PHYSICS SEMINARS

Are usually held

on: Tuesdays 3:30-4:30pm
in: Physics Lecture Room 2.15

For seminar information please contact
(08) 6488 2738

Upcoming Seminars in 2009

Thursday 12 November 2009
3.30-4.30pm
Room 2.15, Physics
Speaker: Chris Fulton (UWA)
Title: Analyses of the 2dF Deep Field

Abstract: We present comprehensive analyses performed on the 2dF deep field to show that high redshift extragalactic objects can be, and in many cases are, physically associated with low redshift extragalactic objects and that consequently redshifts are at least partly intrinsic and therefore not entirely due to doppler shift. We present observational, statistical, and theoretical arguments to support this claim.

We begin with technical and historical accounts of the interpretation of extragalactic redshifts and of observations of ejection and possibly related phenomena in galaxies. We next present the technical and logistical details of the computer-based work done to prepare for and perform the various analyses. We then give the detailed results of the testing done on the 2dF deep field as a whole, followed by detailed human-performed multi-wavelength analyses of individual quasar/galaxy systems that were detected by our computer algorithm.

Monday 23 November 2009
2.30-3.30pm
Room 2.15, Physics
Speaker: Prof. Doug Osheroff, Stanford University (Nobel Laureate)
Title: The Columbia Accident Investigation

Abstract: Human space flight is not and probably will never be a low risk activity. However, the two major space shuttle accidents that took the lives of fourteen brave and dedicated 'astronauts' were accidents that could and should have been avoided. In the Challenger accident it was clear that NASA knew that the rubber o-rings that sealed the solid rocket boosters (SRBs) tended to leak hot gases when the SRBs were first ignited, and since the SRB casings were recovered after launch, NASA knew that the o-rings were typically eroded one third of their thickness through by those hot gases. While this was not supposed to happen, it did repeatedly, and NASA began to believe that this was a normal part of the process by which the o-rings sealed. On January 28, 1986 NASA was informed by the maker of the SRBs that they should not launch in near freezing weather, but NASA management forced Morton Thiokol to over-rule its engineers and proclaim that the conditions did not make it 'unsafe' to launch. The speaker will describe a bit of the history surrounding the Challenger accident, but he was a member of the board that actually investigated the Columbia space shuttle accident.

The Columbia accident resulted from two strategic NASA errors. The first was that throughout the STS (space transportation system, or shuttle program) NASA had found that pieces of the foam that were applied to the external fuel tank (ET) for thermal insulation would separate from the ET upon launch, and often strike the thermal protection tiles on the undersides of the shuttle's wings. NASA was unable to stop this foam shedding, but regarded it as a maintenance issue, and not a safety issue, as typically only small pieces would separate from the ET. However, on six previous occasions NASA had found that rather large pieces of foam, some weighing over a pound, had fallen off the ET during launch. Just two flights before Columbia's last mission on November 16, 2002, a piece had struck one of the SRBs on Atlantis, close to an electronic control box near its base, and left a serious dent. However, NASA did little to remedy this situation, and less still to decide how much of a hazard was posed by these large pieces of foam. Nor did they recognize that the probability of a large piece of foam falling from the ET was considerably higher for Columbia than for any other orbiter. Based on ET separation photographs, it appeared that such events had occurred four times when Columbia was the orbiter, and only twice for all other orbiters combined.

The speaker will describe the Columbia accident in detail, and the efforts by the Columbia Accident Investigation Board (CAIB) to identify both the physical and organizational causes of this accident.

Friday 27 November 2009
3.30-4.30pm
Room 2.15, Physics
Speaker: Dr. Sean Barrett, Macquarie University
Title: Hardware and software approaches to building physically robust quantum computers

Abstract:

2009 SEMINAR HISTORY

Tuesday 3 November 2009
11.00-12.00
Room 2.15, Physics
Speaker: Dr. Sam Dawkins (University of Mainz, Germany)
Title: Fibre-pigtailed atoms

Abstract: Ensembles of laser-trapped atoms will likely be at the core of many future implementations of quantum devices. The physical implementation of this has to date typically involved atoms coupling with freely propagating light beams. This talk will present an alternative implementation: fibre-coupled atomic ensembles realised using tapered optical fibres with a nanofibre waist. In this technique, the evanescent fields of the fibre are used to both trap and interrogate about 2000 caesium atoms about 200 nm above the nanofibre surface of the fibre. It is anticipated that this approach could open a new perspective for the transmission and processing of quantum information via fibre-optical networks.

Wednesday 21 October 2009
1-2pm
Room 2.15, Physics
Speaker: Prof Ken Baldwin, ANU
Title: Metastable Helium:
Atom optics and precision measurement

Abstract: Helium – when excited to the metastable 2 triplet S state – possesses the longest lifetime of any excited neutral atom yet measured. We have determined this lifetime to the greatest precision thus far, and have also measured the lifetime of the 2 triplet P manifold for the first time. All these measurements are in excellent agreement with quantum electrodynamic (QED) theory.

