SPIN QUASI-DISTRIBUTION FUNCTIONS

Two-classes of phase-space spin quasi-distribution functions are intro duced and discussed. The first class of these distributions is based o n the delta function construction. It is shown that such a constructio n can be carried out for an arbitrary spin s and an arbitrary ordering of the spin operators. The second class of the spin distributions is constructed with the help of the spin coherent states. The connection of the spin coherent states to the Stratonovich formalism is establish ed and discussed. It is shown that the c-number phase-space descriptio n of quantum fluctuations provides a simple statistical picture of qua ntum fluctuations of spinoperators in terms of random directions on a unit sphere. For quantum states of the spin system the statistics of t hese random orientations is given by non-positive spin quasi-distribut ion functions. It is shown that the application of these spin quasi-di stribution functions to the Einstein-Podolsky-Rosen correlations provi de an insight into the quantum theory of measurement.