PhD position in the area of atomic-precision coatings for enabling the observation of Gravitational Waves

The COCOON research group at the Department of Solid State Sciences (Ghent University, Belgium) is seeking to fill a full-time (100%)

PhD position in the area of atomic-precision coatings for enabling the observation of Gravitational Waves

under the supervision of Prof. Christophe Detavernier and Prof. Jolien Dendooven.

Context

In 2017, the Nobel prize in Physics was awarded to the first direct detections of gravitational waves, opening up so far unexplored and extreme regions of the universe, and enabling novel precision testing of Einstein’s theory of gravity near black holes and in the early universe.

Gravitational wave detectors are based on laser interferometry. Changes in path length of the order of 10-18 meter need to be detected, i.e. 1/1000th of the typical size of an atomic nucleus. To enable the extremely low noise that is required in these measurements, the quality of the optical components is critical, and in particular the mirrors and their coatings that are installed in the interferometer cavities are crucially important.

Current state-of-the-art mirrors consist of silica test masses, coated with nano-laminated stacks of amorphous materials (e.g. SiO2/Ta2O5) deposited by Ion Beam Assisted Deposition (IBAD). It has proven particularly challenging to reduce the thermal expansion of the mirrors, the quantum vibration (Brownian motion) noise of the mirror coatings and to control the mirror shape and surface roughness to near perfection.

Further upgrades to LIGO and Virgo as existing facilities, as well as the development of a new generation of GW detectors like the Einstein Telescope (ET) and ESA’s Laser Interferometer Space Antenna (LISA), will require further advances in detection technology, and in particular further improvements in the dedicated multilayer coatings that are a crucial part of the optical system in GW detectors.

We aim to explore Atomic Layer Deposition (ALD) as a novel, alternative approach to GW mirror coating. ALD is an industry-proven and scalable thin film deposition technique. The intrinsic properties of ALD (low temperature deposition, atomic scale control of layer thickness, conformal coating of complex 3D shaped substrates, and uniformity across large areas) offer clear potential advantages over IBAD when depositing nanolaminated structures, w.r.t. uniformity, conformality and interfacial sharpness.

Job description

The work will be executed in the Conformal Coating of Nanomaterials (COCOON) research group at the Department of Solid State Sciences, Ghent University, Belgium (www.cocoon.ugent.be). The PhD candidate will develop ALD-based strategies for the atomically precise design of GW mirror coatings. Key challenges concern controlling the density and intrinsic growth stress during the ALD process, to enable dense amorphous layers with sharp, well defined interfaces. To this end, the PhD candidate will explore intermittent exposure of the growth surface to plasma, and will use in situ and ex situ lab-based and synchrotron-based experimental techniques to characterize the growth process, atomic-scale structure, film density, surface roughness, interface sharpness and intrinsic stress. This PhD topic is part of an interuniversity project on “Unlocking the Dark Universe with Gravitational Wave Observations: from Quantum Optics to Quantum Gravity”, in which UGent recently started to collaborate with VUB and KU Leuven to jointly explore novel fabrication techniques for GW mirrors and coatings. Functional testing of the most promising mirror coatings will be performed in collaboration with the project partners.

Profile

The PhD candidate must hold a master of science degree in (engineering) physics and show a strong interest in thin film deposition, plasma techniques and advanced structural analysis. Some experience with Python programming is considered an asset in view of efficient data analysis. The degree should be obtained before the prospective starting date between August 1st and September 15th 2021. The PhD candidate should be fluent in English and have the strong intention to finish a PhD by the end of the 4-year project.

How to apply?

You can apply via email to Christophe Detavernier. Please provide a full CV including your academic/education history, experience with experimental work and programming, list of publications where applicable. Please also provide a motivation letter. For applicants from non-English speaking countries, please attach copies of recent English language certificates where available. The deadline for application is July 7th, 2021.