Demonstration of interferometer enhancement through EPR entanglement

TL;DR

This paper demonstrates a method to enhance interferometer sensitivity for gravitational wave detection using EPR entangled states, potentially replacing costly filter cavities with a simpler setup, at the expense of a 3dB quantum penalty.

Contribution

It introduces a proof-of-principle interferometer setup that uses EPR entanglement to process squeezed states, eliminating the need for long optical filter cavities.

Findings

Achieved processed squeezed spectrum with EPR entanglement

Potential to replace costly filter cavities in GW detectors

Introduced a method with a 3dB quantum penalty

Abstract

The sensitivity of laser interferometers used for the detection of gravitational waves (GWs) is limited by quantum noise of light. An improvement is given by light with squeezed quantum uncertainties, as employed in the GW detector GEO600 since 2010. To achieve simultaneous noise reduction at all signal frequencies, however, the spectrum of squeezed states needs to be processed by 100m-scale low-loss optical filter cavities in vacuum. Here, we report on the proof-of-principle of an interferometer setup that achieves the required processed squeezed spectrum by employing Einstein-Podolsky-Rosen (EPR) entangled states. Applied to GW detectors, the cost-intensive cavities would become obsolete, while the price to pay is a 3dB quantum penalty.