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)PhD Projects and Scholarship
Gravitational waves are ripples of space and time created by violent events in the Universe such as mergers of two black holes or core-collapse of massive stars at supernovae. Their existence was first predicted by Einstein's general theory of relativity. Gravitational waves will represent a completely new spectrum in astronomy and its detection will revolutionize our understanding of how space and time behave in violent events. The ultimate direct detections of gravitational waves are confidently expected in the coming decade, as a result of upgrades to current gravitational-wave detectors.
The development of advanced techniques to improve the sensitivity of gravitational wave detectors leads to exciting new physics phenomena and techniques that may have application beyond gravitational wave detectors. Our project covers a range of projects from gravitational wave data analysis, and optical cavity experiment in both large and small scale.
Proposed PhD projects
High optical power gravitational wave detectors are likely to suffer parametric instability due to the resonant interaction between the cavity optical modes and the high Q acoustic modes of the test mass mirrors. This instability can be suppressed by feeding back optical signals into the cavities. This project will investigate this idea of optical feedback control in a small scale experiment. The research result will be in conjunction with experiments at the Gingin High Optical Power Facility.
Currently an optical cavity with an inside mechanical resonator has been frequency locked to the laser and 3-mode parametric interactions was observed. We expect to first observe the 3-mode parametric instability on the small scale experiment by the end of this year. Then we will setup an optical system to destructively interfere with the field inside the cavity to suppress the instability. This will be achieved by reflect the cavity transmitted beam back into the cavity after frequency shifting and phase masking. The reflected beam needs to be phase locked to the cavity transmission to maintain correct phase to destructively interfere with the beam inside cavity generated by the parametric process.
It has recently been shown that radiation pressure can be used to create stable rigid optical "rods" between suspended mirrors. The stiffness of the optical rod can exceed the stiffness of diamond. This technique offers far reaching possibilities from optically stabilised rigid structures in space to improved low frequency sensitivity in laser interferometers. This project will explore the new techniques and test them on a specially designed 80 meter high optical power cavity at Gingin. We have just purchased two special mirrors for $60,000 for this experiment. This will be supported on our new vibration isolators.
Optical springs are created by radiation pressure forces in optical cavities. Such springs modify both the mechanical frequency and the damping of suspended mirrors in optical cavities. Using two optical frequencies, it is possible to create a double optical spring in which the mechanical response of a mirror responds to weak forces as if it was nearly massless. This scheme has the potential of measuring macroscopic objects with resolution better than the "standard quantum limit" predicted by naive application of quantum mechanics. This offers a new technique for improving gravitational wave detectors as well as allowing a range of new experiments in quantum experiments.
This project aims to experimentally demonstrate that the double optical springs can be tuned to modify the mechanical resonator's response to weak forces so that the effective mass is much less than its actual mass. The experiment involves locking two laser beams with tuneable frequency difference to an optical cavity. By tuning the frequency difference and the individual beam intensity we should be able to tune the double optical spring effect on the mechanical resonator, that is, one of the end mirrors of the cavity. The experiment will be conducted in the gravity wave group optics lab in UWA.
The research group led by Dr. Linqing Wen aims at solving the most critical issues that the entire gravitational wave community is facing, that is, how to best detect a gravitational-wave event and identify its electromagnetic counterpart in a timely manner.
The approach is to participate directly in the on-going international frontier research in the gravitational-wave data analysis to (1) discover and (2) localize in real-time, possibly the first gravitational-wave sources, (3) search for their electromagnetic (EM) counterparts using both radio and optical telescopes, and (4) use theory of gravitation and data from electromagnetic observations to probe the astrophysics of GW sources. Students with proficiency in programming languages C and MATLAB is a plus.
The titles of the specific projects are:
This project is in collaboration with our industrial partner, Gravitec Instruments, to develop sensitive magnetic gradiometer for mineral exploration.
The MG shall be adapted to detect the time varying magnetic gradients induced by active electromagnetic (EM) techniques. These techniques, both airborne and ground, are among the most commonly used methods in mineral exploration. They are capable of direct detection of conductive base-metal deposits, where large conductivity contrasts exist between the deposits and resistive host-rocks or thin overburden cover.
In order to improve the quality of the EM data, a new Extremely Low Frequency (ELF) magnetic gradiometer system will be developed. The difference between the existing EM methods and the proposed one is that there will be magnetic gradient measurements instead of traditional magnetic and electric fields measurements. This would provide new information for data interpretation, such as identifying boundaries of potential deposits.
An active ELF transmitter will also be developed providing a primary ELF magnetic field. This primary magnetic field generates eddy currents in a conductive medium, which in turn create a secondary ELF magnetic field. The spatial gradients of the secondary magnetic field will be measured by the ELF magnetic gradiometer system..
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))Australian and New Zealand citizens and Australian permanent residents are legible to apply UWA post graduate Scholarship http://www.scholarships.uwa.edu.au/home/postgrad
International students can apply for International Postgraduate Research Scholarships (IPRS) and Scholarships for International Research Fees (SIRFs) http://www.scholarships.uwa.edu.au/home/postgrad/international/iprs
Outstanding candidates in receipt of Australian Postgraduate Awards or University Postgraduate Awards may be eligible to receive supplementary scholarships. Tutoring and part-time teaching may also be available for additional income.
Academic visitors: Many of our PhD students first visit here as academic visitors. We have had students and visitors from China, India, France, Chile, Austria, Poland, Singapore, Germany, Romania and USA. Visitors usually receive living allowance equal to the value of a PhD scholarship.