Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 40: Superconductivity: Qubits 1

TT 40.5: Vortrag

Mittwoch, 3. April 2019, 10:30–10:45, H48

A Two-Level-System sensor derived from a superconducting qubit. — •Alexander Bilmes¹, Ioan Pop¹, Martin Weides², Alexey V. Ustinov^1,3, and Jürgen Lisenfeld¹ — ¹Karlsruhe Institut für Technologie, Wolfgang-Gaedestr. 1, 76131 Karlsruhe — ²University of Glasgow, Schottland — ³Russian Quantum Center, MISIS, Moscow 119049, Russia

Since the first experimental realization of superconducting qubits in the 2000s, Two-Level-Systems (TLS) are a main and yet unsolved source of noise and decoherence in quantum circuits. The microscopic origin of TLS in the microfabricated devices is manifold. Tunnelling ions, impurities, trapped electrons and adsorbates are the most common and competeng models explaining formation of TLS in dielectrics and interfaces of the circuits. While examination of TLS in ready-made qubits [1,2] is a useful method to improve the sample geometry and fabrication, another complementary approach is to actively study the TLS nature in specially tailored quantum circuits [3,4]. A novel TLS-sensor has been derived from a transmon-qubit architecture where the Josephson junction is shunted by a small capacitor containing a sample dielectric. This allows for exploring of TLS hosted in dielectric films, bulks and at circuit surfaces. Here, we present the proof of principle for TLS-detection in amorphous AlOx films using such a TLS-sensor, which opens up further possibilities for TLS-studies. [1] J. Lisenfeld et al., Sci. Rep. 6 (23786) (2016) [2] A. Bilmes et al., Phys. Rev. B 96, 064504 (2017) [3] B. Sarabi et al., Phys. Rev. Lett. 116, 167002 (2016) [4] J. Brehm et al., Appl. Phys. Lett. 111, 112601 (2017)