Quantum Cognition: The possibility of processing with nuclear spins in the brain

TL;DR

This paper explores the theoretical possibility that nuclear spin-based quantum processing could occur in the brain, involving phosphorus nuclei, Posner molecules, and quantum entanglement to influence neural activity.

Contribution

It proposes a novel model where nuclear spins in phosphorus and Posner molecules enable quantum processing and entanglement in the brain, a new perspective on neural quantum cognition.

Findings

Posner molecules can protect nuclear spin qubits for long durations

Enzyme reactions can generate entangled phosphate pairs

Quantum binding of Posner molecules may influence neuron firing

Abstract

The possibility that quantum processing with nuclear spins might be operative in the brain is proposed and then explored. Phosphorus is identified as the unique biological element with a nuclear spin that can serve as a qubit for such putative quantum processing - a neural qubit - while the phosphate ion is the only possible qubit-transporter. We identify the "Posner molecule", $\text{Ca}_9 (\text{PO}_4)_6$, as the unique molecule that can protect the neural qubits on very long times and thereby serve as a (working) quantum-memory. A central requirement for quantum-processing is quantum entanglement. It is argued that the enzyme catalyzed chemical reaction which breaks a pyrophosphate ion into two phosphate ions can quantum entangle pairs of qubits. Posner molecules, formed by binding such phosphate pairs with extracellular calcium ions, will inherit the nuclear spin entanglement. A mechanism for transporting Posner molecules into presynaptic neurons during a "kiss and run" exocytosis, which releases neurotransmitters into the synaptic cleft, is proposed. Quantum measurements can occur when a pair of Posner molecules chemically bind and subsequently melt, releasing a shower of intra-cellular calcium ions that can trigger further neurotransmitter release and enhance the probability of post-synaptic neuron firing. Multiple entangled Posner molecules, triggering non-local quantum correlations of neuron firing rates, would provide the key mechanism for neural quantum processing. Implications, both in vitro and in vivo, are briefly mentioned.