Atomic, Molecular and Surface Physics Research Group
Our research fields include positron studies of materials and spin-polarised electron studies of free atoms, molecules and surfaces.
Positron studies of materials
The UWA positron group started as a node within the ARC Centre of Excellence for Antimatter and Matter Studies (CAMS) with the ANU from 2005 to 2015. The UWA positron facilities are an AINSE External Facility led by Prof Emeritus Jim Williams and Prof Sergey Samarin.
Positrons are used to probe time and spatial dimensions of any material with quantum precision. They are a unique atomic probe because there are no positrons in ordinary matter; their lifetimes and spatial signatures vary widely. Indications of their usefulness are seen in 3 figures below for metals, semiconductors and polymers compared with conventional techniques for defect size and defect density using SEM, TEM, Xrays. The technical developments are complementary to those using electrons beams as probes (such as LEED, Auger, SPLEED) and Xrays and techniques at the UWA CMMA and synchrotrons. The combined use of these techniques enables their overlapping and complementary information to establish better understanding of many atomic, surface, thin films and bulk materials.
The positron techniques work because in a material they seek to combine with electrons to form positronium and then annihilate, producing energetic gamma photons. These annihilation gamma photons carry information about the electron distributions in the material and the location and nature of their annihilation. The positrons and positronium particles are often trapped in open- and closed-volumes (pores or defects of a material) before they annihilate. Their lifetime, energy and distribution reveal a specific sensitivity to the size, shape and connectivity of the pores, and the spin-specific (magnetic) electron environment. Sampled times and space range upwards from 1 picosec and 1 nsec and from a single atom.
The positron facilities extend our understanding of fundamental and applied positron science in two major directions. First, the development of modern devices in nano-electronics and medicine requires a deeper knowledge and understanding of materials, surfaces and interfaces, their structure and properties, at nano- and atom-scale dimensions where defects originate. Second, the development of new materials requires experimentation with different combinations of atoms and their metastable combinations and new and different characterization methods. Preferred sample dimensions are 1 cm square, 1 mm (or less) thick.
The applications of the basic science are many and varied and include, for example, measurement of defect depth profiles due to surface modifications and ion beam implantation; tribology (mechanical damage of surface), polymer physics (pores, inter-diffusion); low-momentum materials (thin high porous layers); epitaxial layers (growth defects, misfit defects at interfaces); radiation resistance (space physics); fast kinetics (e.g. precipitation processes in Al alloys, defect annealing).
Examples of applications in materials science from our laboratory (with publication evidence).
- Engineering alloys. The effects of mechanical stressing, e.g. via channel angular pressing which change vacancy concentration with processing in Al- and Ti-alloys has been revealed in lower electron densities localizing positrons with consequently increased lifetime (~240 ps) with respect to the 165 ps of defect-free material.
- In polymer modified cement pastes the water content of pores and water loss associated with the curing process and evaporation, as well as the porosity and hydration processes, determined a stronger and more stable cement.
- The storage environment in nano-porosity of metakaolin-based geopolymers, a replacement for Portland cement and for storing radioactive wastes, was shown to vary near a surface and to vary significantly from the bulk with implications for storage lifetimes.
- Porous materials, e.g. silica particles have an important role in drug therapy as they can be used to protect a drug from metabolism in vivo and transport it to the site of interest.
- Self healing material: Chromate-inhibited primers are used in industry as a component in corrosion protection systems.
New directions in studying fundamental properties of condensed matter.
- Fracturing of metals is explored by comparing lifetimes of positrons diffusing along a dislocation line and subsequent trapping at point-like defects associated with the dislocation.
- Polymer chains, such as biological systems where spatially confined long biopolymers (DNA and RNA) are subject to spatial or topological constraints, are now accessible for measurements of their various length scales.
- Polymeric materials have increasing interest to use in wound healing when the polymer is impregnated with nanoparticle of silver to enhance their anti-bacterial properties.
- The production of natural powders, with silk and wool, often requires chemical treatment of the fibre prior to milling.Positron lifetimes determine changes in the properties of the materials when metals are trapped in the pores or are absorbed on the outer surface of the powder.
- Finally, other new directions are emerging. We have been shown that positrons are very effective in probing surfaces and reduced dimensional systems, such as nanoparticles, which possess high surface-to-volume ratios.
Selected international journal publications indicating variety of study and samples
- Journal American Ceramic Society 95 (2012) 1727. Positron annihilation lifetime studies of Nb-doped TiO2, SnO2, and Zr O2. Guagliardo, P, Vance, E, Zhang, Z, Williams, J, Samarin, S.
- Acta Materialia 60 (2012) 4218. 'Study of vacancy-type defects by positron annihilation in ultrafine-grained aluminum severely deformed at room and cryogenic temperatures',.
Su, L.H., Lu, C., He, L, Zhang, L., Guagliardo, P., Tieu, A., Samarin, S., Williams, JF, Li, H.J.
- Polymer, 53, 4539-4546, (2012). P Ramya, C Ranganathaiah and J F Williams. Experimental determination of interface widths in binary polymer blends from free volume measurements.
