Dresden 2026 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 28: Superconducting Electronics: SQUIDs and other Josephson Circuits and Components

TT 28.6: Talk

Tuesday, March 10, 2026, 10:45–11:00, CHE/0089

Low noise amplification using Nb trilayer Dimer Josephson Junction Array Amplifiers — •Bhoomika R Bhat, Asen L Georgiev, Fabian Kaap, Victor Gaydamachenko, Christoph Kissling, Judith Felgner, Mark Bieler, and Lukas Grünhaupt — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany

Minimizing added noise in amplification is crucial for quantum-based devices requiring microwave readout signals in the femtowatt range. For example, in superconducting qubits, it significantly improves readout fidelity. Extensive efforts over the last decade have been made in the development of parametric amplifiers to address this challenge. We develop a Dimer Josephson Junction Array Amplifier (DJJAA) [1], in which parametric amplification in the degenerate four-wave-mixing regime is facilitated by pairs of resonant modes, referred to as dimers. We design it to feature multiple flux-tunable dimers within the 2 to 8 GHz range, each of which could be utilized for parametric amplification. Our DJJAAs have 900 to 3000 dc-SQUIDs, and we fabricate them using Nb/Al-AlOx/Nb trilayer technology. We present the fabrication flow of our devices and provide an overview of the corresponding experimental results. Our devices show gain on the order of 20 dB with bandwidths in the range of 5 to 10 MHz and the typical input saturation powers are on the order of -110 dBm.
[1] P. Winkel et al., Phys. Rev. Applied 13, 024015 (2020).

Keywords: Superconductivity; Parametric amplifiers; SQUIDs; Niobium-trilayer fabrication; Low noise amplification