Grover's search algorithm: an optical approach

The essential operations of a quantum computer can be accomplished using so lely optical elements, with different polarization or spatial modes represe nting the individual qubits. We present-a simple all-optical implementation of Grover's algorithm for efficient searching, in which a database of four elements is searched with a single query. By 'compiling' the actual set-up , we have reduced the required number:of optical elements from 24 to only 1 2. We discuss the extension to large databases, and the limitations of thes e techniques.