Optimized Coplanar Waveguide Resonators for a Superconductor-Atom Interface

We describe the design and characterization of superconducting coplanar waveguide cavities tailored to facilitate strong coupling between superconducting quantum circuits and single trapped Rydberg atoms. For initial superconductor-atom experiments at 4.2 K, we show that resonator quality factors above $10^4$ can be readily achieved. Furthermore, we demonstrate that the incorporation of thick-film copper electrodes at a voltage antinode of the resonator provides a route to enhance the zero-point electric fields of the resonator in a trapping region that is 40 $\mu$m above the chip surface, thereby minimizing chip heating from scattered trap light. The combination of high resonator quality factor and strong electric dipole coupling between the resonator and the atom should make it possible to achieve the strong coupling limit of cavity quantum electrodynamics with this system.Comment: 4 pages, 4 figure

A low noise 410-495 GHz Nb/Al/sub 2/O/sub 3//Nb SIS waveguide mixer

The noise and gain of a heterodyne waveguide mixer using Nb/Al/sub 2/O/sub 3//Nb superconducting tunnel junctions were measured in the 400-500-GHz frequency range. Three different arrays of two junctions in series are analyzed. The minimum receiver noise temperature is 120 K DSB at 480 GHz, measured with an array having integrated tuning stubs. The authors compare data of the pumped I-V curves with the Werthammer-Tucker theory and demonstrate an excellent agreement at frequencies up to 500 GHz. For an array without integrated tuning stubs. a mixer noise temperature of 90+or-30 K and a DSB mixer gain of -12.5+or-0.6 dB were measured. A comparison of the measured gain versus bias voltage with the quantum theory of mixing shows good qualitative agreement, indicating the applicability of this theory to Nb tunnel junctions up to 500 GHz. The noise temperature of an array with a lower gap voltage is 220 K at 495 GHz. This frequency is 85% of the reduced gap frequency, indicating that Nb superconductor insulator-superconductor (SIS) mixers can be used up at least the gap frequency of 680 GHz.< &gt

Goodwill Impairment: A study of Australian Companies 2007 - 2013

Abstract: This thesis explores the goodwill impairment practices of Australian companies from 2007 – 2013 to ascertain what impact, if any, that the Global Financial Crisis may have had on goodwill value. The thesis also examines determinants of goodwill and whether there is any evidence of earnings management associated with non-impairment of goodwill. The findings contained within this thesis would be useful to accounting practitioners, auditors, academics, policy makers and regulators to gain an understanding of how and why firms choose to impair. The thesis is presented in seven chapters. Chapter one provides an introduction to the outline of the thesis including justification for the research and its relationship to practice based outcomes. Chapter two provides a background to the current goodwill environment and then reviews the extant literature surrounding goodwill and impairment, including agency theory, earnings management and signaling theory. Chapter three provides a technical review of the accounting standards surrounding goodwill and impairment and considers conceptual incongruities within the standards related to internally generated goodwill. Chapter four provides a breakdown of the sample selection and goodwill impairment from 2007 – 2013 using a sample of 237 All Ordinaries listed companies and observes non impairment in 35% of the sampled companies. Chapter five examines potential determinants of goodwill impairment using step-wise regression and identifies a number of factors that increase the likelihood of impairment. Chapter six explores non impairment and finds evidence to support both earnings management and internally generated goodwill being subsumed into acquired goodwill. Chapter seven then concludes the thesis by summarising the findings and suggests potential areas of future research