- Phys. Rev. E 87, 052602 (2013). P. Ramya, P. Guagliardo, T. Pasang, C. Ranganath, C, Samarin, and J. F. Williams, Influence of polar groups in binary polymer blends on positronium formation.
- J Amer Ceramic Soc, 96 3286 (2013) P. Guagliardo, ER Vance, GR Lumpkin, K Sudarshan, S Samarin, JF Williams. Positron Annihilation in Off-Stoichiometric and Ta-Doped Zn2TiO4.
- Diamond & Related Materials 37, 37 (2013). P Guagliardo, K Byrne, J Chapman, K Sudarshan, S Samarin, J Williams. Positron annihilation and optical studies of natural brown type I diamonds,
- Appl Phys A 113 633 (2013). K. Sudarshan, PJ. Wilkie, SN. Samarin, P. Guagliardo, VN. Petrov, AH. Weiss and JF Williams. Influence of surface conditions on thermal positron reemission spectra of W(100)
- J Phys C 443, 012047 (2013) D Meghala, P Ramya, T Pasang, J M Raj, C Ranganathaiah and J F Williams. Positron Annihilation Lifetime study of interfaces in ternary polymer blends.
- Science of Advanced Materials, 6 1338 (2014). L.Su, C. Lu, P. Guagliardo, SN Samarin, and JF Williams. Vacancy-type defects study on ultra-fine grained aluminium processed by severe plastic deformation.
- J. Appl Polymer Science 133 (2016) 43729. A Deore, K Hareesh, S Samarin, J Williams, et al. Structural and antibacterial properties of gamma radiation-assisted in-situ prepared Ag-Polycarbonate matrix
- Materials Research Express 3 (2016) 075010. K. Hareesh, J Williams, Bio-green synthesis of Ag-GO, Au-GO and Ag-Au-GO nanocomposites using Azadirachta indica: in SERS and Cell viability.
- RSC Advances. 7, (2017) 32, p. 20027 10 p. Ultra-stable supercapacitance conducting polymer coated MnO2 nanorods/rGO nanocomposites. Hareesh, K., Shateesh, B., Joshi, RP., Williams, JF.
- Mat Sci Eng B 234 (2017) 28-39. C. Suresh, H., J.F. Williams, K. Hareesh. Positron annihilation and photoluminescence of LaOF:Tb3+ nanophosphor fabricated via ultrasound sonochemical route.
- Mater. Res. Express 4 065018 (2017) .K Hareesh, B Shateesh, J F Williams, et al.
Enhanced supercapacitance behaviour of low energy ion beam reduced graphene oxide
- Materials Research Express. (2018) 5, 015304. Hareesh, K, Sunitha, DV, Ramya, P, Williams, J., Samarin, S., Dhole, S. D. & Sanjeev, G., Gamma radiation-assisted diffusion of Au nanoparticles in nanocavities of polycarbonate: Nano-structural and surface properties
BioMagnetics research group
The BioMagnetics Group investigates the role of physics and magnetism in biology and medicine and works to develop magnetic and nano-based technologies for biomedical applications. We are a dynamic, interdisciplinary research group, equipped with state of the art magnetic measurement facilities and a modern wet lab.
Under the guidance of Professor Tim St Pierre, the members of the group work on a diverse range of topics including iron-overload disorders, magnetic nanoparticles and magnetotactic bacteria. In recent years an increasing level of international interest within the field has resulted in collaborations with institutions both within Australia and overseas. With this continued growth it it seems likely that there will be a bright and exciting future ahead for research within this field.
The BioMagnetics Research Group carries out research on naturally occurring magnetic materials in biological systems and on the development of novel physical methods for their characterization, measurement, detection, and imaging. The Group also is developing magnetic nanoparticle systems and complementary instrumentation for biomedical and medical applications.
The BioMagnetics Group undertakes a variety of research programs from pure basic research to experimental and commercial development. Some examples of our research projects are listed below.
Pure Basic Research
Small Particle Magnetism
As magnetic particles become small, approaching 10 nm, a number of changes occur to the properties these materials exhibit in bulk form. There are changes to coercivity mechanisms, magnetisation values and their time dependent properties. New properties such as superparamagnetism appear and it is possible to observe dipolar and exchange interactions within and between particles. The BioMagnetics group undertakes a range of research into small particle magnetism to better understand how the structure of the particles leads to different magnetic properties.
Iron is critical to nearly all forms of life, but it can catalyse damaging free radical reactions in its free form. Soluble iron is also relatively scarce in the environment and so living things must develop ways to capture and safely store iron. In animals, iron is stored as an iron oxyhydroxide complex within a protein cage called ferritin. The BioMagnetics Group conducts research into how different animals store and use iron in the body. Some of the examples of iron biomineralisation we have studied include marine molluscs (chitons and limpets), which use iron oxides as a hard cutting edge for their teeth, while magnetotactic bacteria use magnetite crystals to provide a sense of direction that gives them an evolutionary advantage over their competitors.
