Parts | Days | Selection | Search | Updates | Downloads | Help
TT: Fachverband Tiefe Temperaturen
TT 58: Poster: Superconductivity II
TT 58.15: Poster
Thursday, March 30, 2023, 15:00–18:00, P2/OG3
Superconducting flux qubits with stacked Josephson junctions — •Alex Kreuzer1, Hossam Tohamy1, Thilo Krumrey1, Markus Griedel1,2, Hannes Rotzinger1,2, and Alexey V. Ustinov1,2 — 1Physikalisches Institut (PHI), Karlsruher Institut für Technologie (KIT) — 2Institut für Quantenmaterialien und -technologien (IQMT), Karlsruher Institut für Technologie (KIT)
Josephson junctions are often employed as nonlinear inductive elements in superconducting qubits as they allow to tailor specific circuit properties. The promising flux qubit types as fluxonium or quarton qubits require compact inductances which are often implemented as arrays of Josephson junctions. Here, the stray capacitance originating, for instance, from the capacitive coupling of an array island to ground, introduces the major limitation of this approach, since it introduces parasitic resonances at GHz frequencies which may degrade the overall qubit performance. We explore the possibility of implementing the qubit inductances by stacking Josephson junctions vertically and thus reducing the capacitance to ground. We present transport as well as microwave measurement data of stacked Josephson junctions and flux qubits made from them. Furthermore, we present a comparison of our experimental data with a detailed numerical simulation.