Generation of nonclassical photon states using correlated photon pairs and linear feedforward

It is shown that nonclassical photon states can be produced by generating correlated photon pairs, measuring the idler mode, and manipulating the signal mode using feedforward and linear attenuators, amplifiers, or phase modulators. The minimum achievable Fano factor for such schemes is (2/π〈n〉${)}^{1/2}$, where 〈n〉 is the mean output photon number. A nondegenerate parametric oscillator followed by linear manipulators can reach this limit. A nondegenerate parametric amplifier followed by linear phase manipulation can produce phase-squeezed states. The minimum achievable phase noise is a factor 1/2G below that of a coherent state, where G is the amplifier gain. The advantages with these schemes are wavelength tunability, potentially very high squeezing bandwidth, and relative simplicity.