It has been shown that a number of animals possess the ability to navigate using the earth’s magnetic field. In order to do so, these animals must have the ability to sense the strength and/or direction of the local magnetic field. A number of potential magneto-receptors have been postulated, but conclusive proof of their existence has not yet been shown. We work with biologists and microscopists in trying to detect and identify magneto-receptors based on iron based particles and compounds.
Strategic Basic Research
Development of MRI contrast agents
In order to improve the effectiveness of medical imaging, or to enhance the visualization of specific components in a living body, it is often necessary to administer chemical compounds, known as contrast agents or media, so that the contrast between different tissues (e.g. healthy against diseased) can be increased. The BioMagnetics Group works on the development and characterisation of novel contrast agents based on superparamagnetic nanoparticles of iron oxide coated with polymer surfactants to improve the biocompatibility and provide targeted biodistribution.
Magnetically targeted and activated drug delivery
One of the most exciting goals in nanotechnology research is the development of techniques for the delivery of drugs to a specific target and the release of those drugs through an activation signal. Magnetic nanocomposites provide a potential vehicle to achieve both these goals. Magnetic particles can be moved by the application of magnetic fields and field gradients through a process known as magnetophoretic motion. In addition, if exposed to an alternating magnetic field the energy released from the magnetic particles can be sufficient to change the magnetic nanocomposite and release an encapsulated drug. We are interested in understanding the mechanisms of both magnetophoresis and activated drug release in order to design better nanocomposites and the equipment to both target and release drugs.
Pathogenic iron deposits
The human body has no efficient mechanism to excrete iron and hence iron levels in the body are largely maintained by control of iron absorption from the diet. However, if the control of iron absorption is defective or if iron is directly administered through supplements or ongoing blood transfusions, then iron levels can increase beyond the limit of the body’s natural iron storage mechanisms. If this happens then it is possible that the excess iron can be deposited in the body in pathogenic forms leading to a range of negative effects. The BioMagnetics Group is interested in understanding the formation and deposition of pathogenic iron deposits their quantitative determination and methods for their removal.
Development of new diagnostic techniques for Schistosomiasis
Schistosoma parasites damage organs, impair growth and cause neural disease among their hosts. Diagnosis of an infection is typically by screening the faeces of the infected person for the eggs of the parasite. The eggs are formed by an interesting biomineralisation process which lends itself to magnetic detection and characterisation.
Liver fat determination using MRI
Around 50% of colorectal cancer (CRC) patients develop secondary cancers, typically in the liver. Liver surgery is the treatment of choice, but chemotherapy that is often administered prior to surgery can lead to the development of fatty liver. Patients with moderate to high levels of liver fat having major liver surgery have an increased risk of death (up to 3 times), more post-operative complications of greater severity and hospital costs up to 70% higher compared to patients with normal levels of liver fat. A reliable liver fat measurement for screening liver resection patients would lead to better-informed surgical planning decisions that could result in more patients becoming eligible for surgery and potentially reduce the rate of post-operative complications and associated costs. Our group has recently developed a highly sensitive and specific, non-invasive, MRI-based approach for measuring liver fat (FDA approval received December 2013) and is researching the application of this technique prior to liver surgery.
FerriScan® - Iron determination in hemoglobinopathies
The BioMagnetics Group is a pioneer in the non-invasive measurement of liver iron concentrations by magnetic resonance imaging (MRI). Present techniques for quantifying tissue iron by MRI rely on the paramagnetic character of the iron stores. The pioneering work of this group led to a non-invasive liver iron measurement technique that is now commercially available through Resonance Health Ltd and is marketed as FerriScan®. Research has progressed to include other iron loaded organs, such as the spleen, heart and brain.
Malaria detection using magnetic fractionation
When a malaria parasite feeds on and digests haemoglobin it produces an iron based waste product called hemozoin. Although only weakly magnetic, the hemozoin makes late stage parasites sufficiently magnetic that they can be magnetically separated from blood using a technique known as magnetic fractionation. We have shown that magnetic fractionation can be used as a highly sensitive and specific diagnostic technique for the presence of gametocytes, the form of the malaria parasite that circulate in the blood and responsible for the transmission of the disease. This technique has similar sensitivity to DNA based techniques, but at a fraction of their cost and can be easily carried out in the field with minimal laboratory equipment. The technique is presently undergoing field trials in Papua New Guinea as part of an assessment of different drug therapies.
Numerous pieces of equipment are owned and operated by the BioMagnetics research group.
- SQUID Magnetometer - With a 7 Tesla solenoid and temperature inserts which allow measurements between 2K and 800K.
- 57Fe Mossbauer Spectrometer - With a liquid helium cryostat, available for measurement of hyperfine fields of Fe-based materials.
- Vibrating Sample Magnetometers - we have two available in the laboratory. They operate using superconducting solenoids to produce magnetising fields of 5 Tesla and 12 Tesla. Sample cryostats permit measurements of magnetic and electrical properties at temperatures ranging from 3.8K up to 1000K.
