  A fast quantum search algorithm for continuous variables is presented. The
result is the quantum continuous variable analog of Grover's algorithm
originally proposed for qubits. A continuous variable analog of the Hadamard
(i.e., Fourier transform) operation is used in conjunction with inversion about
the average of quantum states to allow the approximate identification of an
unknown quantum state in a way that gives a square-root speed-up over search
algorithms using classical continuous variables. Also, we show that this
quantum search algorithm is robust for a generalised Fourier transformation on
continuous variables.
