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Rare-earth solid-state qubits

Nature Nanotechnology volume 2, pages 39–42 (2007)Cite this article

Abstract

Quantum bits (qubits) are the basic building blocks of any quantum computer. Superconducting qubits have been created with a top-down approach that integrates superconducting devices into macroscopic electrical circuits1,2,3, and electron-spin qubits have been demonstrated in quantum dots4,5,6. The phase coherence time (τ2) and the single qubit figure of merit (QM) of superconducting and electron-spin qubits are similar — at τ2 ∼ µs and QM ∼ 10–1,000 below 100 mK — and it should be possible to scale up these systems, which is essential for the development of any useful quantum computer. Bottom-up approaches based on dilute ensembles of spins have achieved much larger values of τ2 (up to tens of milliseconds; refs 78), but these systems cannot be scaled up, although some proposals for qubits based on two-dimensional nanostructures should be scalable9,10,11. Here we report that a new family of spin qubits based on rare-earth ions demonstrates values of τ2 (∼50 µs) and QM (∼1,400) at 2.5 K, which suggests that rare-earth qubits may, in principle, be suitable for scalable quantum information processing at 4He temperatures.

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Figure 1: Energy levels and Rabi frequencies for the erbium-doped RE system 167Er3+:CaWO4.
Figure 2: Rabi oscillations and coherence times.
Figure 3: Changing the damping time with the microwave power.
Figure 4: Maximum and minimum coupling of the microwave field to Er effective spins and direction-dependent Rabi frequencies.

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Acknowledgements

The authors acknowledge the support of INTAS contract no. 2003/03-51-4943. B.M. and I.K. acknowledge the Ministry of Education and Science of the Russian Federation (project RNP 2.1.1.7348) and B.B. the interdisciplinary European Network of Excellence ‘MAGMANet’ for support during the first year of the research.

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Authors and Affiliations

  1. Département Nanosciences, Institut Néel, CNRS, 25 Ave. des Martyrs, BP166, 38042, Grenoble, Cedex 9, France

    S. Bertaina & B. Barbara

  2. Ecole Nationale Supérieure de Physique, INP de Grenoble, Minatec 3 parvis Louis Néel, BP 257, 38016, Grenoble, Cedex 9, France

    S. Bertaina

  3. Laboratoire de Chimie Inorganique et Biologie (UMR-E 3 CEA-UJF), DRFMC, CEA-Grenoble, 17 rue des Martyrs, 38054, Grenoble, Cedex 9, France

    S. Gambarelli

  4. S.I. Vavilov State Optical Institute, St Petersburg, 199034, Russian Federation

    A. Tkachuk

  5. Kazan State University, Kazan, 420008, Russian Federation

    I. N. Kurkin & B. Malkin

  6. Laboratoire de Matériaux et Microélectronique de Provence, Faculté St Jérôme, C142, 13397, Marseille, Cedex 20, France

    A. Stepanov

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Contributions

A.T. provided the samples. S.B. and S.G. performed the experiments, and analysed and discussed them with A.S., I.K., B.M. and B.B. B.B. proposed this study and wrote the manuscript, which was commented on by all the authors.

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Correspondence to B. Barbara.

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The authors declare no competing financial interests.

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Bertaina, S., Gambarelli, S., Tkachuk, A. et al. Rare-earth solid-state qubits. Nature Nanotech 2, 39–42 (2007). https://doi.org/10.1038/nnano.2006.174

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