Reconstructing the density matrix of a spinsthrough Stern - Gerlach measurements
Jean-Pierre Amiet, Stefan Weigert · Journal of Physics A Mathematical and General · 1998
The Pauli problem is solved for a spin of length s prepared in an arbitrary (unnormalized) mixed state which has free real parameters. The reconstruction of its density operator is possible if one knows the probabilities of the spin components along each of directions in space. These probabilties are directly accessible through measurements performed with a Stern - Gerlach apparatus. A multipole expansion of the density operator establishes the link between the matrix elements of and the measured intensities.