Could the Brain Use Quantum Light to Communicate Beyond Neural Signals?

Scientists are exploring whether the brain could use tiny flashes of light, called biophotons, to communicate in ways that go beyond traditional neural signalling. These ultra-weak photons, produced as a byproduct of the brain's metabolism, exhibit strange quantum properties—like entanglement and superposition—that might allow neurons to interact at incredible speeds. But while the idea is intriguing, hard evidence remains scarce, and many questions stay unanswered.

Over the past five years, researchers worldwide have turned to advanced tools to study biophotons in brain tissue. Teams in the Czech Republic and the Netherlands, led by scientists like Cifra and Salari, used ultra-sensitive photomultiplier tubes (PMTs) and electron-multiplying cameras to detect faint photon emissions in brain slices and live neurons. Meanwhile, a group in China, under Wang, combined cryogenically cooled single-photon detectors with real-time imaging to observe hippocampal cultures. In 2025, a UK-US collaboration applied time-correlated spectroscopy to analyse the light's spectral patterns, searching for clues about its role in synaptic communication.

One striking finding was that polarization-entangled photon pairs could maintain their quantum links even after passing through thin slices of brain tissue—up to 400 micrometres thick. This suggests that, in theory, quantum information *could* survive short journeys inside the brain. Yet the challenge remains enormous: for biophotons to influence neural activity, information would need to be encoded into their quantum states, travel without disruption, and then be accurately decoded by another neuron. The brain's natural environment makes this idea difficult to test. High temperatures and constant chemical noise disrupt quantum coherence, limiting any potential effects to extremely small scales. While some theories propose that the brain's electromagnetic field might exploit quantum field dynamics for communication, such ideas remain speculative. The deeper puzzle—the 'hard problem' of consciousness—still looms, as scientists struggle to explain how physical processes in the brain give rise to subjective experience.

Current research has shown that biophotons exist and can carry quantum properties through brain tissue, but their functional role is still unclear. Future experiments will need to determine whether these photons actually affect neural signalling or if they are merely a metabolic side effect. Until then, the possibility of quantum communication in the brain remains an open—and hotly debated—question.