Understanding quantum measurement from the solution of dynamical models

Understand

The quantum measurement problem, understanding why a unique outcome is obtained in each individual experiment, is tackled by solving models.

• After an introduction we review the many dynamical models proposed over the years.
• A flexible and rather realistic model is introduced, describing the measurement of the $z$-component of a spin through interaction with a magnetic memory simulated by a Curie--Weiss magnet, including $N \gg1$ spins weakly coupled to a phonon bath.
• Initially prepared in a metastable paramagnetic state, it may transit to its up or down ferromagnetic state, triggered by its coupling with the tested spin, so that its magnetization acts as a pointer.