Quantum and classical mechanics are often presented as mutually exclusive, separated worlds with their own laws. However, the emergence of quantum biology hints at the role of nature in reconciling these worlds to confer quantum advantages at a macroscopic level. From photosynthesis to genome stability, quantum effects seem to linger in spite of the chaos pertaining to biological systems. This essay examines experimental and theoretical evidence demonstrating the validity of quantum biology, and explores the potential for revolutionizing advances in biological modeling and engineering presented by the field.
Introduction
The history of quantum mechanics is one of skepticism and reluctance. Faced with paradoxes and phenomena that could not be explained using the models available at the time, scientists leaned toward unconventional methods. In the late 1800s, physicists were studying an idealized object – a blackbody – that was theorized to absorb any type of radiation while emitting radiation that depended only on its temperature. Upon comparison, experimental evidence showed a discreteness to the radiation emitted that was inconsistent with theoretical estimates. At that time, physicists lacked the tools to reconcile this discrepancy and the list of paradoxes that could not be explained with their models grew. When the German theoretical physicist Max Planck demonstrated that the blackbody radiation spectrum could be explained by assuming energy is absorbed in discrete values—packets of energy—it marked the beginning of a paradigm shift. However, scientists were reluctant to accept the implications of the quantum world, tip-toeing around them until the effectiveness of the model became incontestable.
Today, something similar is happening at the intersection between quantum physics and biology. Quantum mechanics revolutionized the understanding of the universe in the 20th century, and now it holds the potential to transform our comprehension of how life came to be. While classical mechanics has sufficed to explain most biological processes, some point in the direction of quantum biology. This essay explores experimental and theoretical evidence that quantum effects operate within living organisms; why biological complexity may actually support rather than interfere with quantum phenomena; and how the adoption of a quantum framework represents an opportunity to revolutionize biological research and engineering.
Knock, Knock – Are you there?
The first part in every experiment is the hypothesis—the motivation for what may follow. In this case, what is the motivation for quantum biology? The quantum world decoded and explained the underpinnings of chemistry, and since chemical processes are the foundation of life, it follows by straightforward logic that quantum mechanics might extend into biology. In recent years the scientific community has taken the next step in providing a proof of concept and experimental evidence has gained momentum.
Life on Earth depends on many processes, but photosynthesis stands as one of the pillars. From early education, food-chain charts in textbooks show how plants and other photosynthetic organisms provide energy throughout the ranks, converting solar energy into other usable forms. We learn that photosynthetic organisms capture and utilize the energy from the sunlight to power the generation of chemical energy that cells can use. Although seemingly linear, quantum mechanics adds a new layer to this picture. First, the duality – light travels as a wave from the sun and is absorbed as a particle by the chloroplast's pigment molecule, the chlorophyll. This photon carries energy that excites the electrons in the molecule in a quantum phenomenon called quantum transition. However, this excitation energy behaves like a wave spreading over neighboring molecules, creating a state of superposition despite the fact that the energy available is sufficient for only one excited molecule. The energy is then transported to the reaction center, where this superposition state collapses. Initially, this quantum state may appear to be merely an intermediate stage between two classical points with no discernible advantage, but that is fundamentally incorrect.
Part of being human is making decisions, using information acquired through experience to predict future scenarios. But what if we could experience every outcome and only then decide? While this is only a dream for humans, it is reality for the energy moving through the chloroplast to the reaction center. The superposition state of neighboring chlorophyll molecules allows the excited electron to evaluate all possible paths and determine which one minimizes energy loss. As a result of this optimization, about 99% of the incoming energy reaches the reaction center (Mohseni et al., 2008). By comparison, most commercial solar panels that rely on classical mechanics show below 25% efficiency. But quantum effects can be employed for more than just efficiency.
For years, people have studied the habits of migrating birds. Beyond the complex patterns formed in the sky and the motives for their migration, scientists have been puzzled by how birds are capable of precise navigation around the globe. Recent studies accumulate evidence suggesting quantum mechanics as an underlying mechanism. The classical model proposed that migratory birds potentially contained small magnetite crystals in their tissues that would serve as a microcompass. However, experiments showed that the geomagnetic-sensing mechanism in birds is light-dependent, contradicting this model. Inspired by studies that revealed how radical pairs—short-lived pairs of molecules sharing unpaired electrons—are sensitive to weak magnetic fields (Knapp & Schulten, 1979), biophysicist Prof. Klaus Schulten proposed that Earth's magnetic field could interfere with the quantum spins of the unpaired electrons, ultimately affecting the chemical properties of the outcome and serving as a marker for navigation (Solov’yov & Schulten, 2011). The model has since gained support as recent studies have found an avian photoreceptor molecule expressed in the retina that forms a radical pair upon blue light exposure (Xu et al., 2021). While further experiments are needed to establish and prove this model, its success in reconciling observations and theory adds to the growing body of evidence that quantum effects play a functional role in living systems.
