Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 48: Superconductivity: Tunnelling, Josephson Junctions, SQUIDs 2

TT 48.7: Vortrag

Mittwoch, 22. März 2017, 16:45–17:00, HSZ 201

Transmission-Line Resonators for the Study of Individual Two-Level-Systems — •Jan Brehm, Alexander Bilmes, Alexey V. Ustinov, and Jürgen Lisenfeld — Physikalisches Institut, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany

Parasitic Two-Level-Systems (TLS) arise from microscopic material defects and are one of the main sources of decoherence in superconducting devices such as SQUIDs, resonators and quantum bits (qubits). The high sensitivity of quantum circuits motivates one to build a universal detector for single TLS, which can be applied to various materials. Josephson junction based superconducting qubits, e.g., offer the possibility to resonantly drive individual TLS' and to observe their quantum dynamics using the qubit for TLS readout. Yet, those experiments have been restricted to TLSs hosted in the dielectric tunnel barrier of the qubit's Josephson junctions, which reduces the choice of explorable materials to few dielectrics. Here we show how TLS in thin films can be studied using a superconducting coplanar notch-type resonator whose end is terminated by a capacitor containing TLS in its insulating layer. By tuning TLS via mechanical strain, we observe the signatures of individual strongly coupled TLS in the resonator's reflection spectrum and noise characteristics.