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[Updated June 2021]

My interests are in the physics of ultracold matter and quantum gases, and the emergence of macroscopic quantum phenomena from microscopic quantum mechanics. One of the themes of my work is to understand aspects of quantum many-body physics via the interpretation of experimental data, and I have published several papers with experimental groups from around the world.  I am particularly interested in nonequilibrium phenomena, both in weakly and strongly interacting regimes.

Much of my work has been on Bose-Einstein condensates (BECs), a relatively new state of matter first observed in 1995 (and the discovery of which lead to the Nobel Prize in Physics in 2001).  They form at ultra-cold temperatures and have similar properties to light from a laser.  However, they are rendered much more complex due to the fact that atoms are interacting - they undergo collisions.  One intriguing possibility is the creation of the atom laser, which will be able to be used in ultra-precise measurement devices.

In 2016 I was awarded a new ARC Discovery Project in collaboration with Dr Elena Ostrovskaya, leader of the Polariton BEC group at the Australian National University, titled "Nonequilibrium states of polariton superfluids".   The project summary is as follows:

"Polaritons are hybrid particles of light and matter that exist in thin layers of a semiconductor. At high densities they form a superfluid, exhibiting quantised whirlpools and frictionless flow. This proposal aims to design novel nonequilibrium states of a polariton superfluid, and to identify why some are more robust than others. Furthermore, we aim to realise these states in the laboratory. The project addresses one of the grand challenges of physics - predicting and controlling the emergent properties of materials far from equilibrium. The anticipated outcome is the generation of fundamental knowledge, which can be used to guide the design of polaritonic devices in the future."

My other research interests can be roughly divided into three areas:
  1. "Classical" dynamics of Bose gases.
    One of the major themes of my research has been the development and application of "c-field" methods for the dynamics of Bose gases at finite temperature.  This is a non-perturbative calculation technique that gives access to equilibrium and non-equilibrium properties of finite temperature  Bose systems.  It is valid up to and above the Bose-Einstein condensation phase transition, and thus gives the ability to study the formation of coherence in a BEC.  This forms the basis of my previous ARC QEII Fellowship (2010-14) entitled "Ebb and flow of superfluids: Bose gases far from equilibrium."

    One of the goals of my QEII fellowship was the study of quantum turbulence in BEC.  Recently I have developed a scheme to establish non-equilibrium superfluid flows between reservoirs with different thermodynamic parameters.  This is a very exciting prospect, as it will allow for the establishment of non-equilibrium phase diagrams, and I expect it will be an excellent setup for the study of turbulence.

  2. Quantum dynamics of Bose gases
    A modification of the "c-field" methods above allows the simulation of quantum effects in the dynamics of Bose systems by adding "quantum noise" into the initial states.  This can be used to study non-linear instabilities and quantum phase transitions that occur at zero temperature.  We have used this to understand a number of experiments, and have recently proposed a new experiment to realise a the "Kibble-Zurek" scaling of the formation of topological defects in a quantum phase transition in a two component BEC. 

  3. Thermalisation in isolated quantum systems
    In classical systems it is understood that deterministic chaotic dynamics results in ergodicity and hence thermalisation following a disturbance.  However, quantum systems evolve according to linear dynamics.  It is understood that they may thermalise through contact with their environment, resulting in the loss of information and resulting in pure states becoming mixed.  However, experiments on ultra-cold gases are in principle entirely isolated from their environment.  How quantum systems come to thermal equilibrium through their own dynamics is a major open question.  Significant progress has been made in this area recently, but there are still many issues to be solved. 

I am looking for students to work in all of these areas - either for summer, honours, M.Sc. or Ph.D. projects. Please email me if you are interested.

I am currently principal advisor for the following students:
  • Tim Harris - Quantum nonequilibrium relaxation
  • Abithaswathi Muniraj Saraswathy - Quantum many body heat engines
  • Zhi-Tao Deng (began PhD Q1 2017) - Nonequilibrium flows of superfluids between reservoirs
These PhD students have graduated:

I have supervised honours projects for:

  • Jemima Goodhew (2021)
  • Liam Bond (2020)
  • Tim Harris (2020)
  • Tim Edmonds (2019)
  • Oliver Stockdale (2018)
  • Joshua Guanzon (2018)
  • Oliver Sandberg (2017)
  • Sebastian Kish (2014)
  • Chao Feng (2008)
  • Mark Dowling (2003)

Postdoctoral fellows I have supervised at UQ:

  • Lewis Williamson
  • Andrew Groszek
  • Matt Reeves
  • David Colas
  • Tod Wright
  • Stuart Szigeti
  • Omri Bahat-Treidel
  • Jacopo Sabatini
  • Yongping Zhang
  • Simon Haine
  • Ashton Bradley
  • Sebastian Wuester
  • Beata Dabrowska

Current and former collaborators include:
as well as other researchers at the University of Queensland: