EXTREMAL DECISION RULES IN QUANTUM HYPOTHESIS TESTING

Abstract

We present a complete description of the extreme points of the convex set of all decision rules in testing multiple hypotheses concerning a quantum system whose states are described by density matrices in a finite-dimensional Hilbert space. Holevo's equations for an optimal decision are derived by methods of elementary calculus and a simple example is given in order to illustrate the nonuniqueness of optimal decision rules.