Environmental Geology of Lake and Porter Counties, Indiana - An Aid to Planning

Indiana Geological Survey Special Report 11; Indiana Geological Survey Environmental Study 8Lake and Porter Counties are subdivided into three physiographically and geologically distinct regions: (1) the Calumet Lacustrine Plain, (2) the ValparaisoMorainal Area, and (3) the Kankakee Outwash and Lacustrine Plain. The surficial deposits of these regions, which range in thickness from 40 feet near the Kankakee River to more than 250 feet near Valparaiso, Ind,. Are the products, either directly or indirectly, of the Wisconsinan Age of glaciation. The Calumet lake plain is characterized by low-lying complexly intermixed clay, sand, and silt deposits, mostly of glacial Lake Chicago origin , The Valparaiso Moraine forms high ground in the two counties and is composed of clay-rich to fine sandy till. Sand and fine gravel deposits constitute the bulk of the Kankakee Outwash and Lacustrine Plain, this area being the low-lying outwash and flood plain for the glacially derived rivers as well as for the present Kankakee River. The two-county area has an abundance of geologic and geologically related resources; some of the most important are: (1) groundwater of the Kankakee Outwash and Lacustrine Plain and Valparaiso Morainal Area, (2) sand deposits of glacial Lake Chicago and of recent origin, (3) rich soils developed on the Valparaiso Moraine and Kankakee outwash plain, and (4) surface water in the form of streams, rivers, and small lakes. Some of these resources have already been damaged during the course of man’s habitation and use, but all can, with proper understanding of the problems and the willingness to act, be saved from further unnecessary degradation. Certain kinds of land use, which are partly dependent on the local geology, are potential sources of difficulty. These include (1) siting and use of sanitary landfills, (2) placement of septic systems, sewage lagoons, and industrial holding ponds, (3) management of flood plains, (4) development of the Lake Michigan shoreline, (5) construction of all kinds in areas where little is known about the engineering and hydrologic properties of the materials, (6) disposal of industrial wastes by deep well injection methods, and (7) development of groundwater supplies without sufficient hydrologic and geologic data. The environmental problems of Lake and Porter Counties, are related to geology, are as varied and complex as the materials themselves. Specific questions related to a given problem are best answered by the competent consultant equipped to do so. This report, though intended to supply valuable geologic information on a variety of land use related subjects, should not replace onsite evaluation of the salient parameters involved with each problem that potentially arises whenever man uses earth materials or otherwise disturbs or rearranges the natural earth condition.Indiana Department of Natural Resource

Double Quantum Dot Floquet Gain Medium

Strongly driving a two-level quantum system with light leads to a ladder of Floquet states separated by the photon energy. Nanoscale quantum devices allow the interplay of confined electrons, phonons, and photons to be studied under strong driving conditions. Here we show that a single electron in a periodically driven DQD functions as a "Floquet gain medium," where population imbalances in the DQD Floquet quasi-energy levels lead to an intricate pattern of gain and loss features in the cavity response. We further measure a large intra-cavity photon number n_c in the absence of a cavity drive field, due to equilibration in the Floquet picture. Our device operates in the absence of a dc current -- one and the same electron is repeatedly driven to the excited state to generate population inversion. These results pave the way to future studies of non-classical light and thermalization of driven quantum systems

Threshold Dynamics of a Semiconductor Single Atom Maser

We demonstrate a single-atom maser consisting of a semiconductor double quantum dot (DQD) that is embedded in a high quality factor microwave cavity. A finite bias drives the DQD out of equilibrium, resulting in sequential single electron tunneling and masing. We develop a dynamic tuning protocol that allows us to controllably increase the time-averaged repumping rate of the DQD at a fixed level detuning, and quantitatively study the transition through the masing threshold. We further examine the crossover from incoherent to coherent emission by measuring the photon statistics across the masing transition. The observed threshold behavior is in agreement with an existing single atom maser theory when small corrections from lead emission are taken into account

Spin Transport in a Mott Insulator of Ultracold Fermions

Strongly correlated materials are expected to feature unconventional transport properties, such that charge, spin, and heat conduction are potentially independent probes of the dynamics. In contrast to charge transport, the measurement of spin transport in such materials is highly challenging. We observed spin conduction and diffusion in a system of ultracold fermionic atoms that realizes the half-filled Fermi-Hubbard model. For strong interactions, spin diffusion is driven by super-exchange and doublon-hole-assisted tunneling, and strongly violates the quantum limit of charge diffusion. The technique developed in this work can be extended to finite doping, which can shed light on the complex interplay between spin and charge in the Hubbard model.Comment: 16 pages, 10 figure