STOCHASTIC ESTIMATION WITH Z2 NOISE

We introduce a Z2 noise for the stochastic estimation of matrix invers ion and discuss its superiority over other noises including the Gaussi an noise. This algorithm is applied to the calculation of quark loops in lattice quantum chromodynamics that involves diagonal and off-diago nal traces of the inverse matrix. We will point out its usefulness in its applications to estimating determinants, eigenvalues, and eigenvec tors, as well as its limitations based on the structure of the inverse matrix.