Mitigation of frequency collisions in superconducting quantum processors
Journal article, 2023

The reproducibility of qubit parameters is a challenge for scaling up superconducting quantum processors. Signal cross talk imposes constraints on the frequency separation between neighboring qubits. The frequency uncertainty of transmon qubits arising from the fabrication process is attributed to deviations in the Josephson junction area, tunnel barrier thickness, and the qubit shunt capacitor. We decrease the sensitivity to these variations by fabricating larger Josephson junctions and reduce the wafer-level standard deviation in resistance down to 2%. We characterize 32 identical transmon qubits and demonstrate the reproducibility of the qubit frequencies with a 40 MHz standard deviation (i.e., 1%) with qubit quality factors exceeding 2 million. We perform two-level-system (TLS) spectroscopy and observe no significant increase in the number of TLSs causing qubit relaxation. We further show by simulation that for our parametric-gate architecture, and accounting only for errors caused by the uncertainty of the qubit frequency, we can scale up to 100 qubits with an average of only three collisions between quantum-gate transition frequencies, assuming 2% cross talk and 99.9% target gate fidelity.

Author

Amr Osman

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology

Jorge Fernández-Pendás

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

Christopher Warren

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology

Sandoko Kosen

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology

Marco Scigliuzzo

Swiss Federal Institute of Technology in Lausanne (EPFL)

Anton Frisk Kockum

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

Giovanna Tancredi

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology

Anita Fadavi Roudsari

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology

Jonas Bylander

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology

Physical Review Research

26431564 (ISSN)

Vol. 5 4 043001

Subject Categories

Other Physics Topics

Condensed Matter Physics

DOI

10.1103/PhysRevResearch.5.043001

More information

Latest update

6/18/2024