K V Kheruntsyan

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I believe that the work between a PhD student and their supervisor is a little bit like the research collaboration between two individuals. (One of them just happens to be more experienced and helps the other with their research project.) As such, an important ingredient of a successful collaboration is getting to know the other person. So, here is a little bit about me.

First, you might be wondering about how to pronounce my name Karén. Well, the first name is really easy: it is pronounced the same way as Karen, except the accent is on the letter e, hence the use of the symbol é. Next the surname: try it as KHE-RUN-TSYAN. Here, KH is a single sound the one you would make in Loch Ness (know that monster in Scotland?) if you were to say it with a strong Scottish accent. Next, pronounce RUN like in Rooney. Finally, in TSYAN, the two letters TS should again make a single sound, like in tsetse. There, you've got it: Kheruntsyan! And, by the way, the accent is on the last a.

My name comes from Armenia, which was up until 1991 one of the Republics in the former Soviet Union. Currently Armenia is an independent country, the Republic of Armenia, to be more precise. I graduated from the Yerevan State University and did my PhD during the Soviet Union era. Therefore, my education background comes from the thorough Russian education system, which was the good thing about being part of the Soviet Union! I moved to Australia and settled in Brisbane in 1996, and have been working in the Department of Physics at the University of Queensland since then.

I am a Chief Investigator at the ARC Centre of Excellence for Quantum-Atom Optics and have a few research projects in mind. I cant really keep them all to myself and am looking for a PhD student. So, why dont you come to my office (room 402, Physics Annexe) for a chat?

Five good reasons for doing your PhD project under my supervision:

• You will be working on a research project that is at the forefront of international developments in this field, and is challenging and closely related to the experiments.
• As a measure of the quality of your research, the target will be to publish in the disciplines top tier journals (such as Phys. Rev. Lett. and Phys. Rev. A).
• Seeing you publish early in your PhD will be one of my priorities.
• You will be working in a world-class research environment provided by the UQ Theory Node of the ARC Centre of Excellence for Quantum-Atom Optics one of the first eight Centers of Excellence established to become flagships of Australian science.
• By the end of your PhD you will be an independent and internationally competitive research scientist, having specialist expertise in quantum-atom optics and capable of doing independent world-class research.

Did I mention that students who are successful in obtaining a scholarship for PhD studies at UQ will be offered an additional top-up scholarship of $6,000 per annum from our Centre's research funds. For further details please see http://www.physics.uq.edu.au/BEC/prospective_students.html.

1. Macroscopic correlations and entanglement in quantum atom optics
Co-supervisors: M. J. Davis and M. K. Olsen

Dissociation of a diatomic molecule produces two quantum mechanically entangled atoms with equal and opposite momenta in the molecule's rest frame. These atoms have Einstein-Podolsky-Rosen type correlations in position and momentum, and hence are of fundamental interest to quantum theory. Experimental advances in coherent manipulation of ultracold quantum gases are now enabling the production of molecular Bose-Einstein condensates (BECs) containing thousands of molecules. These molecular BECs can in turn be dissociated into strongly correlated ensembles of constituent atoms containing thousands of particles [1,2], thus extending possible fundamental tests of quantum mechanics into mesoscopic and macroscopic regimes never attainable before.

This PhD project seeks understanding of these macroscopic correlations and will include simulations and modeling of recent breakthrough experiments on generation of correlated states through molecular dissociation. A related atom-optics process that is capable of producing similar correlations is four-wave mixing in BEC collisions [3]. Four-wave mixing will be also studied throughout this PhD project. Your work will include both analytic and computational approaches, with access to our Centre's super-computing cluster. There will be close interactions with the experimental group at the SUT Node of our Centre in Melbourne, as well as with other experimental labs around the world, such as G. Rempe's lab at Max-Planck Institute in Garching, Germany, and A. Aspect and C. Westbrook's lab at the Institut d'Optique in Orsay, France.

[1] C. M. Savage, P. E. Schwenn, and K. V. Kheruntsyan, cond-mat/0606345 (to appear in Phys. Rev. A).
[2] K. V. Kheruntsyan, Phys. Rev. Lett. 96, 110401 (2006).
[3] C. I. Westbrook et al., quant-ph/0609019.

2. Non-local pair correlations in 1D Bose gases
Co-supervisors: J. F. Corney and M. J. Davis

The one-dimensional (1D) Bose-gas model of particles interacting via a repulsive delta-function potential is fundamentally important to quantum many-body physics. On the one hand, the model is one of the very few ones in quantum many-body theory that is exactly solvable. On the other hand, it is now experimentally realizable with ultra-cold alkali atoms in highly anisotropic trapping potentials [1,2]. Thus, there are unique opportunities for accurate tests of theory that were previously unavailable, in turn leading to the development of fundamental knowledge of interacting many-body systems in low dimensions.

This PhD project is aimed at the study of non-local pair correlations in 1D Bose gases, which will be an extension of our earlier work on local correlations [3,4]. The knowledge of atom-atom correlations is crucial for the understanding of coherence properties of 1D Bose gases and for the design of devises such as atom lasers and interferometers operating in 1D environments. The project will involve both analytic and computational approaches, with access to our Centre's super-computing cluster. There will be close interaction with the experimental group of M. Raizen at the University of Texas at Austin, that plans to study such correlations experimentally.

[1] B.L. Tolra, K. O'Hara, J. Huckans, W.D. Phillips, S.L. Rolston, and J.V. Porto, Phys. Rev. Lett. 92, 190401 (2004).
[2] T. Kinoshita, T. Wenger, and D. S. Weiss, Phys. Rev. Lett. 95, 190406 (2005).
[3] K.V. Kheruntsyan, D.M. Gangardt, P.D. Drummond, and G.V. Shlyapnikov, Phys. Rev. Lett. 91, 040403 (2003).
[4] P.D. Drummond, P. Deuar, and K.V. Kheruntsyan, Phys. Rev. Lett. 92, 40405 (2004).

3. Thermometry of quantum gases near absolute zero
Co-supervisor: M. J. Davis

Achievement and measurement of temperatures close to absolute zero are the fundamental ingredients in studies of phase transitions to new states of matter such as dilute gas Bose-Einstein condensates (BECs) and superfluid Fermi gases. Bose-Einstein condensation of magnetically trapped alkali atoms has been first realised in 1995 after almost seventy years since the original prediction by Einstein. The temperatures required for this phase transition are in the nano-kelvin domain and are achieved by a combination of ingenious techniques of laser cooling and evaporative cooling. The current low-temperature record which arguably is the coldest known temperature ever experienced in the entire known Universe stands at 450 pico-kelvins (about half a billionth of a degree above absolute zero) and has been reached by transferring a small sample (2500 atoms) of partially condensed Bose gas into a very week gravito-magnetic trap [1].

The major limitation of the current standard method of thermometry which is based on the measurement of the particle number density is that it becomes less and less sensitive to temperature changes once the temperature is reduced below the BEC transition temperature. The aim of this PhD project is to develop a new method of thermometry of ultra-cold quantum gases. The proposal is based on extracting the temperature from the theory and measurement of atom-atom pair correlations in one-dimensional (1D) Bose gases [2], combined with the methods of adiabatic transfer of 3D gases into 1D regimes. The method relies on the high sensitivity of the pair correlations in 1D to temperature changes and targets ultra-low temperature measurements in the regimes where the standard methods fail. The goal is to provide accurate theoretical predictions for such measurements and to initiate experimental implementations of the new method. The project will involve both analytic and computational approaches, with access to our Centre's super-computing cluster.

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