With a three-bit nuclear magnetic resonance quantum computer, we have experimentally realized a quantum search algorithm that can take a desired function value (or target) t as its input and give the corresponding function argument $x_0$ such that ${f(x}_0)=t$ as a result. The function value is not retrieved from an existing table, but evaluated by the search algorithm in the manner of a typical algorithmic search. A single-query version of the quantum search algorithm is used to search for one of two function arguments.

• Received 21 June 2001

DOI:https://doi.org/10.1103/PhysRevA.65.054301