A multi-object searching algorithm using subgrouped oracles

We present in this work, if a set of well organized suboracles is available, a quantum algorithm for multiobject search with certainty in an unsorted database of N items. Depending on the number of the objects, the technique of phase tunning is included in the algorithm. If one single object is to be searched, this algorithm performs a factor of two improvement over the best algorithm for a classical sorted database. While if the number of the objects is larger than one, the algorithm requires slightly less than log4 N queries, but no classical counterpart exists since the resulting state is a superposition of the marked states.