AEI scientist honoured in New York
International prize for Dr. Henning Vahlbruch
August 11, 2009
In his research work, Vahlbruch has described how a new, highly precise measuring technology can be implemented in gravitational wave research with the help of squeezed light. He works in the Research Group led by Prof. Dr. Roman Schnabel, where the way was paved for this procedure. “Squeezed light means that the temporal, naturally random and irregular distance between light particles, the photons, can be influenced,” explains Dr. Henning Vahlbruch. “We squeeze the photons into rank and file, tame them so to speak, and thereby raise the measurement accuracy and range of the gravitational wave detectors.” Untamed photons, conversely, cause a “shot noise” that seriously reduces the measurement accuracy.
In gravitational wave detectors, laser light is used to measure tiny expansions and compressions of space-time that arise when passing through a gravitational wave. When a gravitational wave passes through a detector, the arm length of the laser beam changes, and thus the intensity of the laser light at the output of the detector. In step with the gravitational wave, a corresponding photocurrent is generated via the photoelectric effect, the data of which is stored and which can be processed. Thus, the laser light itself should show no fluctuations in its intensity, so that even the very tiniest signals can be measured.
Already today, gravitational wave detectors of the first generation, e.g. the German-British GEO600 detector in Ruthe near Hannover, can precisely measure a measuring distance of 10-19 m - which is comparable to one 10,000th of the diameter of a proton. Thanks to such measurement accuracy, neutron stars can be observed up to a distance of 40 million light years from Earth. The thereby accessible part of the universe encompasses several dozen galaxies.
For the first time ever, the installation of squeezed light in a gravitational wave detector, in GEO600, is currently underway in Hannover. GEO600 is a project of the AEI, which is also partner of the QUEST Excellence Cluster. The detector is a think-tank and technological pioneer in gravitational wave research. The bestowal of the GWIC Thesis Prize on Dr. Henning Vahlbruch is a further attestation to this.