Posner qubits: spin dynamics of entangled Ca<sub>9</sub>(PO<sub>4</sub>)<sub>6</sub> molecules and their role in neural processing.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30381344.
- Also identified by DOI 10.1098/rsif.2018.0494 and PMC identifier 6228494.
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Abstract
It has been suggested that <sup>31</sup>P nuclear spins in Ca<sub>9</sub>(PO<sub>4</sub>)<sub>6</sub> molecules could form the basis of a quantum mechanism for neural processing in the brain. A fundamental requirement of this proposal is that spins in different Ca<sub>9</sub>(PO<sub>4</sub>)<sub>6</sub> molecules can become entangled and remain so for periods (estimated at many hours) that hugely exceed typical <sup>31</sup>P spin relaxation times. Here, we consider the coherent and incoherent spin dynamics of Ca<sub>9</sub>(PO<sub>4</sub>)<sub>6</sub> arising from dipolar and scalar spin-spin interactions and derive an upper bound of 37 min on the entanglement lifetime under idealized physiological conditions. We argue that the spin relaxation in Ca<sub>9</sub>(PO<sub>4</sub>)<sub>6</sub> is likely to be much faster than this estimate.
Medical subject headings
- Calcium Phosphates
- Magnetic Resonance Spectroscopy
- Nerve Net
- Quantum Theory