  Motivated by Feynman's 1983 paper on the simulation of physics by computers,
we present a general approach to the description of quantum experiments which
uses quantum bit registers to represent the spatio-temporal changes occurring
in apparatus-systems during the course of such experiments. To illustrate our
ideas, we discuss the Stern-Gerlach experiment, Wollaston prisms, beam
splitters, Mach-Zender interferometers, von Neumann (PVM) tests, the more
general POVM formalism, and a variety of modern quantum experiments, such as
two-particle interferometry and the EPR scenario.
