SPIN-ORBIT PENDULUM - THE MICROSCOPIC STERN-GERLACH EFFECT

We are studying the propagation of a wavepacket in a spherical harmoni c potential to which is added a spin-orbit potential. The conditions a re such that the wavepacket would be coherent and centred on a circula r orbit in the absence of spin-orbit coupling. This additional term sp lits the wavepacket into two components which are approximately cohere nt states and which move in an opposite sense. The interference of the se wavepackets produces the phenomenon of collapse and revival well kn own in the Jaynes-Cummings model; it can also be interpreted as a micr oscopic Stem-Gerlach effect. The spin density exhibits an interesting continuous evolution in time. The oscillations of a fraction of averag e angular momentum between the spin and ordinary subspaces justify the name of spin-orbit pendulum.