Anyons are quasiparticles that may exist in planar systems (an overarching theme of our research) and constitute elementary building blocks for future quantum technologies. Our specific focus areas include quantum vortices in cold atom superfluids, topological quantum computation with non-abelian anyons, two-dimensional quantum turbulence and hydrodynamical quantum analogs of periodically driven non-equilibrium droplet systems.

Our research activities comprise one experimental and three theoretical programs.

Our research projects

Quantum vortices (QV)

Quantised vortices — whirlwinds of the quantum world — are quantum mechanical excitations in superfluids. Understanding their structure and behaviours will be pivotal for future quantum technologies such as room temperature superconductors and topological quantum computers.  

Our current research interests in this field are focused on understanding the microscopic structure, dynamics and internal properties such as the mass and the Berry phase of quantised vortices, with a specific emphasis on cold atom systems comprising Bose-Einstein condensates and superfluid Fermi gases.

Further reading: T. Simula, Quantised Vortices: A handbook of topological excitations, (Morgan&Claypool, 2019)

Illustration of quasiparticle excitation spectra for (a) a Bose—Einstein condensate with a Goldstone boson zero mode (black marker) and (b) a chiral Fermi superfluid with a Majorana fermion zero mode (green marker).
Kelvin wave excitation on a quantized vortex in a Bose—Einstein condensate.

Quantum turbulence (QT)

Quantum turbulence — storms of the quantum world — corresponds to chaotic motion of quantised vortices in superfluids. Understanding such complex non-equilibrium physics of systems governed by quantum mechanics will find applications ranging from problems in fundamental physics to devices of future quantum technologies. 

Our current research interests in this field are focused on understanding the microscopic mechanisms underlying quantum turbulence, with a particular focus on superfluids in which the vortices are constrained to move in two space dimensions. This leads to peculiar phenomena such as the emergence of negative absolute temperature states and ordered “Onsager vortex” structures out of chaos. 

Further reading: Johnstone et al., Evolution of large-scale flow from turbulence in a two-dimensional superfluid, Science 364, 1267 (2019) 

Phase diagram of a two-dimensional vortex fluid. The lowest entropy, positive temperature states corresponding to pairing of vortices and antivortices, and the lowest entropy, negative absolute temperature states corresponding to clustering of same-sign vortices and antivortices are separated by the infinite temperature, maximum entropy random vortex configurations.
Evolution of quantum turbulence in a two-dimensional non-equilibrium superfluid from disordered vortex structures (left) to coherent Onsager vortices (right).

Topological quantum computation (TQC)

Quantum computers are poised to permanently reshape the future of computing. The functioning of conventional quantum computers, currently deployed in research laboratories, is extremely sensitive to environmental noise. This could be mitigated by topological quantum computers that are thought to possess an outstanding fault tolerance against the conventional types of decoherence. 

Our current research interests in this field are focused on understanding the fundamental properties of topological quantum computer technology and the quest for non-Abelian anyons — elusive quasiparticles that are required as elementary building blocks for the construction of a topological quantum computer. We are particularly interested in evaluating the potential of non-Abelian quantum vortex anyons in two-dimensional superfluids.  

Further reading: Mawson et al., Braiding and Fusion of Non-Abelian Vortex Anyons, Phys. Rev. Lett. 123, 140404 (2019)

A braid diagram of a quantum algorithm for computation of the Jones polynomial of a knot using a topological quantum computer.
Braiding and fusion of non-abelian vortex anyons in a single-qubit topological quantum computer.

Droplets Laboratory

Driven non-equilibrium systems are known to host curious phenomena such as period doubling bifurcations. A periodically driven bath of fluid is able to support sustained bouncing of millimetre scale droplets that facilitate the realisation of a broad range of hydrodynamical quantum analogs and superwalking phenomena. 

Our current research interests in this field are focused on laboratory experiments on superwalkers, interacting many-droplet systems and topological non-equilibrium droplet phenomena. We are also interested in developing models to understand the behaviours and theoretical underpinnings of such periodically driven droplets systems.  

Further reading: Valani et al., Superwalking Droplets, Phys. Rev. Lett. 123, 024503 (2019)

Superwalking droplets bouncing on the surface of a driven-dissipative fluid.

Our team

Are you an Honours or PhD student?

You could join a broad range of experimental projects within the Droplets Laboratory program, as well as theoretical and computational projects within any of our four research areas: Quantum Vortices, Quantum Turbulence, Topological Quantum Computation and Droplets Laboratory. Please email Associate Professor Tapio Simula to discuss these opportunities in further detail or check out more project opportunities within our other research areas. 

Funding and linkages

  • ARC FT180100020 (CI Simula) 
  • ARC DP 170104180 (CI Simula, PI Galitski, PI Zwierlein) 
  • ARC DP 130102321 (CI Helmerson, CI Simula)

Quantised vortices: A handbook of topological excitations

Written by Associate Professor Tapio Simula, this handbook provides a dictionary-style portal to the fascinating quantum world of vortices.

Find out more

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