  Quantum optical technologies promise advances in sensing, computing, and
communication. A key resource is squeezed light, where quantum noise is
redistributed between optical quadratures. We introduce a monolithic,
chip-scale platform that exploits the $\chi^{(2)}$ nonlinearity of a thin-film
lithium niobate (TFLN) resonator device to efficiently generate squeezed states
of light. Our system integrates all essential components -- except for the
laser and two detectors -- on a single chip with an area of one square
centimeter, significantly reducing the size, operational complexity, and power
consumption associated with conventional setups. Our work addresses challenges
that have limited previous integrated nonlinear photonic implementations that
rely on either $\chi^{(3)}$ nonlinear resonators or on integrated waveguide
$\chi^{(2)}$ parametric amplifiers. Using the balanced homodyne measurement
subsystem that we implemented on the same chip, we measure a squeezing of 0.55
dB and an anti-squeezing of 1.55 dB. We use 20 mW of input power to generate
the parametric oscillator pump field by employing second harmonic generation on
the same chip. Our work represents a substantial step toward compact and
efficient quantum optical systems posed to leverage the rapid advances in
integrated nonlinear and quantum photonics.
