Tuning quantum tunneling in a flux qubit

  • Venue:

    KIT - Campus South - Wolfgang-Gaede-Str. 1
    Seminar Room 10.01, Bldg. 30.23 (Physikhochhaus)

  • Date:

    20.05.2010

  • Speaker:

    Dr. Arkady Federov
    Laboratory for Solid State Physics
    ETH Zürich, Switzerland

  • Time:

    12:30

  • Abstract: In the symmetry point the energy splitting of a flux qubit is minimal (the gap) and determined solely by the tunnel coupling of the circulating current states in a double well potential. In our experiment we tune the barrier between the wells by means of an additional flux loop and are able to control the gap over two decades from 150 MHz to 12 GHz. Good coherence together with large tunability opens new possibilities for a study of coherent physical phenomena. In particular in the low gap regime (<1GHz) we establish extra long relaxation  time for the flux qubit away of the symmetry point and demonstrate macroscopic quantum oscillations of the magnetic moment of the qubit in real time at symmetry.