Quantum biology

Quantum biology is an emerging discipline that aims to investigate quantum phenomena—e.g., coherence, tunneling, entanglement—in living systems, and consider applications of the findings to science and technology—e.g., artificial photosynthesis, quantum computing.

In reference to quantum mechanical descriptions of cellular processes, the Theoretical and Computational Biophysics Group at the Beckman Institute of the University of Illinois at Urbana-Champaign give these examples:

Many important biological processes taking place in cells are driven and controlled by events that involve electronic degrees of freedom and, therefore, require a quantum mechanical description. An important example are enzymatically catalyzed, cellular biochemical reactions. Here, bond breaking and bond formation events are intimately tied to changes in the electronic degrees of freedom.

Key events during photosynthesis in plants and energy metabolism in eucaryotes also warrant a quantum mechanical description - from the absorption of light in the form of photons by the photosynthetic apparatus to electron transfer processes sustaining the electrochemical membrane potential.

Because of the importance of sensing light to both plants (for regulating vital functions) and animals (for vision), the interaction between light and biological photoreceptors is widespread in nature, and also requires a quantum mechanical description. A prime example is the protein rhodopsin which is present in the retina of the human eye and plays a key role in vision.

Demonstration of genuine quantum phenomenon in living systems in their natural setting will help in generating a convincing argument that support the role of those phenomena in the self-sustaining dynamics of living systems. Studies of biochemical processes in isolation from its natural surroundings contribute to understanding quantum physics but not certainly to understanding living systems.

Arnt et al. ask whether there are "nontrivial quantum phenomena relevant for life?" They follow up with:

Nontrivial quantum phenomena are here defined by the presence of long-ranged, long-lived, or multiparticle quantum coherences, the explicit use of quantum entanglement, the relevance of single photons, or single spins triggering macroscopic phenomena.

Photosynthesis, the process of vision, the sense of smell, or the magnetic orientation of migrant birds are currently hot topics in this context. In many of these cases the discussion still circles around the best interpretation of recent experimental and theoretical findings.

Hierarchically-distant of molecular biology, genuine quantum phenomena as critical determining factors in cell biology will have to have acquired immunity to destructive physico-chemical conditions, such as those causing dechorence and dephasing—vide infra.

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