Strong photon non-linearities and photonic Mott insulators

We show, that photon non-linearities in electromagnetically induced transparency can be at least one order of magnitude larger than predicted in all previous approaches. As an application we demonstrate that, in this regime they give rise to very strong photon - photon interactions which are strong enough to make an experimental realization of a photonic Mott insulator state feasible in arrays of coupled ultra high-Q micro-cavities.Comment: minor changes, to appear in Phys. Rev. Let

REDISCOVERY OF A NATIVE AMERICAN CULTURAL LANDSCAPE: THE CHICKASAW HOMELAND AT REMOVAL

Little information beyond generalities exists regarding the cultural landscape of the Chickasaw Indians in their ancestral homelands prior to Removal in the late 1830s. This dissertation evaluates one possible archival source for specifics of Chickasaw land use, the field notes and survey plats compiled as part of the Public Land Survey System (PLSS). The process of original survey following land cession treaty divided the ceded area up into the familiar square-mile rectangular system of townships and ranges that extends from the Mississippi Territory westwards, in the so-called public land states. The research compiles all cultural observations made by the surveyors within a fourteen township area (totaling 504 square miles). This study area, generally located on the west bank of Town Creek between present-day Tupelo and Pontotoc MS, was chosen to cover the traditional center of Chickasaw settlement and elements of important roads such as the Natchez Trace. The resulting catalog of observations was compared to similar features on the township plats and to other cultural resource inventories to identify patterns of inscription and possible erasure of Native American cultural activities. Geographic Information Systems (GIS) technology was used to consolidate and compare these data resources. The PLSS survey documents provide a useful but not complete resource for identifying Chickasaw cultural presence within the study area. No consistent pattern of omission or erasure of Chickasaw activities was identified. The analysis identifies several opportunities and caveats for future researchers who might extend this analysis, including technical challenges in applying GIS technology to this data

Analysis of Nitrogen Loading Reductions for Wastewater Treatment Facilities and Non-Point Sources in the Great Bay Estuary Watershed

In 2009, the New Hampshire Department of Environmental Services (DES) published a proposal for numeric nutrient criteria for the Great Bay Estuary. The report found that total nitrogen concentrations in most of the estuary needed to be less than 0.3 mg N/L to prevent loss of eelgrass habitat and less than 0.45 mg N/L to prevent occurrences of low dissolved oxygen. Based on these criteria and an analysis of a compilation of data from at least seven different sources, DES concluded that 11 of the 18 subestuaries in the Great Bay Estuary were impaired for nitrogen. Under the Clean Water Act, if a water body is determined to be impaired, a study must be completed to determine the existing loads of the pollutant and the load reductions that would be needed to meet the water quality standard. Therefore, DES developed models to determine existing nitrogen loads and nitrogen loading thresholds for the subestuaries to comply with the numeric nutrient criteria. DES also evaluated the effects of different permitting scenarios for wastewater treatment facilities on nitrogen loads and the costs for wastewater treatment facility upgrades. This modeling exercise showed that: Nitrogen loads to the Great Bay, Little Bay, and the Upper Piscataqua River need to be reduced by 30 to 45 percent to attain the numeric nutrient criteria. Both wastewater treatment facilities and non-point sources will need to reduce nitrogen loads to attain the numeric nutrient criteria. The percent reduction targets for nitrogen loads only change minimally between wet and dry years. Wastewater treatment facility upgrades to remove nitrogen will be costly; however, the average cost per pound of nitrogen removed from the estuary due to wastewater facility upgrades is lower than for non-point source controls. The permitting options for some wastewater treatment facilities will be limited by requirements to not increase pollutant loads to impaired waterbodies. The numeric nutrient criteria and models used by DES are sufficiently accurate for calculating nitrogen loading thresholds for the Great Bay watershed. Additional monitoring and modeling is needed to better characterize conditions and nitrogen loading thresholds for the Lower Piscataqua River. This nitrogen loading analysis for Great Bay may provide a framework for setting nitrogen permit limits for wastewater treatment facilities and developing watershed implementation plans to reduce nitrogen loads