Atoms in the metastable state are also useful for experiments aimed at understanding the quantum behaviour of matter waves. We have created a Bose-Einstein condensate (BEC) of metastable helium atoms, from which we have developed a metastable helium atom laser. We have been able to guide the atom laser in a dipole potential which has created the analogue of single mode optical fibre guiding for matter waves. We have also been able to image atomic speckle for the first time. The single mode guiding of atomic de Broglie waves may lead to future applications, such as the realisation of more sensitive atom interferometers.

Thursday 24 September 2009
12-1pm
Ross Lecture Theatre, G41 Physics
Speaker: Dr. Tom Stace, University of Queensland
Title: Quantum Computers still work with half their Bits missing

Abstract: Imperfections and errors in any computer can lead to incorrect results. This problem is even more pronounced when the computer relies on quantum mechanical coherences, i.e. for quantum computers. However, there are methods for doing computation in spite of the fact that real devices are never perfect, and rely on error correction. In a quantum computer, errors are classified as computational errors, in which the logical state of the quantum bit suffers an uncontrolled change; or loss errors, in which the quantum bit is taken out of the computational space completely – it is lost. This talk will give an overview of topological error correction, which is a beautiful approach to error detection and correction, and how it is extremely robust against both classes of errors.

Tuesday 15 September 2009 3:30-4:30pm
Physics Lecture Room 2.15
Speaker: Prof. Yanbei Chen
(California Institute of Technology, USA)
Title: Quantum noise in laser-interferometer gravitational-wave detectors and macroscopic quantum mechanics

Abstract: Current gravitational-wave detectors are operating at a factor of ~10 above the Standard Quantum Limit, which arises from the Heisenberg Uncertainty Principle – as applied to ~10 kg test masses. With the reduction of classical (e.g., thermal, seismic, etc.) noises and the increase of laser power, the SQL may pose a challenge toward the future improvement of detector sensitivity. I will first discuss strategies that allow us to circumvent the SQL while still keeping the optical design practical for km-scale interferometers. I will then motivate the possibility of using gravitational-wave experiments to demonstrate and explore quantum mechanical behaviours of macroscopic test masses – and possible (although I believe very unlikely) deviations.

Tuesday 28 July 2009 3:30-4:30pm
Physics Lecture Room 2.15
Speaker: Professor David McKenzie
(University of Sydney)
Title: The Linear Quadratic Model for Describing the Effects of Radiation on Cell Survival

Abstract

The linear quadratic model is a well accepted empirical model for describing the effects on living cells of radiation. The linear term describes lethal damage and the quadratic term describes "latent" damage that can combine to become lethal. The model has been extended to include the effects of repair of latent damage and in this form predicts that the time course of a radiation exposure effects the outcome as well as the dose delivered. In this talk some predictions will be made that have been tested experimentally. Implications for the treatment of cancer will be discussed.

About the speaker

Professor David McKenzie is based at the University of Sydney. He has made substantial contributions to the science of biomaterials, especially carbon based and polymer biomaterials, and their applications in medicine and biology. In collaboration with colleagues in Physics and Biochemistry, he has developed a technology for the covalent immobilisation of proteins on surfaces. This technology is being developed for use with cardiovascular stents, antibody array technologies and biosensors. In collaboration with Ventracor Ltd he has developed forms of amorphous carbon suitable for biocompatibility applications and one of the coatings performs well as the protective coating on the interior of the Ventracor ventricular assist device, a lifesaving device for assisting patients with chronic heart failure, which entered clinical trials in 2003.

Professor McKenzie became involved in radiotherapy physics in the early 2000's when, in collaboration with A/Prof Suchowerska, he developed a new type of fibre optic dosimeter system which has enabled such dosimeters to be used for radiotherapy dose verification. He has also been involved in investigations of basic tumour response mechanisms including bystander effects, and now has a collection of publications in radiotherapy physics.

Professor McKenzie is an ISI "highly cited" researcher. He has received awards for the impact of his published work, the most recent being as an ISI Citation Laureate.

