An information-theoretic analysis of Grover's algorithm

A quantum algorithm for identifying a target element in an unstructured search universe of N items in approximately π/4√N queries to a quantum oracle was discovered. It was proved that this square-root speed-up was the best attainable performance gain by any quantum algorithm. This paper presents an information-theoretic analysis of Grover's algorithm and gives a tight lower bound on the complexity of search algorithms using Grover's oracle