Periodically poled thin-film lithium niobate ring Mach Zehnder coupling interferometer as an efficient quantum light source

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 -12 dB with sub-milli-watt (mW) pump power. The proposed device can also generate single photons with purity as high as 99(95)<i>%</i> with heralding efficiency 94(99)<i>%</i> using only 20 ps long pulses. Our proposed design is fully compatible with current fabrication technology.