Tuesday 30 June 2009 3:30-4:30pm
Physics Lecture Room 2.15
Speaker: Dr. Gerhardt Meurer
(Johns Hopkins University)

Abstract: I will show results and ongoing work from the Survey of Ionization in Neutral Gas Galaxies (SINGG) and the Survey of Ultraviolet emission in Neutral Gas Galaxies (SUNGG) which survey the star formation properties of galaxies as traced by H-alpha and Ultraviolet emission, respectively. Our simple HI only selection criteria results in a sample that captures all types of star forming galaxies, while the use of two star formation tracers gives us sensitivity to the Initial Mass Function. Our team has found strong correlations between the Halpha/FUV flux ratio and the optical surface brightness of galaxies. The only plausible explanation of this result is that the IMF is not constant. This result has enormous implications for galaxy evolution in both the near and distant universe. Our sample also shows strong correlations between the HI, star-formation, and old stellar population properties of galaxies. These scaling relations are tighter than the Kennicutt-Schmidt Star Formation Law. The existence of an HI - star formation connection has been somewhat of a mystery since stars form in the molecular not the neutral ISM, while the highest mass stars and the HI have very different distributions in galaxies. I will argue that the IMF and the other star formation scaling relations result from pressure-regulated star-formation in a disk maintained at near critical dynamical stability.

Tuesday 23 June 2009 3:30 - 4:30 pm
Physics Lecture Room 2.15
Speaker: Dr. Brian O'Brien
Title: Apollo and Moon Dust - From Unknown Unknowns in 1966 to Known Unknowns in 2009

Abstract: This talk covers developments in scientific knowledge of dust on the moon from 1965 when 7 experiments were chosen from 90 proposals to be part of the Apollo Lunar Surface Experiments Package (ALSEP) put on the moon as a remote scientific observatory transmitting 1 watt of information back to Earth for a nominal two years. Because neither NASA nor aerospace contractors made any proposal to measure lunar dust, Prof. O’Brien invented a minimalist, matchbox-sized Dust Detector Experiment (DDE) to hitch-hike a ride as part of his risk-management plan for his selected Charged Particle Lunar Environment Experiment (CPLEE), a part of his rocket and satellite studies of auroral and magnetospheric phenomena. A DDE was one of only two active scientific instruments deployed by Buzz Aldrin on Apollo 11 in July 1969. The other was a 47 kg Passive Seismometer (to measure moonquakes), which overheated and failed prematurely.

O’Brien published DDE results in J. Appl. Phys. Oct. 1970 showing contamination by dust and debris thrown up by rocket exhausts of the Lunar Module as Armstrong and Aldin departed. NASA SP-214 claimed no significant effect occurred. Other DDEs flew on Apollo 12 to 15. In 2006 NASA web-site www.nssdc.nasa.gov revealed that original computer tape records of DDE data had been misplaced. So O’Brien revisited his personal files, including 173 computer tapes, and published his latest paper on 6 May 2009 in Geophysical Research Letters. This gives the first hard data of in situ lunar measurements of effects of rocket exhausts and natural phenomena causing movements of lunar dust, so that extensive theoretical modelling and hypotheses can now be tested. Further publications are pending. Further riches are in 6 million DDE measurements and being able to read once-again the 40-year-old 7-track 10-inch computer tapes that were the “bees-knees” in 1969. NASA invited O’Brien to give two papers at the 2nd Lunar Science Forum at NASA Lunar Science Institute 21-23 July 2009. This Seminar is an adapted preview of these talks.

Friday 29 May 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: A/Prof. Christine Charles
(Australian National University)
Title: To planets or just to the shops, Plasmas pave the path

Abstract: Plasmas have existed since the very first moments of the Universe. It is the stuff of stars. It fills the space between stars. It gives us the beautiful northern and southern aurorae. Our houses have plasma TV displays, plasma lights (fluorescent tubes).Everywhere we look, there is plasma. But we stand on solid earth and the solid state accounts for less than one percent of the total mass of the Universe. The rest is plasma, a hot ionised gas containing positive and negative charges (except, perhaps, for dark matter). By properly harnessing the plasma state we can make microchips for computers, we can make plasma engines (thrusters) to get to the planets and we can make fuel cells to take people just down to the shops. The discovery in Australia of a current-free electric double layer (a cliff of potential like a river waterfall which energise charged particles falling through them) in a laboratory plasma is the basis of a new space engine: the Australian Helicon Double Layer Thruster.

Tuesday 26 May 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: Dr. Mark Baxendale
(Queen Mary, University of London)
Title: Carbon Nanotubes: The Building Blocks of Nanotechnology?

Abstract: There has been a large worldwide research into this fascinating macromolecule since discovery in 1992. Currently there are c.7000 publications per year in the physical, chemical, and life sciences devoted to the fundamental science and applications of carbon nanotubes. Carbon nanotubes have attracted the label ‘building blocks of nanotechnology’. The degree of interest stems from the unique physical attributes that follow from sp2 bonding and low dimensionality. This talk gives on overview of developments and the contribution made to the advancement of nanotechnology with an emphasis of the research activity at Queen Mary University of London.

