Extended Data Fig. 2: Light occupancy in the leftmost column when a Gaussian beam is launched from the middle of the lattice.

a, b, Illustrated intensity (colour bar; peak intensity is set to 1) of the initial Gaussian beam launched in real space (a) and synthetic space (b). c, Measured output intensity of the leftmost column for the input shown in a and b. d, Measured interference of the lattice output at the leftmost column with the input beam, showing that all of the seven peaks are in phase (the dashed line represents equal phase), indicating that the light at the leftmost column occupies the lowest spatial mode of the column. e, Measured normalized intensity cross-section (blue line) at the leftmost column of the lattice output, compared with the theoretically calculated (tight-binding) intensity profile of the first mode of the column (orange circles). The sum of peak intensities is normalized to 1.