  The sensitivity of atom interferometers is usually limited by the observation
time of a free falling cloud of atoms in Earth's gravitational field.
Considerable efforts are currently made to increase this observation time, e.g.
in fountain experiments, drop towers and in space. In this article, we
experimentally study and discuss the use of magnetic levitation for
interferometric precision measurements. We employ a Bose-Einstein condensate of
cesium atoms with tuneable interaction and a Michelson interferometer scheme
for the detection of micro-g acceleration. In addition, we demonstrate
observation times of 1s, which are comparable to current drop-tower
experiments, we study the curvature of our force field, and we observe the
effects of a phase-shifting element in the interferometer paths.