Tuesday 19 May 2009 3:30-4:30pm
Physics Lecture Room 2.15
Speaker: Prof. Frederico Rosei
(Université du Québec)
Title: Strategies for controlled assembly at the nanoscale

Abstract: The bottom

–up approach is considered a potential alternative for low cost manufacturing of nanostructured materials. It is based on the concept of self–assembly of nanostructures on a substrate. We propose various strategies to control nanostructure assembly (both organic and inorganic) at the nanoscale. Our approach includes:
(i) deposition on naturally patterned substrates, which exploit long–range reconstructions;
(ii) we are able to control the size and luminescence properties of semiconductor nanostructures, synthesized by reactive laser ablation;
(iii) we have developed new experimental tools and comparison with simulations are presented to gain atomic scale insight into the surface processes that govern nucleation, growth and assembly;
(iv) by controlling inter- molecular interactions, we demonstrate that it is possible to create specific nanoscale patterns;
(v) we developed a simple surface modification strategy for biomaterials which enhances biocompatibility.

Tuesday 12 May 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: Dr Robert Braun (CSIRO, ATNF)
Title: Rotation Measure Synthesis of Nearby Galaxy Disks

Abstract: We present results of the first extensive survey of magnetic field structures within nearby galaxy disks employing the so-called "Rotation Measure Synthesis" method. This method permits the coherent detection of linearly polarized radio continuum emission over large fractional bandwidths while simultaneously assessing the degree of Faraday rotation experienced by the radiation along each line-of-sight. Of the 28 galaxies in the sample, 21 are detected in polarized radio continuum at 18- and 22-cm wavelengths in images that reach a sensitivity of about 10 microJy/beam. The most prominent trend that is seen across the sample is a systematic modulation of the brightest detected polarized intensity with galactic azimuth, such that a global minimum in the polarized intensity is seen toward the kinematically receding major axis. The implied large-scale magnetic field geometry is that of a family of conical spirals that open toward the observer in all cases. This emission is likely to arise from only the nearest side of each galaxy disk. A much fainter component of polarized emission is detected in several galaxies that is likely the rearward facing counterpart. This second component suffers substantial Faraday depolarization and rotation while passing through the galaxy mid-plane. A second novel result is the detection of multiple nuclear Faraday depth components that are offset to both positive and negative RM by 100-200 rad/m**2 in all targets that host polarized (circum-)nuclear emission. The implication is that such emission must routinely span the site of (presumably) nuclear field reversal.

Thursday 30 April 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker:Professor John Close
(The Australian Centre for Quantum Atom Optics, ANU)

Abstract: This talk is an introduction to Bose Einstein condensation, the atom laser and their application to precision measurement in fundamental and applied physics. The atom laser is the direct analogue of the optical laser. Both produce a highly coherent, bright beam of Bosons that can be focussed, diffracted, and interfered. Both are based on Bose enhanced scattering for their operation. In both cases, we have the opportunity to manipulate the quantum field that describes the output beam to perform precision measurements at sensitivities that exceed the shot noise quantum limit. I will discuss our recent research on the development of the first pumped atom laser and its application to precision measurement. I will also discuss some new experiments we are performing to squeeze the quantum noise on an atom laser and the relevance of these experiments to precision measurement.

Tuesday 21 April 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: Dr Tobias Westmeier (ATNF)
Title: Structure formation and galaxy evolution in group and cluster environments

Abstract: Broadband Radio Observations of Local Groups with ASKAP (BROLGA) is a proposed large survey science project for the Australian SKA Pathfinder (ASKAP). The aim of BROLGA is to carry out sensitive and large-scale observations of nearby galaxy groups and clusters in both the 21-cm line of neutral hydrogen as well as radio continuum emission. The survey will allow us to study the effects of structure formation, galaxy evolution, and feedback processes in group and cluster environments in unprecedented detail. Major scientific goals of BROLGA include (1) the study of tidal interaction and accretion in group and cluster environments, (2) search for unknown and dark satellites, (3) study of the cosmic web in HI and radio continuum, (4) determination of the structure and dynamics of galaxies in groups and clusters, (5) study of mechanisms to induce or suppress star formation in galaxies, and (6) study of magnetic fields in galaxies and their environment. I will introduce the basic observational parameters of BROLGA and then motivate the different science drivers and discuss their impact on our current understanding of galaxy evolution and feedback mechanisms between galaxies and their environment. Throughout my talk I will also present new results of our precursor studies of the Sculptor Group at optical and radio wavelengths.

Tuesday 7 April 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: Dr Martin Zwaan (ESO)
Title: The Atacama Large Millimeter/submillimeter Array (ALMA): project overview and science prospects

Abstract: The Atacama Large Millimeter/submillimeter Array (ALMA) is a telescope under construction in northern Chile by Europe, North America, East Asia, Chile and partners. ALMA will be situated on the high altitude Chajnantor plateau, which provides excellent atmospheric transmission over the instrument's wavelength range of 0.3 to 3 mm. ALMA will be comprised of an array of 12-m diameter antennas arranged in multiple configurations ranging in size from 0.15 to 14 km, and a closely-packed array of 7-m diameter antennas known as the Atacama Compact Array. This combination will provide sensitive interferometric and total-power astronomical information over a broad range of angular scales. Array control and support will primarily be carried out at the Operations Support Facility at 3000m, and ALMA Regional Centers in Europe, the US and East Asia will provide the scientific portals for the use of the instrument. In this talk I will present an overview of the ALMA project, its key components and science goals.

