Implementation of the quantum Fourier transform

A quantum Fourier transform (QFT) has been implemented on a three qubit nuc lear magnetic resonance (NMR) quantum computer to extract the periodicity o f an input state. Implementation of a QFT provides a first step towards the realization of Shor's factoring and other quantum algorithms. The experime ntal implementation of the QFT on a periodic state is presented along with a quantitative measure of its efficiency measured through state tomography. Experimentally realizing the QFT is a clear demonstration of the ability o f NMR to control quantum systems.