Connected Network Model for the Mechanical Loss of Amorphous Materials

For over 50 years, the two-level system (TLS) model has stood as the prevailing description of thermal and acoustic properties of amorphous solids. Atomistic modeling shows that TLS are not independent as typically assumed, but form a sparse, interconnected network. I will discuss the mechanical loss in amorphous solids based on the nonequilibrium thermodynamics of connected networks, providing a major advance beyond the quintessential two-level system model, and revealing new avenues for the study amorphous materials. Amorphous mirror coatings with exceptionally low mechanical loss are critical components in the next generation of gravitational wave detectors. I will also briefly discuss how these results could impact the TLS model for dielectric loss in superconducting qubits.