CREOL: CROL-103

Title: Pioneering Optical Coating Technology for Space Exploration with Gravitational Waves - Precision Metrology at the Thermodynamic Limit

Abstract: The world-wide effort to detect gravitational waves has lifted the veil on a gravitational sky full of violent cosmic events with rich stories to tell. The sensitivities of the current observatories - marvels of precision engineering and optical metrology - have evolved to allow routine observations of binary mergers of black holes and neutron stars, revealing much about the history of our universe and becoming probes for fundamental physics in extreme limits. Future observatories are set to continue this trend, leading to new discoveries and improved observational constraints - through observations with higher signal fidelity and sampling larger volumes for source populations - on theoretical descriptions of gravity, progenitor physics of binary merger events, and the equation of state of highly degenerate neutron stars. Additionally, mature concepts for space-based gravitational wave detectors aim to use inter-spacecraft laser links across millions of kilometers. This will allow to probe mergers of supermassive black holes in colliding galaxies and extreme mass ratio inspirals, mapping complex space-times and populations at cosmological scales. On the experimental side, gravitational wave detection has been a major driver for the development of optical and photonic technologies, e.g. high-power low-noise lasers, quantum-enhanced readout with non-classical squeezed light, and ultra-low loss precision optics. A big hurdle towards the sensitivity improvement sought by next-generation ground-based facilities are thermal fluctuations in mirror coatings and substrates. A range of materials, deposition methods, and the use of cryogenics are being explored to reduce the impact of coating thermal noise and promise a leap in audio-band performance for future upgrades. I will give an overview of the concerted ground and space-based gravitational wave detection efforts and discuss mitigation strategies for thermal noise, showcasing promising avenues for research into novel coating materials and deposition techniques.

About the Speaker: Dr. Johannes Eichholz is a Research Fellow at the Australian National University (ANU) in Canberra, Australia. He was awarded his Ph.D. at the University of Florida in Gainesville, FL after receiving his Master's degree from the Max Planck Institute for Gravitational Physics in Hannover, Germany, and spending a small portion of his PhD at NASA Goddard Space Flight Center in Greenbelt, MD. Following his PhD, he joined the LIGO Laboratory at the California Institute of Technology in Pasadena, CA in 2016 as a Postdoctoral Scholar, before moving to ANU in 2018, where he now works at the Centre for Gravitational Astrophysics. He received a Discovery Early Career Research Award (DECRA) Fellowship from the Australian Research Council (ARC) and is an Associate Investigator of the ARC Centre of Excellence for Gravitational Wave Discovery. He is a member of the LIGO Scientific Collaboration since 2012 and was involved in the coordinated effort that led to the first observation of gravitational waves from binary black holes (GW150914) and neutron stars (GW170817), for which he was co-awarded the Special Breakthrough Prize in Fundamental Physics (2016), the Gruber Cosmology Prize (2016), the Bruno Rossi Prize (2017), the Princess of Asturias Award for Technical & Scientific Research (2017), and the RAS Group Achievement Award (2017). His work focuses on pathfinding optical technologies for future ground-based gravitational wave detectors, including optical coatings, thermal noise mitigation, cryogenic interferometry, and low-noise lasers. He is also the scientific lead for a newly established optical coating facility at ANU and is currently engaged in producing optics for the next hardware upgrade of the US LIGO detectors.