Consciousness as a State of Matter
  I examine the hypothesis that consciousness can be understood as a state of matter, "perceptronium", with distinctive information processing abilities. I explore five basic principles that may distinguish conscious matter from other physical systems such as solids, liquids and gases: the information, integration, independence, dynamics and utility principles. This approach generalizes Giulio Tononi's integrated information framework for neural-network-based consciousness to arbitrary quantum systems, and provides interesting links to error-correcting codes and condensed matter criticality, as well as an interesting connections between the emergence of consciousness and the emergence of time. (For more technical details, see arXiv:1401.1219). 
Max Tegmark (MIT)
physics.pop-ph