In photosynthesis, for example, organisms use specialized pigments and proteins to harvest light with nearly perfect quantum efficiency; they convert almost every incoming photon into useful chemical energy. In 2007, new evidence suggested that life might accomplish this feat by taking advantage of a quantum effect called coherence. The result buoyed the controversial idea that, despite being a warm, wet, and decidedly classical environment, a living cell could maintain — and even exploit — fragile quantum states.

Gregory Scholes, a chemist at Princeton University, was initially enthusiastic about the result. He and colleagues followed up with experiments on photosynthesizing proteins and pigments and came away with similar conclusions. But today, Scholes is skeptical that quantum effects play a role in life. In fact, he’s convinced that the way forward for quantum biology might not be quantum at all. Rather than taking advantage of genuine quantum effects, Scholes proposes, life might be imitating them instead. In several papers published over the past three years, Scholes and colleagues have shown that complex networks of classical objects can conspire to produce phenomena that mathematically mimic quantum objects.

Don’t be fooled: The states that these networks produce are not truly quantum; they’re only “quantumlike.” They arise when many interacting, oscillating parts add up to a collective whole whose behavior obeys the same mathematics that makes predictions about the quantum world.

“Maybe quantum biology, at the biggest scales, means using 3 1/2 billion years of evolution to work out how to get the functionality that you could get from quantum systems,” Scholes said.

Researchers in the foundations of quantum mechanics have been exploring how to classically re-create certain aspects of the quantum world for decades, said Markus Müller, a physicist at the Institute for Quantum Optics and Quantum Information in Vienna. What Scholes has done, Müller said, is show how quantumlike behavior can emerge from relatively unremarkable complex networks — of the sort that abound in nature.

“Classical systems can mimic some of the key features of quantum information,” said Sabre Kais, a quantum chemist developing quantum computing algorithms for complex systems at North Carolina State University. “This is an exciting new direction.”

The Bounds of Quantum Biology

The temptation to recast life’s mysteries as quantum in nature is about as old as quantum mechanics itself. In a 1929 lecture, the quantum pioneer Niels Bohr made the vague but enticing statement that quantum mechanics, which at the time was just starting to find its mathematical footing, “may perhaps be of decisive importance, particularly in the discussion of the position of living organisms in our picture of the world.”

Bohr’s contemporary Pascual Jordan spent several decades writing on Quantenbiologie, or quantum biology, arguing that life has a unique ability to amplify the strange indeterminism of the quantum world to macroscopic scales, and claiming this as the basis of human thought and free will. J.B.S. Haldane, a geneticist and evolutionary biologist, echoed Jordan in a 1934 paper arguing that the ability to scale up quantum indeterminacy was what made life special. (Jordan, who joined the Nazi Party and its paramilitary forces in 1933, damaged the credibility of quantum biology by attempting to link it to Nazism.)

These early proponents of quantum biology sought explanations for the puzzling properties of life at the classical scale in the counterintuitive laws of physics at the quantum scale. A classical particle can be in only one place, in one way, at a time; a quantum particle is smeared out across all the places and ways it could potentially be, in a kind of wave of possibility. This smear is described mathematically by a wave function which, like a classical wave, has peaks and troughs.

Until a particle is observed, all of its possible configurations effectively exist at once. They’re stacked up in superposition, like overlapping waves of water or sound. And like overlapping waves, stacked quantum states add up, cancel one another out, or otherwise transform each other. When quantum states in superposition have tidy enough wave properties to affect each other this way, they’re called coherent. Coherent quantum systems can also become entangled with each other, essentially merging into a single, unified entity with a shared wave function.

Quantum states are delicate things; they’re easily destroyed when jostled against the outside world. Even a tiny amount of environmental noise, like the atomic jiggle of heat, can trigger decoherence, a collapse into classical behavior. (Quantum computers aren’t supercooled just for fun.) And in the interior of a cell, decoherence should be basically instantaneous — quantumness shouldn’t survive long enough in such an environment to have any bearing on biology.

It’s true that, even in a cell, very, very small particles like hydrogen atoms can “quantum tunnel,” popping up beyond energetic barriers that would otherwise slow them down or prevent them from crossing. And there’s evidence that tunneling in certain enzymes could explain their speedy reaction rates. But that’s not really what quantum biologists are after, Scholes said. There’s no long-lived coherence involved in this kind of tunneling. The quantumness involved is simple, fleeting, and kind of unavoidable — even in a flask of dead chemicals, some tiny particles will tunnel through energetic barriers. The question is whether life can do what dead chemistry can’t: hold quantum states in coherence long enough to use coherence itself as a resource.

A Light-Harvesting Letdown

Scientists first toyed with the idea that quantum coherence could explain the remarkable efficiency of photosynthesis as early as the 1930s.

