All posts by Maarten

Dr Maarten Hoogerland is the group leader of the Quantum Information Laboratory at the University of Auckland


A kiwi from the atom lab to brighten your day. All kiwis are made from atoms – the only difference is that the one on the right was made today from rubidium atoms.

The image is made with 20000 atoms expanding from a Bose-Einstein Condensate of rubidium atoms in a plane (the plane is made by interfering two 1064 nm laser beams, having a lower frequency that the main resonance in rubidium).

The image on the left is this is made with the spatial light modulator, which lets us make any image that we like. 532 nm light has a higher frequency than the main resonance, and is hence repulsive for rubidium, so by making the outline of the shape with 532 nm light, the atoms expand until they “hit the wall”, which in this case is in the shape of a kiwi.
Some parameters:
  • The kiwi is 150 micrometres in length.
  • The atoms have a temperature of 10 nK.
  • The height of the barrier made by the green laser is 2 microkelvin.

Calorimetry of a BEC submitted

Direct measurement of the heat capacity of a Bose-Einstein condensate

S. K. Ruddell,∗ D. H. White, A. Ullah,† and M. D. Hoogerland Department of Physics, University of Auckland, Private Bag 92019, Auckland, New Zealand

We transfer a known quantity of energy to a harmonically trapped Bose-Einstein condensate in order to study the resulting thermodynamics. We consider two methods, the first using a free expansion under gravity and the second using an optical standing wave to diffract the atoms in the potential. We investigate the effect of interactions on the resulting thermodynamics and compare our results to theory, with no adjustable parameters, providing a quantitative analysis of the heat capacity of our system.

BEC is back

Our all-optical BEC has been back for a little while, no real problems. We had some standard issues of shutters not shutting at the appropriate time, and magnetic fields not being what they should be, but everything is up and running. Atom numbers are comparable to previously, and we’re working on improving this.