Quantum memory proposal: Phys. Rev. A 79, 022310 (2009).

Quantum Information

Quantum information is the study of how to apply quantum mechanics in the development of new technologies. We are interested in quantum memories, as an enabling technology for many areas of quantum information. A quantum memory is able to store a quantum state indefinitely, to be read out on demand. Possible quantum memory devices range from cold atoms to superconducting circuits and nano-oscillators.

Foundations of Quantum Mechanics

The well-known 1935 paper of Einstein et al. (EPR) led to the famous Bell theorem, which rules out local realism--a result that has been called "the most profound discovery of Science". The Schrödinger cat paradox raises an even more important issue -- how to reconcile quantum realities with classical realities at the macroscopic level. Specific research topics include:

• The Bell and EPR paradox in macroscopic systems,
• Signatures of macroscopic superpositions and entanglement.

Spin-EPR proposal
Rev. Mod. Phys. 81, 1727 (2009)

Colliding BEC quantum dynamics: Phys. Rev. Lett. 98, 120402 (2007). (Editor's Suggestion)

Bose-Einstein Condensates and Atom Lasers

Atom lasers, or Bose-Einstein condensates (BEC) exist at temperatures below one nano-Kelvin -- a billion times colder than interstellar space.  The bosonic atoms occupy an identical quantum state, so BECs are quantum systems on a macroscopic scale, with atoms behaving as waves but having particle-like qualities when detected.  High-precision interferometry applications are being studied experimentally at Swinburne University.  Theory projects on the quantum noise properties of BECs are:

• Quantum Brownian motion of impurities inside a BEC, and
• Dephasing, decoherence and entanglement effects in BEC interferometry.

Quantum Simulations

We are developing new algorithms based on phase-space representations for simulating quantum many-body systems. These include the world's best-tested and the largest known quantum simulations, with experimental verification down to well below the vacuum noise level. Methods include Wigner representations, positive-P representations, general Gaussian phase-space methods and spin representations. Recent work has included quantum simulations of: dynamical Bell violations, large multipartite entangled spin systems, early universe quantum fluctuations, interferometers using Bose-Einstein condensates and quantum opto-mechanics. Simulations use the Swinburne gStar GPU based supercomputer, as well as desktop GPU systems, programmed with Australian developed codes.

Domains in a 3D model of the early Universe: Ann. Phys. 525, 866–876 (2013).

Universal Impurity-Induced Bound State in Topological Superfluids, Phys. Rev. Lett. 110, 020401 (2013).

Ultracold Fermi gases

This research programme is motivated by the rapid experimental developments in degenerate Fermi gases. These systems are controlled at an unprecedented level and are well-described by quantum many-body models. The programme involves themes designed to develop fundamental knowledge of the underlying physics, and to provide theoretical guidance to experiments at Swinburne University. Specific topics include:

• Few-body physics and virial expansions,
• Low dimensional physics of multi-species Fermi gases,
• Entanglement, correlations and coherent manipulations of ultracold Fermi gases, and
• Quantitative strong-coupling theory of ultracold Fermi gases.