# Room temperature optomechanical squeezing

## TL;DR

This paper demonstrates room-temperature optomechanical squeezing of light in the audio-frequency range, achieving sub-shot-noise quantum noise reduction, which is significant for enhancing precision measurements like gravitational wave detection.

## Contribution

The work presents the first measurement of optomechanical squeezing at room temperature in a broad audio-frequency band relevant to gravitational wave detectors, using two independent measurement methods.

## Key findings

- Achieved 0.7 dB quantum noise reduction below shot noise at 45 kHz.
- Demonstrated room-temperature optomechanical squeezing in the 30-70 kHz range.
- Used two independent measurement techniques, one calibration-free.

## Abstract

The radiation-pressure driven interaction of a coherent light field with a mechanical oscillator induces correlations between the amplitude and phase quadratures of the light. These correlations result in squeezed light -- light with quantum noise lower than shot noise in some quadratures, and higher in others. Due to this lower quantum uncertainty, squeezed light can be used to improve the sensitivity of precision measurements. In particular, squeezed light sources based on nonlinear optical crystals are being used to improve the sensitivity of gravitational wave (GW) detectors. For optomechanical squeezers, thermally driven fluctuations of the mechanical oscillator's position makes it difficult to observe the quantum correlations at room temperature, and at low frequencies. Here we present a measurement of optomechanically (OM) squeezed light, performed at room-temperature, in a broad band near audio-frequency regions relevant to GW detectors. We observe sub-poissonian quantum noise in a frequency band of 30 kHz to 70 kHz with a maximum reduction of 0.7 $\pm$ 0.1 dB below shot noise at 45 kHz. We present two independent methods of measuring this squeezing, one of which does not rely on calibration of shot noise.