Ultracold quantum matter

Abstract:

We have measured the time taken for a magnetically trapped cloud of cold cesium atoms in the (F =3,mF=-3) ground state to rethermalize from a nonequilibrium spatial and velocity distribution. From these measurements we infer the dependences of the elastic scattering cross section on temperature and magnetic field in the ranges 1 - 30 μΚ and 0.05-2.0 mT, respectively. We determine a lower bound on the magnitude of the (3,-3) + (3,-3) s-wave scattering length of 940a0.

Abstract:

We describe the construction and operation of a time-orbiting potential trap that has different oscillation frequencies along its three principal axes. These axes can be rotated and we have observed Bose-Einstein condensates of 87Rb with a rotating ellipsoidal shape. Under these conditions it has been predicted that quantized vortices form and are stable.

Abstract:

We describe in detail our caesium atom interferometer which uses a combination of microwaves and momentum-changing adiabatic transfer pulses. This combination allows us to achieve spatial separation between the arms of the interferometer. We account for the observed visibility of the resulting interference fringes and find that the effects which contribute the most are optical pumping and magnetic fields.

Abstract:

We report on the demonstration of Berry’s phase in an atomic state interacting with a laser field. We draw an analogy between this system and that of a spin interacting with a directionally varying magnetic field. This allows us to identify an effective magnetic quantum number for the atom-light system that governs the maximum Berry phase the atomic state can acquire. We realize two systems that have different effective magnetic quantum numbers, and use a recently developed atom interferometer to make measurements of Berry’s phase. © 1999 The American Physical Society.