Strong Quantum Spin Correlations Observed in Atomic Spin Mixing

We have observed sub-Poissonian spin correlations generated by collisionally induced spin mixing in a spin-1 Bose-Einstein condensate. We measure a quantum noise reduction of -7 dB (-10 dB corrected for detection noise) below the standard quantum limit (SQL) for the corresponding coherent spin states. The spin fluctuations are detected as atom number differences in the spin states using fluorescent imaging that achieves a detection noise floor of 8 atoms per spin component for a probe time of 100 $\mu$s.Comment: 5 pages, 4 figure

The effect of annealing pressure and time on the crystallinity of CZTSe

In this study, the effect of annealing pressure and time on the homogeneity and the formation of the CZTSe structure was investigated. The deposition of the CZTSe coating was carried out using an electroplating method. The morphology and crystal structure of the coating was investigated using SEM-EDS, XRD and Raman spectroscopy. CZTSe films with optimised crystallinity and uniformity were obtained using an annealing process performed at 10 Torr for 1 hour. The use of lower pressures increases the crystallinity and the purity of the CZTSe film and decreases the density of secondary phases and the annealing time providing an additional benefit

Cupric oxide-based p-type transparent conductors

This study examines the impact of doping on the resistivity of sputtered cupric oxide (CuO), and investigates the effects of co-sputtering CuO with tin dioxide (SnO2). It was found that films sputtered from a 2 at. % sodium-doped target have resistivities of four orders of magnitude lower than equivalent undoped films. Addition of oxygen was found to reduce the resistivity further. The best films were found to have resistivities of 4.3x10-2 Ω.cm. Co-sputtering with SnO2 was found to increase the band gap significantly, although it also caused an increase in the resistivity. All mixed oxide films were both amorphous and p-type

On-demand single-photon state generation via nonlinear absorption

We propose a method for producing on-demand single-photon states based on collision-induced exchanges of photons and unbalanced linear absorption between two single-mode light fields. These two effects result in an effective nonlinear absorption of photons in one of the modes, which can lead to single photon states. A quantum nonlinear attenuator based on such a mechanism can absorb photons in a normal input light pulse and terminate the absorption at a single-photon state. Because the output light pulses containing single photons preserve the properties of the input pulses, we expect this method to be a means for building a highly controllable single photon source.Comment: 5 pages, 2 figures, to appear in PRA. To be published in PR

Optimisation of the CZTSe thin film composition obtained by a sequential electrodeposition process

The influence of the elemental composition of CuZnSn coatings deposited by electrodeposition on the formation of the Cu2ZnSnSe4 crystal structure following a selenisation process was investigated using X-ray diffraction, scanning electron microscopy and Raman spectroscopy. This study showed that the optimum alloy ratio to achieve the Cu2ZnSnSe4 crystal without impurity phases was in the range of 0.37–0.50 for Cu/(Zn+Sn) and 2.5–4 for Zn/Sn

Urban Land Markets as Spatial Justice

A common view is that urban land markets subtract from, or subvert, spatial justice in cities, with spatial justice thus a definable outcome of market functions. This article explores urban land markets as spatial justice, which is multi-dimensional and subjective and integral to the functioning of markets. Seen from this perspective, urban land markets present a very particular way in which the ‚happening‘ of spatial justice unfolds. Thinking of urban land markets in this way offers considerable value to being able to grasp the ways in which they both configure and constitute spatial justice, and thus broadens our understanding of their emancipatory or conservative potential in urban development. While a distributional understanding of justice represents a fundamental tenet of much progressive thinking, in which the fairness of outcome is seen as fundamentally more important than that of the process, we argue that there is considerable benefit in viewing spatial justice as a process of the struggle to lay claim to place or space. Viewed this way, urban land markets represent a key context within which that struggle occurs, but interventions designed to improve spatial justice must focus on the social relations that inform that struggle as much or more than on land markets themselves