Atomic quantum phase studies with a longitudinal Stern-Gerlach interferometer

A general description of atomic interferometers in terms of the scattering operator is given. The action of a longitudinal interferometer on an atom described by an incident polarized wavepacket is shown to be equivalent to a frame transformation, leading to a “beaded” atom. The special case of a pure longitudinal gradient of magnetic field and that of a spatially precessing field are examined. An experiment using metastable hydrogen atoms is presented and the results obtained in both situations mentioned above are discussed. Properties of beaded atoms produced by relatively strong fields (∼10 G) are investigated by means of the intensity diagram of their electrically induced radiative decay.