  Amplifier is at the heart of almost all experiment carrying out the precise
measurement of a weak signal. An idea amplifier should have large gain and
minimum added noise simultaneously. Here, we consider the quantum measurement
properties of a hybrid nonlinear cavity with the Kerr and OPA nonlinear media
to amplify an input signal. We show that our hybrid-nonlinear-cavity amplifier
has large gain in the single-value stable regime and achieves quantum limit
unconditionally.
