Therefore, the interferometer mirrors are suspended as sophisticated multistage pendulums and are situated in ultrahigh-vacuum systems. An ideal probe for space-time disturbances requires test masses which are free-falling in the direction of the laser beams.

The targeted GW-frequency band extends from below 10 Hz to about a few kHz. 2010 owing to upgrade activity), the Virgo project of the European Gravitational Observatory (with 3 km arms 7) and the German–British detector GEO 600 (with 600 m arms 8, 9) exists, with further observatories planned or proposed in Japan 10, Australia 11 and Europe 12. Michelson-type laser interferometers are suitable observatories to measure gravitational waves 5.Īt present, a global network comprising two LIGO observatories in the USA (with an arm length of 4 km (ref. The strain would be just h≈10 −22 in the case that the same event is located somewhere in the Virgo cluster of galaxies, being about 1,000 times farther away. Two neutron stars merging at the other side of our galaxy would produce a maximum space strain amplitude h here at the Earth of just h≈10 −19. The direct measurement of GWs is one of the greatest challenges of contemporary physics.

GWs propagate at the speed of light and reveal themselves as an alternating stretching and compressing of space-time, transverse to their direction of propagation. Just as electromagnetic radiation is produced by accelerated charges, gravitational waves (GWs) are generated by accelerated mass distributions, such as supernova explosions or neutron star and black hole binary systems spiralling into each other 2. GEO 600 now operates with its best ever sensitivity, which proves the usefulness of quantum entanglement and the qualification of squeezed light as a key technology for future GW astronomy 4. Here we demonstrate the squeezed-light enhancement of GEO 600, which will be the GW observatory operated by the LIGO Scientific Collaboration in its search for GWs for the next 3–4 years. A quantum technology-the injection of squeezed light 3-offers a solution to this problem. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. These waves are predicted by Einstein’s general theory of relativity 1 and are generated, for example, by black-hole binary systems 2. Around the globe several observatories are seeking the first direct detection of gravitational waves (GWs).

Beyond Binary by Lee Mandelo