On-Chip Optical Squeezing

A squeezed light source, i.e. a source with ultra low noise level, below the standard quantum limit (SQL), can enable quantum enhanced sensing, spectroscopy1, 2, metrology3 and quantum information processing4,5. To date, such a non classical light source on-chip, scalable, compact and robust has not been demonstrated. Such a source could not only enable ultrasensitive measurements on chip, but also provide squeezing over high bandwidths in contrast to most sources which usually rely on large optical cavities with narrow bandwidths. Here, we report the observation of squeezed light in an on-chip monolithically integrated platform, generated in a micron-size silicon nitride oscillator6 with GHz cavity linewidth. We show 1.7dB noise squeezing, i.e. reduction of the noise level below the standard quantum limit, of the intensity difference between two beams generated by an on-chip optical parametric oscillator. The noise of a light source can in principle be lowered below a level determined by quantum mechanical fluctuations (standard quantum limit, SQL), by using a squeezing process that reduces the noise in the intensity (phase) at the expense of increasing phas