Available PhD Positions

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Atomic-scale structural, electronic and optoelectronic studies on light-harvesting metal-halide perovskites

Hybrid organic-inorganic perovskites are an emerging class of photovoltaic materials with the potential to outperform silicon. Solar cells made of metal-halide perovskite offer material costs below $2/m2 and certified efficiencies beyond 20%. However, the underlying physical mechanisms allowing for strong light absorption and efficient electron-hole separation in metal-halide perovskites are not fully understood. In particular, very few studies have been performed on the atomic-scale properties of these materials. This project aims expertise in synthesis, crystal growth, solar cell assembly and morphology control, with scanning-probe based surface analysis, in order to deepen our understanding of the structural and electronic properties of perovskite materials at the atomic scale. Metal-halide perovskite crystals will be synthesised by collaborating groups. The PhD candidate will study the atomic-scale structural, electronic and optoelectronic properties of such materials by low-temperature scanning tunnelling microscopy (STM) and spectroscopy (STS), non-contact atomic force microscopy (ncAFM), as well as synchrotron-based x-ray studies (x-ray photoelectron spectroscopy (XPS), near-edge x-ray absorption fine structure (NEXAFS)). Perovskite crystals will be cleaved in ultrahigh vacuum (UHV) and characterised in situ. These experiments will allow to correlate atomic-scale electronic structure with the materials’ light-harvesting functionality.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin

Convection in massive stars

The final stages of massive stars already forebode the violent fate that ultimately awaits them when they explode as a supernova. In the last phases of their lives, these stars go through ever shorter episodes of nuclear burning in the stellar core and the surrounding shells, which drives increasingly violent convective overturn. Immediately before the collapse of the core to a neutron star, convective motions can reach velocities of several hundred kilometres per second in the silicon and oxygen shell around the iron core.

How these convective motions affect the structure of the stellar core by compositional mixing, transport of angular momentum, and excitation of waves is not yet fully understood. Neither do we yet fully understand how they affect the subsequent collapse and explosion. Today, three-dimensional (3D) simulations of convective burning have become a powerful tool for learning about the deep interiors of massive stars. Such 3D simulations are still limited to relatively short time-scales, and cannot consistently follow the entire lifetime of the last burning stages (silicon core burning and silicon and oxygen shell burning). In this project, you will develop efficient numerical methods to enable long-time simulations of the final burning stages and use them to investigate mixing and angular momentum transport in the innermost convective zones and/or to create better 3D progenitor models for supernova simulations.

Students interested in high-performance computing will acquire first-hand experience with modern supercomputers during the course of their PhD. This is a computational project suited for students with a background in astronomy, applied mathematics, or nuclear/particle physics. Experience with computational fluid dynamics is advantageous.

For inquiries, please contact Dr Bernhard Mueller (bernhard.mueller@monash.edu).

Astronomy & Astrophysics Dr Bernhard Mueller

Coloured X-ray Imaging at the Quantum Level

X-ray interactions with matter are highly dependent upon the energy of the incident photons. Yet in X-ray imaging it is common to ignore this effect even though most images are made using poly-energetic X-ray sources. If the energy of each photon can be recorded then it becomes possible to recover the electron density of materials in complex structures and to isolate specific chemical signatures. This information would be extremely useful for improving detection of diseases in medical imaging, and for isolating dangerous materials in border security [1]. Energy-resolving, photon counting detectors do exist, but they are extremely expensive and suffer poor spatial and/or temporal resolution. On the positive side, they produce a virtually noise free image. This project will explore the possibility of using new high-speed X-ray cameras for detecting individual X-ray photons and determining their energy. When successful, this technology will be employed to enable noise free, material specific imaging in real-time with spatial resolution on the micron scale – a kind of "Holy Grail" for X-ray imaging.

This project will involve experimental studies using our high powered liquid metal jet X-ray source, one of only a few in the world, and the Imaging and Medical Beamline at the Australian Synchrotron adjacent to Monash University. Energy resolved images will be employed to enable high contrast, low noise imaging with both phase and absorption contrast imaging in 2D and 3D.

