Simulation of inhomogeneous distributions of ultracold atoms in an optical lattice via a massively parallel implementation of nonequilibrium strong-coupling perturbation theory

We present a nonequilibrium strong-coupling approach to inhomogeneous systems of ultracold atoms in optical lattices. We demonstrate its application to the Mott-insulating phase of a two-dimensional Fermi-Hubbard model in the presence of a trap potential. Since the theory is formulated self-consistently, the numerical implementation relies on a massively parallel evaluation of the self-energy and the Green's function at each lattice site, employing thousands of CPUs. While the computation of the self-energy is straightforward to parallelize, the evaluation of the Green's function requires the inversion of a large sparse $10^d\times 10^d$ matrix, with $d > 6$. As a crucial ingredient, our solution heavily relies on the smallness of the hopping as compared to the interaction strength and yields a widely scalable realization of a rapidly converging iterative algorithm which evaluates all elements of the Green's function. Results are validated by comparing with the homogeneous case via the local-density approximation. These calculations also show that the local-density approximation is valid in non-equilibrium setups without mass transport.Comment: 14 pages, 9 figure

James Hulless Oats

A new hulless oat, James, C.I. 5015, has been described. This variety was derived from the cross of ( Bond x Double Cross Bond) x Nakota. It is stiff-strawed, mid-early and has produced a high yield of good quality grain in eastern South Dakota. James has the White Russian type of stem rust resistance, Puccinia graminis avenae, Eriks, and Henn., and the Bond type leaf rust resistance, Puccinia coronata (Pers.) Cda. It is resistant to both species of smut, U stilago kolleri Wille. and Ustilago avenae (Pers.) Rostr

An Analysis of Small Grain Performance in South Dakota, 1942-1951

The small grain performance tests were located at the State Experiment Station, Brookings, the Central Substation, Highmore, the Range Field Station, Cottonwood and the North Central Substation, Eureka. In most cases the yields at the outlying stations were taken from nursery plots, with the exception of the winter wheat, rye and flax data which came from still strip plots of approximately 1/50th acre in size. The yields at Brookings were taken from drill trip plots 1/40th acre in size. Since yielding quality cannot be measured with absolute accuracy, small differences in yield are not important. Unless the difference exceeds the “least significant difference” given in the yield tables, little emphasis should be placed on the superiority in yield of one variety over another

Theoretical Description of Coherent Doublon Creation via Lattice Modulation Spectroscopy

Using a recently developed strong-coupling method, we present a comprehensive theory for doublon production processes in modulation spectroscopy of a three-dimensional system of ultracold fermionic atoms in an optical lattice with a trap. The theoretical predictions compare well to the experimental time traces of doublon production. For experimentally feasible conditions, we provide a quantitative prediction for the presence of a nonlinear "two-photon" excitation at strong modulation amplitudes.Comment: 5 pages, 5 figure

Progress in Agricultural Research at the North Central Substation

Thousands of acres of farm land in the north central part of South Dakota have their productive future tied up with the 240 acres used for experimental research at the Substation at Eureka. Established nearly 50 years ago by the state legislature, which set aside state school lands for agricultural research, the North Central Substation is the proving ground for new agricultural methods and a living record of the accumulative effects of the old. As early as 1908, rotation experiments were started which became the first historical record in the northern plains area of the effects of cropping practices on the soil. At that time, the entire surrounding country was in wheat. There were no crop rotations, since the organic matter of the soil was good and the fertility level high. Also, there was no weed problem then. Later, the Experiment Station was to be accused of scattering weeds in one of the most interesting stories to be uncovered in the development of experimental research in this area. Foreseeing the time when the fertility of the land might become dangerously lowered by the practice of continuous cropping which was being carried on at that time, the Substation set up experimental plots. These included the basic crops of rotation-cultivated crops, small grain and legumes. In this case, the legume was sweet clover. (See more in Text

Irrigation Research in the James River Basin: A Five-Year Progress Report

The prospect of irrigation in the James River Basin has created much interest in the past few years. To provide a scientific foundation and proceed with a minimum of costly trial and error, research on crop varieties, soil fertility and management, pastures, and water management was increased in the area in 19 4 8. Experiments were conducted on non-irrigated and irrigated land to determine the results and benefits under each condition. The expanded research work was conducted primarily on the Huron Development Farm and the Red field Development Farm

Transport Through Andreev Bound States in a Graphene Quantum Dot

Andreev reflection-where an electron in a normal metal backscatters off a superconductor into a hole-forms the basis of low energy transport through superconducting junctions. Andreev reflection in confined regions gives rise to discrete Andreev bound states (ABS), which can carry a supercurrent and have recently been proposed as the basis of qubits [1-3]. Although signatures of Andreev reflection and bound states in conductance have been widely reported [4], it has been difficult to directly probe individual ABS. Here, we report transport measurements of sharp, gate-tunable ABS formed in a superconductor-quantum dot (QD)-normal system, which incorporates graphene. The QD exists in the graphene under the superconducting contact, due to a work-function mismatch [5, 6]. The ABS form when the discrete QD levels are proximity coupled to the superconducting contact. Due to the low density of states of graphene and the sensitivity of the QD levels to an applied gate voltage, the ABS spectra are narrow, can be tuned to zero energy via gate voltage, and show a striking pattern in transport measurements.Comment: 25 Pages, included SO

Aggregate Building Simulator (ABS) Methodology Development, Application, and User Manual

As the relationship between the national building stock and various global energy issues becomes a greater concern, it has been deemed necessary to develop a system of predicting the energy consumption of large groups of buildings. Ideally this system is to take advantage of the most advanced energy simulation software available, be able to execute runs quickly, and provide concise and useful results at a level of detail that meets the users needs without inundating them with data. The resulting methodology that was developed allows the user to quickly develop and execute energy simulations of many buildings simultaneously, taking advantage of parallel processing to greatly reduce total simulation times. The result of these simulations can then be rapidly condensed and presented in a useful and intuitive manner