  Two-level system fluctuators in superconducting devices have demonstrated
coherent coupling with superconducting qubits. Here, we show that universal
quantum logic gates can be realized in these two-level systems solely by tuning
a superconducting resonator in which they are imbedded. Because of the large
energy separation between the fluctuators, conventional gate schemes in the
cavity QED approach that are widely used for solid-state qubits cannot be
directly applied to the fluctuators. We study a scheme to perform the gate
operations by exploiting the controllability of the superconducting resonator
with realistic parameters. Numerical simulation that takes into account the
decay of the resonator mode shows that the quantum logic gates can be realized
with high fidelity at moderate resonator decay rate. The quantum logic gates
can also be realized between fluctuators inside different Josephson junctions
that are connected by a superconducting loop. Our scheme can be applied to
explore the coupling between two-level system fluctuators and superconducting
resonators as well as the coherent properties of the fluctuators.
