The Brain’s Quantum Whispers: How Myelin Sheaths Might Generate Entangled Photons
26 Apr 2025, Yanjiang
Imagine the brain as a vast biological city, with billions of neurons firing in coordinated patterns that somehow give rise to thought, memory, and consciousness. For decades, neuroscientists have marveled at the brain’s ability to synchronize neural activity across distant regions, but the mechanism behind this orchestration has remained one of neuroscience’s deepest puzzles. Now, a team of researchers from Shanghai University, the University of Shanghai for Science and Technology, and Sichuan University has proposed a startling possibility: the brain might be using quantum mechanics to coordinate its neural symphony.
In a preprint (arXiv:2401.11682) published on arXiv, Zefei Liu and colleagues at Shanghai University’s Center for Quantitative Life Sciences have developed a theoretical framework suggesting that the myelin sheath—the fatty insulation wrapping around nerve fibers—could act as a natural cavity for generating entangled photon pairs. If confirmed, this finding would suggest that quantum entanglement, long thought too fragile to survive in the warm, wet environment of the brain, might play a fundamental role in neural communication.
The key to this proposal lies in the structure of myelin itself. Composed primarily of lipid molecules, the myelin sheath forms a cylindrical tube around the axon, much like the insulation around an electrical wire. But Liu and colleagues realized that this cylindrical geometry might do something far more interesting than simply insulating electrical signals: it could function as an optical cavity, similar to the carefully engineered cavities used in quantum optics laboratories.
Think of it like a perfectly designed concert hall. Just as sound waves can resonate and amplify within a room of the right shape and size, electromagnetic waves can resonate within a cavity of the right dimensions. The myelin sheath’s cylindrical structure, the team calculated, could trap photons in precisely this way—not unlike the cavity between two mirrors in a tabletop quantum optics experiment.
But the myelin sheath isn’t empty. It’s packed with lipid molecules whose long hydrocarbon chains are held together by carbon-hydrogen (C-H) bonds. These bonds vibrate at specific frequencies, and when they do, they can emit photons. Here’s where the quantum story begins.
The team applied cavity quantum electrodynamics (cQED)—a framework normally used to describe how atoms interact with light in carefully engineered cavities—to this biological system. What they found is remarkable. The vibrational modes of the C-H bonds can undergo a process called cascade emission, where a single excited bond relaxes through multiple intermediate states, emitting not one but two photons in sequence. And crucially, these two photons can be quantum entangled—their properties linked in ways that classical physics cannot explain.
Unlike dinner guests who must choose one seat, quantum particles can exist in multiple states simultaneously, and entangled particles share a connection that persists even across vast distances. If the myelin sheath can indeed generate entangled photon pairs, those photons could potentially carry quantum information between different parts of a neuron, or even between different neurons.
The abundance of C-H bonds in neurons is staggering. Each lipid molecule contains dozens of such bonds, and each neuron is wrapped in multiple layers of myelin. Liu and colleagues estimate that a single neuron could generate thousands of entangled photon pairs per second through this mechanism. Across the brain’s roughly 86 billion neurons, that represents an enormous potential resource for quantum information processing.
This is not a question that can be answered by theory alone. The team acknowledges that their calculations rely on several assumptions about the optical properties of myelin and the coupling between vibrational modes and the cavity field. Experimental verification would require detecting entangled photons emerging from living neural tissue—an extraordinarily challenging task given the brain’s opacity and the fragility of quantum states.
The philosophical implications are profound. For decades, the question of whether quantum effects play any functional role in biology has been hotly debated. We now know that quantum coherence matters in photosynthesis and that enzymes can use quantum tunneling. But the brain—warm, wet, and full of thermal noise—has seemed an unlikely venue for quantum mechanics to operate. This work suggests we may need to reconsider that assumption.
Perhaps, in the coming years, when experimentalists finally attempt to detect these entangled photons—perhaps in cultured neurons or brain slices—they won’t simply be testing a theoretical prediction. They’ll be listening for the first whispers of a quantum language that the brain may have been speaking all along.
Yanjiang is an online editor of Loom Science
References
- Zefei Liu et al., Entangled biphoton generation in myelin sheath, arXiv:2401.11682