Fundamental limits of laser power stabilization via a radiation pressure transfer scheme.

Traditional active laser power stabilization schemes are fundamentally limited by quantum shot noise on the in-loop photodetector. One way to overcome this limitation is to implement a nondemolition sensing scheme where laser power fluctuations are transferred to motion of a micro-oscillator, which can be sensed with a high signal-to-noise ratio. In this Letter, we analyze the power stability achievable in a nondemolition scheme limited by quantum and thermal noise.

A new quantum speed-meter interferometer: measuring speed to search for intermediate mass black holes.

The recent discovery of gravitational waves (GW) by Advanced LIGO (Laser Interferometric Gravitational-wave Observatory) has impressively launched the novel field of gravitational astronomy and allowed us to glimpse exciting objects about which we could previously only speculate. Further sensitivity improvements at the low-frequency end of the detection band of future GW observatories must rely on quantum non-demolition (QND) methods to suppress fundamental quantum fluctuations of the light fields used to readout the GW signal. Here we present a novel concept of how to turn a conventional Michelson interferometer into a QND speed-meter interferometer with coherently suppressed quantum back-action noise.

Quantum Measurement Theory in Gravitational-Wave Detectors.

The fast progress in improving the sensitivity of the gravitational-wave detectors, we all have witnessed in the recent years, has propelled the scientific community to the point at which quantum behavior of such immense measurement devices as kilometer-long interferometers starts to matter. The time when their sensitivity will be mainly limited by the quantum noise of light is around the corner, and finding ways to reduce it will become a necessity. Therefore, the primary goal we pursued in this review was to familiarize a broad spectrum of readers with the theory of quantum measurements in the very form it finds application in the area of gravitational-wave detection.