The following is a guest posting from Ken Krechmer of the College of Engineering at Applied Science at the University of Colorado, at Boulder.
The dichotomy between quantum measurement theory and classical measurement results has been termed: the measurement disturbance, measurement collapse and the measurement problem. Experimentally it is observed that the measurement of the position of one particle changes the momentum of the same particle instantaneously. This is described as the measurement disturbance. Quantum measurement theory calculates the probability of a measurement result but does not calculate an actual measurement result. What occurs that causes the quantum measurement probability to collapse into a classical measurement result? Different approaches have been proposed to resolve one or both of these issues including hidden variables, non-local variables and decoherence, but none of these approaches appear to fully resolve both these aspects of the measurement problem.
Further complicating this measurement problem: 1. The quantum effect called entanglement is another measurement disturbance where the measurement of one particle instantaneously impacts a similar measurement of another, far remote, particle. 2. The quantum effect called uncertainty which defines the minimum variation between two measurement results and changes depending on the order of the ...