Spinor Condensates

Spinor Condensates

These experiments investigate the dynamics of several coupled condensates. A spinor condensate is one which possesses a spin degree of freedom with full rotational symmetry. We use an optically trapped gas of atoms in the F=1 hyperfine level of ⁸⁷Rb. A far-detuned optical trap, unlike the more common magnetic trap, provides equal confinement for the three spin states. When a condensate is formed from atoms distributed among the various spin states, the result is three separate but coupled condensates, or equivalently a single multicomponent "spinor" condensate. The fact that the components belong to a true atomic angular-momentum vector results in a very simple form for the coupling interaction.

Image signal height as a function of time and axial position, showing time-resolved imaging of the Larmor-precessing cloud. In particular, our experiments use the optical properties of the spinor condensate to look directly at the spin state as it evolves in time. Recent work has looked at the Larmor precession of the spin-1 gas both above and below the BEC transition temperature. We see rapid decay associated with magnetic field inhomogeneity for the thermal cloud, but no decoherence for the BEC over its lifetime. Moreover, the collisional interactions of the BEC appear to freeze the condensate atoms in place, rather than allowing them to explore the magnetic inhomogeneity over the extent of the condensate. (See publications for our paper on the topic.)