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Rabi spectroscopy of a qubit-fluctuator system

Jürgen Lisenfeld, Clemens Müller, Jared H. Cole, Pavel Bushev, Alexander Lukashenko, Alexander Shnirman, and Alexey V. Ustinov
Phys. Rev. B 81, 100511(R) – Published 25 March 2010

Abstract

Superconducting qubits often show signatures of coherent coupling to microscopic two-level fluctuators (TLFs), which manifest themselves as avoided level crossings in spectroscopic data. In this work we study a phase qubit, in which we induce Rabi oscillations by resonant microwave driving. When the qubit is tuned close to the resonance with an individual TLF and the Rabi driving is strong enough (Rabi frequency of order of the qubit-TLF coupling), interesting four-level dynamics are observed. The experimental data show a clear asymmetry between biasing the qubit above or below the fluctuator’s level splitting. Theoretical analysis indicates that this asymmetry is due to an effective coupling of the TLF to the external microwave field induced by the higher qubit levels.

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  • Received 26 February 2010

DOI:https://doi.org/10.1103/PhysRevB.81.100511

©2010 American Physical Society

Authors & Affiliations

Jürgen Lisenfeld1, Clemens Müller2,3, Jared H. Cole4,3, Pavel Bushev1,3, Alexander Lukashenko1, Alexander Shnirman2,3, and Alexey V. Ustinov1,3

  • 1Physikalisches Institut, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany
  • 2Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany
  • 3DFG-Center for Functional Nanostructures (CFN), D-76128 Karlsruhe, Germany
  • 4Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany

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Issue

Vol. 81, Iss. 10 — 1 March 2010

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