References

[1] Marcus J Kitchen, David M Paganin, Kentaro Uesugi, Beth J Allison, Robert A Lewis, Stuart B Hooper, and Konstantin M Pavlov, "Phase contrast image segmentation using a Laue analyser crystal", Physics in Medicine and Biology, volume 56, number 3, 515-534 (2011).

Imaging Physics Dr Marcus Kitchen,
Dr Kaye Morgan

Detecting gravitational waves with Advanced LIGO

The Laser Interferometer Gravitational-wave Observatory (LIGO) seeks to detect gravitational waves: ripples in the fabric of spacetime caused by violent astrophysical events such as the coalescence of two stars. The newly upgraded Advanced LIGO detector is expected to begin taking science data in late 2015. At design sensitivity, Advanced LIGO is expected to detect dozens of gravitational wave events every year. The first detections of gravitational waves will be a watershed moment in astronomy, confirming a prediction of general relativity, probing some of the most extreme objects in the Universe, and potentially testing new physics in regimes that are not accessible through other means. This project is to analyse Advanced LIGO data in order to detect gravitational waves. A number of specific research directions are possible depending on student interests including searches for stochastic backgrounds, searches for persistent point sources, and searches for transients. The project will require engagement in multiple facets of gravitational-wave astronomy: working to understand the behaviour of the detector, analysing Advanced LIGO data, and determining the astrophysical implications of the results. As a bonus, the student working on this project will gain highly marketable expertise with Big Data, statistics, and algorithm development. Applicants should have a strong background in physics/astronomy data analysis including experience with computer programming. Experience with astrophysics/cosmology is advantageous.

Astronomy & Astrophysics Dr Eric Thrane

Development of a neutral helium beam microscope

Both light and electrons are routinely used to probe and image structures and have resulted in huge advances in our understanding of the physical world. Probing samples with neutral helium atoms offer advantages over these established techniques due to the low energy and non-reactive nature of the atoms used to probe a surface, and the high spatial resolution (< 1 micron) achievable. This experimental project will be to develop a prototype neutral helium beam microscope capable resolving structures below 100 nm. The project builds on preliminary work in focusing cold (0.1 K) jets of Helium atoms using highly intense (1e16 W/m^2) laser beams to form a narrow, intense atom probe (100 nm diameter) for sample interrogation. Multiphoton ionization of the atoms scattered off a sample, using intense lasers, is used to detect structures and provide imaging. Applicants should have a strong background in experimental physics and experience with laser and/or electron optics is advantageous.

Imaging Physics Dr Alexis Bishop

Femtosecond atomic-scale dynamics on a surface

The advent of scanning tunnelling microscopy more than 30 years ago has allowed for real-space imaging of single atoms and molecules on a surface. Normally, this technique is able to study the equilibrium properties of a system, and does not allow to access real-time ultrafast dynamics occurring at femtosecond timescales. Indeed, the intrinsic time resolution of scanning tunnelling microscopy is dictated by the speed of conventional electronics, which is at best on the order of hundreds of picoseconds. Many processes on surfaces however, such as charge dynamics or vibrations of molecules, can unfold at much faster timescales, below 1 picosecond.

Recent advances in scanning tunnelling microscopy combined with techniques of nonlinear optics, ultrafast photonics and pump-probe spectroscopy have allowed to access ultrafast dynamics of processes on a surface, with real-time sub-picosecond resolution, and, at the same time, real-space single atom resolution. The approach relies on coupling quasi-single-cycle, ultrashort electromagnetic waveforms (e.g., a terahertz, infrared or optical pulse) to the junction of the scanning tunnelling microscope.

