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Ultrafast hole spin qubit with gate-tunable spin–orbit switch functionality

An Author Correction to this article was published on 05 July 2021

This article has been updated

Abstract

Quantum computers promise to execute complex tasks exponentially faster than any possible classical computer, and thus spur breakthroughs in quantum chemistry, material science and machine learning. However, quantum computers require fast and selective control of large numbers of individual qubits while maintaining coherence. Qubits based on hole spins in one-dimensional germanium/silicon nanostructures are predicted to experience an exceptionally strong yet electrically tunable spin–orbit interaction, which allows us to optimize qubit performance by switching between distinct modes of ultrafast manipulation, long coherence and individual addressability. Here we used millivolt gate voltage changes to tune the Rabi frequency of a hole spin qubit in a germanium/silicon nanowire from 31 to 219 MHz, its driven coherence time between 7 and 59 ns, and its Landé g-factor from 0.83 to 1.27. We thus demonstrated spin–orbit switch functionality, with on/off ratios of roughly seven, which could be further increased through improved gate design. Finally, we used this control to optimize our qubit further and approach the strong driving regime, with spin-flipping times as short as ~1 ns.

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Fig. 1: Experimental set-up and EDSR.
Fig. 2: Coherent qubit control.
Fig. 3: Electrical tunability of qubit parameters.
Fig. 4: Ultrafast coherent control.

Data availability

The data supporting the plots of this paper are available at the Zenodo repository at https://doi.org/10.5281/zenodo.4290131.

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Acknowledgements

We thank S. Bosco, B. Hetényi, C. Kloeffel, D. Loss, A. Laucht and A. Hamilton for useful discussions. Furthermore, we acknowledge S. Martin and M. Steinacher for technical support. This work was partially supported by the Swiss Nanoscience Institute (SNI), the NCCR QSIT, the NCCR SPIN, the Georg H. Endress Foundation, Swiss NSF (grant no. 179024), the EU H2020 European Microkelvin Platform EMP (grant no. 824109) and FET TOPSQUAD (grant no. 862046).

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F.N.M.F., L.C.C., F.R.B. and D.M.Z. conceived the project and experiments. F.N.M.F. fabricated the device. A.L. and E.P.A.M.B. synthesized the nanowire. F.N.M.F., L.C.C., O.A.H.v.d.M., F.R.B. and D.M.Z. performed the experiments. F.N.M.F., L.C.C., F.R.B. and D.M.Z. analysed the measurements and wrote the manuscript with input from all the authors.

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Correspondence to Dominik M. Zumbühl or Floris R. Braakman.

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Supplementary Notes 1 and 2, Figs. 1–4 and Table 1.

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Froning, F.N.M., Camenzind, L.C., van der Molen, O.A.H. et al. Ultrafast hole spin qubit with gate-tunable spin–orbit switch functionality. Nat. Nanotechnol. 16, 308–312 (2021). https://doi.org/10.1038/s41565-020-00828-6

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