  Single photons and squeezed light are the two primary workhorses for quantum
computation and quantum communication. Generating high-efficiency single
photons with high purity and heralding efficiency is the prerequisite for
photonic quantum computers. At the same time, generating high-efficiency
scalable squeezed light is the prerequisite for continuous variable quantum
computing along with sensing applications. Here, we propose a symmetric
ring-Mach-Zehnder interferometer (RMZI), which includes a periodically poled
lithium niobate (PPLN) waveguide as an efficient source of squeezed light and a
single-photon source. We numerically show that our proposed design can generate
tunable squeezed light with a squeezing level higher than -12dB with
sub-milli-watt (mW) pump power. The proposed device can also generate single
photons with purity as high as 99(95)% with heralding efficiency 94(99)% using
only 20ps long pulses. Our proposed design is fully compatible with current
fabrication technology.
