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Research Projects
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GEO600
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Theory of General Relativity predicts the existence of gravitational waves (GW).
These are changes in the curvature of space-time propagating with the speed of light.
Their origin are accelerated masses. As detectable sources of GW only astrophysical objects or processes are a possibility.
Typically they cause relative changes in the distance between test objects of 10-21.
GEO600 is a gravitational wave detector of 600 m armlength which is operated by AEI, Teilinstitut Hannover.
Leading detector technology has been developed for GEO600 and is being exported to other GW detector in the world, i. e. LIGO and Virgo.
The GEO600 team is also part of the LIGO Science Collaboration which means that data recording and detector blocking for tachnical upgrades are coordinated between the four major site of GW detectors, namely LIGO 1 & 2, Virgo and GEO600 such that at least two (or one) detectors are taking data in parallel.
Furthermore, the data taken by these GW detectors are analsysed jointly within this collaboration.
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eLISA: evolved Laser Interferometer Space Antenna
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For the space detector eLISA the Institute is part of an international
project of ESA. Two of the ten European members of the eLISA Working
Team are from the AEI. For LISA Pathfinder, the technology demonstration
space mission, we are Co-Principal Investigator (Co-PI) of the LISA
technology package (LTP).
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Laser Research
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Lasers with very stable properties (in frequency and amplitude) and high output power in continuous operation are required for the detection of gravitational waves. Suitable advanced laser technology is developed and permanently improved at AEI (Teilinstitut Hannover) in close collaboration with the LaserZentrum Hannover (LHZ). The monolithic Nd:YAG ring laser which is used at the GEO600 GW detector for example is subject to constant improvement.
AEI has also provided, delivered and installed the Enhanced LIGO 34W lasers both at the Hanford and Livingston observatory sites in 2008. The lasers have shown extremely stable and reliable operations since then. In 2010 AEI has also provided the Advanced LIGO 200W pre-stabilized laser systems and will be carrying subsystem responsibility for these systems.
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Thermal Noise
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Thermal noise is expected to be a serious limit for the sensitivity of future generations of gravitational wave detectors. We are trying to measure and characterize the off-resonant thermal noise far away from the system resonances in a laboratory experiment using small mirrors suspended from a multiple pendulum as a miniature Fabry-Perot cavity. We study the coupling between the various degrees of freedom in order to develop completely new multiple-stage suspensions. The influence of radiation pressure noise due to laser amplitude fluctuations is studied, further the design of an auto-alignment system that permits stable and reproducible locking of the whole system.
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Quantum Interferometry and Squeezed Light
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The standard quantum limit (SQL) is now no longer regarded as a fundamental limit for the sensitivity of laser interferometric gravitational wave detectors. The quantum noise of GEO600 in the detuned signal recycling mode will be considerably below the SQL for signal frequencies around 100 Hz. We work on non-classical light and the development of interferometric techniques to go below the SQL. We are developing OPA-based sources of squeezed light for application in table-top interferometers.
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Prototype Interferometer
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The 10m prototype interferometer facility will be used to test and develop some of the techniques for potential future upgrades of the gravitational-wave detector GEO600.
Furthermore, experiments to explore quantum mechanical effects in macroscopic objects will be run in this facility. In the first round of experiments a Michelson interferometer with a sensitivity that is solely limited by quantum noise at all relevant Fourier frequencies will be set up. The sensitivity reached under these conditions is referred to as the Standard Quantum Limit (SQL). However, even this remarkable sensitivity limit can be overcome by the injection of squeezed states of light.
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 webteam@aei.mpg.de |
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© 2012, Max Planck Institute for Gravitational Physics, Potsdam |
