  We analyze a system composed of a superconducting flux qubit coupled to a
transmission-line resonator driven by two signals with frequencies close to the
resonator's harmonics. The first strong signal is used for exciting the system
to a high energetic state while a second weak signal is applied for probing
effective eigenstates of the system. In the framework of doubly dressed states
we showed the possibility of amplification and attenuation of the probe signal
by direct transitions at the Rabi frequency. We present a brief review of
theoretical and experimental works where a direct resonance at Rabi frequency
have been investigated in superconducting flux qubits. The interaction of the
qubit with photons of two harmonics has prospects to be used as a quantum
amplifier (microwave laser) or an attenuator.
