Quantum coherent manipulation of two-level systems in superconducting circuits
Alexander L. Burin, Andrii Maksymov, Kevin D. Osborn · Superconductor Science and Technology · 2014
Two-level systems (TLSs) appear in the insulating layers of microfabricated superconducting circuits and are known to be a source of superconducting qubit decoherence. Here we theoretically analyze the quantum evolution of a TLS bath, which is related to a recent experiment performed with a superconducting resonator. During the application of simultaneous time-varying bias and continuous microwave fields, TLSs pass through resonance with the latter field such that Landau?Zener crossings cause the TLS to remain in the ground (Floquet) state or become inverted. The TLSs are analyzed for insulating films, which convey a distribution of tunneling parameters and associated TLS inversion regimes. Under certain conditions, we indeed find that the TLS population should be inverted over a wide range of frequencies. Discussion is included on how new TLS environments could affect the operation of resonators and qubits.