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German Micro BEC at the Max Planck

Hänsch/Reichel graph

[Historical report created from GSU BEC Homepage:]

"The report from the Max Planck Institute:

We have achieved Bose-Einstein condensation in a MAGNETIC MICROTRAP on 12 June 2001.

Figure above: Absorption images of the atom cloud , taken after 20 ms of free expansion.

We use a single chamber apparatus and load 87Rb atoms from the background gas. Evaporative cooling is accomplished within only 2.1 s. The complete duty cycle for the creation of BEC is approximately 10 s.

Parameters of our trap are:

  • Loading time: 8 s
  • Cooling time: 2.1 s
  • Initial number of atoms: 3 x 106
  • Number of condensed atoms: 6,000
  • Current in the microwire: 2 A
  • Magnetic bias field: 8 - 57 Gauss
  • Life time in the magnetic trap: 6 s

Miniaturized Magnetic trap [figure below]:

A Ioffe-Pritchard-type magnetic trap is established using a current of 2A in a z-shaped wire (red) and adding a homogenous magnetic field of 8 - 57 Gauss. The wire is created by thin-film hybrid technology and has a cross section of 50 x 7 micron (width x height). A thin silver layer is glued on top of the substrate to serve as mirror for the MOT-beams (not shown).

Experimental procedure:

We load 6 x 106 87Rb atoms into the mirror-MOT, located at 4 mm distance from the surface. We transfer 3 x 106 atoms into the magnetic microtrap and cool them evaporatively in two stages at two different trap positions.

We finally observe 6,000 atoms in the condensate.

The variety of magnetic fields accessible with such miniaturized traps may now be applied to manipulate coherent ensembles of atoms.

The microtrap team:

  • Jakob Reichel
  • Wolfgang Haensel
  • Peter Hommelhoff
  • Romain Long
  • Tilo Steinmetz
  • Tim Rom
  • Prof. Theodor W. Haensch

Max-Planck-Institut fuer Quantenoptik, Garching and
Ludwig-Maximilians-Universitaet, Muenchen

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