Energy Preserved in Quantum Measurements

This dissertation addresses the question of how energy is conserved in quantum measurement. This question is significant for a number of reasons: the conventional way of expressing conservation laws pertains only to isolated systems (whereasmeasurement always involves coupling to an external apparatus), the superposition principle implies that the energy of a quantum system may be poorly defined before and/or after a measurement, and measurements can affect the energy of a quantum system(either increasing or decreasing it on average).