We propose that cerebral dynamics can be considered as a non-Hermitian quantum system which during a short interval of the cardiac cycle has real eigenvalues. We show that driving the system into PT symmetry is only possible with the help of the active matter changing from a laminar flow into a Ceilidh dance-like flow. During this change, the flow experiences  a transition from broken to unbroken PT symmetries which results in a topological phase. The topological phase is then imparted onto the topological defects which are an essential part of this Ceilidh dance flow. This so-called topological braid could be the basis of topological computing in the brain. Our recent experimental findings in conscious humans have shown that the predicted PT symmetry changes may exist. This is important because it is also related to consciousness underpinning  the computational aspect of the phenomenon. 

Controversial hypotheses to explain consciousness exist in many fields of science, psychology and philosophy. Recent experimental findings in quantum cognition and magnetic resonance imaging have added new controversies to the field, suggesting that the mind may be based on quantum computing. Quantum computers process 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 either of these. Nevertheless, we show here why the brain has the incredible ability to perform quantum computing and how that may be realized. 

For many years, it has been speculated that consciousness and cognition could be based on quantum information  \cite{sep-qt-consciousness} which opposes the view that quantum coherence, the primary basis of quantum computing \cite{nielsen_chuang_2010}, cannot survive in complex biological systems \cite{Koch_2006,Tegmark_2000}. However, recent findings in photosynthesis \cite{Engel_2007,Collini_2010,Scholes_2017} have challenged this view suggesting that only long-range quantum coherence between molecules can account for its efficiency in light-harvesting. Here, we investigated if long-range quantum coherence may also play a decisive role in brain function. We found, surprisingly, that the cardiac pressure pulse evoked zero-quantum coherence (iZQC) \cite{Warren_1998} which were by a magnitude higher than theoretically expected. From this finding, we concluded that the underlying physiological process is - cautiously speaking - of an unknown macroscopic non-classical kind. The process reveals its importance by its temporal appearance; during consciousness it is highly synchronized with the cardiac pulse, while during sleep, no or only sporadic iZQC could be detected. These findings suggest that this non-classical phenomenon is most likely a necessity for consciousness. 

For many years, it has been speculated that consciousness and cognition could be the based on quantum information  (Atmanspacher 2015) which opposes the view  that  quantum coherence, the primary basis of quantum computing (Nielsen 2010), cannot survive in complex biological systems (Koch 2006, Tegmark 2000). However, recent findings in photosynthesis (Engel 2007, Collini 2010)  have challenged this view suggesting that only long-range quantum coherence between molecules can account for its efficiency in light-harvesting. Here, we investigated if long-range quantum coherence may also play a decisive role in brain function. We found  surprisingly that the cardiac pressure pulse  evoked  zero-quantum coherence (iZQC) (Warren 1998) which were by a magnitude higher than theoretically expected.  From this finding, we concluded that underlying physiological process is  - cautiously speaking - of an unknown macroscopic non-classical kind. The process reveals it importance by it temporal appearance; during consciousness it is highly synchronized with the cardiac pulse,  while during sleep,  no or only sporadic  iZQC could be detected. This findings suggest that this non-classical phenomenon is most likely a necessity for consciousness. 

The Quantum brain (QB) question.Thanks to the so-called Copenhagen interpretation, quantum mechanics has been connected with consciousness since its early days. The group around Niels Bohr suggested that  an observer is an essential part of quantum mechanics. Schrödinger's cat was an attempt to questioning that idea, not to explain it. Although many alternative interpretation have been proposed since then, the Copenhagen interpretation is still the predominant which will be found in most text books.