Reconfigurable cluster-state generation in specially poled nonlinear waveguide arrays

We present an approach for generating cluster states on-chip, with the state encoded in the spatial component of the photonic wave function. We show that for spatial encoding, a change of measurement basis can improve the practicality of cluster-state algorithm implementation and demonstrates this by simulating the Grover's search algorithm. Our state generation scheme involves shaping the wave function produced by spontaneous parametric down-conversion in on-chip waveguides using specially tailored nonlinear poling patterns. Furthermore, the form of the cluster state can be reconfigured quickly by driving different waveguides in the array.