Unimon qubit

• DOI: 10.1038/s41467-022-34614-w
• Publication Date: 2022-11-12T15:03:18Z
• Authors: Eric Hyyppä; 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 Li; Caspar Ockeloen-K...; Johannes Heinsoo; Kuan Yen Tan; Juha Hassel; Mikko Möttönen
• Keywords: Flux qubit; Charge qubit

Superconducting qubits are one of the most promising candidates to implement quantum computers. The superiority superconducting computers over any classical device in simulating random but well-determined circuits has already been shown two independent experiments and important steps have taken error correction. However, currently wide-spread qubit designs do not yet provide high enough performance enable practical applications or efficient scaling logical owing several following issues: sensitivity charge flux noise leading decoherence, too weak non-linearity preventing fast operations, undesirably dense excitation spectrum, complicated design vulnerable parasitic capacitance. Here, we introduce demonstrate a superconducting-qubit type, unimon, which combines desired properties non-linearity, full insensitivity dc noise, simple structure consisting only single Josephson junction resonator. We measure frequency, $\omega_{01}/(2\pi)$, anharmonicity $\alpha$ dc-flux range observe, agreement with our models, that is greatly enhanced at optimal operation point, yielding, for example, 99.9% 99.8% fidelity 13-ns single-qubit gates on $(\omega_{01},\alpha)=(4.49~\mathrm{GHz}, 434~\mathrm{ MHz})\times 2\pi$ $(3.55~\mathrm{GHz}, 744~\mathrm{ 2\pi$, respectively. energy relaxation time $T_1\lesssim 10~\mu\mathrm{s}$ stable hours seems be limited by dielectric losses. Thus, future improvements design, materials, gate may promote unimon break 99.99% target correction possible advantage noisy systems.