Weird plus weird becomes a reality when physics meets biology: Quantum Entanglement in Neurons ‘May’ Actually Explain Consciousness

Weird plus weird becomes a reality when physics meets biology:

Quantum Entanglement in Neurons ‘May’ Actually Explain Consciousness

A research group in China has shown that many entangled photons can be generated inside the myelin sheath that covers nerve fibers. It could explain the rapid communication between neurons, which so far has been thought to be below the speed of sound, too slow to explain how the neural synchronization occurs.

The paper is published in the journal Physical Review E.

The proposal is a bold one, not least because quantum effects tend to blur into irrelevance on scales larger than atoms and molecules. Several recent findings are forcing researchers to put their doubts on hold and reconsider whether quantum chemistry might be at work inside our minds after all.

The brain communicates within itself by firing electrical signals called synapses between neurons, which are the main components of nervous tissue. It is the synchronized activity of millions of neurons that consciousness (among other brain business) relies on. But the way this precise synchronization takes place is unknown.

Connections between neurons are called axons—long structures akin to electrical wires—and covering them is a coating ("sheath") made of myelin, a white tissue made of lipids.

Comprised of up to hundreds of layers, myelin insulates the axons, as well as shaping them and delivering energy to the axons. (In actuality, a series of such sheaths stretches across the length of the axon. The myelin sheath is typically about 100 microns long, with 1 to 2 micron gaps between them.) Recent evidence suggests myelin also plays an important role in promoting synchronization between neurons.

But the speed at which signals propagate along the axons is below the speed of sound, sometimes much below—too slow to create the millions of neuron synchronizations that are the basis for all the amazing things the brain can do.

To remedy this problem, researchers investigated if there could be entangled photons within this axon-myelin system that could, through  quantum entanglement, communicate instantly across the involved distances.
A tricarboxylic acid cycle releases energy stored in nutrients, with a cascade of infrared photons released during the cycling process. These photons couple to vibrations from carbon-hydrogen (C-H) bonds in lipid molecules and excite them to a higher vibrational energy state. As the bond then transitions to a lower vibrational energy state, it releases a cascade of photons.

The researchers applied cavity quantum electrohydrodynamics to a perfect cylinder surrounded by the myelin, making the reasonable assumption that the outer wall of the myelin sheath is a perfectly cylindrical conducting wall.
Using quantum mechanical techniques, they quantized the electromagnetic fields and the electric field inside the cavity, as well as the photons—that is, treated them all as quantum objects—and then, with some simplifying assumptions, solved the resulting equations.

Gaps between segments of myelin sheaths (a) are small enough to consider the entire myelin-coated axon as a cylinder (b) with the axon's radius as 𝑎, the entire cylinder's radius as 𝑏, and the thickness of the myelin sheath as 𝑑=𝑏−𝑎. The length of the cylinder is denoted by 𝐿. (c) Phospholipid molecules in myelin have tails with a large number of carbon-hydrogen bonds. (Source: Liu et al., Physical Review E, 2024)

Doing so gave the wavefunction for the system of the two photons interacting with the matter inside the cavity. They then calculated the photons' degree of entanglement by determining its quantum entropy, a measure of disorder, using an extension of classical entropy developed by the science polymath John von Neumann.
The researchers showed that the two photons can indeed have higher rate of being entangled under occasions.
The conducting wall limits the electromagnetic wave modes that can exist inside the cylinder, making the cylinder an electromagnetic cavity that keeps most of its energy within it. These modes are different from the continuous electromagnetic waves ("light") that exist in free space.

It is these discrete modes that result in the frequent production of highly entangled photons within the myelin cavity, whose rate of production can be significantly enhanced compared to two untangled photons.

Entanglement means the two-photon state is not a classical combination of two photon states. Instead, measuring or interacting with one of the photons instantly affects the same property of the second photon, no matter how far away it is.
Entanglement has been demonstrated for a system whose members are over 1,000 km apart. Nothing like it exists in classical physics; it is purely a quantum phenomenon. Here entanglement would raise the possibility of much faster signaling along the sections of myelin that encase segments of the axon's length.

One possibility, the authors write, is that the entanglement of photons could transform into entanglement along potassium ion channels in the neuron. If so, the opening and closing of one channel may affect the performance of another somewhere else.
These results are a combination of two phenomena that exist but are still largely mysterious: consciousness (let alone quantum consciousness) and quantum entanglement.
The researchers didn't say there is a direct connection. At this early stage, their primary goal is to identify possible mechanisms of neural synchronization, which affects numerous neurobiological processes. Through this work, they hope to gain a better understanding.

Zefei Liu et al, Entangled biphoton generation in the myelin sheath, Physical Review E (2024). DOI: 10.1103/PhysRevE.110.024402. On arXiv: DOI: 10.48550/arxiv.2401.11682