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The germanium quantum information route

Nature Reviews Materials volume 6, pages 926–943 (2021)Cite this article

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Abstract

In the effort to develop disruptive quantum technologies, germanium is emerging as a versatile material to realize devices capable of encoding, processing and transmitting quantum information. These devices leverage the special properties of holes in germanium, such as their inherently strong spin–orbit coupling and their ability to host superconducting pairing correlations. In this Review, we start by introducing the physics of holes in low-dimensional germanium structures, providing key insights from a theoretical perspective. We then examine the materials-science progress underpinning germanium-based planar heterostructures and nanowires. We go on to review the most significant experimental results demonstrating key building blocks for quantum technology, such as an electrically driven universal quantum gate set with spin qubits in quantum dots and superconductor–semiconductor devices for hybrid quantum systems. We conclude by identifying the most promising avenues towards scalable quantum information processing in germanium-based systems.

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Fig. 1: Quantum confined holes in germanium.
Fig. 2: Planar Ge/SiGe heterostructures.
Fig. 3: Ge-based nanowires.
Fig. 4: Quantum dots and qubits in core–shell nanowires, hut wires and planar systems.
Fig. 5: State-of-the-art coherence times and single-qubit gate fidelities for core–shell nanowires, hut wires and planar heterostructures.
Fig. 6: Superconductor–semiconductor hybrids in Ge nanowires and planar systems.
Fig. 7: Ge-based quantum technology.

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Acknowledgements

G.S., M.V. and F.A.Z. acknowledge financial support from the Netherlands Organization for Scientific Research (NWO). F.A.Z., D.L. and G.K. acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 862046. G.K. acknowledges funding from FP7 ERC Starting Grant 335497, FWF Y 715-N30 and FWF P-30207. S.D.F. acknowledges support from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 81050 and from the Agence Nationale de la Recherche through the TOPONANO and QSPIN projects. J.-J.Z. acknowledges support from the National Key R&D Program of China (grant no. 2016YFA0301701) and Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB30000000). D.L. and C.K. acknowledge the Swiss National Science Foundation and NCCR QSIT.

Author information

Authors and Affiliations

  1. QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands

    Giordano Scappucci & Menno Veldhorst

  2. Department of Physics, University of Basel, Basel, Switzerland

    Christoph Kloeffel & Daniel Loss

  3. MESA+ Institute for Nanotechnology, University of Twente, Enschede, Netherlands

    Floris A. Zwanenburg

  4. Department of Physics, University of Warwick, Coventry, UK

    Maksym Myronov

  5. Institute of Physics and CAS Center for Excellence in Topological Quantum Computation, Chinese Academy of Sciences, Beijing, China

    Jian-Jun Zhang

  6. Univ. Grenoble Alpes and CEA, IRIG/PHELIQS, Grenoble, France

    Silvano De Franceschi

  7. Institute of Science and Technology Austria, Klosterneuburg, Austria

    Georgios Katsaros

Authors
  1. Giordano Scappucci
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  2. Christoph Kloeffel
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  3. Floris A. Zwanenburg
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  4. Daniel Loss
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  5. Maksym Myronov
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  6. Jian-Jun Zhang
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  7. Silvano De Franceschi
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  8. Georgios Katsaros
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  9. Menno Veldhorst
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Contributions

All authors contributed to the writing of the manuscript.

Corresponding author

Correspondence to Giordano Scappucci.

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Scappucci, G., Kloeffel, C., Zwanenburg, F.A. et al. The germanium quantum information route. Nat Rev Mater 6, 926–943 (2021). https://doi.org/10.1038/s41578-020-00262-z

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