  We theoretically propose a circuit QED system implemented with triple-leg
stripline resonator (TSR). Unlikely from linear stripline resonator, the
fundamental intra-cavity microwave modes of the TSR are two-fold degenerate.
When a superconducting qubit is placed near one of the TSR legs, one
fundamental mode is directly coupled to the qubit, while the other one remains
uncoupled. Our system closely resembles an optical cavity QED system, where an
atom in a cavity couples only to the incident photon with a specific
polarization by placing a polarization beamsplitter in front of the optical
cavity.
  Using our circuit QED system, we have theoretically studied a two-qubit
quantum gate operation in a hybrid qubit composed of flying microwave qubit and
superconducting qubit. We have demonstrated that for the hybrid qubit, the
quantum controlled phase flip (CPF) gate can be reliably implemented for the
experimentally available set of parameters.
