Quantum manipulation of low-frequency fluctuators with a superconducting resonator

Spurious two-level systems (fluctuators) in superconducting devices have demonstrated long coherence time and can be considered as qubits instead of sources of decoherence. Coherent coupling between two-level system (TLS) and superconducting phase qubit has been observed in experiments. Here, we show that universal quantum logic gates on the TLS qubits can be implemented via the coupling between the TLSs and a superconducting microwave resonator in a cavity QED setup. By adjusting the driving on the resonator mode, parameters of individual TLS can be controlled to realize single qubit gates. Meanwhile, effective coupling can be generated between TLSs via their simultaneous coupling to the resonator mode. We present concrete designs for the gate operations and our numerically simulation shows that high fidelity can be achieved for the gate operations in the presence of resonator decay even at decay rates of a few megahertz. The nonlocal nature of the resonator mode also makes the TLSs intrinsically scalable for testing quantum algorithms.