[Physics] What processes cause the collapse of a wavefunction and break entanglement

Question

This question states that measuring the spin of an entangled particle causes the collapse of the wavefunction and thus the entanglement is broken.

Then this question states that we don't know what exactly is the cause for the collapse of wavefunctions.

However, what processes are known to collapse the wavefunction, and specifically break entanglement?

So measuring the spin collapses the wavefunction. What else does?

• Chemical processes?
• Presence in magnetic field without a screen (similar to Stern-Gerlach experiment)?
• Irradiation of some form?
• Heating?

EDIT

Given comments that the collapse of the wavefunction is still not understood, I'd like to emphasize experimental observations.
Also, given that the collapse of a wavefunction may or may not be an artificial construct, can we focus on what processes have been observed to destroy entanglement?

(From what I understand of current theory, entanglement is only broken by the resolution/collapse of the wavefunction, thus asking "what has been observed to collapse the wavefunction" and "what has been observed to break entanglement" should be questions with the same answers.)

Answer 1

Since you already talk about Stern-Gerlach, I suspect that the focus of your question is more about at which point in existing experimental techniques the collapse occurs, and not about learning existing techniques. In Stern-Gerlach that would be the deflection, not the screen, because this is where the spin value gets to be determined. If I got the question right, then the general answer is "at the point in the experiment where the studied property gets a specific value and superposition ends".

Also: Measuring is interacting with the system under study. There is nothing special putting measurement apart from any other physical process. This means that any interaction of the original system with anything else in the universe will break the wavefunction, preparing a new state.

I think the most concise (and entertaining) answer was the first comment (source) in the first of your links:

Basically, for observations to happen, there has to be an interaction between particles, or as the post put it less/more(?) eloquently, whenever a physicist says "observe", mentally replace it with "hit with sh*t.