Electronic nanoholography

We have developed a quantum holographic method to advance information density beyond the areal limits set by the discreteness of matter. We present experiments on information encoding using nanoscale writing with degenerate two-dimensional electrons. We show ``pages'' (letters encoded at specific energies) materialized by precisely engineering electron scattering environments with the tip of a scanning tunneling microscope. We then demonstrate that multiple pages can be encoded into the same region of space, using energy as a third holographic dimension. This form of holography produces non-volatile subnanometer features, tens of times smaller than the most precise optical or scanned-probe lithography, and information densities exceeding 5 bits per square nanometer.