Collective Spin Behavior in an Ultracold Quantum Gas

In an ultracold quantum gas, collective interactions among the particles can lead to many forms of unusual behavior, such as superfluidity. Researchers have now observed a new collective phenomenon in a spinor gas—an ultracold atomic cloud that has both magnetic and superfluid properties. Laurent Vernac and colleagues from the University of Paris 13 in Villetaneuse have discovered that a magnetic field can excite a collective spin oscillation in the gas.