Honours Projects
David Jamieson
Steven Prawer
Shane Huntington
Jeff McCallum
More information:
Microanalytical Research Centre
http://www.ph.unimelb.edu.au/marc/
Centre of Excellence for Quantum Computer Technology
Quantum
Communications
QC implementation in silicon
Arrays of single atoms for quantum computation
We have demonstrated that silicon quantum devices containing a single pair of atoms can be fabricated and tested. We now need to move to the next step where this process is scaled up to larger scale arrays. This can be accomplished by several promising technologies involving scanned cantilevers containing precision apertures machined by a focused ion beam. This project involves experimental tests of this system for the fabrication of large scale arrays.
Implanting single atoms for quantum devices: towards higher precision
with avalanche detectors.
Fabrication of quantum devices that use single atoms as their function elements presents formidable challenges. Our method, based on the implantation of single ions into silicon, successfully meets this challenge. For the near future we must improve the accuracy of this method by reducing the ion energy. To do this we will need to improve the sensitivity of the single ion implantation detection system. One promising way of doing this is by raising the internal electric fields of the silicon substrate so that ion impact produce avalanches of electrons that can easily be detected. Numerical modelling with a large semiconductor device modelling code and experimental measurements are involved in this project.
Nanoscale effects in semiconductor materials and devices
Nanoscale phenomena at the boundaries between classical and quantum physics can now be studied with new methods based on the fabrication of nanoscale devices using tools developed for semiconductor technology. Important issues that are of interest to our group is impurity activation during ultra-shallow junction formation in silicon including ion implantation effects in metal-oxide semiconductor (MOS) devices and the synthesis of Al2SiO5 in sapphire by ion implantation. These projects make use of the advanced infrastructure in our new clean room facilities.
Additional projects involving detailed theory are offered by Lloyd Hollenberg.
QC implementation in diamond
Growth of nanodiamond on fibres
Diamond has very promising optical properties which can be exploited for quantum information processing and transmission. To make this work, diamond must be integrated with conventional optical fibres. This project involves the use of our diamond reactor to grow nanodiamond crystals on the ends of optical fibres. Sophisticated machining with a focused ion beam microscope then allows the diamond to be configured for useful applications. Optical characterisation and modelling are also required.
Characterisation of single photon sources
Colour centres in diamond have interesting properties that allow information to be stored as quantum states of excited electrons. Optical stimulation allows these quantum states to be programmed and read out. We seek new colour centres with wavelengths well matched to long distance signal transmission in silica fibres. This project involves measurement of the quantum states of colour centres in diamond to assess their suitability for information storage and transmission.
Fabrication of single colour centres in diamond
Selected isotopes of some elements, when implanted into diamond, produce colour centres with useful properties. For example, 14N and 15N differ in their nuclear spin and quadrupole moment. This results in colour centres with different quantum properties. For the construction of useful devices containing these colour centres, we need to reliably implant single atoms and read-out the characteristics of the resulting colour centre. This project combines ion implantation and optical characterisation to fabricate and study colour centres in diamond.
Ion beam lithography in diamond
Using a novel combination of ion beams it is possible to machine microstructures in diamond. By fabrication of arrays of nano-scale holes it is possible to make an optical crystal which can capture the luminescence of embedded colour centres for useful applications. It is may also be possible to make micron-scale optical resonators that can process light in novel ways. Micromechanical devices fabricated with this method take advantage of the exceptional mechanical properties of diamond. This project involves the design, fabrication and test of novel nano-scale diamond optical and mechanical devices.
Trace elements
There are two potential areas associated with the CSIRO nuclear microprobe that provide challenging joint supervision honours projects in applications of sophisticated ion beam physics applied to trace element imaging.
Age mapping of accessory minerals
Proton induced x-ray analysis (PIXE) of selected minerals provides the opportunity to map the growth of the crystal over time and in some cases gives timing for geological events such as metamorphism. The method uses the radioactive elements U & Th (and the products - Pb) to generate a map of crystal age from an x-ray elemental image, on a pixel by pixel basis. This project would involve the analysis of a series of "standards", in the first instance, to establish the precision and accuracy of the method before testing "unknowns". In addition to the PIXE analysis for the elements U & Th & Pb, as well as other trace elements in one or more mineral types (eg. monazite, zircon), the project could involve some programming - (say IDL) to carry out the age calculations (iteratively) for each pixel of a sample image. If the student has reasonable mathematics, they could develop/formulate a error treatment for the PIXE-derived age calculation.
Quantification of fluorine in the proton induced gamma-ray analysis
(PIGE) of inclusions
The fluorine content of solid, homogeneous specimens can be determined with reasonable precision using established PIGE techniques. However, inhomogeneous substrates such as layered samples or those containing inclusions (solid or fluid) pose considerable challenges. This project would look at determining suitable combinations of proton beam energies and inclusion depth to exploit narrow p,gamma resonances in order to optimise (and quantify) the gamma-ray yield from such samples. The project would involve the design and analysis of layered specimens (and possibly synthetic inclusions) using the PIGE capabilities of the nuclear microprobe. There is also scope for a more mathematically orientated modelling of results to develop a predictive capability, with the possibility of programming of the algorithms if that is desirable.
More information:
Prof David Jamieson
ph: (03) 8344 5376