Scalable Atomic Arrays for Spin-Based Quantum Computers in Silicon.

Jakob, Alexander M; Robson, Simon G; Firgau, Hannes R; Mourik, Vincent; Schmitt, Vivien; Holmes, Danielle; Posselt, Matthias; Mayes, Edwin L H et al. · Adv Mater · 2024

basic_science · Level V

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Abstract

Semiconductor spin qubits combine excellent quantum performance with the prospect of manufacturing quantum devices using industry-standard metal-oxide-semiconductor (MOS) processes. This applies also to ion-implanted donor spins, which further afford exceptional coherence times and large Hilbert space dimension in their nuclear spin. Here multiple strategies are demonstrated and integrated to manufacture scale-up donor-based quantum computers. <sup>31</sup>PF<sub>2</sub> molecule implants are used to triple the placement certainty compared to <sup>31</sup>P ions, while attaining 99.99% confidence in detecting the implant. Similar confidence is retained by implanting heavier atoms such as <sup>123</sup>Sb and <sup>209</sup>Bi, which represent high-dimensional qudits for quantum information processing, while Sb<sub>2</sub> molecules enable deterministic formation of closely-spaced qudits. The deterministic formation of regular arrays of donor atoms with 300 nm spacing is demonstrated, using step-and-repeat implantation through a nano aperture. These methods cover the full gamut of technological requirements for the construction of donor-based quantum computers in silicon.