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Dr. Peter Aufmuth

Max Planck Institute for Gravitational Physics (Hannover), Hannover
Phone:+49 511 762-2386Fax:+49 511 762-2784

Publication reference

Roman Schnabel and Hartmut Grote for the LIGO Virgo Science Collaboration
A gravitational wave observatory operating beyond the quantum shot-noise limit

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Astrophysics . Quantum Physics

Squeezed laser will bring gravitational waves to the light of day

A quantum phenomen on allows detectors which sense oscillations of space-time to measure with 50 percent more accuracy

September 11, 2011

Measuring at the limits of the laws of nature – this is the challenge which researchers repeatedly take up in their search for gravitational waves. The interferometers they use here measure with such sensitivity that a particular quantum phenomenon of light – shot noise – limits the measuring accuracy. With the “squeezed light” method scientists from the Max Planck Society and the Leibniz University Hannover likewise use quantum physics in a countermove in order to remove the interfering effect. The new type of laser light improves the measuring accuracy of the gravitational wave detector GEO600 by around 50 percent and thus increases its effective sensitivity. This is the first time this technology has been used outside of a test laboratory anywhere in the world. The results will be published in the specialist journal Nature Physics, online on 11th September 2011. (http://dx.doi.org/10.1038/NPHYS2083)
The new squeezed light laser of GEO600. A highly complex laser system produces light which particularly quiet in the gravitational wave detector. Zoom Image
The new squeezed light laser of GEO600. A highly complex laser system produces light which particularly quiet in the gravitational wave detector. [less]

Some 50 years after the development of the first lasers, the technology of “squeezed light” can be used to generate a completely new quality of laser light. The light from a squeezed laser radiates much more calmly than light from a conventional laser source. “Thanks to the squeezed laser, we were able to increase the measuring sensitivity of GEO600 to 150%,” says Hartmut Grote, who heads the detector operation. “The new light source fulfils all requirements as expected.” In future, this technology could be used to even double the measuring accuracy. In the search for the almost undetectable gravitational waves, this increase in sensitivity is an important step to their direct detection.

The GEO600 experiment at the QUEST (Center for Quantum Engineering and Space-Time Research) Cluster of Excellence is part of the international LIGO Virgo Collaboration (LVCon) and is putting the researchers from the Max Planck Institute for Gravitational Physics (Sub-Institute Hanover, Albert Einstein Institute/AEI) and from the Institute for Gravitational Physics at the Leibniz University Hannover on the track of gravitational waves. Einstein predicted these oscillations in space-time around a hundred years ago in his General Theory of Relativity. They arise during turbulent cosmic events such as supernova explosions, for example.

Gravitational waves are scarcely noticeable on Earth, however. One reason is that the interaction between matter and space is very weak. Changes to the structure of space-time which occur in our immediate astronomical vicinity as a result of the movements of relatively low-mass objects, such as moons or planets, are way below what is measurable. Turbulent supernova explosions which violently shake space-time occur at a great distance, in contrast. The gravitational waves generated in the process are considerably attenuated when they reach Earth. The relative measuring path in a gravitational wave detector would change by only around a thousandth of a proton diameter if a supernova occurred within our Milky Way. With GEO600, the scientists are meanwhile able to measure such differences in length.

 

 
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