Hybrid Quantum Dot-2D Electron Gas Devices for Coherent Optoelectronics

We present an inverted GaAs 2D electron gas with self-assembled InAs quantum dots in close proximity, with the goal of combining quantum transport with quantum optics experiments. We have grown and characterized several wafers -- using transport, AFM and optics -- finding narrow-linewidth optical dots and high-mobility, single subband 2D gases. Despite being buried 500 nm below the surface, the dots are clearly visible on AFM scans, allowing precise localization and paving the way towards a hybrid quantum system integrating optical dots with surface gate-defined nanostructures in the 2D gas.Comment: 4 pages, 5 figures (color

Maternity Coalition: Australia's national maternity consumer advocacy organization

This chapter tells the story of the Maternity Coalition (MC), an Australian advocacy organization which represents an often ‘forgotten’ strand of the women’s movement — the maternalist feminist emphasis on reclaiming women’s rights in birth and breastfeeding. Having originated in the late 1980s to lobby state government inquiries for improved maternity services in the Australian states of New South Wales and Victoria, by 2008 the organization was established nationally and was acknowledged as a key stakeholder in the incoming federal government’s agenda for improving maternity care. This chapter first examines how the Maternity Coalition developed, its rationale and mothering discourse, and then considers challenges which the organization faces in the early 21st century. Developing from a state-based to a national organization, MC faces internal sustainability difficulties in terms of communicating and managing a voluntary organization mostly comprised of busy young mothers. The external challenges are also considerable—MC aims to change the entrenched system of maternity services but in a cultural context which values technology and professional expertise and a political economic context in which the medical profession holds significant power. Nonetheless, Australia’s Maternity Coalition has achieved a national profile and credibility, bringing women’s rights to options and optimal care in birth to public attention at a level not achieved in many comparable countries

Identifying better systems design in Australian maternity care: a boundary critique analysis

This article examines the background and limitations of maternity care policy and provision in Australia using the Boundary Critique method from critical systems thinking. We argue that the historical legacy of funding maternity care within medically dominated fee-for-service structures and acute hospital budgets is seriously flawed. Furthermore, it cannot deliver the policy goals of healthy and socially equitable birth practices. Despite the 2009 national Maternity Services Review and progress of a National Maternity Services Plan (2011), most mainstream Australian maternity services remain out-of-step with both health service research and evidence-based ‘best practice’. The present system drives unnecessary clinical interventions, increased expenditure, short-term adverse health outcomes and the potential for a larger, unacknowledged legacy of future chronic disease. By contrast, boundary critique analysis suggests that redesigning for good maternity service provision can act as a population-level preventative health strategy, offering better value, better health and improved equity in maternity care

A scalable optical detection scheme for matter wave interferometry

Imaging of surface adsorbed molecules is investigated as a novel detection method for matter wave interferometry with fluorescent particles. Mechanically magnified fluorescence imaging turns out to be an excellent tool for recording quantum interference patterns. It has a good sensitivity and yields patterns of high visibility. The spatial resolution of this technique is only determined by the Talbot gratings and can exceed the optical resolution limit by an order of magnitude. A unique advantage of this approach is its scalability: for certain classes of nano-sized objects, the detection sensitivity will even increase significantly with increasing size of the particle.Comment: 10 pages, 4 figure

Quantum critical behavior induced by Mn impurity in CuGeO3

Results of high frequency (60-315 GHz) studies of ESR in CuGeO3 single crystals containing 0.9% of Mn impurity are reported. Quantitative EPR line shape analysis allowed concluding that low temperature magnetic susceptibility for T <40 K diverges following power law with the critical exponent 0.81 and therefore manifests onset of a quantum critical (QC) regime. We argue that transition into Griffiths phase occurs at TG~40 K and disorder produced by Mn impurity in quantum spin chains of CuGeO3 may lead to co-existence of the QC regime and spin-Peierls dimerisation.Comment: 2 pages, submitted to SCES05 proceeding

Enhanced spin-orbit coupling in core/shell nanowires

The spin-orbit coupling (SOC) in semiconductors is strongly influenced by structural asymmetries, as prominently observed in bulk crystal structures that lack inversion symmetry. Here, we study an additional effect on the SOC: the asymmetry induced by the large interface area between a nanowire core and its surrounding shell. Our experiments on purely wurtzite GaAs/AlGaAs core/shell nanowires demonstrate optical spin injection into a single free-standing nanowire and determine the effective electron g-factor of the hexagonal GaAs wurtzite phase. The spin relaxation is highly anisotropic in time-resolved micro-photoluminescence measurements on single nanowires, showing a significant increase of spin relaxation in external magnetic fields. This behavior is counterintuitive compared to bulk wurtzite crystals. We present a model for the observed electron spin dynamics highlighting the dominant role of the interface-induced SOC in these core/shell nanowires. This enhanced SOC may represent an interesting tuning parameter for the implementation of spin-orbitronic concepts in semiconductor-based structures