- 10, 20, 40 and 60 MHz Bruker MiniSpec proton relaxometers with variable sample temperature control (25°C to 40°C)
- Optical microscope with digital video capture
- Magneto-Optic Magnetometers - Both a high speed (microsecond timescale) unit and a high stability (1000's of seconds timescale) unit with fields up to a 2.2 Tesla and temperatures from room temperature to liquid helium.
- Radio-Frequency Sputtering System - For plasma deposition of thin films, under high vacuum conditions.
- Pulsed Inductive Microwave Magnetometer (PIMM) - for measuring magnetic response of materials to pulsed fields on picosecond timescales
Members of the group have access to other analytical equipment, including XRD, ICP-MS and electron and magnetic force microscopes (through the Centre for Microscopy, Characterisation and Analysis) for materials characterisation.
Experimental quantum dynamics research group
The core research activities of this group concern the interaction of photons and electrons with gas phase atoms and molecules.
To achieve results in these studies, we have invented ground-breaking technology and are in the process of continuing its development.
Photon impact experiments at Synchrotron and free electron laser light sources
This project involves sub-picosecond time domain measurements of photoelectrons and sub-nanosecond time domain measurements of photo-ions.
Electron impact experiments in the UWA laboratory
- Sub-nanosecond time domain measurements of auto-detached electrons and ion fragments arising in sub-nanosecond pulsed electron impact experiments.
- Experiments utilising stored charged particles in a novel, low-kinetic-energy, charged particle Recycling Spectrometer (RS).
We have strong research collaborations with:
- Dr Timothy Reddish, University of Windsor, Canada where the prototype Electron RS (ERS) that was invented by Hammond in 1998, and jointly designed, is located.
- Dr Kevin Prince (VUV and Soft X-ray Group, Sincrotrone Trieste, Italy) and Dr Lorenzo Avaldi (IMAI de CNR, Rome, Italy) for the photon impact experiments
These strong collaborations have been supported by the recently awarded ARC Discovery Project for 2008-2010 (DP) Sub-Picosecond Studies of Matter using Intense Light from a Free Electron Laser, in which Hammond is Chief Investigator and Reddish, Prince and Avaldi are Principal Investigators.
In addition, the EQD group was invited to be a member of the European consortium ULiSSE, which is designing and developing new detector technology for novel experiments at the FERMI Free Electron Laser Source.
Field Theory and Quantum Gravity Research Group
Unification of gravity with the other fundamental interactions within a consistent quantum theory is one of the central problems of high-energy physics. The complete structure of such a theory is not yet known despite numerous efforts undertaken over several decades to construct it. The most interesting models for quantum gravity include string theory and its low-energy approximations known as supersymmetric theories of gravity (supergravity).
Prof Sergei Kuzenko
- A/Prof Evgeny Buchbinder
- Dr Darren Grasso
- Prof Ian McArthur
The group's research activities include:
- Supergravity-matter systems in diverse dimensions.
- Superconformal field theories and the AdS/CFT correspondence.
- String theory and its applications to particle physics.
- Models for spontaneously broken supersymmetry.
- Supersymmetric higher spin gauge theories.
- Effective actions in gauge theories and quantum gravity.
Past Group Members
- Dr Daniel Butter (postdoc 2010—2012)
- Dr Joseph Novak (postdoc 2013—2015)
- Dr Gabriele Tartaglino-Mazzucchelli (postdoc 2006—2008, ARC DECRA Fellow 2012—2015)
- Dr Igor Samsonov (postdoc 2014—2016)
- Dr Mirian Tsulaia (postdoc 2016—2018)
ARC Funded Projects in the last 10 years
- Advances in Higher Spin Gauge Theory, (2016—2018, initial funding: $377,600) [S. M. Kuzenko (UWA), D. Sorokin (National Institute for Nuclear Physics, Padua) and M. A. Vasiliev (PN Lebedev Physical Institute, Moscow)].
- Novel Conformal Techniques in Quantum Field Theory, Gravity and Supergravity, (2014—2016, initial funding: $346,000) [S. M. Kuzenko (UWA), E. I. Buchbinder (UWA), G. Tartaglino-Mazzucchelli (UWA), S. Theisen (Albert Einstein Institute, Potsdam) and A. A. Tseytlin (Imperial College, London)].
- Relating string theory and particle physics: model building and strong coupling phenomena (2012-2016, initial funding $586,028) [E. I. Buchbinder (UWA)]
- Superspace and Dualities in Supersymmetric Field Theories, Supergravity and String Theory (2012–2014, Initial funding: $375,000) [G. Tartaglino-Mazzucchelli (UWA)]
- Quantum and Geometric Aspects of Gauge Theories, Supergravity and String Theory, (2010—2014, initial funding $775,000) [S. K. Kuzenko (UWA), U. G. Lindstrom (Uppsala University) and A. A. Tseytlin (Imperial College, London)].
