Subangstrom ion beam engineering of buried ultrathin oxides for scalable quantum computing.

Smirnov, Nikita S; Krivko, Elizaveta A; Moskaleva, Daria A; Moskalev, Dmitry O; Solovieva, Anastasia A; Matanin, Aleksei R; Echeistov, Vladimir V; Ivanov, Аnton I et al. · Sci Adv · 2025

basic_science · Level V

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Abstract

Multilayer nanoscale systems incorporating ultrathin tunnel barriers, magnetic materials, amorphous oxides, and promising dielectrics are essential for next-generation logics, memory, quantum, and neuro-inspired computing. Still, an ultrathin film control at the atomic scale remains challenging. Here, we introduce a complementary metal-oxide semiconductor-compatible approach using focused ion beam irradiation for buried ultrathin films' engineering with subangstrom thickness control. Molecular dynamics simulations confirm the pivotal role of ion-induced crystal defects. Its performance is exemplified by Josephson junction resistance tuning in the range of 2 to 37% with a 0.86% standard deviation in completed chips. Furthermore, it enables ±17-megahertz frequency accuracy (±0.172 angstrom tunnel barrier thickness variation) in superconducting multiqubit processors, as well as qubit energy relaxation and echo coherence times exceeding 0.5 milliseconds.