The project here consists of investigating structural, charge and magnetization dynamics in photo-active molecular assemblies on surfaces, with sub-picosecond time resolution, and at the scale of a single atom.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin

Few- and many-body physics in ultracold atomic gases

Ultracold atomic gases have emerged as an ideal platform for investigating the physics of strongly correlated materials in a highly controllable environment. The Theory of Quantum Matter group at Monash University works primarily at the interface between condensed matter physics and the physics of ultracold atoms. We are particularly interested in systems where strong few-body correlations impact the many-body behaviour. As such, we investigate a wide range of topics, including few-body systems, impurities in degenerate quantum matter, systems out of equilibrium, and low-dimensional systems.

Applications should have a strong background in theoretical physics. Experience with few- and/or many-body physics of ultracold gases would be advantageous, although it is not necessary. A number of specific research directions are possible, depending on the student’s interests.

An introduction to our research group including recent publications can be found at qm.physics.monash.edu

Theoretical & Computational Physics,
Quantum Gases
Associate Professor Meera Parish,
Dr Jesper Levinsen

Graphene as a platform for new topological phases of electronic matter

Graphene is an atom-thick plane of carbon and the basic constituent of graphite. Electrons in graphene behave as massless relativistic particles and obey an analogue of the Dirac equation in two dimensions; the experimental observation of these properties led to the 2010 Nobel Prize in Physics. A variety of schemes have been proposed to realize new electronic states by introducing a mass and bandgap in graphene. One scheme involves transition metal adatoms on graphene which add strong spin-orbit coupling, resulting in a bandgap and a topological insulating quantum spin Hall phase, or, in the case of magnetic order, a quantum anomalous Hall phase. Such phases could carry dissipationless edge currents at room temperature and could be used in future electronics or quantum computing technologies. This PhD project will characterize the electronic properties of graphene with metal adatoms. In the Fuhrer laboratory at Monash adatom-modified graphene will be created controllably in ultra-high vacuum (UHV), and studied with in situ electronic transport measurements and low-temperature scanning probe microscopy capable of imaging the atomic structure of the modified material. Complementary experiments will be carried out at the Australian Synchrotron to probe the electronic structure of adatom-modified graphene using photoemission spectroscopy.

Condensed Matter Physics Professor Michael Fuhrer

High dimensional data visualisation in high energy physics

Many areas of physics produce very large numbers of results that depend on multiple parameters. The parameters can be theoretical, experimental or from modelling. One example would be Higgs physics, where the LHC experiments are releasing many measurements of its properties. In this case the multiple parameters are the Higgs properties. Typically these measurements are compared with theoretical expectations from the standard model. But they can also be parametrised by an effective Lagrangian to search for deviations from the standard model. In this case the multiple parameters are those in the effective theory.

In this project we will begin to implement modern statistical visualisation tools to large, multidimensional data sets with the aim of gaining intuition into the fits that are normally made.  The data sets to be used in the project can be from particle physics, or with a suitable co-advisor, from any area of physics or astrophysics.

Particle Physics Professor German Valencia

Interacting electrons in atomically thin semiconductors

Single atomically thin planes of layered transition metal dichalcogenides such as MoS2 have recently been discovered to be two-dimensional semiconductors with direct bandgaps. Because of their atomically thin nature, electronic screening in these materials is poor, and electron-electron and electron-impurity interactions are unusually strong. The interaction strength is also tunable through changing the surrounding dielectric environment, impossible in conventional semiconductors. This PhD project will experimentally probe the effect of strong electron-electron and electron-impurity interaction in MoS2. In the Fuhrer laboratory at Monash MoS2 devices will be fabricated using lithographic techniques and transferred into ultra-high vacuum (UHV) where they will be studied with in situ electronic transport measurements and low-temperature scanning probe microscopy capable of imaging their atomic structure. Dopants such as alkali metals will be controllably placed on MoS2 and the screening cloud of individual dopant atoms will be imaged at the atomic scale. The effect of dopants on electronic transport properties will be measured directly. Electron-electron interactions will be controlled through the choice of substrate dielectric constant, and the effect on electronic and optical properties will be studied. Low-temperature scanning probe microscopy will be used to search for signatures of exotic interaction-driven physics such as Wigner crystallization at low carrier densities.