Tuesday 31 March 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: Professor Tim St Pierre
Title: Biogenic Magnetic Nanoparticles and Nanostructures in Human Disease

Tuesday 24 March 2009 3.30 – 4.30pm
Physics Building Lecture Room 2.15
Speaker: Peter Metaxas
Title:"From inkblots to MRAMs: magnetic domain wall motion in disordered structures"

Abstract: A knowledge of how elastic interfaces propagate through disordered materials is vital in understanding the properties of a myraid of physical systems, ranging from vortices in superconductors to coffee stains on paper. Magnetic domain walls, the boundaries between domains in ferromagnetic films, are another example of intrinsically elastic objects. Interacting with structural inhomogeneities in the films in which they move, they represent an almost perfect system in which to study interface dynamics in disordered media. In this presentation, I will discuss the work carried out during my PhD, presenting measurements of domain wall motion in both single layer and multilayer magnetic structures, the latter having applications for magnetic memory devices (MRAMs). I'll consider first the various dynamic regimes exhibited by domain walls in single layer systems and show how it is possible to extract information about both disorder-induced pinning and intrinsic dissipation. In terms of multilayer structures, I will present the results of experiments on dynamically bound walls, where domain walls in separate layers propagate together. The effect of ordered periodic pinning potentials, generated non-destructively, will also be considered.

Tuesday 17 March 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: Professor Simon Driver (University St. Andrews)
Title: "Galaxy And Mass Assembly" (GAMA)

Abstract: I will introduce a new galaxy survey (GAMA) which will combine the data flows from a number of the worlds latest ground-based and space-based facilities (AAT/AAOmega, VST, VISTA, GALEX, HERSCHEL, GMRT, ASKAP, VLT) to produce the next generation nearby galaxy database. The motivation is two-fold: Firstly to conduct a number of specific tests of the Cold Dark Matter concept for galaxy formation; and secondly, to provide the best possible resource for the international extragalactic community to use to study the evolution of the stellar, dust, and gas content of galaxies over the most recent 4 billion year timeline. The specific tests of CDM galaxy formation include measuring the Halo Mass Function, galaxy merger rates, and the stellar mass function. The more generic databases will provide measurements of the energy outputs of ~250k galaxies from the UV to radio wavelengths, key optical spectral line features, structural decompositions, and dynamical profiles/markers

Tuesday 10 March 2009 3:30 - 4:30pm
Physics Lecture Room 2.15
Speaker: Dr Jean-Pierre Marquart (Curtin)
Title: Sub-AU imaging of turbulent structures in the Interstellar Medium

Abstract: Turbulence in the ionized Interstellar Medium (ISM) of our Galaxy scatters the radio emission of some pulsars so heavily that their radiation undergoes multipath propagation, so that their scattered images contain thousands of sub-images, or speckles, of the pulsar. We have developed a technique to construct the first-ever speckle image of a highly scattered pulsar. This probes the underlying magneto-hydrodynamic turbulence of the ISM on scales ~0.01 to 20 AU and has revealed several unexpected features. The most striking is the presence of a highly inhomogeneous object located ~10AU off-axis whose properties are consistent with an Extreme Scattering Event (ESE) cloud. ESE clouds are also implicated in large (10-50%), one-off flux density excursions of some radio quasars. Their existence is problematic because the electron densities implied by simple models require the clouds to be ~10^3 times overpressured with respect to the ambient ISM; such clouds would appear be very short-lived and much less prevalent than is observed. We discuss the properties of ESE clouds as revealed by our observations. We also discuss the relevance of similar off-axis clouds to precision pulsar timing arrays, especially those trying to detect gravitational radiation.

Tuesday 24 February 2009 3:30-4:30pm
Physics Lecture Room 2.15
Speaker: Dr. Giorgio Santarelli (LNE-SYRTE, Observatoire de Paris)
Title: "Ultra stable optical cavities and high-resolution optical frequency dissemination on a telecommunication network"

Abstract: After a short overview on the laboratory activities I will focus on the Optical Metrology group developments and in particularly on 2 hot topics:

Laser stabilisation on ultra stable optical cavities Ultra-stable laser light is a key element for a variety of applications ranging from optical frequency standards, tests of relativity, generation of low phase noise microwave signals to gravitational wave detection. I will present the details of designs for an ultra stable optical cavity for laser stabilization. Finite Element Modelling analysis is used to predict and subsequently decrease the influence of vibrations on these stabilized laser cavities. Measurements of the two independent cavity stabilized lasers show a relative frequency stability of 7 × 10-16 between 1s and 10s.

