For a long time, consciousness was considered as unobservable and with that, it was reserved to philosophy where it has been a controversial topic ever since. The advantage of philosophy over science in regard to consciousness is that it can consider something like "experience" wherefore science has no measure of yet. To approach experience, we will use David Chalmers division of consciousness into two part. The first part is the "easy problems of consciousness" which we may eventually be able to explain including the following phenomena: the ability to discriminate, categorize, and react to environmental stimuli; the integration of information by a cognitive system; the reportability of mental states; the ability of a system to access its own internal states; the focus of attention; the deliberate control of behaviour; and the difference between wakefulness and sleep \cite{Chalmers_1998}. On the contrary, the hard problem refers then to the problem of explaining why and how sentient organisms have qualia \cite{Frankish_2012} or phenomenal experience.
The difficulty of the hard problem emerge from the conception of qualia. Depending on its
Thomas Nagel \cite{Nagel_1974} claims that qualia may need new concepts in neuroscience to be understood. Others argue that qualia and hence the hard problem can never be explained cite.
Are qualia reducible, physical entities?
The now following proposal departs clearly from ideas in quantum mind theories which are mostly based on von Neumann's measurement process derived from the Copenhagen’s interpretation. It is also not a quantum field theory based on Umezawa ideas in the 1960s \cite{Ricciardi_1967}. Most importantly, it opposes, as the quantum mind theory of Penrose \cite{penrose1989emperor} did, the idea that the mind could be based on classical computation. Instead, we propose that the brain is a quantum computer which can experience consciousness; a quantum computer that processes information in quantum bits (qubits) using quantum gates. At a first glance, it seems unrealistic or impossible that the brain can meet the challenges to provide both. Nevertheless, we will sketch a rough roadmap to show that the brain may have the incredible ability to perform quantum computing in the following way. First, we will suggest the existence of an unknown non-neuronal computing network in the brain. Then, we will further argue that this network must be based on quantum computing. Finally, we look at how the brain could realize it.