Condensed Matter Physics Professor Michael Fuhrer

Light transformed materials

Progress in condensed matter physics is often driven by the discovery of novel materials. Topological materials are one such class of material, displaying unique quantum mechanical properties. Topological insulators (TIs) are a particular class of topological materials that are the subject of ongoing intense research interest. As they arise from a qualitatively new aspect of quantum mechanics - the topology of the Hilbert Space - they have opened an entirely new aspect of materials physics. Of particular interest is their ability to transport charge at very low resistance potentially leading to future applications in low-power electronic technologies.

The last 30 years has also seen significant developments in the fields of nonlinear optics, ultrafast photonics and pump-probe spectroscopy.  These now allow us to access ultrafast dynamics of processes with real-time sub-picosecond resolution. Moreover, they also allow us to generate extremely high, transient fields.

The project here consists of probing and manipulating the topological phases of matter using quasi-single-cycle, ultrashort electromagnetic waveforms (e.g., a terahertz, infrared or optical pulse).

Systems of interest will consist of 2D and 3D topological insulators (e.g. Na3Bi, Bi2Se3), transition metal dichalcogenides (e.g. MoS2, WS2) and Dirac semimetals (e.g. graphene). These systems will be prepared via chemical vapour deposition (CVD) and molecular beam epitaxy (MBE) by our collaborators within the New Horizons Center.

The PhD candidate will gain expertise in experimental nonlinear optics, pump-probe spectroscopy, ultrafast lasers, condensed matter physics and surface science. The candidate will perform experiments, analyse and interpret experimental data, compare these experimental data with theoretical models (developed by theoretical collaborators (e.g. with expertise in density functional theory) or the PhD candidate her/himself, time permitting). They will conduct their own research project independently and will collaborate with other members of Schiffrin’s research group to manage the ultrafast laser system and acquire relevant expertise in the aforementioned fields of research. They will also have the opportunity to participate in experiments at collaborating international institutions. The PhD candidate will be supervised by Beane and Schiffrin, with help from Schiffrin’s research group members.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Gary Beane at gary.beane@monash.edu or Agustin Schiffrin at agustin.schiffrin@monash.edu

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html


Condensed Matter Physics
Dr Gary Beane,
Dr Agustin Schiffrin

Making X-rays Safe: Radiation dose reduction factors in the thousands using Phase Retrieval Tomography

The biggest problem with X-ray imaging in diagnostic medicine is the use of potentially dangerous ionizing radiation. Researchers across the globe are exploring Phase Contrast X-ray Imaging (PCXI) techniques to revolutionise X-ray imaging for applications in diagnostic imaging, materials science and security applications [1]. PCXI modalities increase the contrast of interfaces between materials by rendering gradients in the X-ray wavefield visible. Its advent has had a profound impact in many fields of science from biomedical imaging to materials characterization for industrial research. Using synchrotron radiation, our team has shown that this sensitivity can increase the signal-to-noise ratio of 3D tomographic imaging (CT) by up to two orders of magnitude [2, 3]. Remarkably, this enables us to reduce the radiation dose by factors in the tens of thousands. Our aim is to develop this technology for use on smaller X-ray sources, with the end goal of translating it for massively reducing the radiation dose in human diagnostic imaging.

This project will investigate the use of new laboratory-based, high powered, highly coherent X-ray sources for developing an ultra-low dose CT capability. These sources include the liquid metal jet anode X-ray source at Monash University and potentially the Compact Light Source (using inverse Compton Scatter) at the Technical University of Munich. Using phase contrast images produces on these sources in combination with phase retrieval and iterative reconstruction algorithms, we aim to produce high quality 3D images of the inner structures of objects using extremely low doses of radiation.

References

[1] Bravin, A., P. Coan, and P. Suortti, X-ray phase-contrast imaging: from pre-clinical applications towards clinics. Physics in Medicine and Biology, 2013. 58: p. R1-R35.