- Prof Sergei Kuzenko: Australian Professorial Fellow (2010—2014)
- A/Prof Evgeny Buchbinder: Future Fellow(2012—2016)
- Dr Gabriele Tartaglino-Mazzucchelli: DECRA Fellow (2012—2015), Future Fellow (2019—2023)
Past Group Members' Achievements
- Dr Gabriele Tartaglino-Mazzucchelli: Marie Curie Intra-European Fellowship (2010—2012, Uppsala University, Sweden)
- Dr Daniel Butter: Marie Curie Intra-European Fellowship (2014—2016, University of Amsterdam)
- Dr Joseph Novak: Research Fellowship of the Alexander von Humboldt Foundation (2017-2019, Albert Einstein Institute, Potsdam)
Frequency and Quantum Metrology Research Group
We aim to build instruments with world-class precision and performance that we can use to make measurements of high value and interest in both fundamental physics and more practical applications.
Many modern developments in today's society are based on high-quality clocks and oscillators: the Global Positioning System (GPS) satellite system, radar, optical fibre communications, even mobile phones. The group's goal is to develop new frequency standards and technologies with two endpoints in mind: to improve systems that are based on high-quality clocks and oscillators (such as those listed above), and to use these as precision tools to test the foundations of physics.
We are dedicated to commercialising our inventions and thus hold patents in conjunction with industry. Our research programs include strong international and industrial collaborations.
Our group undertakes research projects that cover a broad spectrum of interests, ranging from engineering to fundamental physics. Some of our projects include:
- Quantum Metrology within the ARC Centre of Excellence for Engineered Quantum Systems (EQuS).
- Advancing the Cryogenic Sapphire Oscillator – one of the world’s most stable frequency sources.
- The Ytterbium Lattice Clock.
- Space applications: Ground Station for the European Space Agency's ACES mission.
- Low noise frequency and phase synthesis and measurement techniques.
- Testing Lorentz invariance by measuring speed of light isotropy, in collaboration with Humboldt University of Berlin.
- Measurement of electronic and magnetic properties of materials.
- Novel high-Q microwave and millimetre wave resonators.
- Laboratory based searches for Weakly Interacting Slim Particles.
Yb Lattice Clock
A ground based Yb lattice clock for participation in future space-clock missions.
Industry, defence and commerce all depend on accurate time keeping, and as clock technologies have improved they have unveiled capabilities such as the global positioning system (GPS) and very long baseline interferometry (VLBI). Atomic clocks have been at the forefront of physics for several decades and now they probe nature’s behaviour at the most fundamental level — in ways comparable in significance to high energy collider experiments, by searching for temporal changes in fundamental constants. Rather than rely on extraordinarily high energies, atomic spectroscopy relies on extraordinary levels of precision. The improvement in accuracy of clocks is advancing at approximately a factor of 500 per decade (compared to ~13 for Moore’s law). This rapid scientific advance suggests a certain inevitability with regard to finding new phenomena.
Recent measurements in various laboratories have shown astonishingly high accuracy for a number of different clock transition frequencies and ratios. These clocks are isolated in separate laboratories around the globe, thus the means to compare the clocks is heavily sought. With future space-clock missions such as the Atomic Clock Ensemble in Space (ACES) mission and possible future missions, such as Space Optical Clock (SOC) and STE-QuEST (Space-Time Explorer and Quantum Equivalence Principle Space Test), a much greater opportunity will be granted for frequency comparisons between clocks distributed around the earth.
At UWA we are developing an optical lattice clock based on a particular electronic transition in 171Yb, with the aim of participating in future space-clock missions. Such clocks have already demonstrated outstanding performance (e.g. at NIST, NMIJ, RIKEN & KRISS). The 171Yb ‘clock’ transition is included in the CIPM’s (Comité International des Poids et Mesures) list of secondary representations of the second.
Progress on the Yb lattice clockThe UWA atomic clock was first put into operation after 2.5 years of development (the first of its kind in the southern hemisphere). By comparison with a hydrogen-maser, its accuracy is in the parts per trillion range.
The experiment has also accomplished the following.
- A dual-wavelength magneto-optical trap (MOT) has been installed that laser cools and traps neutral ytterbium atoms. The device uses unconventional laser wavelengths at 399nm and 556nm. Both require moderately complex schemes for their generation. The temperatures achieved in the dual-wavelength MOT are 20 μK for (171)Yb (fermionic) and 40 μK for (172)Yb (bosonic). We use a new, cost effective, means of generating the 556nm radiation.
- The absolute frequency of the 1S0-3P1(F’=3/2) inter-combination line in 171Yb has been measured to be 539390406833 ±310 kHz. The frequency separation between this line and the clock transition is found to be 21094570280 ± 36 (stat.) ±310 (syst.) kHz.
- An inverted crossover resonance has been observed in saturated absorption spectroscopy of 171Yb for the first time. This may also be the first occasion where the effect has been seen in a group II atom. We have used the signal to stablize the frequency of 556nm light needed for laser cooling of 171Yb and demonstrated a temperature of 20 μK.
- A frequency comb has been generated to cover the relevant wavelengths of the (lattice) clock; for example: 1156nm, 1112nm and 759nm. The mode-locked laser light from a master oscillator (centred at 1550nm) has been amplified and coupled into a section of highly nonlinear fibre (high step index) to extend the wavelength range to below 1100nm. The frequency comb mode spacing is steered by a hydrogen maser.
