Symposium X—MRS/The Kavli Foundation Frontiers of Materials

Abstract

The realisation of a large-scale error corrected quantum computer relies on our ability to reproducibly
manufacture qubits that are fast, highly coherent, controllable and stable. The promise of achieving
this in a highly manufacturable platform such as silicon requires a deep understanding of the materials
issues that impact device operation. In this talk, I will demonstrate our progress to engineer every
aspect of device behaviour in atomic qubits in silicon for fast, controllable exchange coupling;¹
fast, high fidelity qubit initialisation and read-out;² low noise all-epitaxial gates allowing for highly
stable qubits;³ and qubit control^4,5 that provides a deep understanding of the impact of the solid-state
environment⁶ on qubit designs and operation. I will also discuss our latest results in quantum
machine learning,⁷ analogue simulation^8,9 and demonstration of the highest efficiency Grover’s
algorithm to date.¹⁰

¹Y. He, S.K. Gorman, D. Keith, L. Kranz, J.G. Keizer, M.Y. Simmons, A fast
( ns) two-qubit gate between phosphorus donor electrons in silicon. Nature 571, 371 (2019).
² D. Keith, M.G. House, M.B. Donnelly, T.F. Watson, B. Weber, M.Y. Simmons,
Microsecond spin qubit readout with a strong-response single electron transistor.
Phys. Rev. X 9, 041003 (2019); D. Keith, S.K. Gorman, L. Kranz, Y. He,
J.G. Keizer, M.A. Broome, M.Y. Simmons, Benchmarking high fidelity single-shot readout of
semiconductor qubits, New J. Phys. 21, 063011 (2019).
³ L. Kranz, S.K. Gorman, B. Thorgrimsson, Y. He, D. Keith, J.G. Keizer, M.Y. Simmons, Exploiting
a single-crystal environment to minimize the charge noise on qubits in silicon. Adv. Mater.
32(40), 2003361 (2020).
⁴ L. Fricke, S.J. Hile, L. Kranz, Y. Chung, Y. He, P. Pakkiam, J.G. Keizer, M.G. House,
M.Y. Simmons, Coherent spin control of a precision placed donor bound electron qubit in silicon.
Nat. Commun. 12, 3323 (2021).
⁵ J. Reiner, Y. Chung, C. Lehner, S.H. Misha, S. Monir, D. Poulos, K. Charde, L. Kranz,
B. Thorgrimsson, P. Macha, D. Keith, Y-L. Hsueh, R. Rahman, J.G. Keizer, S.K. Gorman,
M.Y. Simmons, Control of multiple nuclear spin quantum registers. Nat. Nanotechnol. 19,
584 (2024).
⁶ M. Koch, J.G. Keizer, P. Pakkiam, D. Keith, M.G. House, E. Peretz, M.Y. Simmons,
Spin read-out in atomic qubits in an all-epitaxial three-dimensional transistor. Nat.
Nanotechnol. 14(2), 137 (2019).
⁷ S.A. Sutherland, M. Donnelly, J.G. Keizer, C.R. Myers, B. Thorgrimsson, Y. Chung, S.K. Gorman,
M.Y. Simmons, Experimental quantum enhanced machine learning using quantum many body
systems. Paper in review (2024).
⁸ M. Kiczynski, S.K. Gorman, H. Geng, M.B. Donnelly, Y. Chung, Y. He, J.G. Keizer,
M.Y. Simmons, Engineering topological states in atom-based semiconductor quantum dots.
Nature 606(7915), 694 (2022).
⁹ M.B. Donnelly, Y. Chung, R. Garreis, S. Plugge, D. Pye, M. Kiczynski, M.M. Munia,
S. Sutherland, B. Voisin, L. Kranz, Y.L. Hsueh, A.M. Saffat-Ee Huq, C.M. Moehle, C.R. Myers,
R. Rahman, J.G. Keizer, S.K. Gorman,  M.Y. Simmons, Large-scale analogue quantum
simulation using precision atom-based quantum dot arrays. Paper in review (2024).
¹⁰ I. Thorvaldson, D. Poulos, C.M. Moehle, S.H. Misha, H. Edlbauer, J. Reiner, H. Geng, B. Voisin,
M.T. Jones, M.B. Donnelly, L.F. Peña, C.D. Hill, C.R. Myers, J.G. Keizer, Y. Chung,
S.K. Gorman, L. Kranz, M.Y. Simmons, Grover’s algorithm in a four-qubit silicon processor
above the fault-tolerant threshold. arXiv:2404.08741v1 (2024).