[2] Beltran, M.A., et al., Interface-specific x-ray phase retrieval tomography of complex biological organs. Physics in Medicine and Biology, 2011. 56(23): p. 7353-7369.

[3] Beltran, M.A., et al., 2D and 3D X-ray phase retrieval of multi-material objects using a single defocus distance. Optics Express, 2010. 18(7): p. 6423-6436.

Imaging Physics Dr Marcus Kitchen,
Dr Matthew Dimmock,
Dr Kaye Morgan

Modelling the electronic structure of low-dimensional organic nanostructures on surfaces

Supramolecular and metal-organic self-assembly on surfaces holds promise for the synthesis of functional low-dimensional nanostructures with ultimate atomic-scale precision. This approach consists of depositing atoms and functionalised organic molecules onto clean surfaces, in a controlled environment, to achieve well-defined configurations via programmed inter-adsorbate and adsorbate-surface interactions.

Potential functionality of these nano-assemblies arise from their atomic-scale electronic structure, which is dictated by quantum mechanics. Understanding and predicting such electronic structure is non-trivial, given the typically large size of the unit cell of these many-body systems. Density functional theory (DFT) offers a viable numerical method for determining the energy-dependent electronic density in such systems, allowing to understand and predict their morphology and electronic properties at the atomic scale.

The project here consists of using computational DFT tools for determining the atomic-scale morphology and electronic structure of low-dimensional nanostructures on surfaces. Systems of interest will consist of 1D and 2D metal-organic frameworks on metals, semiconductors and atomically thin materials. In particular, these systems are relevant for the design of solid interfaces with functionality in photovoltaics, photocatalysis, molecular nanoelectronics and molecular magnetism. This project will be co-supervised by Dr. Schiffrin (School of Physics and Astronomy) and Prof. Medhekar (Department of Materials Science and Engineering).

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin,
Professor Nikhil Mendhekar

On-surface organic nano-electronics

Modern electronics relies on the control of electric charge in nanoscale devices. Current mass production methods for device miniaturisation are not only reaching their inherent limit, but are also facing fundamental challenges arising from quantum phenomena at the nanoscale. The design of next-generation electronic devices requires the development of radically new approaches to nanotechnology, including novel materials to supplement or substitute silicon as the active material.

The aim of this project is to design electronically functional nanodevices based on supramolecular self-assembly on surfaces as novel active electronic materials. This approach employs molecules as building blocks to assemble nanostructures with atomic-scale structural precision and tailored electronic functionality. These systems offer extraordinary tunability and extensibility, spanning from the micro- down to the nanoscale. Engineered nanodevices will consist of low-dimensional organic and metal-organic nanostructures, synthesized from the bottom-up with atomic-scale precision. These active materials will be connected to macroscopic electrodes, allowing to access the macroscopic electronic properties of the organic systems via electron transport measurements. This will bridge the gap between atomic-scale electronic structure and overall electronic functionality of the device.

The PhD candidate will gain expertise in experimental surface science, nanoscience, supramolecular chemistry, low-temperature physics, scanning tunnelling microscopy and spectroscopy, atomic force microscopy, electron transport, nanofabrication and ultrahigh vacuum. The candidate will perform experiments, analyse and interpret experimental data, compare these experimental data with theoretical models (developed by theoretical collaborators (e.g. with expertise in density functional theory) or the PhD candidate her/himself, time permitting). S/he will conduct his own research project independently. S/he will work within a research team and acquire relevant expertise in the aforementioned fields of research. The PhD candidate will be supervised by Schiffrin and Weber, with help of other research group members.

Applicants should hold an Honours or Master’s degree, and have a strong background in experimental physics.

If you have any questions, please contact Dr Agustin Schiffrin at Agustin.Schiffrin@monash.edu and Dr Bent Weber at Bent.Weber@monash.edu.

