Regensburg 2022 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 27: Quantum Coherence and Quantum Information Systems (joint session TT/DY)

TT 27.5: Talk

Thursday, September 8, 2022, 10:30–10:45, H22

Probing the coherence of superconducting Fluxmon qubits — •Benedikt Berlitz, Alexander Neumann, Alexander Bilmes, Jürgen Lisenfeld, and Alexey V. Ustinov — Physikalisches Institut, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

The Fluxmon qubit combines a transmission line resonator with a DC-SQUID and offers wide control over the circuit's potential energy via two independently applied bias flux channels. This allows one to operate the qubit as a phase or flux qubit, provides means for fast single-shot qubit readout, and offers a path to characterize decoherence due to surface spins and tunneling defects in a wide frequency range. We will review the Fluxmon qubit design and fabrication, and present measurements of its potential energy landscape which demonstrate single- and double well qubit physics. Our time-resolved measurements confirm that the Fluxmon qubit's performance is strongly limited by microscopic sources of decoherence, which might render it a suitable detector for defect spectroscopy applications.