Optical transfer of ultra stable optical signals fiber networksThe transfer of ultra-stable frequencies between distant laboratories is an important issue for a large number of high-sensitivity experiments in metrology and fundamental physics, for example tests of the temporal stability of fundamental constants. I will present a new approach for ultrastable frequency transfer which consists in using the already existing optical telecommunication network and transmitting the optical frequency reference together with the internet data traffic, the transmission of an optical frequency reference over 108 km carrying simultaneously digital data is demonstrated. This opens the way to a wide dissemination of ultra stable optical clock signals between distant laboratories via the Internet network

Tuesday 10 February 2009 - 3.45pm
Physics Building Lecture Room 2.15
Speaker: Dr Ivan Baldry
(Liverpool, John Moores University)
Title: "Accounting for stellar and baryonic mass in the galaxy population: Checks and balances"

Abstract: I will describe recent measurements of the galaxy stellar and baryonic mass functions in the context of the current cosmological paradigm: where are all the baryons? I will conclude with prospects of definitive measurement of galaxy mass functions, with the recently started survey GAMA and future surveys, such as with ASKAP

Wednesday 4 February 2009 - 3.15pm
Physics Building Lecture Room 2.15
Speaker: Dr Andrew Hopkins
Title: "Progress and Opportunities at the Anglo Australian Observatory"

Abstract: Recent developments at the AAO on both scientific and instrumentation fronts will be presented. These include research results from AAO staff, an overview of the ongoing AAT Large Programs (Anglo-Australian Planet Search, WiggleZ, GAMA), progress on the WFMOS concept study, the HERMES instrument, and a striking demonstration of the OH suppression fibre technology. Opportunities for students at the AAO will also be highlighted, including PhD top-up scholarships, as well as the currently open Magellan Fellow positions.

Monday 12 January 2009 - 3.00pm
Physics Building Lecture Room 2.15
Speaker: Professor Jeremy O'Brien (University of Bristol)
Title: "Quantum Information Science Using Photons on a Chip"

Abstract: We have developed an integrated waveguide approach to photonic quantum circuits [1]. We demonstrate high-fidelity silica-on-silicon integrated optical realizations of key quantum photonic circuits, including two-photon quantum interference with a visibility of 94.8(5)%; a controlled-NOT gate with an average logical basis fidelity of 93.3(2)%; and a path entangled state of two photons, relevant to quantum metrology, with fidelity >92%. We use these devices to demonstrate multi-photon effects relevant to quantum metrology [2] and quantum information processing [3]. The monolithic nature of these devices means that the correct phase can be stably realized in what would otherwise be an unstable interferometer, greatly simplifying the task of implementing sophisticated photonic quantum circuits. We fabricated 100’s of devices on a single wafer and find that performance across the devices is robust, repeatable and well understood.

[1] A. Politi, M. J. Cryan, J. G. Rarity, S. Yu, J. L. O’Brien, Science 320, 646 (2008)

[2] T. Nagata, R. Okamoto, J. L. O. Brien, K. Sasaki, S. Takeuchi, Science 316,72(2007)

[3] J. L. O’Brien, Science 318, 1567 (2007)

2008 SEMINAR HISTORY

Tuesday 18 November 2008 3.30 -4.30pm
Physics Building Fifth Floor Tea Room
Speaker:Dr John Wojdylo
Title: "On the Physics of Dilute Ultracold Atoms - How to Tune the Strength and Sign of their Interaction to Anything you Want"

Abstract: The achievement of Bose-Einstein condensation in 1995, and of Fermi degeneracy in 1999-2001, in dilute, ultracold gases opened a new chapter in atomic and molecular physics, in which particle statistics and particle interactions, rather than the study of single atoms or photons, takes centre stage. The main focus until recently has been the exploration of the many phenomena associated with coherent matter waves. In the last few years, however, two major developments have considerably enlarged the range of physics that is accessible with ultracold gases. These are: (1) the ability to tune the interaction strength by exploiting Feshbach resonances; and (2) the use of optical potentials to create restricted geometries (as well as strongly-periodic potentials) that are, moreover, friendly to theorists. In this seminar, I will explain some basic ideas in the physics of ultracold, dilute atoms; illuminate the effect of restricted geometry on the atomic interaction; and highlight a recent theoretical success: Confinement Induced Resonance in cylindrical atomic waveguides, predicted by Maxim Olshanii in 1998, was confirmed by experiment in 2005.

