One approach to the development of quantum search algorithms is the quantum walk. A spatial search can be effected by the continuous-time evolution of a single quantum particle on a graph containing a marked site. In many physical implementations, however, one might expect to have multiple particles. In interacting bosonic systems at zero temperature, the dynamics is well described by a discrete nonlinear Schrödinger equation. We investigate the role of nonlinearity in determining the efficiency of the spatial search algorithm within the quantum walk model, for the complete graph. The analytical calculations reveal that the nonlinear search time scales with the size of the search space $N$ like $\sqrt{N}$, equivalent to the linear case, though with a different overall constant. The results indicate that interacting Bose-Einstein condensates at zero temperature could be natural systems for implementation of the quantum search algorithm.

• Received 15 March 2013

DOI:https://doi.org/10.1103/PhysRevA.88.032310