Fermionic Superfluidity with Imbalanced Spin Populations
Martin W. Zwierlein,*
André Schirotzek,
Christian H. Schunck,
Wolfgang Ketterle
We established superfluidity in a two-state mixture of ultracold fermionic atoms with imbalanced state populations. This study relates to the long-standing debate about the nature of the superfluid state in Fermi systems. Indicators for superfluidity were condensates of fermion pairs and vortices in rotating clouds. For strong interactions, near a Feshbach resonance, superfluidity was observed for a broad range of population imbalances. We mapped out the superfluid regime as a function of interaction strength and population imbalance and characterized the quantum phase transition to the normal state, known as the Pauli limit of superfluidity.
Department of Physics, Massachusetts Institute of Technology (MIT)–Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, MIT, Cambridge, MA 02139, USA.
* To whom correspondence should be addressed. E-mail: zwierlei{at}mit.edu
