  We have studied far-infrared charge dynamics of Sr- and O- co-doped
La1.985Sr0.015CuO4+delta with delta = 0.024 (p = 0.063 per Cu) and delta =
0.032 (p = 0.07). We found that two-dimensional Wigner lattice order is the
ground state of cuprates away from half-filling. We found that the presence of
2D Wigner lattice and the pinned Goldstone mode is essential for the cuprate
physics and superconductivity. We propose that all the high Tc physics are
based on the existence of these peculiar 2D electron lattices.
