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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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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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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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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DOI: https://doi.org/10.1038/nnano.2006.174
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