LIGO Newtonian Noise Cancellation Using Metamaterial-Based Periodic Structures

This paper presents a novel approach to mitigating Newtonian noise (NN) in laser interferometer gravitational wave observatory (LIGO) on Earth's surface. The proposed method offers an unprecedented means to enhance the sensitivity of terrestrial gravitational wave (GW) detectors in the low-frequency range by leveraging seismic metamaterial-based unit cell analysis. The key concept involves deploying metamaterial-based piles in the ground surrounding the primary test masses of a gravitational wave detector. This strategic placement aims to reduce the coupling of Rayleigh waves, contributing to seismic disturbances affecting test mass displacement. The discussion delves into the design considerations of cylindrical pile shapes, emphasizing their effectiveness in minimizing seismic interference. By harnessing metamaterial principles and carefully engineering the configuration of these piles, the proposed method holds promise for substantially improving the performance of terrestrial GW detectors, particularly in mitigating low-frequency noise sources. The study utilized finite-element simulations to investigate how the parameters of the metastructure and the frequency of seismic excitation impact the reduction of NN. These simulations reveal a frequency-dependent suppression of NN for the advanced LIGO configuration, particularly affecting sensitivity in the 9-15 Hz frequency band. Moreover, the analysis extends to quantifying the reduction of gravity gradient noise through both time and frequency domain analyses. An analytical expression is provided to estimate the density perturbations induced by Rayleigh waves in the medium. This approach demonstrates a favorable advantage-to-cost ratio and enhanced practicality for future infrastructures. By applying these findings, there is potential to significantly improve the sensitivity of current and future ground-based gravitational wave detectors. Additionally, the metamaterials approach holds promise for safeguarding critical infrastructure such as nuclear power plants, particularly in regions where the estimation of hazards is challenging. This indicates broader applications beyond gravitational wave detection, highlighting the versatility and importance of metamaterials in various fields.