Resonance phenomena in ultracold dipole-dipole scattering

Elastic scattering resonances occurring in ultracold collisions of either bosonic or fermionic polar molecules are investigated. The Born-Oppenheimer adiabatic representation of the two-bodydynamics provides both a qualitative classification scheme and a quantitative WKB quantization condition that predicts several sequences of resonant states. It is found that the near-threshold energy dependence of ultracold collision cross sections varies significantly with the particle exchange symmetry, with bosonic systems showing much smoother energy variations than their fermionic counterparts. Resonant variations of the angular distributions in ultracold collisions are also described.Comment: 19 pages, 6 figures, revtex4, submitted to J. Phys.

Low-loss criterion and effective area considerations for photonic crystal fibers

We study the class of endlessly single-mode all-silica photonic crystal fibers with a triangular air-hole cladding. We consider the sensibility to longitudinal nonuniformities and the consequences and limitations for realizing low-loss large-mode area photonic crystal fibers. We also discuss the dominating scattering mechanism and experimentally we confirm that both macro and micro-bending can be the limiting factor.Comment: Accepted for Journal of Optics A - Pure and Applied Optic

Can spacetime curvature induced corrections to Lamb shift be observable?

The Lamb shift results from the coupling of an atom to vacuum fluctuations of quantum fields, so corrections are expected to arise when the spacetime is curved since the vacuum fluctuations are modified by the presence of spacetime curvature. Here, we calculate the curvature-induced correction to the Lamb shift outside a spherically symmetric object and demonstrate that this correction can be remarkably significant outside a compact massive astrophysical body. For instance, for a neutron star or a stellar mass black hole, the correction is $\sim$ 25% at a radial distance of $4GM/c^2$, $\sim$ 16% at $10GM/c^2$ and as large as $\sim$ 1.6% even at $100GM/c^2$, where $M$ is the mass of the object, $G$ the Newtonian constant, and $c$ the speed of light. In principle, we can look at the spectra from a distant compact super-massive body to find such corrections. Therefore, our results suggest a possible way of detecting fundamental quantum effects in astronomical observations.Comment: 13 pages, 3 figures, slight title change, clarifications and more discussions added, version to be published in JHE

An Atom Laser with a cw Output Coupler

We demonstrate a continuous output coupler for magnetically trapped atoms. Over a period of up to 100 ms a collimated and monoenergetic beam of atoms is continuously extracted from a Bose- Einstein condensate. The intensity and kinetic energy of the output beam of this atom laser are controlled by a weak rf-field that induces spin flips between trapped and untrapped states. Furthermore, the output coupler is used to perform a spectroscopic measurement of the condensate, which reveals the spatial distribution of the magnetically trapped condensate and allows manipulation of the condensate on a micrometer scale.Comment: 4 pages, 4 figure

BNCI systems as a potential assistive technology: ethical issues and participatory research in the BrainAble project

This paper highlights aspects related to current research and thinking about ethical issues in relation to Brain Computer Interface (BCI) and Brain-Neuronal Computer Interfaces (BNCI) research through the experience of one particular project, BrainAble, which is exploring and developing the potential of these technologies to enable people with complex disabilities to control computers. It describes how ethical practice has been developed both within the multidisciplinary research team and with participants. Results: The paper presents findings in which participants shared their views of the project prototypes, of the potential of BCI/BNCI systems as an assistive technology, and of their other possible applications. This draws attention to the importance of ethical practice in projects where high expectations of technologies, and representations of “ideal types” of disabled users may reinforce stereotypes or drown out participant “voices”. Conclusions: Ethical frameworks for research and development in emergent areas such as BCI/BNCI systems should be based on broad notions of a “duty of care” while being sufficiently flexible that researchers can adapt project procedures according to participant needs. They need to be frequently revisited, not only in the light of experience, but also to ensure they reflect new research findings and ever more complex and powerful technologies

A Peer-reviewed Newspaper About_ Post-digital Research

Post-digital Research addressed the messy and paradoxical condition of art and media after digital technology revolutions. Publication resulting from research workshop at Kunsthal Aarhus, in collaboration with Kunsthal Aarhus, and trans,ediale festival for art and digital culture, Berlin

Deriving and critiquing an empirically-based framework for pharmaceutical ethics.

Background: The pharmaceutical industry has been responsible for major medical advances, but the industry has also been heavily criticized. Such criticisms, and associated regulatory responses, are no doubt often warranted, but do not provide a framework for those who wish to reason systematically about the moral dimensions of drug development. We set out to develop such a framework using Beauchamp and Childress’s “four principles” as organizing categories. Methods: We conducted a qualitative interview study of people working in the “medical affairs” departments of pharmaceutical companies to determine: (1) whether our data could meaningfully be organized under the headings of “autonomy,” “beneficence,” “nonmaleficence,” and “justice”; (2) how principles might be expressed in this particular commercial setting; and (3) if these principles are expressed, whether and how competing principles are balanced. We then critiqued these findings using existing normative theory. Results: Our interviews demonstrated that three of Beauchamp and Childress’ four principles were salient to our participants: beneficence, non-maleficence, and justice. Within each of these principles, participants had two broad ethical orientations: an altruistic public focus (“other-ness”) and a commitment to their companies (“firm-ness”). Our participants also demonstrated efforts to balance these principles and highlighted the importance of phronesis (or practical wisdom) in balancing and enacting principles. Notably, however, our participants did not spontaneously emphasize the importance of autonomy. Conclusions: It is possible to use qualitative empirical research, together with normative analysis, to derive a framework for pharmaceutical ethics. We suggest that our framework would be useful for those who wish to reason ethically within, or in collaboration with, the pharmaceutical industry. Keywords: Empirical ethics, principle-based ethics, pharmaceutical industry, pharmaceutical ethics, qualitative researchNHMRC Career Development Fellowship APP106356

Cold-atom clock based on a diffractive optic

Clocks based on cold atoms offer unbeatable accuracy and long-term stability, but their use in portable quantum technologies is hampered by a large physical footprint. Here, we use the compact optical layout of a grating magneto-optical trap (gMOT) for a precise frequency reference. The gMOT collects 10 7 87Rb atoms, which are subsequently cooled to 20 µK in optical molasses. We optically probe the microwave atomic ground-state splitting using lin┴lin polarised coherent population trapping and a Raman-Ramsey sequence. With ballistic drop distances of only 0.5 mm, the measured short-term fractional frequency stability is 2 × 10 −11/√τ