  We experimentally study a Stub photonic lattice and excite their localized
linear states originated from an isolated Flat Band at the center of the linear
spectrum. By exciting these modes in different regions of the lattice, we
observe that they do not diffract across the system and remain well trapped
after propagating along the crystal. By using their wave nature, we are able to
combine -- in phase and out of phase -- two neighbor states into a coherent
superposition. These observations allow us to propose a novel setup for
performing three different all-optical logical operations such as OR, AND, and
XOR, positioning Flat Band systems as key setups to perform concrete
applications at any level of power.

Optics;Mesoscale and Nanoscale Physics