Minimum criteria for quantum state dissolution

Question

What are the minimum conditions required to cause the colapse of the quantum state ? Or, what forces/equations determine when an object (for instance an electron) is forced out of its quantum state in to a determined position ?

Answer 1

The minimum condition is interaction with another quantum system, leading to entanglement of the electron's position with the scattering angle of a photon bouncing off, for instance. When the other system goes far away, it cannot interact anymore, and the state of the electron is collapsed to one or another approximate position, depending on the photon state. The exact state of the electron depends on the measured outgoing direction of the photon.