Abstract

The results of a hypothetical experiment requiring a sequence of quantum measurements are obtained retrospectively, after the experiment has been completed, from a single reading of an “apparatus register.” The experiment is carried out reversibly and Schrödinger's equation is satisfied until the terminal reading of the register. The technique is illustrated using a feasible method of measuring photon spin as the quantum “object” observable and using the photon energy as the “apparatus register.” The technique is used to discuss the “watchdog” effect, the effect of repeated measurements inhibiting quantum jumps