Demonstration of interferometer enhancement through EPR entanglement

Understand

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.