Demonstration of a squeezed light source on thin-film lithium niobate with modal phase matching

Squeezed states are essential for continuous-variable (CV) quantum information processing, with wide-ranging applications in computing, sensing, and communications. Integrated photonic circuits provide a scalable, convenient platform for building large CV circuits. Thin-film lithium niobate (TFLN) is particularly promising due to its low propagation loss, efficient parametric down conversion, and fast electro-optical modulation. In this work, we demonstrate a squeezed light source on an integrated TFLN platform, achieving a measured shot noise reduction of 0.46 dB (1.5 dB on-chip) using modal phase matching and grating couplers with an efficiency of up to −2.2 dB. The achieved squeezing is comparable to what has been observed using more complex circuitry based on periodic poling. The simpler design allows for compact, efficient, and reproducible sources of squeezed light.