Berlin 2024 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 41: Superconducting Qubits (joint session QI/TT)
TT 41.1: Talk
Wednesday, March 20, 2024, 09:30–09:45, HFT-FT 131
Improving Fabrication Methods for High Coherence Superconducting Qubits — •Niklas Bruckmoser1,2, Leon Koch1,2, David Bunch1,2, Ivan Tsitsilin1,2, Kedar E. Honasoge1,2, Thomas Luschmann1,2, Lasse Södergren1,2, Christian Schneider1,2, Max Werninghaus1,2, and Stefan Filipp1,2 — 1Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching, Germany — 2Technical University of Munich, TUM School of Natural Sciences, Physics Department, 85748 Garching, Germany
The development of superconducting qubits and resonators with long coherence times and high quality factors is an essential milestone on the way towards useful quantum applications. While significant improvements in coherence time have been achieved over the last years, reaching qubit lifetimes well beyond 0.1 ms involves careful investigation of all fabrication processes. In this talk, we show that achieving such high-quality devices becomes possible through a combination of substrate cleaning, etching optimization, and post-process sample cleaning. By using resonator measurements as a figure of merit to minimize TLS loss, we achieve internal quality factors of more than Qint= 1 × 107 for thin-film niobium coplanar waveguide resonators in the single-photon regime and observe transmon qubits with single-shot lifetimes as high as T1 = 0.7 ms. Additionally, we exploit the high quality of the niobium resonators as sensors to investigate losses arising from different types of silicon substrates.
Keywords: Fabrication; Transmon; Quality factor