OBSERVING A SUPERFLUID HALL EFFECT IN A BOSE-EINSTEIN CONDENSATE

 

Lindsay J. LeBlanc, Karina Jiménez-Garcia, Ross A. Williams, Matthew C. Beeler, Abigail R. Perry, William D. Phillips, and Ian B. Spielman

 

Joint Quantum Institute, National Institute for Standards and Technology and University of Maryland

 

In condensed matter physics, the Hall effect is widely used to measure the internal properties of solids, from the charge carrier concentrations of semiconductors to the quantum Hall effects in a two-dimensional electron gas.  Though Hall physics generally stems from the behavior of charged particles in a magnetic field, we observed a superfluid Hall effect in an ultracold gas of neutral bosons under the influence of an artificial magnetic field [1,2].  

 

Beginning with a 87Rb Bose-Einstein condensate (BEC), we effected an artificial magnetic field B* for the charge-neutral atoms by Raman-coupling the atoms’ internal states, which were energetically split by a spatially-dependent external field. By modulating the BEC’s external trapping potential, we created an alternating atomic current and studied its behavior as a function of B*.  In the presence of an artificial magnetic field, we observed a response in the direction transverse to the expected hydrodynamic flow, indicating a Hall effect.  We found good agreement between our measurements and a superfluid hydrodynamic model, indicating that the observed superfluid Hall effect is associated with the system’s irrotational superfluidity. Having established this technique, we expect that similar measurements in more complicated ultracold systems, such as those used for quantum simulations, will provide insight into new regimes of collective phenomena and many-body physics.

 

 [1] Y. J. Lin et al.  Synthetic mangetic fields for ultracold neutral atoms.   Nature, 462, 628-632 (2009).

[2] I. B. Spielman, Raman processes and effective gauge potentials, Phys. Rev. A  79, 063613 (2009).