e.g., Ti, whose thermal contraction coefficient is significantly different from that of GaAs/AlAs [00] , meaning that the 0D electrons in alternating strips would occupy either X or Y valleys. As illustrated in Fig. 0 , when current is passed parallel to the valley-polarized strips at the ν = 0 integer quantum Hall state [00] , the large B ⊥ -induced one-dimensional edge states should be confined within each strip. This paves the way to realizing counterpropagating, edge channels of different valleys ( X and Y ) at the boundary between two strips. 0 00.0000/PhysRevLett.000.000000.f0 FIG. 0. Schematic of realizing valley helical edge states from a valley superlattice subjected to large perpendicular magnetic fields. The valley-polarized edge modes depicted in Fig. 0 mimic the spin-polarized one-dimensional helical channels where an electron