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TT: Fachverband Tiefe Temperaturen

TT 31: Superconducting Electronics and Cryogenics: Poster Session

TT 31.19: Poster

Donnerstag, 8. September 2022, 15:00–18:00, P1

Compact high-kinetic inductance using stacked Josephson junctions — •Alex S. Kreuzer¹, Thilo Krumrey¹, Hannes Rotzinger^1,2, and Alexey V. Ustinov^1,2 — ¹Physikalisches Institut (PHI), Karlsruher Institut für Technologie (KIT) — ²Institut für Quantenmaterialien und -technologien (IQMT), Karlsruher Institut für Technologie (KIT)

Highly inductive elements are often required in modern superconducting quantum circuits, e.g. to form, together with a suitable capacitance, a large non-dissipative impedance. One way of creating such a high inductance is to employ series arrays of Josephson junctions, as it is done in the fluxonium qubit. For conventionally made chains of Josephson junctions, a major limitation arises from the stray capacitance of the islands forming the junctions. This capacitance leads to undesirable parasitic resonances at GHz frequencies, which degrade the quantum coherence of the qubit.

We propose a new way of creating high-inductance elements by stacking Josephson junctions vertically thus avoiding the influence of the through-substrate capacitive coupling of the junction electrodes to the environment. Furthermore, we demonstrate that our approach allows for making extremely compact circuit components.