Rabi spectroscopy of a qubit-fluctuator system

摘要: 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, induce Rabi oscillations by resonant microwave driving. When the qubit is tuned close resonance with an individual TLF and driving strong enough (Rabi frequency order qubit-TLF coupling), interesting four-level dynamics are observed. The experimental data clear asymmetry between biasing above or below fluctuator's splitting. Theoretical analysis indicates that due effective external field induced higher levels.