SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Superconductivity: Tunnelling and Josephson Junctions
TT 20.2: Vortrag
Dienstag, 28. März 2023, 09:45–10:00, HSZ 103
Measurement of two coupled Bloch oscillators based on Al/AlOx/Al-Josephson junctions — •Fabian Kaap and Sergey Lotkhov — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Deutschland Braunschweig
We investigate a system of two coupled Bloch oscillators based on ∼ 50 × 50 nm2 Josephson junctions, where one oscillator is a flux tunable SQUID and one is a single junction, respectively. To suppress the quantum oscillations of charge and enable the occurrence of coherent Bloch oscillations, the leads include high ohmic microstrips made from oxidized titanium. Between the resistors and junctions, we design the connection via a capacitively coupled pair of high-kinetic-inductance meanders of granular aluminum. When only the single junction is actively driven by an external bias current IB1 the Coulomb blockade of this junction can be tuned by the flux through the passive, non-driven SQUID. If additionally a current IB2 is applied through the SQUID we observe synchronisation effects in the IV-curves of both Bloch oscillators when the currents coincide, IB1 ≈ IB2. We address experimental issues, such as electron overheating in the leads, the presence of higher harmonics at low bias currents and the onset of Zener tunneling.