Connected Network Model for the Mechanical Loss of Amorphous Materials

Abstract

Dissipation in amorphous solids at low frequencies is commonly attributed to activated transitions of isolated two-level systems (TLS) that come in resonance with elastic or electric fields. Materials with low mechanical or dielectric loss are urgently needed for applications in gravitational wave detection, high precision sensors, and quantum computing. Using atomistic modeling, we explore the energy landscape of amorphous silicon and titanium dioxide, and find that the pairs of energy minima that constitute single TLS form a sparsely connected network with complex topologies. Motivated by this observation, we develop an analytically tractable theory for mechanical loss of the full network from a nonequilibrium thermodynamic perspective. We demonstrate that the connectivity of the network introduces new mechanisms that can both reduce low frequency dissipation through additional low energy relaxation pathways, and increase dissipation through a broad distribution of energy minima. As a result, the connected network model predicts mechanical loss with distinct frequency profiles compared to the isolated TLS model. This not only calls into question the validity of the TLS model, but also gives us many new avenues and properties to analyze for the targeted design of low mechanical loss materials.

References in corpus (20)

• Cavity Optomechanics
• Stochastic thermodynamics, fluctuation theorems, and molecular machines
• Decoherence in Josephson Qubits from Dielectric Loss
• Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
• Fluctuations of Energy-Relaxation Times in Superconducting Qubits
• The network topology of a potential energy landscape: A static scale-free network
• Connected Network of Minima as a Model Glass: Long Time Dynamics
• Amorphous optical coatings of present gravitational-wave interferometers
• Modern computational studies of the glass transition
• Depletion of two-level systems in ultrastable computer-generated glasses
• Low mechanical loss TiO${}_2$:GeO${}_2$ coatings for reduced thermal noise in Gravitational Wave Interferometers
• Decoherence of a Josephson qubit due to coupling to two level systems
• Theory of harmonic dissipation in disordered solids
• Energy landscape of relaxed amorphous silicon
• Two-Level Systems in Evaporated Amorphous Silicon
• Origin of Mechanical and Dielectric Losses from Two-Level Systems in Amorphous Silicon
• Simulating noise on a quantum processor: interactions between a qubit and resonant two-level system bath
• Characterization of the Dynamics of Glass-forming Liquids from the Properties of the Potential Energy Landscape
• Elastic measurements of amorphous silicon films at mK temperatures
• Decoupling between propagating acoustic waves and two-level systems in hydrogenated amorphous silicon