Some New Effects in Atom Stern-Gerlach Interferometry

Abstract

Stern-Gerlach interferometry is based on the interaction of the magnetic moment of the atom (or molecule) with external magnetic fields. It owes its name to the use of magnetic field gradients to macroscopically split the incident beam into separated partial beams, as in the original Stern and Gerlach experiment. It is a polarization interferometry, which has much in common in its principle with the birefringent crystal-plate optical interferometry : the incident light wave is first linearly polarized at 45° with respect to the neutral axes of the crystal. Then at the entrance side of the plate, the state is a superposition with equal amplitudes of the polarization basis set vectors inside the crystal. Because of the multivalued refraction index, each polarization component accumulates a different phase shift inside the crystal. At the output side, the total state is a combination of two orthogonal polarization states. To be able to observe the interference pattern, one needs to project it on a single state ; this is achieved by the second polarizer, also called the analyzer.