Given an unknown state, it's not possible to know if the parts are entangled. There is no experiment to determine this. The "facts" of quantum have this weird d

Given an unknown state, it's not possible to know if the parts are entangled. There is no experiment to determine this. The "facts" of quantum have this weird disconnect with reality. If you have access to many copies of the same state, then you can do tomography to learn if the state is entangled or not. But this is a different situation to what you are asking in your question. Actually I'm not entirely sure what your question is asking, but I won't delete this comment just yet.