I am partial to the idea that the quantum state is a state of knowledge (about a system that we can only observe during the time slices in which we exist, and with uncertainty about our own state), but Nielsen opens an important discussion that is rarely make explicit.https://twitter.com/AndreasAtETH/status/1073455979919040512 …
No, it is not epiphenomenal. The self is a representation that plays a causal role in the regulation. But the way in which you (the subjective inhabitant of your brain generated reality) exist is different from the way in which physicsl reality exists.