Laser-annealing Josephson junctions for yielding scaled-up superconducting quantum processors

• Published in: npj quantum information Vol. 7; no. 1; pp. 1 - 8
• Main Authors: Hertzberg, Jared B., Zhang, Eric J., Rosenblatt, Sami, Magesan, Easwar, Smolin, John A., Yau, Jeng-Bang, Adiga, Vivekananda P., Sandberg, Martin, Brink, Markus, Chow, Jerry M., Orcutt, Jason S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19-08-2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/1130/1064; 639/766/483/2802; 639/766/483/481; Circuits; Classical and Quantum Gravitation; Fault tolerance; Lasers; Mathematical models; Physics; Physics and Astronomy; Quantum Computing; Quantum Field Theories; Quantum Information Technology; Quantum Physics; Relativity Theory; Spintronics; Standard deviation; String Theory
• ISSN: 2056-6387; 2056-6387
• DOI: 10.1038/s41534-021-00464-5

As superconducting quantum circuits scale to larger sizes, the problem of frequency crowding proves a formidable task. Here we present a solution for this problem in fixed-frequency qubit architectures. By systematically adjusting qubit frequencies post-fabrication, we show a nearly tenfold improvement in the precision of setting qubit frequencies. To assess scalability, we identify the types of “frequency collisions” that will impair a transmon qubit and cross-resonance gate architecture. Using statistical modeling, we compute the probability of evading all such conditions, as a function of qubit frequency precision. We find that, without post-fabrication tuning, the probability of finding a workable lattice quickly approaches 0. However, with the demonstrated precisions it is possible to find collision-free lattices with favorable yield. These techniques and models are currently employed in available quantum systems and will be indispensable as systems continue to scale to larger sizes.