E. Oelker

Structural thermal noise in gram-scale mirror oscillators

The thermal noise associated with mechanical dissipation is a ubiquitous limitation to the sensitivity of precision experiments ranging from frequency stabilization to gravitational wave interferometry. We report on the thermal noise limits to the performance of 1gm mirror oscillators that are part of a cavity optomechanics experiment to observe quantum radiation pressure noise. Thermal noise limits the observed cavity displacement spectrum from 80Hz to 5kHz. We present a calculation of the thermal noise, based on finite element analysis of the dissipation due to structural damping, and find it to be in excellent agreement with the experimental result. We conclude with the predicted thermal noise for an improved oscillator design, which should be capable of revealing the noise that arises from quantum backaction in this system.

Ultra-low phase noise squeezed vacuum source for gravitational wave detectors

Squeezed states of light are a valuable resource for reducing quantum noise in precision measurements. Injection of squeezed vacuum states has emerged as an important technique for reducing quantum shot noise, which is a fundamental limitation to the sensitivity of interferometric gravitational wave detectors. Realizing the most benefit from squeezed-state injection requires lowering optical losses and also minimizing squeezed quadrature fluctuations—or phase noise—to ensure that the large noise in the anti-squeezed quadrature does not contaminate the measurement quadrature. Here, we present an audio band squeezed vacuum source with 1.3−0.5+0.7 mrad of phase noise. This is a nearly tenfold improvement over previously reported measurements, improving prospects for squeezing enhancements in current and future gravitational wave detectors.

Demonstration of Frequency Dependent Squeezing in the Audio Frequency Band

We use a high finesse optical cavity to rotate squeezed light quadrature as function of frequency in the audio band, which is suitable for improving the sensitivity of gravitational-wave detectors over a wide frequency band.