Spin nematic order in antiferromagnetic spinor condensates (Dr. T. Zibold)

  • Date: Nov 26, 2015
  • Time: 13:30 - 15:00
  • Speaker: Dr. Tilman Zibold, Laboratoire Kastler-Brossel / Collège de France, Paris
  • Room: Herbert Walther Lecture Hall
  • Host: MPQ, Laser Spectroscopy Division
Large spin systems can exhibit unconventional types of magnetic ordering different from the ferromagnetic or N\'eel-like antiferromagnetic order commonly found in spin 1/2 systems.

Spin-nematic phases, for instance, do not break time-reversal invariance and their magnetic order parameter is characterized by a second rank tensor with the symmetry of an ellipsoid. Here we show direct experimental evidence for spin-nematic ordering in a spin-1 Bose-Einstein condensate of sodium atoms with antiferromagnetic interactions. In a mean field description this order is enforced by locking the relative phase between spin components. We reveal this mechanism by studying the spin noise after a spin rotation, which is shown to contain information hidden when looking only at averages. The method should be applicable to high spin systems in order to reveal complex magnetic phases.

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