The Einstein Telescope (ET) is a design concept for a European third-generation gravitational-wave (GW) detector, which will be 10 times more sensitive than the current advanced instruments of the second generation.
Three detector generations
Like the first two generations of GW detectors, the concept for the Einstein Telescope is based on the measurement of tiny changes (far less than the size of an atomic nucleus) in the lengths of two connected arms several kilometres long, caused by a passing gravitational wave. Laser beams in the arms record their periodic stretching and shrinking as brightness changes on a central photodetector.
The first generation of these interferometric detectors built a few years ago (GEO600, LIGO, Virgo and TAMA) successfully demonstrated the proof-of-principle and constrained the gravitational wave emission from several sources. The next generation (Advanced LIGO and Advanced Virgo), which were constructed until late 2015, have made the first direct detection of gravitational waves and have observed 50 signals so far. However, these detectors will not be sensitive enough for very precise astronomical studies of the GW sources – new detector sites are required.
The strategy behind the ET project is to build an observatory that overcomes the limitations of current detector sites by hosting more than one GW detector. It will consist of three nested detectors, each composed of two interferometers with arms 10 kilometres long. One interferometer will detect low-frequency gravitational wave signals (2 to 40 Hz), while the other will detect the high-frequency components. The configuration is designed to allow the observatory to evolve by accommodating successive upgrades or replacement components that can take advantage of future developments in interferometry and also respond to a variety of science objectives.
Currently, possible detector sites in the border area of Belgium, Germany, and the Netherlands as well as Sardinia are being evaluated.
The role of the AEI in the Einstein Telescope project
The AEI Hannover have long been a leading institution in gravitational-wave research and is a co-initiators of the Einstein Telescope. The research focuses on quantum-limited interferometric measurements, laser development, the development of squeezed-light sorces and the control and operation of gravitational-wave detectors.
Harald Lück and Karsten Danzmann are members of the Einstein Telescope steering committee. Harald Lück is also the co-chair of the committee.
Current Einstein Telescope research at AEI Hannover
At the institute a laser source for the Einstein Telescope Pathfinder – a prototype of the observatory – is to be developed and tested in Hannover and installed in the prototype in Maastricht. In addition, the participating researchers will investigate questions concerning the generation of squeezed light and the use of this technology in 3rd generation gravitational-wave detectors.
The 10 m prototype interferometer is a test bed for new technologies of future laser interferometric gravitational-wave detectors.