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-initiator 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
ET Pathfinder Laser
At the institute pre-stabilized laser sources for the Einstein Telescope are being developed and tested. Additionally, a laser system for the Einstein Telescope Pathfinder, a prototype of the observatory in Maastricht, is being constructed.
Squeezed light for the 3rd generation
Researchers at AEI also investigate questions concerning the generation of squeezed light and the use of this technology in third-generation gravitational-wave detectors.
10 m Prototype
The 10 m prototype interferometer is a test bed for new technologies of future laser interferometric gravitational-wave detectors.
Glass Technologies for the Einstein Telescope
In the collaboration with the Fraunhofer Institute for Applied Optics and Precision Engineering the project “Glass Technologies for the Einstein Telescope” (GT4ET) develops miniaturised opto-mechanics for the Einstein Telescope.