Nuclear Spin Qubits in Posner Molecules: A Physical Substrate for Quantum Cognition — E8 Intelligence Research

FINDING: Matthew Fisher proposes nuclear spin qubits in phosphorus atoms (¹³C-coupled ³¹P) as the physical substrate for quantum cognition, with a specific molecular candidate—Posner molecule (Ca₉(PO₄)₆)—enabling long-lived entangled spin states in the brain. | MATH: Fisher's key mechanism: ³¹P nuclear spin (I=1/2) with hyperfine coupling to unpaired electron; ¹³C (I=1/2) as ancilla. Decoherence time T₂ for ³¹P in Posner molecule estimated ~10⁵ s (days) at physiological temperature due to symmetric cage shielding. Entanglement generation via singlet/triplet spin states of ³¹P pairs; the Posner molecule's 6 phosphate groups form an octahedral arrangement (O_h symmetry), with Ca²⁺ ions in a lattice matching the phosphate tetrahedra. The quantum error correction threshold (~10⁻⁴) and the ratio of ³¹P to ¹³C natural abundance (100% vs 1.1%) are critical parameters. | CONNECTION: The Posner molecule's octahedral symmetry (O_h point group, 48 elements) is a crystallographic root system of ty Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com