Among the numerous types of architecture being explored for quantum computers are systems utilizing ion traps, in which quantum bits (qubits) are formed from the electronic states of trapped ions and coupled through the Coulomb interaction. Although the elementary requirements for quantum computation have been demonstrated in this system, there exist theoretical and technical obstacles to scaling up the approach to large numbers of qubits. Therefore, recent efforts have been concentrated on using quantum communication to link a number of small ion-trap quantum systems. Developing the array-based approach, we show how to achieve massively parallel gate operation in a large-scale quantum computer, based on techniques already demonstrated for manipulating small quantum registers. The use of decoherence-free subspaces significantly reduces decoherence during ion transport, and removes the requirement of clock synchronization between the interaction regions.
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We acknowledge the experimental contributions of the NIST Ion Storage group, and also J. Beall for assistance with microfabrication. We thank D. Leibfried and M.A. Rowe for comments on the manuscript. D.K. and D.J.W. were supported by the US National Security Agency (NSA), Advanced Research and Development Activity (ARDA) and the Office of Naval Research. C.M. was supported by the US NSA, ARDA and the National Science Foundation ITR programme.
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Kielpinski, D., Monroe, C. & Wineland, D. Architecture for a large-scale ion-trap quantum computer. Nature 417, 709–711 (2002). https://doi.org/10.1038/nature00784
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