Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 22: Superconductivity – Poster I
TT 22.25: Poster
Monday, March 9, 2026, 18:00–20:00, P1
Planar Broadband Superconducting Waveguide for Coherent Control of Rare-Earth Spin Ensembles — •Arjun Bhasker1,2, Georg Mair2,1, Léa Richard2,1, Michael Stanger1, Andreas Erb2,1, Hans Huebl2,1,3, and Nadezhda Kukharchyk2,1,3 — 1School of Natural Sciences, Technische Universität München, 85748 Garching, Germany — 2Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany — 3Munich Center for Quantum Science and Technology, 80799 München, Germany
Solid-state quantum memories based on rare-earth ions require highly homogeneous microwave fields to enable coherent control of large spin ensembles. While coplanar waveguides can be used for this purpose, they inherently produce non-uniform field distribution: The microwave field peaks at the center conductor, and the field direction varies substantially within the gaps, which leads to a variety of Rabi frequencies. To overcome this limitation, we introduce a new planar superconducting broadband transmission-line architecture implemented via a technique such as flip-chip bonding, designed to generate a highly uniform microwave field across the active region. In this approach, a CaWO4 crystal doped with erbium ions has to be thinned producing a flat and uniform membrane to ensure proper impedance matching and optimal coupling to the microwave field. Such a design provides a promising platform for implementing rare-earth-based quantum memories with microwave superconducting quantum technologies.
Keywords: Spin ensembles; Rare-earth elements; Quantum memories; Flip-chip bonding; Lapping and Polishing