Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 40: Superconductivity: Qubits 1

TT 40.9: Vortrag

Mittwoch, 3. April 2019, 11:45–12:00, H48

Design and fabrication of a granular aluminum fluxonium qubit — •Lukas Grünhaupt¹, Martin Spiecker¹, Daria Gusenkova¹, Nataliya Maleeva¹, Sebastian T. Skacel^{1, 2}, Ivan Takmakov^{1, 2, 3}, Francesco Valenti^{1, 4}, Patrick Winkel¹, Hannes Rotzinger¹, Alexey V. Ustinov^{1, 3}, and Ioan M. Pop^{1, 2} — ¹Physikalisches Institut, KIT, Karlsruhe, Germany — ²Institute of Nanotechnology, KIT, Karlsruhe, Germany — ³Russian Quantum Center, National University of Science and Technology MISIS, Moscow, Russia — ⁴Institute for Data Processing and Electronics, KIT, Karlsruhe, Germany

Superconducting materials with low microwave losses and high kinetic inductance are a valuable resource in quantum circuit design, enabling the design of so-called superinductors, which can provide electromagnetic environments with characteristic impedance larger than the resistance quantum R_Q = 6.5 kΩ. To implement superinductors, a promising alternative to the predominantly used mesoscopic Josephson junction arrays is granular aluminum (grAl). Its microstructure consists of pure aluminum grains embedded in an AlO_x matrix, effectively forming a compact self-assembled Josephson junction network. We present a superconducting fluxonium qubit employing a superinductor with impedance Z > R_Q, fabricated from a grAl thin film, in-situ integrated with a conventional Al/AlO_x/Al Josephson junction. The measured qubit spectrum is in good agreement with the fluxonium Hamiltonian.