Demonstration of a squeezed light enhanced power- and signal-recycled Michelson interferometer

TL;DR

This paper demonstrates the experimental integration of advanced interferometer techniques, including squeezed light injection, to enhance gravitational wave detection sensitivity, achieving a 2.8 dB noise reduction beyond shot noise.

Contribution

It is the first experimental demonstration of combining power-recycling, detuned signal-recycling, and squeezed field injection in a Michelson interferometer.

Findings

Signal-to-noise ratio improved by up to 2.8 dB

Compatibility of signal-recycling and squeezed injection proven

Stable locking of the complete setup achieved

Abstract

We report on the experimental combination of three advanced interferometer techniques for gravitational wave detection, namely power-recycling, detuned signal-recycling and squeezed field injection. For the first time we experimentally prove the compatibility of especially the latter two. To achieve a broadband non-classical sensitivity improvement we applied a filter cavity for compensation of quadrature rotation. Signal to noise ratio was improved by up to 2.8 dB beyond the coherent state's shot noise. The complete set-up was stably locked for arbitrary times and characterized by injected single-sideband modulation fields.