Single atom edge-like states via quantum interference

We demonstrate how quantum interference may lead to the appearance of robust edge-like states of a single ultracold atom in a two-dimensional optical ribbon. We show that these states can be engineered either within the manifold of local ground states of the sites forming the ribbon, or of states carrying one unit of angular momentum. In the former case, we show that the implementation of edge-like states can be extended to other geometries, such as tilted square lattices. In the latter case, we suggest to use the winding number associated to the angular momentum as a synthetic dimension.Comment: 5 pages, 5 figure

Trapping of Bose-Einstein condensates in a three-dimensional dark focus generated by conical refraction

We present a novel type of three-dimensional dark focus optical trapping potential for ultra-cold atoms and Bose-Einstein condensates. This 'optical bottle' is created with blue-detuned laser light exploiting the phenomenon of conical refraction occurring in biaxial crystals. We present experiments on confining a Rb87 Bose-Einstein condensate in this potential and derive the trapping frequencies and potential barriers under the harmonic approximation and the conical refraction theory

Wave-vector and polarization dependence of conical refraction

We experimentally address the wave-vector and polarization dependence of the internal conical refraction phenomenon by demonstrating that an input light beam of elliptical transverse profile refracts into two beams after passing along one of the optic axes of a biaxial crystal, i.e. it exhibits double refraction instead of refracting conically. Such double refraction is investigated by the independent rotation of a linear polarizer and a cylindrical lens. Expressions to describe the position and the intensity pattern of the refracted beams are presented and applied to predict the intensity pattern for an axicon beam propagating along the optic axis of a biaxial crystal

Conceptual Trade Study of General Purpose Heat Source Powered Stirling Converter Configurations

This Technical Manual describes a parametric study of general purpose heat source (GPHS) powered Stirling converter configurations. This study was performed in support of MSFC s efforts to establish the capability to perform non-nuclear system level testing and integration of radioisotope power systems. Six different GPHS stack configurations at a total of three different power levels (80, 250, and 500 W(sub e) were analyzed. The thermal profiles of the integrated GPHS modules (for each configuration) were calculated to determine maximum temperatures for comparison to allowable material limits. Temperature profiles for off-nominal power conditions were also assessed in order to better understand how power demands from the Stirling engine impact the performance of a given configuration

Optical vault: reconfigurable bottle beam by conically refracted light

We employ conical refraction of light in a biaxial crystal to create an optical bottle for trapping and manipulation of particles. We show that by just varying the polarization of the input light the bottle can be opened and closed at will. We experimentally demonstrate stable photophoretic trapping and controllable loading and unloading of light absorbing particles in the trap.Comment: 4 pages, 5 figure

Polarization tailored novel vector beams based on conical refraction

Coherent vector beams with involved states of polarization (SOP) are widespread in the literature, having applications in laser processing, super-resolution imaging and particle trapping. We report novel vector beams obtained by transforming a Gaussian beam passing through a biaxial crystal, by means of the conical refraction phenomenon. We analyze both experimentally and theoretically the SOP of the different vector beams generated and demonstrate that the SOP of the input beam can be used to control both the shape and the SOP of the transformed beam. We also identify polarization singularities of such beams for the first time and demonstrate their control by the SOP of an input beam

Synthesis of Australian cross-cultural ecology featuring a decade of annual Indigenous ecological knowledge symposia at the Ecological Society of Australia conferences

Indigenous Australians are Australia’s first ecologists and stewards of land, sea and freshwater Country. Indigenous biocultural knowledge, as coded in story, song, art, dance and other cultural practices, has accumulated and been refined through thousands of generations of Indigenous tribal groups who have distinct cultural responsibilities for their ancestral estates. European colonisation of Australia had and is still having severe impacts on Indigenous cultural practice, knowledge, people and Country. In contemporary ecology and environmental management, re-recognition of the unique values of Indigenous biocultural knowledge and practice is occurring and increasingly being deployed alongside Western approaches in what has been described as cross-cultural, two-way or right-way work. This article describes the development of cross-cultural ecology and environmental approaches in Australia. We then provide an overview of 10 years of conference presentations associated with the annual Indigenous Ecological Knowledge symposiums of the Ecological Society of Australia (ESA). From 2010 to 2020, 173 people participated in the symposia from around Australia and Aotearoa (New Zealand), of which 62% were Indigenous Australians and 3% Maori. Most participants were from Indigenous Ranger groups followed by University staff, with a roughly even split of men and women. A total of 100 presentations were given and a word frequency analysis of the presentation titles revealed the dominant words (themes) were: Indigenous, management, Country, fire, working, knowledge and cultural. The increasing Indigenous participation in the ESA conferences was coincident with increasing Indigenous-led projects across Australia, although we recognise that much more work needs to be done to increase Indigenous participation and control in Australian ecology and environmental management to move from cross-cultural to Indigenous-led approaches