PhD defence Sarah Luise Kranzhoff

Keywords: Gravitational-wave detection, Precision interferometry, Quantum noise reduction, Cryogenic vibration isolation

"Stay Cool in a Polarised World"

Just as your house vibrates when a heavy plane flies overhead or a large lorry rumbles past, so too does space itself vibrate when extremely massive objects, like black holes, collide. The difference is that these vibrations, or gravitational waves, are so minuscule they can only be detected by instruments operating at the very limits of what is measurable.

Current gravitational wave detectors have already delivered many new insights about the universe, but noise limits their sensitivity. Thermal noise, caused by temperature fluctuations, and quantum noise, resulting from random fluctuations in the number of light particles, both reduce the accuracy of measurements. 

The future Einstein Telescope is designed to perform far better than the current detectors by reducing noise sources. In her research, Luise Kranzhoff is exploring ways to achieve this: by actively damping vibrations from cooling mirrors to extreme temperatures, and by investigating a new measurement concept called the speedmeter to suppress quantum noise. These innovations are crucial for the next generation of gravitational wave telescopes, which will enable measurements of gravitational waves from new sources and events further away in the universe.

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