- An ultra-stable laser at 1156nm has been set up, including a 4×105 finesse optical cavity inside a vacuum chamber with surrounding thermal shields. This laser, when frequency doubled, probes the clock transition in the Yb atoms (at 578.4nm). The drift rate of the laser is presently 60mHz/s (4×10-16 s-1), and steadily falling. We perform the clock transition spectroscopy with a Rabi frequency of ~6kHz.
Laboratory Searches for Weakly Interacting Slim Particles
Many attempts to expand the Standard Model of particle physics via string theories or supersymmetry theories inevitably predict the existence of new particles that we have yet to observe. One such family of these hypothetical particles are the Weakly Interacting Slim Particles, or WISPs. As the name suggests, not only do WISPs interact very weakly with standard matter but they also have extremely small masses of less than 1 electronvolt. For comparison, a proton has a mass on the order of one billion electronvolts. What this means is that on an intrinsic level WISPs are remarkably difficult to detect and measure. It is these same properties that also allow WISPs to be formulated as compelling dark matter candidates.
The primary focus of our work is designing and performing experiments to search for a type of WISP known as the Hidden Sector Photon, or Paraphoton. This particle is coupled very weakly to the standard photon and does not interact with standard matter. We aim to constrain the strength of this photon / paraphoton coupling as a function of paraphoton mass.
One of our main experiments is known as a “Light Shining Through a Wall” experiment. Photons are generated on one side of an impenetrable barrier; in order to cross this partition the photon would need to convert to a paraphoton and pass through. By searching for photons on the other side of the barrier we can attempt to detect photon to paraphoton to photon conversion events. In order to reduce the level of background noise present in the detector the experiment is performed at cryogenic temperatures (approximately -270 C). As usual, we employ a variety of experimental tricks to enhance the sensitivity of our experiment and we are always applying the advances in measurement techniques we develop to other areas of research.
Gravitational Wave Astronomy
With the first gravitational wave signal detected in 2015, gravitational wave astronomy emerges as a new branch of astronomy that involves both detecting gravitational waves and using gravitational wave observations to advance our understanding of the Universe.
Ground-based laser interferometers aim to detect gravitational waves in the audio frequency band, from 10 Hz to several kHz. The Laser Interferometer Gravitational Wave Observatory (LIGO) in the United States made the first two detections of gravitational wave signals from coalescing binary black holes in 2015. On the other front, pulsar timing arrays exploit the exceptional rotational stability of millisecond pulsars in order to detect nanohertz gravitational waves. The first detection in the nanohertz gravitational waves is likely to happen within the next decade.
Our group is part of the LIGO Scientific Collaboration, which consists of more than 1000 scientists who have joined force to search for gravitational waves. We are leading one of the online detection pipelines for gravitational waves from coalescing binaries of black holes and neutron stars using LIGO data. Our group was actively searching for gravitational waves when the first two signals were detected in 2015 and will continue to be actively involved in gravitational wave searches in future science runs of LIGO as well as the Virgo detector in Europe.
Our group is also a Tier-1 member of the Australia-based Parkes Pulsar Timing Array (PPTA) collaboration and is actively involved in using Parkes pulsar timing data to search for gravitational waves from binaries of supermassive black holes. We are also part of the International Pulsar Timing Array collaboration, formed by PPTA and its international counterparts in Europe and North America.
Our group’s ongoing research activities include:
- Real-time detection of audio-band gravitational waves from binary coalescences of black holes and neutron stars
- Acceleration of the detection pipelines using high-performance supercomputing technologies including the use of Graphics Processing Units (GPUs)
- Astrophysics of gravitational wave sources and electromagnetic follow-up observations
- Searching for gravitational waves from individual supermassive black hole binaries using Parkes Pulsar Timing Array data
- Investigating the potential of future large radio telescopes including FAST and pathfinders for the Square Kilometer Array (SKA) in detecting gravitational waves and studying the formation and co-evolution of galaxies and supermassive black holes
We are looking for highly motivated applicants with interest in gravitational wave data analysis and multi-messenger astronomy including gravitational waves. Background with physics, astronomy and related disciplines is desirable. Experience with high-performance computing is a plus.
The prospect student will work on two broad areas of gravitational wave detection:
- Detecting gravitational waves from coalescing binaries of neutron stars and black holes with ground-based interferometers
- Detecting nanohertz gravitational waves with pulsar timing arrays.
Please visit the School of Physics site of PhD opportunities for more details.
Gravitational Wave Detection Instrumentation
Gravitational wave detection is in its infancy. It is the fastest growing field of astronomy as we discover more and more sources of gravitational waves across the universe. The improvement of detectors, and development of new detectors is crucial for the field to continue to advance.
Gravitational wave instrumentation research in Australia began at UWA, where we pioneered one of the world’s first high sensitivity resonant mass gravitational wave detectors. Today our research is focused on the development of advanced techniques to improve the sensitivity of gravitational wave detectors. Our team is part of the LIGO Scientific Collaboration (LSC) and contributed some key technologies towards the first detection of the gravitational waves. We are part of the ARC centre of Excellence for Gravitational Wave Discovery (OzGrav). Our research areas include precision measurement, quantum optics, high optical power suspended cavities, advanced vibration isolation techniques and control systems. The research is exploring exciting new physics phenomena and techniques that have applications beyond gravitational wave detectors, including quantum measurement technologies and airborne exploration devices.
