Atom Lasers and Bose-Einstein Condensates
This project investigates the quantum dynamics of atom lasers and dilute gas Bose-Einstein Condensates (BECs). These are highly quantum mechanical systems in which atoms behave like waves. The 2001 Nobel Prize in Physics was awarded for pioneering experimental work in this area.
r62, x27, d66
PC, SC, VPP, MDSS
Physics and Theoretical Physics
Faculty of Science
Significant Achievements, Anticipated Outcomes and Future Work
Our first publication for 2001 was a clarification of the limitations on producing macroscopic quantum superpositions (Schrödinger Cats) in BECs. Our next publication concerned the quantum statistics of coupled atomic and molecular condensates in three dimensions.
A paper has been submitted describing a previously unknown type of instability in atom lasers. We have developed new numerical techniques for computational modelling of the full quantum field theory of atom lasers. Modelling of the ANU BEC and atom laser experiments is ongoing.
A major new direction is the modelling of the "Bosenova" BEC explosions observed in experiments this year. Once we have developed an adequate model of the phenomenon we anticipate using it, in conjunction with experiments, to explore important new atomic physics.
Computational Techniques Used
We solve nonlinear Schrödinger type partial differential equations in up to three dimensions. We use a pseudo-spectral method which takes advantage of the efficiently parallelised FFT algorithm. Our variant, developed at the University of Otago, is particularly effective, as it uses a fourth order Runge-Kutta time step.
Our quantum field work adds stochastic terms, representing quantum noise, to the nonlinear partial differential equations. Useful results are obtained by averaging over ensembles of solutions.
The APAC National Facility has made it possible for us to model actual experimental conditions. This enables us to make definitive statements about the physics involved in particular cases. Without the National Facility only very limited ensembles could be used in our quantum field calculations, limiting their relevance.
Publications, Awards and External Funding
C.M. Savage, ARC Large Grant, The quantum theory of atom lasers, 2000-2002.
P. J. Y. Louis, P. M. R. Brydon, C. M. Savage, Macroscopic quantum superposition states in Bose-Einstein condensates: Decoherence and many modes, Physical Review A, 64, 2001, 053613.
J.J. Hope, Quantum effects in coupled atomic and molecular Bose-Einstein condensates, Physical Review A, 64, 2001, 053608.