Spin read-out in atomic qubits in an all-epitaxial three-dimensional transistor


The realization of the surface code for topological error correction is an essential step towards a universal quantum computer1,2,3. For single-atom qubits in silicon4,5,6,7, the need to control and read out qubits synchronously and in parallel requires the formation of a two-dimensional array of qubits with control electrodes patterned above and below this qubit layer. This vertical three-dimensional device architecture8 requires the ability to pattern dopants in multiple, vertically separated planes of the silicon crystal with nanometre precision interlayer alignment. Additionally, the dopants must not diffuse or segregate during the silicon encapsulation. Critical components of this architecture—such as nanowires9, single-atom transistors4 and single-electron transistors10–have been realized on one atomic plane by patterning phosphorus dopants in silicon using scanning tunnelling microscope hydrogen resist lithography11,12. Here, we extend this to three dimensions and demonstrate single-shot spin read-out with 97.9% measurement fidelity of a phosphorus dopant qubit within a vertically gated single-electron transistor with <5 nm interlayer alignment accuracy. Our strategy ensures the formation of a fully crystalline transistor using just two atomic species: phosphorus and silicon.

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Fig. 1: A vertically gated SET for high-fidelity single-shot spin read-out.
Fig. 2: Etched trench registration markers.
Fig. 3: Use of kinetic growth manipulation to optimize the regrowth surface for second-layer lithography.
Fig. 4: Comparison of electrical stability of the vertical SET using top and in-plane gates.
Fig. 5: High-fidelity single-shot read-out of a donor qubit in a vertically gated SET.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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This paper is dedicated to Mira Koch. This research was conducted by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology (project number CE110001027). M.Y.S. acknowledges an ARC Laureate Fellowship.

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M.K., J.G.K. and M.Y.S. conceived and designed the experiment. M.K., J.G.K., P.P. and E.P. fabricated the devices. M.K. and P.P. obtained all electrical measurements. The data were analysed by M.K. and J.G.K., and discussed critically with all authors. M.K. performed the spin read-out analysis. M.G.H. performed the noise characterization. D.K. calculated the read-out fidelity of the device. The manuscript was written by M.K., J.G.K. and M.Y.S., with input from all other authors. M.Y.S. supervised the project.

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Correspondence to Matthias Koch.

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Koch, M., Keizer, J.G., Pakkiam, P. et al. Spin read-out in atomic qubits in an all-epitaxial three-dimensional transistor. Nature Nanotech 14, 137–140 (2019). https://doi.org/10.1038/s41565-018-0338-1

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