Interested applicants must meet Monash Universities PhD entry requirements. See following link: http://monash.edu/science/about/schools/physics/postgrad/apply-postgrad.html.


Condensed Matter Physics
Dr Agustin Schiffrin, Dr Bent Weber

Optimal correlations

Concurrent localisation in the position and wavelength of any object is constrained by the Heisenberg Uncertainty Principle. Real world applications that seek to maximise such localisation aspects range from synthetic aperture imaging to watermarking digital media. They often rely on the construction of discrete signals with 'all or nothing' properties: an embedded signal is either exactly locatable to within a single pixel position or they remain completely transparent to a large range of probe signals.

This project examines methods to construct large families of discrete signals that have maximal and/or minimal correlations between family members. A recently discovered class of such signals has been extended from binary to multivalued functions. Ideally, these multivalued signals will retain their 'perfect' properties when constructed using purposefully chosen combinations of values (for example functions that have a uniformly flat or linear histogram of grey values). A related goal is to investigate 'ghosts' in N-dimensions. These are N-dimension signed discrete functions whose projected views in less than N dimensions are exactly zero across the full width of the domain they occupy. A longer term goal is to construct compact N-dimensional functions that have optimal correlations and retain the zero sum property.

Imaging Physics Dr Imants Svalbe

Photoacoustic imaging of cerebrovascular anatomy and function

Photoacoustic (PA) imaging relies on generating ultrasound pressure waves when tissue absorbs a short pulse of light. Usefully it has been shown that photoacoustics can provide imaging of structures at depths of several centimetres beneath tissue and bone. The lack of ionizing radiation, high resolution (1- 100 microns), and tissue discrimination make this technique attractive for medical diagnostics.This experimental project is to develop an imaging system, using PA tomography, to visualise the vascular anatomy of the cerebrovasculature through the intact rat skull using a recently-developed optically-based acoustic sensor. The apparatus is aimed towards use in stroke research, allowing researchers, for the first time, to see the effects that various protocols have, in near real time, on the vascular system of the rat brain. Using the PA sensor system with multi-wavelength excitation will allow measurements of the oxygen delivery capacity of the brain blood vessel network beneath the intact rat skull. The ultimate aim of this project is to extend the use of PA measurement technique to humans to enable visualisation of the damaged region of brain tissue due to stroke. Applicants should have a strong background in experimental physics and experience with optics is advantageous.

Imaging Physics Dr Alexis Bishop

Predicting the next big discovery in fundamental physics

A Can we predict the next fundamental discovery? With certainty, no. Based on our present knowledge of new physics theories and on the reach of near future experiments, however, we can calculate a probability that a given future experiment will discover an aspect of one of the new physics scenarios. Knowing this probability is important because today chance discoveries are very rare. During the last few decades most fundamental phenomena were predicted before discovered: tau lepton (1975), bottom quark (1977), top quark (1995), neutrino mass (1998), tau neutrino (2000), Higgs Boson (2012), gravitational waves (2015).

How can we calculate the probability that a near future experiment will discover a new theory? First, we have to use data from most known experiments to calculate the most feasible parameter region of the theory. Then, we can calculate the probability mass for the theory at hand that falls within the reach of any given future experiment. This information can then be used to guide experimental searches. The challenge is to do this for many promising theories, so that we do not miss any potential discoveries. The described generic algorithm is coded in the Global And Modular Beyond-the-Standard-Model Inference Tool (GAMBIT).

This project uses GAMBIT to assess the discovery potential of various near future experiments. We will consider a wide range of the most promising new physics scenarios, such as Higgs extensions, supersymmetric models, Grand Unified models, models described by effective field theories. We will calculate the discovery potential within these theories for additional Higgs bosons, supersymmetry, new forces and particles, gravitational waves and alike. Where necessary, we will extend GAMBIT with automated observable calculations and/or likelihood functions describing the (future) reach of experiments. Excellent numerical skills are required for this project.

