Unimon qubit

Eric Hyyppä (Corresponding Author), Suman Kundu, Chun Fai Chan, András Gunyhó, Juho Hotari, David Janzso, Kristinn Juliusson, Olavi Kiuru, Janne Kotilahti, Alessandro Landra, Wei Liu, Fabian Marxer, Akseli Mäkinen, Jean Luc Orgiazzi, Mario Palma, Mykhailo Savytskyi, Francesca Tosto, Jani Tuorila, Vasilii Vadimov, Tianyi LiCaspar Ockeloen-Korppi, Johannes Heinsoo, Kuan Yen Tan, Juha Hassel, Mikko Möttönen (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)


Superconducting qubits seem promising for useful quantum computers, but the currently wide-spread qubit designs and techniques do not yet provide high enough performance. Here, we introduce a superconducting-qubit type, the unimon, which combines the desired properties of increased anharmonicity, full insensitivity to dc charge noise, reduced sensitivity to flux noise, and a simple structure consisting only of a single Josephson junction in a resonator. In agreement with our quantum models, we measure the qubit frequency, ω01/(2π), and increased anharmonicity α/(2π) at the optimal operation point, yielding, for example, 99.9% and 99.8% fidelity for 13 ns single-qubit gates on two qubits with (ω01, α) = (4.49 GHz, 434 MHz) × 2π and (3.55 GHz, 744 MHz) × 2π, respectively. The energy relaxation seems to be dominated by dielectric losses. Thus, improvements of the design, materials, and gate time may promote the unimon to break the 99.99% fidelity target for efficient quantum error correction and possible useful quantum advantage with noisy systems.

Original languageEnglish
Article number6895
JournalNature Communications
Issue number1
Publication statusPublished - 12 Nov 2022
MoE publication typeA1 Journal article-refereed


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