Tuesday 11 November 2008 3.30 -4.30pm
Physics Building Fifth Floor Tea Room
Speaker: Professor Lister Staveley-Smith (UWA)
Title: "How to be a Radio Astronomer"

Abstract: Modern radio astronomy has its roots in experimental and theoretical physics. However, the emphasis on observation as opposed to experimentation, combined with the sparseness of data, make for some interesting differences in approach. I will present some historical radio astronomy results, and illustrate the practice of modern radio astronomy with some examples of projects I am currently working on, including measuring signals from galaxies in cases where the noise exceeds the signal strength, looking for giant oscillations in space, and monitoring the continuing exponential rise of the radio flux density from Supernova 1987A. Finally, I'll discuss the likely scientific impact of the forthcoming generation of new WA-based radio telescopes. 2009 is the International Year of Astronomy, so this is your chance to check up on some local astronomical research activity and understand how, when and where radio astronomers conduct their research!

Tuesday 4 November 2008 3.30 -4.30pm
Physics Building Room 2.15
Speaker: Dr Ilana Feain (CSIRO-Australia Telescope National Facility)
Title: "A long overdue synthesis image of Centaurus A"

Abstract: Centaurus A is a spectacular giant radio galaxy that can be viewed by the naked eye in very dark skies. It is by far the closest galaxy in the Universe with an active, supermassive black hole and would be among the best-studied of all astronomical sources. I will present some preliminary results of our imaging survey to create the first full aperture synthesis image of Centaurus A at radio wavelengths. I will show the images and discuss a particular (preliminary) result based on the polarisation properties of the compact extragalactic radio sources behind the lobes of Centaurus A.

Friday 31 October 2008 2.00 - 3.00pm
Physics Building Room 2.15
Speaker: Dr Maxim Voronkov (Australia Telescope National Facility)
Title: "Studies of methanol masers with ARNF Facilities"

Abstract: Methanol molecule is responsible for the largest number of spectral lines in the range of frequencies, which can be observed by ATNFinstruments. Some of these transitions are known to produce bright masers in the regions of massive star-formation. Different maser transitions don't share the same behavior because they are excited under different circumstances. It is well established that the collisional pumping is responsible for the masers at, for example, 44 GHz (also known as class I masers), while the other group of transitions (also known as class II masers like that at 6.7 GHz) are excited by radiation. It has also been suggested that there is a link between evolutionary stage of the star formation and the types of methanol masers observed. I will review the results of a number of methanol maser surveys carried out with ATNF facilities and the plans for future observations.

Tuesday 21 October 2008 (3:30-4:30pm)

Physics Building Room 2.15

Speaker: Stuart Napier

Title: Electron correlation effects in zinc activated by inner-shell excitation.

Abstract: The most successful theoretical treatments of atom-electron collisions rely on the "frozen-core" approximation, where only the outermost atomic electrons participate in the scattering process. However for zinc, which has an outermost electron configuration of 3d^104s^2, there is interaction and interdependence between the the outermost 4s shell and the inner 3d shell. As a result, electron- electron interactions (or electron correlations) associated with the excitation of an inner-shell, 3d electron are very significant for electron scattering from zinc. This can be seen, for example, in the strong influence that phenomena such as negative-ion resonance and postcollision interaction have on electron-zinc scattering near the threshold for 3d excitation. This talk will present an experimental investigation of the electron correlation effects associated with 3d excitation.

Tuesday 14 October (3.30 - 4.30pm)

Speaker:Professor David Blair (UWA)

Title: "Opto-acoustic Parametric Amplifiers, Quantum Cooling and Gravitational Wave Detectors"

Abstract: The UWA gravitational wave research group is developing technology for the next generation of gravitational wave detectors. In 2005 members of the UWA group showed theoretically that advanced gravitational wave detectors would have a high risk of experiencing at type of opto-acoustic interaction described as a three mode parametric instability. We first thought that the problem was exclusively related to the enormous optical cavities required for gravitational wave detectors. In 2006 we observed the predicted interaction at the high optical power laboratory at Gingin, and now we have worked out how to harness it. We have designed small scale devices called Opto-acoustic parametric amplifiers (OAPA). One is being developed in Paris and another at UWA. The OAPA allow the direct amplification of sound with light, with ability to detect ultrasound at the single phonon level. Perhaps of greater interest, they can be used as negative feedback amplifiers to cool acoustic resonators to the quantum ground state, and to create entangled photon-phonon pairs. These ideas also provide a method for suppressing the predicted instabilities in advanced gravitational wave detectors. This talk will introduce and review work done by many members of the UWA gravitational waves group, and show how we have turned a severe problem into a useful new tool.

3.30pm, Monday 13 Oct 2008 15:30

Venue: Physics Building Tea Room on 5th Floor

Speaker: Rajaram Nityananda (NCRA Director)
Title: Overview of GMRT-science

Abstract: A general overview of what's happening at GMRT - science, ongoing upgrades of feeds/ receivers, and also time allocation for large projects.