A specific area of research explores new concepts in amplification and measurement based on the interactions between optical photons and acoustic phonons. Devices based on this frontier of measurement technology require very low loss opto-mechanical systems in which light and sound (or mechanical vibration) interact very strongly without being contaminated by thermal fluctuations.
We are testing and inventing many novel opto-mechanical resonators, including nano-scale optical pendulums made from synthetic crystalline mirrors, others made from photonic and phononic crystals, and some made from ultrapure crystals of quartz. With these devices we observe and predict many new phenomena such as optical springs, optical dilution, optomechanically induced transparency, frequency dependent optical squeezing, negative dispersion and white light resonance. The phenomenon of white light resonance (that violates the normal theory of resonance) offers enormous opportunities for improving the sensitivity of gravitational wave detectors, which in turn will allow new astrophysical phenomena to be explored.
We operate the large High Optical Power Facility with 80m suspended cavity at Gingin in beautiful bushland 80km from UWA. Here we study high optical power related phenomenon such as thermal lensing and parametric instability in gravitational wave detectors. The facility uses high performance vibration isolation systems and control systems for gravitational wave detectors. We are currently developing systems based on silicon optics at 2 microns wavelength, where silicon is a high performance optical material. We are building the first large scale silicon optical cavities that use newly developed 2 micron laser technology.
Our research also leads to spin-off technology that has applications in airborne survey industry.
Our group also leads the Einstein-First Project in which we are creating a revolutionary new school curriculum in which the fundamental concepts of general relativity and quantum physics are taught at an early age. See www.einsteinianphysics.com
Most of our students get the opportunity to visit LIGO as LIGO-fellows, where they participate in observations as well as technology improvements. We work in close collaboration with teams across Australia and around the world. Many students get to visit our collaborators and learn new skills.
Current research topics
Some specific research topics include:
- Very low loss opto-mechanical cavities with micro-resonators such as photonic crystals, GaAl coating based cat-flap resonators, and bulk acoustic wave resonators
- Optical springs and optical dilution experiments for ultra-low thermal noise cavities
- Parametric instability in high optical power cavities
- Silicon optics and crystalline coated silicon test masses for next generation detectors
- Advanced low frequency rotation accelerometers
- Seismic imaging array for microseismic noise reduction in gravitational wave detectors
- High performance vibration isolation and control
- Airborne exploration Instrumentation
For more details please visit our webpage.
- Gingin High Optical Power Facility
- Large 20m x20m x10m corner station and 2 end stations connected by two 80m vacuum pipes to form two 80m suspended optical cavities. The facility includes several cleanrooms with optics, high power lasers, large high vacuum tanks housing high performance vibration isolation systems and suspended high quality kg scale mirrors, large oil-free vacuum pumps. The facility also has a fully equipped mechanical workshop as well as an accommodation block for researchers.
- UWA campus facility
- Cleanroom optical laboratories for precision optical experiments.
- Large laboratory for vibration isolation and exploration experiments
We have exciting projects for PhD, Master of Physics and internships. We are a vibrant, friendly, international group. We are looking for highly motivated students to join us. Contact details are available here.
Medical Physics Research Group
The Medical Physics Research Group conducts research into radiobiology, radiation safety, clinical medicine and health technologies, and provides teaching in biophysics, nuclear physics, radiation health and medical physics.
In addition to the key researchers, this group comprises Medical Physics students undertaking PhDs and the Master of Physics: Medical Physics program. Our Medical Physics program was first offered in 2011 and has full accreditation from the Australasian College of Physical Scientists & Engineers in Medicine (ACPSEM). Enquiries about the course can be directed to Pejman Rowshan-Farzad.
Active areas of research include:
- Basic research into radiobiology using computational approaches.
- Research in clinical medicine and health technologies.
- Synthesis of new radionuclides for nuclear medicine.
- Calibration of radiotherapy equipment.
- Radiation safety and shielding.
Quantum dynamics and computation
Instead of brute-force miniaturisation of basic electronic components, quantum computation utilises entirely new design architecture and promises to solve problems that are intractable on conventional computers. It offers the prospect of harnessing nature at a much deeper level than ever before, as well as a wealth of new possibilities for communication and data processing.
Core activitiesThe quantum dynamics and computation group conducts research in the areas of quantum dynamics, quantum information processing, and quantum computation. In addition to using advanced mathematical methods and numerical techniques to model the dynamics of quantum systems and to investigate quantum algorithms, the group also has extensive HPC and computer algebra expertise to solve a wide range of science and engineering problems.
Spintronics and Magnetisation Dynamics Research Group
Our research focus is on magnetic materials. We are interested in microwave, magneto-optical, spintronic and left-handed properties of ferro-, ferri- and anti-ferromagnetic thin films, multilayers and nanostructures.
