Silicon spin qubits with implanted single donor ions 

Dannielle Holmes – University of New South Wales

Implanted single group-V donor ions in isotopically-enriched silicon (28Si) provide a promising platform for quantum computing due to their long spin coherence times [1]. Electron and nuclear donor spins can be controlled and read out using surface nanoelectronics and various donor spin coupling mechanisms exist over a range of length scales. High spin nuclei, such as antimony (123Sb), provide exciting opportunities for storing more quantum information, all electrical control and exploring quantum chaos. 

Large-scale arrays of qubits, such as in the flip-flop qubit architecture for donor spins [2], are required to run useful quantum algorithms. Deterministic ion implantation, in which single ions are implanted into precise locations, is essential for producing these donor qubit arrays. Recent work [3] has shown the excellent detection fidelity (99.85 %) of near-surface implanted single phosphorus (P) ions using ion beam induced charge (IBIC) detectors. The detection fidelity can be boosted by employing PF2 molecule ions, in which the bystander fluorine (F) ions increase the charge signal produced upon implantation but diffuse away from the active region of the device upon annealing. The production of deterministically-implanted PF2 arrays is demonstrated using a step-and-repeat process in which ions are implanted through a moveable nanostencil into an IBIC detector. The next generation of detectors will enable the integration of qubit control and readout nanocircuitry with deterministically-implanted donor spins, to drive the scale-up of quantum computers.  

[1] J. T. Muhonen et al.,  Nature Nano. 9, 986 (2014) 

[2] G. Tosi et al., Nature Comm. 8, 450 (2017) 

[3] A. M. Jakob et al., Adv. Mat. 34, 2103235 (2022)