Beyond the direct employment of quantum phenomena to confer advantages, nature shows signs of mirroring the quantum world and its strategies. In the ovary, several follicles start to develop at the same time, but once the first one reaches a certain developmental stage, it releases growth-suppressing proteins and hormones that ultimately induce apoptosis in the other follicles, a winner-takes-all selection mechanism that confers biological advantages. Follicle development and the subsequent egg-cell generation is a costly process, so commitment to one or two enables for resource conservation. Besides optimizing resource allocation, selecting for ontogenic advantages reflected by asymmetries in developmental progression aligns with evolutionary theories of selection. Comparing such dynamics with the role of quantum superposition in allowing for optimized efficiency of energy transfer in photosynthesis renders a striking parallel and a powerful insight: nature could be leveraging quantum principles in both direct and indirect ways.
Another clear example of quantum-resembling processes in nature is cellular differentiation. Stem cells have gained much attention in recent years, given their ability to differentiate into a diverse pool of specialized cells. Naturally, researchers have attempted to unlock this mechanism and control cell commitment through interventions, an effort that has yielded groundbreaking results. For instance, scientists have already been able to turn induced pluripotent stem cells (iPSCs) into neurons. Meanwhile in the neighboring field of physics, scientists face a fundamentally similar conundrum. The probabilistic nature of quantum mechanics allows for particles to have multiple allowed states that eventually collapse to a single classical outcome upon observation or some other interaction with the environment. Physicists, like researchers in the field of stem cell biology, aspire to guide systems between discrete states. In a Nobel Prize-winning effort, researchers have developed technologies capable of moving electrons between specific states, allowing for greater control of quantum phenomena and resulting properties. But while the striking parallels demonstrate solid ground for collaboration, the exchange of knowledge in the form of both framework and technology is virtually inexistent.
Several fields have made tremendous progress by adopting ways of thinking from other disciplines—economics and physics, biology and chemistry, and so on. Besides biological processes that directly leverage quantum advantages, those that resemble quantum phenomena may also benefit from a quantum mechanical framework. Further building on these analogies across disciplines could broaden our understanding of biological systems. In neuroscience, employing a quantum model for neuron networks has already revealed patterns and behaviors that classical models failed to capture (Maksimovic & Maksymov, 2025). As a thought experiment, interpreting genes and pathways to be more than building blocks, but rather analogous to energy levels between states, the implications are numerous. Thus, beyond asking how quantum phenomena impact life on a functional level, we should also inquire how quantum principles can guide our understanding of biological organization and function.
However, not all processes in living organisms mimic quantum dynamics—some are simply classical and straightforward. In DNA replication, an essential step for most forms of life on Earth, enzymes and other molecules split the two strands of DNA and match the nucleotides on each with their respective pairs, creating two copies of the original. Occasionally, single nucleotide mutations may occur between the separation and matching processes, resulting in a mutation that will be passed on. In biological research, mutations have provided scientists with a window into the intricacies of pathways and genetic regulation. By purposefully mutating genes and other functional genomic regions, researchers are capable of inferring their functionality and impact on phenotype. Technologies that facilitate genetic engineering experiments, like CRISPR, have significantly expanded the horizons of what is possible, propelling research and therapeutic discovery. But these techniques have limits. Scientists often have to juggle several conditions and requirements in order to apply them, and the yield rate of successful edits can be discouraging at times. Fortunately, these limitations could point to an opportunity – leveraging quantum advantages into new technologies.
