pretty much "it can be implemented algorithmically no matter what". There is just no evidence that the physical brain takes advantage of subtle quantum effects to do what it can do; it's extremely unlikely that any machine could do so at normal body temperature.

Intuitively, I don't see any vital need to introduce special types of computation to explain consciousness. It seems very likely to be a phenomenon that emerges from the right kind of information processing, regardless of the physical nature of the computation.