Building blocks of a flip-chip integrated superconducting quantum processor. (1st July 2022)

• Record Type: Journal Article
• Authors: Kosen, Sandoko; Li, Hang-Xi; Rommel, Marcus; Shiri, Daryoush; Warren, Christopher; Grönberg, Leif; Salonen, Jaakko; Abad, Tahereh; Biznárová, Janka; Caputo, Marco; Chen, Liangyu; Grigoras, Kestutis; Johansson, Göran; Kockum, Anton Frisk; Križan, Christian; Lozano, Daniel Pérez; Norris, Graham J; Osman, Amr; Fernández-Pendás, Jorge; Ronzani, Alberto; Roudsari, Anita Fadavi; Simbierowicz, Slawomir; Tancredi, Giovanna; Wallraff, Andreas; Eichler, Christopher; Govenius, Joonas; Bylander, Jonas
• Is Part Of: Quantum science and technology. Volume 7:Number 3(2022)
• Publication Date: 2022-07-01
• Subjects: transmon -- superconducting qubit -- design and simulation -- coherence times -- gate fidelities -- flip-chip integration; Quantum theory -- Periodicals; Quantum theory; Periodicals; 530
• DOI: 10.1088/2058-9565/ac734b
• Languages: English
• ISSNs: 2058-9565

Abstract

Abstract: 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.