Particle Physics Associate Professor Csaba Balazs

Quantum Batteries

As mobile devices become more and more indispensable to our way of life, it is crucial to have batteries that are both efficient and fast-charging. While batteries based on current technology have achieved a reasonable speed and efficiency, they still perform well below the fundamental limits set by nature, and they are unlikely to be adequate for the next generations of devices. This project seeks to find those fundamental limits using the tools of quantum information theory.We will consider many-body systems as energy storage devices with the aim of enhancing performance as a battery using quantum entanglement. This project is part of a growing effort in quantum thermodynamics that aims to understand the movement of energy in mesoscopic technologies. The overarching aim of this project is to investigate under which conditions a quantum many-body system can be used as a battery, and to determine the optimal procedures for their charging and discharging. This work will eventually lead to designs for a battery with greater energy storage and higher charging power than can be achieved in current (classical) systems. The PhD student will play a central role in this investigation. After an initial period of training, they will work with Drs. Meera Parish, Kavan Modi, Jesper Levinsen and Felix Pollock to design algorithms to search for optimal battery structure within a series of theoretical models. In the course of this project, the student will acquire familiarity with a range of numerical and analytical techniques, from both condensed matter physics and quantum information theory. Applicants should hold a good first class Honours degree and should have a strong background in undergraduate theoretical physics. In addition, this project would suit an applicant with experience of and an interest in programming.

Theoretical & Computational Physics Dr Kavan Modi, Associate Professor Meera Parish, Dr Jesper Levinsen, Dr Felix Pollock

Revealing fundamental physics with gravitational waves

Originating from the time when the Universe was opaque for light, gravitational waves carry information about fundamental physics from the early Universe well above 1 eV energies. Combined with information from the Large Hadron Collider, this enables us to begin to piece together the thermal history of the early Universe at those energies. Gravitational waves are crucial in this since they carry imprints of thermodynamic phase transitions that played an important role in the early Universe.

The mechanism of spontaneous electroweak symmetry breaking, by which all known elementary particles acquire mass, was accompanied by a thermal phase transition in the early Universe. Fundamental fields acquiring a vacuum expectation value, the breakdown of a unified force into the known four forces, and condensing hidden sectors may have caused a succession of phase transitions. Gravitational waves can tell us whether any of these phase transitions were a first order transition.

The aim of this project is to calculate gravitational wave amplitudes and frequencies in well motivated new physics theories that lead to a first order phase transition in the early Universe. We constrain the parameter space of these theories using various particle experiments and astrophysical observation and check whether their gravitational wave signals are in reach of future gravitational wave detectors such as eLISA, DECIGO, BBO, or aLIGO. This project requires a solid background in particle physics, cosmology and excellent analytical and/or numerical skills.

Particle Physics Associate Professor Csaba Balazs

Simulating the explosions of massive stars

Core-collapse supernovae mark the death of massive stars: In an evolved star that has gone through the various burning stages, its iron core eventually collapses, leaving behind a neutron star, while the envelope is expelled in a violent and very bright explosion. These explosions are fascinating laboratories for matter under extreme conditions and cosmic furnaces that make many of the chemical elements that are the building block of planets like ours. Supernovae are also promising sources of neutrinos and gravitational waves, messengers that come directly from the innermost few hundreds kilometres of the collapse star and could allow us a direct glimpse at the supernova engine once such an explosion occurs within our Milky Way.

It has only recently become possible to successfully simulate such supernova explosions in three dimensions based on first principles. Many questions about these phenomena are still not fully unanswered: What makes supernovae explode? How do the explosion energy, the remnant mass, and the composition of the ejecta depend on the progenitor? Do some supernovae produce the heavy neutron-rich elements (like gold and the actinides)? Which progenitors form black holes? How do extremely energetic “hypernovae” come about?

Understanding these explosions requires sophisticated simulation codes. In this project, you will have the opportunity to contribute to a state-of- the-art relativistic radiation hydrodynamics code that has been successfully used model 3D supernova explosion driven by neutrino heating. Depending on your abilities and inclinations, you will add/improve modules to better treat the (magneto-)hydrodynamics, the radiation transport, or the neutrino and nuclear physics in the code. This will prepare you to solve some of the many open problems that current supernova simulations still face.

