2018/09/27 by Lukas Grünhaupt, Martin Spiecker, Daria Gusenkova +9 · 1 citation
Physics and Astronomy · #Amplifier #Coherence (philosophical gambling strategy) #Electronic circuit #Josephson effect #Kinetic inductance #Mechanical and Optical Resonators #Mesoscopic physics #Quantum Mechanics and Non-Hermitian Physics #Quantum and electron transport phenomena #Qubit #Superconductivity #cond-mat.supr-con #quant-ph
paper · pdf · doi:10.1038/s41563-019-0350-3
published as Nature Materials 18, 816-819 (2019) · L.G. and M.S. contributed equally. 4 pages, 3 figures, and supplemental material
arxiv created 2018/09/27 · openalex created_date 2018/10/05 · openalex publication_date 2019/04/29 · arxiv updated 2019/08/14 · openalex updated_date 2026/08/06
Superconducting quantum information processing machines are predominantly based on microwave circuits with relatively low characteristic impedance, of about 100 Ohm, and small anharmonicity, which can limit their coherence and logic gate fidelity. A promising alternative are circuits based on so-called superinductors, with characteristic impedances exceeding the resistance quantum RQ = 6.4 kΩ. However, previous implementations of superinductors, consisting of mesoscopic Josephson junction arrays, can introduce unintended nonlinearity or parasitic resonant modes in the qubit vicinity, degrading its coherence. Here we present a fluxonium qubit design using a granular aluminum (grAl) superinductor strip. Granular aluminum is a particularly attractive material, as it self-assembles into an effective junction array with a remarkably high kinetic inductance, and its fabrication can be in-situ integrated with standard aluminum circuit processing. The measured qubit coherence time T2R up to 30 μs illustrates the potential of grAl for applications ranging from protected qubit designs to quantum limited amplifiers and detectors.