PT - JOURNAL ARTICLE
AU - Chiaverini, J.
AU - Britton, J.
AU - Leibfried, D.
AU - Knill, E.
AU - Barrett, M. D.
AU - Blakestad, R. B.
AU - Itano, W. M.
AU - Jost, J. D.
AU - Langer, C.
AU - Ozeri, R.
AU - Schaetz, T.
AU - Wineland, D. J.
TI - Implementation of the Semiclassical Quantum Fourier Transform in a Scalable System
AID - 10.1126/science.1110335
DP - 2005 May 13
TA - Science
PG - 997--1000
VI - 308
IP - 5724
4099 - http://science.sciencemag.org/content/308/5724/997.short
4100 - http://science.sciencemag.org/content/308/5724/997.full
SO - Science2005 May 13; 308
AB - We report the implementation of the semiclassical quantum Fourier transform in a system of three beryllium ion qubits (two-level quantum systems) confined in a segmented multizone trap. The quantum Fourier transform is the crucial final step in Shor's algorithm, and it acts on a register of qubits to determine the periodicity of the quantum state's amplitudes. Because only probability amplitudes are required for this task, a more efficient semiclassical version can be used, for which only single-qubit operations conditioned on measurement outcomes are required. We apply the transform to several input states of different periodicities; the results enable the location of peaks corresponding to the original periods. This demonstration incorporates the key elements of a scalable ion-trap architecture, suggesting the future capability of applying the quantum Fourier transform to a large number of qubits as required for a useful quantum factoring algorithm.