Quantum biology refers to applications of quantum mechanics to biological objects and problems. Usually, it is taken to refer to applications of the "non-trivial" quantum features such as superposition, nonlocality, entanglement and tunneling, as opposed to the "trivial" but ubiquitous quantum mechanical nature of chemical bonding, ionization, and other phenomena that are the basis of the fundamental biophysics and biochemistry of organisms. It is still a tentative field, with research into it often being neglected in favor of other applications of quantum phenomena. It can be defined as the study of quantum phenomena within biological systems. Originally it had been thought that the heat engines of biological systems were not enough to produce quantum phenomena, but as evidence mounts that view has ceased to be popular.
Recent studies have identified quantum coherence and entanglement between the excited states of different pigments in the light-harvesting stage of photosynthesis. Although this stage of photosynthesis is highly efficient, it remains unclear exactly how or if these quantum effects are relevant biologically.
^Iannis Kominis: "Radical-ion-pair reactions are the biochemical equivalent of the optical double-slit experiment", Physical Review E 83, 056118 (2011) (abstract)
^Erik M. Gauger, Elisabeth Rieper, John J. L. Morton, Simon C. Benjamin, Vlatko Vedral: Sustained quantum coherence and entanglement in the avian compass, Physics Review Letters, vol. 106, no. 4, 040503 (2011) (abstract, preprint)
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