Quantum biology: does nature use quantum tricks?

The recent development of technologies based on fundamental quantum physical phenomena such as superposition and entanglement adds new weight to the question whether nature may have found similar solutions.

From a quantum physicist’s perspective, spins and photons stand out as degrees of freedom that are well suited to exhibiting quantum phenomena even under the “warm, wet, and noisy” conditions of biology. Over the last few decades, the radical pair mechanism, which involves the quantum dynamics of electron and nuclear spins, has become established as a leading explanation for how migrating birds sense magnetic fields. We recently suggested that such radical pair phenomena may in fact underlie a wide range of magnetic field effects that have been observed across biology [1], and we made predictions on this basis, several of which have now been verified experimentally. I will highlight three examples, namely magnetic field effects on superoxide levels in stem-cell driven growth in planarians [2], magnesium isotope effects on microtubule polymerization in vitro, and magnetic field effects on ultraweak photon emission from leaves. This last example, which shows that spins play an important role in the emission of photons from cells, adds a new aspect to the long-standing question whether such so-called biophotons might serve as biological signals. In the context of the brain, we have suggested that axons are well suited to serve as biological photonic waveguides [3]. I will review current experimental and theoretical evidence regarding the existence of classical or quantum photonic biological communication.

Finally, I will discuss the still highly speculative question whether the brain might use quantum information processing for certain tasks, and specifically for generating consciousness, which has a holistic character reminiscent of entanglement. In this context, I have argued that combining spin and photonic degrees of freedom could be a viable approach in terms of biological hardware [4]. In terms of “software”, a leading neuroscientific theory suggests that consciousness serves as a global workspace, which has already inspired recent work in classical artificial intelligence, motivating us to explore quantum workspace-based architectures as potential models for consciousness.

[1] H. Zadeh-Haghighi and C. Simon, Magnetic field effects in biology from the perspective of the radical pair mechanism, J. Roy. Soc. Interface 19, 20220325 (2022)

[2] Rishabh, J. Vuckovic, H. Zadeh-Haghighi, W.S. Beane, and C. Simon, Verification of radical pair mechanism predictions for weak magnetic field effects on superoxide in planarians, bioRxiv 2024.11.20.624392 (2024)

[3] S. Kumar, K. Boone, J. Tuszynski, P.E. Barclay, and C. Simon, Possible existence of optical communication channels in the brain, Sci. Rep. 6, 36508 (2016)

[4] C. Simon, Can quantum physics help solve the hard problem of consciousness?, Journal of Consciousness Studies 26, 204 (2019)