Such materials are highly promising candidates for a new generation of smaller, faster and energy efficient electronics for communications, data processing and storage, and for field-, substance- and bio-sensing.
The group is strong in both experiment and theory. Extensive and close co-operation between experimentalists and theoreticians within the group ensures the highest degree of research quality and completeness.
Our experimental research relies on the most advanced methods of fabrication and characterisation of magnetic materials and nanostructures. A number of experimental methods and technologies used in our research are unique in Australia. Among them are nanostructuring of magnetic films and multilayers, fabrication of microscopic microwave components, magneto-optical and SQUID magnetometry, spin-transfer torque microwave nano-oscillator technology, magneto-optical imaging, quasi-static measurements of domain wall dynamics, broadband and cavity-based ferromagnetic resonance and traveling spin wave spectroscopy.
Theoretically we are strong in both analytical and computational methods of describing the physics of magnetic materials as well as the physics of waves and oscillations in general, including non-linear waves, solitons, wave instabilities and chaos.
Current research topics
Our current research focuses on theoretical and experimental aspects of:
- Microwave dynamics of microscopic travelling and standing spin waves in magnetic nanostructures;
- Microwave spintronic phenomena in ferromagnetic and half-metallic materials, such as spin transfer torque, spin-Hall, spin-Seebeck and spin pumping effects, etc.;
- Surface plasmon-polaritons in magnetic materials, including sub-wavelength nanostructures such as gratings and nano-antennae;
- Domain wall dynamics for magnetic storage and data processing applications;
- Magnetic left-handed materials;
- Application of spintronic and magneto-plasmonic nanostructures for sensing applications and for the generation and reception of microwave and optical radiation.
Our group’s laboratories form part of the well-equipped UWA Magnetic Characterisation Facility (UWA MCF) and are currently home to:
- Three ferromagnetic resonance spectrometers (using both cavities as well as broadband striplines and coplanar waveguides)
- Film deposition facilities
- Magneto-optical magnetometer (polar and longitudinal geometries)
- Three radiofrequency magneto-transport setups (contact method: rf probes or wire bonding)
- 7T Quantum Design SQuID magnetometer
- Magneto-optical microscope
- Computational facilities: GPU and CPU workstations as well as access to Pawsey supercomputers
Group members also have access to UWA's Centre for Microscopy, Characterisation and Analysis as well as the local node of the Australian National Fabrication Facility.
Join our group
There are a number of ways to get involved with our research projects both at an undergraduate and postgraduate level:
- PhD and MSc research projects
- Summer vacation scholarships within the School of Physics
- iVEC supercomputing internships
- Small undergraduate research projects during semester
Don't hesitate to contact one of our research group members to find out about potential projects.
International students from Indonesia and China wishing to pursue MSc or PhD study with our group may consider applying for an ADS (Indonesia) or an UWA-China scholarship respectively.
Terahertz research group
The Terahertz and Optical Technology research group is involved with developing and applying new technologies to a number of biomedical and other applications.
Our main focus is on terahertz imaging and spectroscopy.
What is Terahertz?
The Terahertz (THz) or submillimeter region of the electromagnetic spectrum lies on the border of where we perceive electronics and optics to meet. This 'borderline status' is one reason why these frequencies (0.1-10 THz) had been difficult to produce until relatively recently.
Microwaves are generated by using high-speed oscillating devices, while infrared is generated thermally or by other light sources. Infrared sources become very dim as we approach the THz region. However, the advances in femtosecond lasers have facilitated the convenient generation of short bursts of THz, opening up a new part of the spectrum for study.
In the late 1980s the first coherent pulses of THz had been demonstrated, but the field did not take off until the late 1990s when THz time domain spectroscopy and imaging was introduced. Now there is a large and still increasing number of research groups around the world working in this field and some commercial companies producing THz systems with applications in non-destructive testing, pharmaceutical science, chemistry, physics and biology.
Some of the key projects we are working on
- Theoretical modelling of the interaction of terahertz radiation with biologic tissue
- Modulation of Neurons with THz light
- Assessment of Burns and Scars
- Multi-modal imaging for improved cancer detection
- Development of an Intra-Operative Tool for Tumour Margin Assessment During Surgery
The Zadko Telescope is a one-metre telescope funded by a generous donation from James Zadko to UWA.
The telescope has opened a new window to the “transient universe” - a universe that is filled with fleeting flashes of light originating from the most exotic phenomena in the cosmos.
The telescope is located in a purpose-built observatory, close to the UWA gravitational research facility about 70 kilometres north of Perth.
It scans the sky for potentially hazardous asteroids, and is helping to inspire the next generation of scientists.
Zadko is an important facility for astronomy research at UWA, and is a joint resource for the UWA School of Physics.
Zadko is partially supported by the ARC Centre of Excellence Ozgrav.
Zadko collaborates with a number of international partners, including the following.
- Observatoire de Haute-Provence, France
- L'Observatoire de la Côte d'Azur
- Institut de Mécanique Céleste et de Calcul des Ephémérides (Paris Observatory)