Letter abstract
Nature Physics 4, 463 - 466 (2008)
Published online: 27 April 2008 | doi:10.1038/nphys961
Subject Categories: Atomic and molecular physics | Information theory and computation | Quantum physics
Towards fault-tolerant quantum computing with trapped ions
Jan Benhelm, Gerhard Kirchmair, Christian F. Roos & Rainer Blatt
Today, ion traps are among the most promising physical systems for constructing a quantum device harnessing the computing power inherent in the laws of quantum physics1, 2. For the implementation of arbitrary operations, a quantum computer requires a universal set of quantum logic gates. As in classical models of computation, quantum error correction techniques3, 4 enable rectification of small imperfections in gate operations, thus enabling perfect computation in the presence of noise. For fault-tolerant computation5, it is believed that error thresholds ranging between 10- 4 and 10- 2 will be required—depending on the noise model and the computational overhead for realizing the quantum gates6, 7, 8—but so far all experimental implementations have fallen short of these requirements. Here, we report on a Mølmer–Sørensen-type gate operation9, 10 entangling ions with a fidelity of 99.3(1)% . The gate is carried out on a pair of qubits encoded in two trapped calcium ions using an amplitude-modulated laser beam interacting with both ions at the same time. A robust gate operation, mapping separable states onto maximally entangled states is achieved by adiabatically switching the laser–ion coupling on and off. We analyse the performance of a single gate and concatenations of up to 21 gate operations.
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Otto-Hittmair-Platz 1, A-6020 Innsbruck, Austria
Correspondence to: Christian F. Roos e-mail: Christian.Roos@uibk.ac.at
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