I was thinking of a lifeforms that would have a brain more similar to that of a quantum computer than an ordinary brain. I was thinking the brain would use something similar to qubits that could be in superpositions of states instead of or in addition to braincells.
There's theoretically nothing preventing it, but we don't know how it would be done. One of the requirements for a quantum computer is to keep the qbits in coherence with each other. So far we are not aware of any way to do this at reasonable temperatures. The first quantum computer, the D-wave had to operate at a frigid 0.2 kelvin. Just last year there was a breakthrough that let us operate a quantum computer at 1.0 kelvin. That's a far cry from the 293.0 kelvin that is room temperature, or 310 kelvin which is the temperature of the human body.
Again, there's nothing theoretically preventing it, but we haven't discovered any mechanism by which it can occur. There's even people who claim that our brain is a quantum computer, though they have had little luck explaining the mechanisms in a way that is accepted by the scientific community at large.
There is a "heretical" school of thought which says it is inconceivable that evolution has not already caused neural networks to take advantage of quantum computing in some way. And we really do not understand how brains work. So we cannot categorically state that the quantum processes of thought are restricted to local chemistry of single molecules in synapses, although that is the majority view.
Some people even wonder whether "Is Quantum Biocomputing ahead of us?" in terms of quantum computing (asked in the currently-in-beta QC-SE). You might find some background on the realistic possibilities of quantum processes that employ biomolecules in my answer to that question. Of course in a sci-fi context things could be stretched quite a bit further than in reality...