We present the first robust implementation of a coined quantum walk over five steps using only passive optical elements. By employing a fiber network loop we keep the amount of required resources constant as the walker's position Hilbert space is increased. We observed a non-Gaussian distribution of the walker's final position, thus characterizing a faster spread of the photon wave-packet in comparison to the classical random walk. The walk is realized for many different coin settings and initial states, which opens the way for the implementation of a quantum walk-based search algorithm.
@article{arxiv.0910.2197,
title = {Photons Walking the Line: A quantum walk with adjustable coin operations},
author = {A. Schreiber and K. N. Cassemiro and V. Potocek and A. Gabris and P. J. Mosley and E. Andersson and I. Jex and Ch. Silberhorn},
journal= {arXiv preprint arXiv:0910.2197},
year = {2015}
}