The boson sampling experiments were performed on silica-on-silicon photonic chips. This photo shows such a chip (bottom center) during the fabrication process, where ultraviolet lasers (center) are focused into a doped layer of silica to create a localized refractive index increase. The chip is moved on a precision translation stage to trace out the desired circuit geometry (see figure 2A in the manuscript). This image relates to a paper that appeared in the Dec. 20, 2012, issue of Science Express, published by AAAS. The paper, by Justin Spring at University of Oxford in Oxford, UK, and colleagues was titled, "Boson Sampling on a Photonic Chip."