Building blocks of a flip-chip integrated superconducting quantum processor

Sandoko Kosen (Corresponding Author), Hang Xi Li, Marcus Rommel, Daryoush Shiri, Christopher Warren, Leif Grönberg, Jaakko Salonen, Tahereh Abad, Janka Biznárová, Marco Caputo, Liangyu Chen, Kestutis Grigoras, Göran Johansson, Anton Frisk Kockum, Christian Križan, Daniel Pérez Lozano, Graham J. Norris, Amr Osman, Jorge Fernández-Pendás, Alberto RonzaniAnita Fadavi Roudsari, Slawomir Simbierowicz, Giovanna Tancredi, Andreas Wallraff, Christopher Eichler, Joonas Govenius, Jonas Bylander

Research output: Contribution to journalArticleScientificpeer-review

39 Citations (Scopus)


We have integrated single and coupled superconducting transmon qubits into flip-chip modules. Each module consists of two chips - one quantum chip and one control chip - that are bump-bonded together. We demonstrate time-averaged coherence times exceeding 90 μs, single-qubit gate fidelities exceeding 99.9%, and two-qubit gate fidelities above 98.6%. We also present device design methods and discuss the sensitivity of device parameters to variation in interchip spacing. Notably, the additional flip-chip fabrication steps do not degrade the qubit performance compared to our baseline state-of-the-art in single-chip, planar circuits. This integration technique can be extended to the realisation of quantum processors accommodating hundreds of qubits in one module as it offers adequate input/output wiring access to all qubits and couplers.

Original languageEnglish
Article number035018
JournalQuantum Science and Technology
Issue number3
Publication statusPublished - Jun 2022
MoE publication typeA1 Journal article-refereed


We acknowledge the use of support and resources from Myfab Chalmers, and Chalmers Centre for Computational Science and Engineering (C3SE, partially funded by the Swedish Research Council through Grant Agreement No. 2018-05973). This work was funded by the EU Flagship on Quantum Technology H2020-FETFLAG-2018-03 project 820363 OpenSuperQ and by the Knut and Alice Wallenberg (KAW) Foundation through the Wallenberg Centre for Quantum Technology (WACQT).


  • coherence times
  • design and simulation
  • flip-chip integration
  • gate fidelities
  • superconducting qubit
  • transmon


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