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Magnetic lattice on a Chip
Periodic optical lattices produced by the interference of intersecting laser beams are widely used for
manipulating ultracold atoms and Bose-Einstein condensates and for performing fundamental physics experiments such as quantum
tunnelling experiments including the superfluid to Mott insulator quantum phase transition. Periodic lattices also have potential
application in quantum information science since they may provide storage registers for qubits based on single atoms.
We have been investigating an alternative approach for producing periodic lattices for ultracold atoms based on magnetic potentials
generated by periodic arrays of magnetic microtraps These "magnetic lattices" use permanent magnets which have several distinct
and advantageous characteristics. They are highly stable with low technical noise and low heating rates; they can have large and
controllable barrier heights and large trap curvature leading to high trap frequencies; and they can be constructed with a wide
range of periods, down to about 1 μm. The atoms are trapped in low magnetic field-seeking states, thus allowing RF evaporative
cooling in situ and the use of RF spectroscopy techniques. We consider magnetic lattices to be complementary to optical lattices,
in much the same way as magnetic traps are complementary to optical dipole traps.
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The team
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Academic and Research Staff
Peter Hannaford
Russell McLean
Andrei Sidorov
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Students
Smitha Jose (experiment)
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Former students
Saeed Ghanbari (theory)
Mandip Singh (experiment)
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Research |
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One dimensional lattice of permanent magnetic
microtraps for ultracold atoms on an atom chip
We report on the loading and trapping of ultracold atoms in a one
dimensional permanent magnetic lattice of period 10 µm produced on an atom chip.
The grooved structure which generates the magnetic lattice potential is fabricated
on a silicon substrate and coated with a perpendicularly magnetized multilayered
TbGdFeCo/Cr film of effective thickness 960 nm. Ultracold atoms are evaporatively
cooled in a Z-wire magnetic trap and then adiabatically transferred to the magnetic
lattice potential by applying an appropriate bias field. Under our experimental
conditions trap frequencies of up to 90 kHz in the magnetic lattice are measured
and the atoms are trapped at a distance of less than 5 µm from the surface with a
measured lifetime of about 450 ms.
Paper:
M. Singh et al, J. Phys. B: At. Mol. Opt. Phys. 41, 065301 (2008)
arXiv 0801.0624
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Permanent magnetic lattices for ultracold atoms and
quantum degenerate gases
We have investigated the use of periodic arrays of
permanent magnetic films for
producing magnetic lattices of microtraps for confining, manipulating and
controlling small clouds of ultracold atoms and quantum degenerate gases.
Using analytical expressions and numerical calculations we show that periodic
arrays of magnetic films can produce one-dimensional (1D) and twodimensional
(2D) magnetic lattices with non-zero potential minima, allowing
ultracold atoms to be trapped without losses due to spin flips. For arrays with
micron-scale periodicity, the magnetic microtraps can
have very large trap depths (0.5 mK for the realistic parameters chosen for
the 2D lattice) and very tight confinement.
Papers:
S.Ghanbari et al, J. Phys. B: At. Mol. Opt. Phys. 39, 847 (2006)
S. Ghanbari et al, J. Phys. B: At. Mol. Opt. Phys. 40, 1283
(2007) |
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Grants |
Swinburne Strategic Initiative grant "Atom Optics" (2001-2005)
ARC Centre of Excellence for Quantum-Atom Optics, project "Coherence of BEC on an atom chip" (2003-2010) |
Research Podcast |
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Towards Absolute Zero on an Atom Chip ·
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