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Cold Molecules Group
Laser and evaporative cooling of neutral atoms has paved the way
for studies of quantum degenerate gases in which the bosonic or
fermionic nature of the particles determines the behaviour. The
importance of this field has been recognised by the award of two
recent Nobel prizes in physics in 1997 for laser cooling and trapping
and in 2001 for the first production and studies of Bose-Einstein
Condensates (BECs).
In the cold molecules group at Swinburne, we cool gases of fermionic
Li-6 down to temperatures below 100nK and, by tuning the interactions
between particles, we can prepare a degenerate system of bosonic
molecules or fermionic atoms. The ability to control the interparticle
interactions through the use of Feshbach resonance allows unique
access to different types of superfluid which span from a BEC of
bound molecules to a degenerate Fermi gas of correlated Cooper pairs.
Our goal is to use these cold gases to understand
the physical processes at play in these different types of superfluids.
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The team
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Academic
and Research Staff
Chris Vale
Peter Hannaford
Wayne Rowlands
Chris Ticknor
Mark Kivenen (Technical support) |
Students
Gopi Veeravalli (PhD)
Paul Dyke (PhD)
Eva Kuhnle (PhD)
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Former Members
Bryan Dalton
Grainne Duffy (postdoc)
Jurgen Fuchs (PhD)
Heath Kitson (PhD)
David Lau (postdoc)
Michael Vanner (R&D)
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Research |
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BEC
of 6Li2 Molecules
We have produced Bose-Einstein
condensates of Li-6 molecules in a low power crossed optical
dipole trap. Our experimental procedures for generating condensates
and degenerate Fermi Gases are described in the paper below.
More recently we have introduced a 100 W fibre laser to our
experiments, now we can produce near pure molecular condensates
containing over 200,000 molecules.
Paper:
J Fuchs et al., J.Phys.B 40 4109 (2007) |
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Degenerate
Fermi Gas of 6Li
With our system we can readily compare degenerate Fermi gases with Bosonic molecular gases. The image to the
left shows a gas of bosonic molecules and Fermionic atoms prepared in the same trap at the same temperature, but at different magnetic
fields. Much higher densities are observed in the bosonic cloud due to the formation of a BEC while Fermi pressure decreases the atomic
density of the fermionic gas to below what would be expected for a classical gas at the same temperature.
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p-wave Feshbach Molecules
We have measured the binding energies of 6Li2 p-wave Feshbach molecules using magneto-association spectroscopy. These
allow us to determine the magnetic moment of the molecules and our values are in good agreement with theoretical predictions. We have also
investigated the size of p-wave molecules which we find to be much smaller than s-wave molecules even within a few mG of the
Feshbach resonance.
Paper:
J. Fuchs et al., Phys. Rev. A 77, 053616 (2008).
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EIT
and EIA in 6Li
We have also performed measurements
of electromagnetically induced transparency and absorption
using a Li-6 atomic beam line.
Papers:
J. Fuchs et al., J. Phys. B: At. Mol. Opt. Phys. 40, 1117-1129 (2007)
J. Fuchs et al., J. Phys. B: At. Mol. Opt. Phys. 39, 3479–3489 (2006)
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Scattering
of Polar Molecules (Theory)
Polar molecules represent an exciting
new direction in ultra-cold gas research. Currently we have
a theoretical program investigating the scattering properties
of polar molecules which will form a basis for understanding
the many body physics of dipolar quatum gases.
Papers:
C. Ticknor, Phys. Rev. Lett. 100, 133202 (2008)
C. Ticknor, Phys. Rev. A 76, 52703 (2007)
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Grants |
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ARC Centre of Excellence for
Quantum-Atom Optics, project “Molecular BEC” (2003-2010)
ARC Australian Postdoctoral Fellowship (2008-2010) Dr. C. Ticknor
ARC LIEF grant “Advanced microwave facility for quantum atom optics”
(2006)
ARC LIEF grant "Quatum limited single atom detectors"
(2008)
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Research Podcast |
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Towards Absoltue Zero on an Atom Chip ·
Windows Media Player
· QuickTime
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