Students interested in high-performance computing will acquire first-hand experience with modern supercomputers during the course of their PhD. This is a computational project suited for students with a background in astronomy, applied mathematics, or nuclear/particle physics. Experience with computational fluid dynamics is advantageous.

For inquiries, please contact Dr Bernhard Mueller (bernhard.mueller@monash.edu).

Astronomy & Astrophysics Dr Bernhard Mueller

Single Shot X-ray Tomography for Real-Time 4D Functional Imaging

X-ray imaging can provide high resolution imagery of bodily organs in two and three dimensions (2D and 3D). 4D imaging is also possible, but only for slowly moving objects [1]. However, for extra dimension massively increases the ionizing radiation dose to the patient. Contrast in X-ray imaging relies on differential absorption of X-rays as they pass through materials of different chemical composition. A large fraction of the X-rays are Compton scattered at random angles to the incident beam direction. These create a problematic source of noise to X-ray images that greatly reduces image contrast and resolution. There are several methods employed in the clinic to remove these scattered photons to enhance image quality.

We have patented a technique to use the Compton scattered radiation as a source of information about the sample. We have shown that it is theoretically possible to quantitatively reconstruct the 3D structure of an object from a single short exposure. By taking multiple exposures as the object moves should enable 4D imagery with potentially very low radiation dose. For this project the student will work with our team to develop a robust image reconstruction algorithm and validate our theory using experimental data to be acquired at the Australian Synchrotron. The major benefits expected from this research are the potential for substantial dose reduction and real-time 4D imaging.

References

[1] Fouras A, Kitchen MJ, Dubsky S, Lewis RA, Hooper SB, Hourigan K, "The past, present and future of x-ray technology for in vivo imaging of function and form", Journal of Applied Physics, volume 105, issue 1 (2009).

Imaging Physics Dr Marcus Kitchen

Study of Flavour Anomalies

An important component of particle physics research is the study of rare processes in `flavour physics’. In current experiments this typically refers to decays of bottom mesons that have very small branching fractions. Recent experimental studies of these decays have produced a number of `anomalies’, or disagreements with the standard model expectations.

In this project we will study these anomalies from the theoretical perspective, looking for common threads that can lead to global explanations in terms of new physics. When good explanations are found, they also produce predictions for upcoming experiments that can rule them out (or, with much luck, confirm them).

Particle Physics Professor German Valencia

The origin of matter

Various extensions of the Standard Model (SM) of fundamental particles have the potential to explain the origin of all matter in the Universe, baryonic (visible) and non-luminous (dark) matter alike. Unfortunately, we are missing key pieces of information: the global feasibility of these theories and their precise matter abundance predictions. The main reason for the latter is that, while several automated tools exist for the calculation of dark matter abundance, the generic techniques to calculate the baryon abundance are lagging behind.

The Monash Particle Phenomenology Group, together with the Global And Modular Beyond-the-SM Inference Tool (GAMBIT) international collaboration, are working on remedying this problem. For simplicity, we are focusing on electroweak baryogenesis, a promising and relatively easily falsifiable mechanism proposed to generate baryons in the early Universe. While GAMBIT is gearing up to calculate the feasibility of many SM extensions, the Monash group is creating robust and precise calculational techniques for electroweak baryogenesis.

In this project, we examine the calculation of cosmic baryon abundance in the context of electroweak baryogenesis in a particle model independent context. Where necessary, we develop new analytical methods to solve parts of the problem.These methods will then be used to create numerical algorithms (partly) by auto-generation of computer code. This project requires a solid background in particle physics, cosmology and excellent analytical and/or numerical proficiency. Insight into other areas of physics, such as thermal field theory, is useful.

Particle Physics Associate Professor Csaba Balazs