In this work, we study a series of tunable flux qubits inductively coupled to a coplanar waveguide resonator fabricated on a sapphire substrate. Each qubit includes an asymmetric superconducting quantum interference device, which is controlled by the application of an external magnetic field and acts as a tunable Josephson junction. The tunability of the qubits is typically ±3.5GHz around their central gap frequency. The measured relaxation times are limited by dielectric losses in the substrate and can attain T1∼8μs. The echo dephasing times are limited by flux noise even at optimal points and reach T2E∼4μs, almost an order of magnitude longer than state of the art.
|Journal||Physical Review Applied|
|State||Published - Feb 2023|
Bibliographical noteFunding Information:
This research is supported by the Israeli Science Foundation under Grants No. 426/15, No. 898/19, and No. 963/19. G.C. acknowledges support by the German Federal Ministry of Education and Research (BMBF), funding program Quantum technologies—from basic research to market, project QSolid (Grant No. 13N16149).
© 2023 American Physical Society.