Quantum dynamics of thermalizing systems

We introduce a method "DMT" for approximating density operators of 1D systems that, when combined with a standard framework for time evolution (TEBD), makes possible simulation of the dynamics of strongly thermalizing systems to arbitrary times. We demonstrate that the method performs well for both near-equilibrium initial states (Gibbs states with spatially varying temperatures) and far-from-equilibrium initial states, including quenches across phase transitions and pure states

Jet substructure and probes of CP violation in Vh production

We analyse the hVV (V = W, Z) vertex in a model independent way using Vh production. To that end, we consider possible corrections to the Standard Model Higgs Lagrangian, in the form of higher dimensional operators which parametrise the effects of new physics. In our analysis, we pay special attention to linear observables that can be used to probe CP violation in the same. By considering the associated production of a Higgs boson with a vector boson (W or Z), we use jet substructure methods to define angular observables which are sensitive to new physics effects, including an asymmetry which is linearly sensitive to the presence of CP odd effects. We demonstrate how to use these observables to place bounds on the presence of higher dimensional operators, and quantify these statements using a log likelihood analysis. Our approach allows one to probe separately the hZZ and hWW vertices, involving arbitrary combinations of BSM operators, at the Large Hadron Collider.Comment: 37 pages, 17 figures; v3 matches published versio

Open-system spin transport and operator weight dissipation in spin chains

We use non-equilibrium steady states to study the effect of dissipation-assisted operator evolution (DAOE) on the scaling behavior of transport in one-dimensional spin chains. We consider three models in the XXZ family: the XXZ model with staggered anisotropy, which is chaotic; XXZ model with no external field and tunable interaction, which is Bethe ansatz integrable and (in the zero interaction limit) free fermion integrable; and the disordered XY model, which is free-fermion integrable and Anderson localized. We find evidence that DAOE's effect on transport is controlled by its effect on the system's conserved quantities. To the extent that DAOE preserves those symmetries, it preserves the scaling of the system's transport properties; to the extent it breaks those conserved quantities, it pushes the system towards diffusive scaling of transport.Comment: Published version, 14+5 pages, 11+5 figure

Geotechnical Solutions for Soil Improvement, Rapid Embankment Construction, and Stabilization of the Pavement Working Platform, Performance Assessment of Lime and Fly Ash Chemically Treated Subgrade

Chemical treatment and stabilization of subgrades is a long-standing method to construct working platforms and improve the support conditions for pavement systems. Lime, cement, and fly ash are common chemical stabilization agents and are often incorporated with subgrade materials to improve volumetric stability, freeze-thaw performance, and/or subgrade stiffness. Although laboratory test methods and design procedures are relatively well established, the long-term (5+ years) field performance characteristics of treated or stabilized subgrades is poorly documented and was the focus of this study. The main objectives of this project were as follows: Document engineering properties (in situ strength/stiffness) and mineralogical/micro-structural characteristics of chemical stabilized subgrades, in comparison with natural subgrades at the same sites Understand factors that contribute to long-term engineering behavior of stabilized subgrade Nine test sections were selected to assess engineering properties of old stabilized subgrades in Texas, Oklahoma, and Kansas. The selection of the test sites was based on the type of subgrade, availability of old construction records, and age. Subgrades at six of these sites were stabilized with lime and the other three with fly ash. Eight of these test sites were more than 10 years old, and one test site was about 5 years old. Eight sites consisted of flexible pavement supported on base and stabilized subgrade or just stabilized subgrade, and one site consisted of concrete pavement supported on cement treated base and stabilized subgrade Results from this study provide new information that should be of great interest to pavement designers dealing with selection of design parameters for chemically stabilized subgrade layers

Reuse of water treatment residuals from lime softening, Part I: Applications for the reuse of lime sludge from water softening

Lime sludge, an inert material mostly composed of calcium carbonate, is the result of softening hard water before distribution as drinking water. A large city such as Des Moines, Iowa, produces about 32 000 tons of lime sludge (dry-weight basis) annually. This is about half of the lime sludge produced in Iowa per year in eight different cities, and these cities currently have 371 800 tons (dry-weight basis) stockpiled. The Iowa Department of Natural Resources directed those cities using lime softening in drinking-water treatment to stop digging new lagoons to dispose of lime sludge. The situation in surrounding Midwestern states is similar, and there will be millions of tons of lime sludge in stockpiles. Five Iowa water-treatment plants, all producers of lime sludge, funded the research. The research goal was to find useful and economical alternatives for the disposal of lime sludge. Feasibility studies tested the efficacy of using lime sludge in cement production, power-plant SOx control, dust control on gravel roads, wastewater neutralization, and infill materials for road construction. All the potential applications were demonstrated to be at least feasible, except for dust control. Fill material from admixture with fly ash showed the most promise as a bulk, if variable, demand application

Numerical Methods for Many-Body Quantum Dynamics

This thesis describes two studies of the dynamics of many-body quantum systems with extensive numerical support. In Part I we first give a new algorithm for simulating the dynamics of one-dimensional systems that thermalize (that is, come to local thermal equilibrium). The core of this algorithm is a new truncation for matrix product operators, which reproduces local properties faithfully without reproducing non-local properties (e.g. the information required for OTOCs). To the extent that the dynamics depends only on local operators, timesteps interleaved with this truncation will reproduce that dynamics. We then apply this to algorithm to Floquet systems: first to clean, non-integrable systems with a high-frequency drive, where we find that the system is well-described by a natural diffusive phenomenology; and then to disordered systems with low-frequency drive, which display diffusion — not subdiffusion — at appreciable disorder strengths. In Part II, we study the utility of many-body localization as a medium for a thermodynamic engine. We first construct a small ("mesoscale") engine that gives work at high efficiency in the adiabatic limit, and show that thanks to the slow spread of information in many body localized systems, these mesoscale engines can be chained together without specially engineered insulation. Our construction takes advantage of precisely the fact that MBL systems do not thermalize. We then show that these engines still have high efficiency when run at finite speed, and we compare to competitor engines.</p

A review of methodologies applied in Australian practice to evaluate long-term coastal adaptation options

Rising sea levels have the potential to alter coastal flooding regimes around the world and local governments are beginning to consider how to manage uncertain coastal change. In doing so, there is increasing recognition that such change is deeply uncertain and unable to be reliably described with probabilities or a small number of scenarios. Characteristics of methodologies applied in Australian practice to evaluate long-term coastal adaptation options are reviewed and benchmarked against two state-of-the-art international methods suited for conditions of uncertainty (Robust Decision Making and Dynamic Adaptive Policy Pathways). Seven out of the ten Australian case studies assumed the uncertain parameters, such as sea level rise, could be described deterministically or stochastically when identifying risk and evaluating adaptation options across multi-decadal periods. This basis is not considered sophisticated enough for long-term decision-making, implying that Australian practice needs to increase the use of scenarios to explore a much larger uncertainty space when assessing the performance of adaptation options. Two Australian case studies mapped flexible adaptation pathways to manage uncertainty, and there remains an opportunity to incorporate quantitative methodologies to support the identification of risk thresholds. The contextual framing of risk, including the approach taken to identify risk (top-down or bottom-up) and treatment of uncertain parameters, were found to be fundamental characteristics that influenced the methodology selected to evaluate adaptation options. The small sample of case studies available suggests that long-term coastal adaptation in Australian is in its infancy and there is a timely opportunity to guide local government towards robust methodologies for developing long-term coastal adaptation plans