random walk search with imperfect gates was discussed in some detail by Li [*et al*]{} [@Li2006Gate-imperfecti], who have considered the case when the Grover operator applied in the search is systematically modified. Such an imperfection decreases the search probability and also shifts its first maximum in time.

In this paper we analyze the impact of noise on the SKW algorithm typical for the experimental situations of the SQRW. In particular, first we focus on photon losses and show that, somewhat contradicting the naïve expectation, non-trivial effects such as the enhancement of the search efficiency can be observed. As a second type of errors we study randomly distributed phase errors in two complementary regimes. The first regime is characterized by rapid fluctuation of the optical path lengths, that leads to the randomization of phases for each run of the algorithm. We show that the classical limit of the SKW algorithm, reached by increasing the variance of the phase fluctuations, does not correspond to a search algorithm. In the other regime, the stability of the optical path lengths is maintained over the duration of one run, thus the errors are caused by static random phases. This latter case has not yet been 