SummaryLet a classical algorithm be determined by sequential applications of a black box performing one step of this algorithm. If we consider this black box as an oracle which gives a value f (a) for a query a, we can compute T sequential applications of f on a classical computer relative to this oracle in time T .It is proved that if T = O(2 n/7 ), where n is the length of input, then the result of T sequential applications of f can not be computed on quantum computer with oracle for f for all possible f faster than in time Ω(T ). This means that there is no general method of quantum speeding up of classical algorithms provided in such a general method a classical algorithm is regarded as iterated applications of a given black box.For an arbitrary time complexity T a lower bound for the time of quantum simulation was found to be Ω(T 1/2 ).
It is proved that a quantum computer with fixed and permanent interaction of diagonal type between qubits proposed in the work quant-ph/0201132 is universal. Such computer is controlled only by one-qubit quick transformations, and this makes it fea-
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.