Modified nonclassical coherent state: Squeezing, antibunching, sub-Poissonian photon statistics, realization scheme with the χ(2)-nonlinearity, and generation of a macroscopic entangled state

The nonlinear χ(2) Mach-Zehnder interferometer is proposed as a device for conditional generation of a modified coherent nonclassical state. We show that the generated macroscopic state exhibits nonclassical effects, such as squeezing, photon antibunching, and sub-Poissonian statistics. The modified coherent state generates a macroscopic entangled state. The scheme works without the photon number resolving detection but requires high-efficiency photodetectors. We explain the mechanism of generation of the modified coherent non-classical state