  A superconducting flux qubit is inductively coupled to a Superconducting
QUantum Interference Device (SQUID) magnetometer, capacitively shunted to form
a 1.294-GHz resonator. The qubit-state-dependent resonator frequency is weakly
probed with a microwave signal and detected with a Microstrip SQUID Amplifier.
At a mean resonator occupation $\bar{n}$ = 1.5 photons, the readout visibility
is increased by a factor of 4.5 over that using a cryogenic semiconductor
amplifier. As $\bar{n}$ is increased from 0.008 to 0.1, no reduction in $T_1$
is observed, potentially enabling continuous monitoring of the qubit state.
