ALP Seminar: Testing the unitarity of the quantum measurement process

Joint work with Adán Cabello

Quantum mechanics involves two types of evolution for a physical system: the unitary evolution described by the Schrödinger equation and the indeterministic "jump" or "collapse" induced by a measurement. This doubled evolution is sometimes considered to make quantum mechanics inconsistent. We challenge this view by splicing the a measurement into a three-phase process, where Phase I and Phase II are governed by the Schrödinger equation and Phase III resembles a classical Bayesian update. We show that this update is not a physical process but only an incorporation of knowledge, while the unitarity of the evolution in the other two phases is accessible to experimental tests.