3:30pm, Tuesday 7 October 2008

Venue: Physics Seminar Room 2.15

Speaker: Prof. Martin A. Hendry (University of Glasgow)

Title: "Cosmological Distance Indicators: Past, Present and Future"

Abstract: The study of the cosmic distance scale has a long and illustrious history in astronomy, stretching back to the pioneering work of Edwin Hubble himself. Within the past 15 years observations with the Hubble Space Telescope have greatly improved our calibration of the distance scale, largely removing the factor of two uncertainty in the expansion rate of the Universe which previously dogged cosmology for decades.

Meanwhile the focus of attention has switched to cosmological distance indicators at higher redshift, and their use in constraining the nature and distribution of dark energy. Despite entering this new and exciting phase, however, many of the classic statistical issues that fuelled the old "factor of two" controversy are still present, and their impact on the calibration and use of high-redshift distance indicators is now an important topic.

In this talk I will review recent progress on mapping the cosmic distance scale, and its implications for constraining cosmological models. After focussing on "traditional" distance indicators, such as Cepheids and supernovae, I will then discuss the future prospects for extending the extragalactic distance scale to much higher redshift using gravitational wave observations of binary black hole mergers - so called "standard sirens". I will illustrate some cosmological questions that might be addressed with future siren observations, as well as highlighting the potential systematic errors to which they are vulnerable, and which must be overcome if they are to be fully exploited as cosmological probes.

3:30pm, Tuesday 23 September 2008

VENUE: Physics Lecture Room 2.15

SPEAKER: Dr D.J. Pisano (US National Radio Astronomy Observatory)

TITLE: "A Multiwavelength Study of Luminous Compact Blue Galaxies over 8 Billion Years"

ABSTRACT: The star formation rate in the Universe has dropped by an order of magnitude in the past 8 billion years. Why? Luminous Compact Blue Galaxies (LCBGs) may account for this drop. LCBGs were common 8 billion years ago, representing about 20% of the galaxy population and contributing about 40% of the total star formation rate density at that time, but are a factor of ten rarer by the present day. While we know that LCBGs are rapidly evolving, we do not know what drives their evolution or into what type of galaxy they evolve. I will present results from our current radio studies of nearby LCBGs as part of a larger multiwavelength study of the properties of these galaxies. Our data will constrain the current evolutionary state and future evolutionary path of LCBGs. These data will also serve as a benchmark for future studies of LCBGs at all wavelengths and distances.

3:30pm, Tuesday 9 September 2008

VENUE: Physics Lecture Room 2.15

TITLE: "Doppler-free Spectroscopy of Mercury's Doubly-Forbidden 1S0-3P0 Transition - A Step Towards a Neutral Mercury Optical Lattice Clock"

SPEAKER: : Dr Sam Dawkins (Paris Observatory)

ABSTRACT: In 2002 an innovative proposal was made to build an ultra-accurate clock based on neutral atoms trapped in an optical lattice. Several clocks around the world now operate on this principle and show great promise of pushing the world's-best performance to new levels. So far, these clocks have utilised the atomic species of strontium and ytterbium, with the fundamental limit of performance set by the blackbody radiation shift. At the Paris Observatory, we are building a lattice clock based on mercury, chosen for its substantially lower sensitivity to blackbody radiation. This seminar will cover the recent progress made on this project, in particular the Doppler-free frequency measurement of the clock transition.

3:30pm, Tuesday 2 September 2008

VENUE:

Physics Lecture Room 2.15

TITLE: "Producing and using entanglement of photons and atoms"

SPEAKER: Professor Hans Bachor (ANU)

ABSTRACT: Entanglement of many particle systems is one of the key components of future quantum technologies. ACQAO has made excellent progress in a range of parallel, intertwined projects. We are creating the ideas and building blocks for the entanglement of matter waves in the form of atom laser beams. Already we can report the complete demonstration of the original EPR Gedankenexperiment with laser beams, the interaction and storage of squeezed light with atoms and a pumped atom laser. A summary of some of the activities of ACQAO will be given.

3:30pm, Tuesday 26 August 2008

VENUE:

Physics Lecture Room 2.15

TITLE: "Gravitational wave astronomy"

SPEAKER: Ik Siong Heng (University of Glasgow)

ABSTRACT: Ground-based interferometric laser gravitational wave detectors have rapidly improved their sensitivities over the last few years. The LIGO detectors are now at design sensitivity, with the GEO 600 and Virgo detectors having comparable sensitivities at high frequencies. At such unprecedented sensitivites, the era of gravitational wave astronomy has already begun.

In this talk, an overview of the detectors and results from recent runs by the LIGO Scientific Community will be presented. In particular, joint observations with gamma-ray and radio observatories will be highlighted.The data analysis methods, with particular emphasis on the Bayesian approach, will also be discussed.