Nucleotides are held together through hydrogen bonds, which consist of protons being shared between atoms, and the number of bonds is what defines the pair specificity observed in DNA. According to quantum mechanics, protons do not have a definite position but are described by a wavefunction representing their probability of being found elsewhere. These wavefunctions convey the energy of the system and, therefore, the allowed states for the particle given its own energy. However, particles such as protons are able to bypass these energy barriers even when their classical energy is insufficient, in a phenomenon called quantum tunneling. The protons found in hydrogen bonds between nucleotides are no exception to this phenomenon, with direct implications for DNA stability. Through quantum tunneling, protons can change their location and yield abnormal nucleotide pairing in DNA, which can cause mutations that are passed on to the next generation of cells. Scientists have performed simulations and shown that this mechanism is a potential factor contributing to genomic variation across life forms (Slocombe, Sacchi, & Al-Khalili, 2022). This phenomenon raises an intriguing possibility: if quantum tunneling occurs spontaneously in nature, could it be deliberately harnessed? Physicists have already successfully engineered quantum tunneling in other systems (Devoret, Martinis, & Clarke, 1985), proving that such precise control of the quantum world is indeed possible. Building on this proof of concept, utilizing quantum tunneling as a genetic engineering technology could allow for targeted single nucleotide mutations and expand what is currently possible. Since nucleotides are the building blocks of DNA, having a fine-tuned method of editing them at will would exponentially increase our control over genomic expression and reduce noise in experimental designs. Ultimately, this is just one of the countless possibilities that emerges from the intersection of life and quantum engineering.
Final Remarks
One may wonder whether quantum advantage might be limited to a few cases, arguing that quantum effects become lost in the chaos of living matter. However, this view is rather limited and biased toward current ways of thinking. First, even if we assume that quantum advantages are indeed limited to a small number of biological processes, this argument is insufficient to discourage their thorough investigation, given the potential impact the ones we are aware of have on the world. The energy transfer efficiency observed in photosynthesis, if mimicked, could pave the way forward for clean energy and contribute to solving one of the greatest challenges faced by humanity—climate change. Additionally, understanding how quantum effects may be preserved in nature has the potential to direct future research toward systems that present the necessary mechanisms, thus facilitating the discovery of other quantum-reliant phenomena.
Another fault in this skepticism is the assumption that the complexity observed in living systems and the effects observed in the quantum world are unrelated or even mutually exclusive. For thousands of years, DNA has evolved, accumulating mutations and selecting for the most beneficial genes under certain conditions. This flexibility has allowed nature to bloom into a diverse ecosystem of countless species and survival mechanisms. At the same time, multicellular beings had to learn how to minimize and overcome chaos and randomness in the maintenance of genetic material. In humans, for example, cells must replicate multiple times while preserving the integrity of their DNA. This duality—the balance between allowing and combating change—hints at the idea that the complexity in biological systems, often stated as an obstacle to experiments and measurements, is rather another mechanism purposefully employed by nature. Simulations of how the energy stored in photons is transported during photosynthesis have shown that some level of noise is actually required for the state of superposition to be maintained (Caruso et al., 2009), suggesting that what critics see as the reason against quantum advantage is actually part of its preservation.
Quantum biology has evolved as an idea and stands today to represent a promising field of both fundamental and applied research. Accumulating robust experimental evidence reveals the presence of quantum effects at the heart of important biological processes, portraying the intersection of quantum physics and biology as a necessary framework for understanding life. While the discovery of novel quantum advantages in nature to further establish quantum biology as a field remains challenging, deepening our understanding of documented cases will elucidate the mechanisms and conditions necessary for the preservation of quantum effects, thus guiding the discovery of additional cases. Insights gained from studying these established examples also hold potential to revolutionize the efforts on clean energy, quantum engineering, and biological modeling and engineering. Additionally, the field of quantum biology paves the way for the introduction of quantum technologies in biological systems. Cross-disciplinary technology transfer has long been central to biological research, and quantum technologies represent a natural progression in this direction. Hence, beyond investigating naturally occurring quantum-reliant processes in nature, quantum biology will also enable investigations into how quantum advantages can be introduced to biological systems.
The journey ahead is arduous, as investigations into the quantum world require highly controlled conditions that are difficult to replicate in biological systems. As with the birth of any field, novel experimental designs, protocols and technologies will need to be devised along the way before the potential of quantum biology becomes fully realized. However, even at its dawn, quantum biology already demonstrates significant promise in revolutionizing not only biology but science as a whole, pushing the frontiers of what is possible and known while equipping researchers with novel tools. And perhaps posing the question of how quantum life is will take us a step closer toward comprehending what life actually is.
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