Photosynthetic organisms use arrays of pigments and proteins called light-harvesting complexes to soak up light. When a photon strikes one of these complexes, its electromagnetic energy is absorbed and boosts an electron in the complex into an excited state. This quasiparticle — called an exciton — heads toward a reaction center, where it is transformed into chemical energy that can perform the key steps of photosynthesis.

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The process is nearly 100% efficient: Almost every single photon absorbed ends up powering photosynthesis. Scientists thought that if excitons maintained quantum coherence across multiple molecules in the light-harvesting complex, they could simultaneously explore several routes to the reaction center, rather than hopping around haphazardly and potentially getting lost.

In 2007, Graham Fleming of the University of California, Berkeley tested this idea using a light-harvesting complex of pigments and proteins from a bacterium. He and his colleagues pumped the pigments and proteins with extremely fast pulses of laser light to generate excitons, then probed them with follow-up pulses. This revealed synchronized “beats” that, at the time, seemed like evidence that excitons were interfering with each other via quantum coherence. Other researchers, including Scholes, performed similar experiments and found similar beats — even in experiments conducted at room temperature.

But just as quantum biology started to build momentum, it hit a wall. Upon closer examination, beats like the ones that Fleming’s team described turned out to reflect not quantum coherence, but a resonance between wiggling molecular bonds. The resonance was an interesting effect that scientists are still working out, but it wasn’t long-lived, long-range quantum coherence.

“People were disappointed,” said Richard Cogdell, a photobiologist at the University of Glasgow. “It would be exciting if there really was something to this, and there was something special about biology that no one had realized before.”

Researchers have hypothesized that quantum effects are at play in a variety of biological phenomena — including the magnetic sense that helps birds navigate and, more speculatively, human consciousness — with varying degrees of empirical support. But at this point, there’s still no definitive proof for any long-lived quantum coherence with a biological function.

Scholes has grown skeptical that scaling up effects such as coherence and entanglement in life is possible at all. “It’s that scale-up that gets the wow factor. And the real quantum world isn’t going to scale up like that,” he said.

At a conference in December 2023, Scholes had a conversation about what needed to happen to advance the field. He recalls returning to his hotel room and jotting down an idea: Maybe the “quantum” in quantum biology doesn’t come from quantum mechanics at all, but emerges out of wavelike ripples across huge, complex networks.

“I’m now convinced that you could get transformative effects, but they would come from classical systems mimicking what you can do with quantum systems,” Scholes said. “Does it matter if you can’t tell the difference?”

A World of Quantumlike States

Scholes wondered if the emergence of special synchronized states in complex networks, like flocks of birds or schools of fish, might produce quantumlike behavior.

Strip away the physics from a quantum state, and the mathematical object you’re left with is a vector — an ordered list of numbers that acts like coordinates for a location in a mathematical space of possibilities. Quantum states are represented in a particular kind of vector space called a Hilbert space.

Vectors in Hilbert space follow specific rules. One of those rules says that any two states can be added together, and the result will also be a valid vector that, once normalized, will yield a valid quantum state. This is, mathematically, what quantum superposition gets at. States are coherent if they have neat phase relationships that allow them to interfere — adding up or canceling out, depending on how they line up. The coordinates of a vector in Hilbert space include information that corresponds to this alignment of peaks and troughs, called a wave’s phase.

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Andrei Khrennikov, a mathematician at Linnaeus University in Sweden, noticed a connection between quantum interference and the classical world in the 1990s when he began borrowing mathematics from quantum mechanics to model probabilities. His idea, essentially, was that probabilistic outcomes — in fields as different as neuroscience and economics — can interfere with themselves like quantum states in superposition.

In 2024, Scholes found a way to design complex networks of oscillators such that they produced emergent states — stable patterns of synchronized behavior, like a crowd that claps in time — that could be mathematically described as vectors in a Hilbert space. Specifically, he showed that networks can be constructed to produce emergent states that mathematically mimic the simplest quantum unit: a qubit, which has two states (like 1 or 0) and can exist in a superposition of both.

“This strictly arises from the mathematical structure of the graph,” said Ethan Dickey, a computer scientist at Purdue University. “If you build graphs in certain ways which are not that unreasonable, they happen to pop up with this very nice, very elegant mathematical object that simulates — or almost approaches — a quantum object.

Redefining Quantum Biology

Very different physics can underlie similar mathematical forms. Both the parabolic arc of a flying baseball and the parabolic arc at the tip of a cactus spine can be described using quadratic equations, but the two are fashioned by different forces. So a mathematical connection between the classical and quantum worlds shouldn’t be mistaken for a physical one.

There’s a complicated history of both serious research and fanciful speculation about quantum effects in life. Ebrahim Karimi, a physicist at the University of Ottawa, thinks researchers should be careful about putting too much stock in this mathematical link. He praises Scholes’ new framework for its elegance and says it could be useful, but he thinks quantum vocabulary doesn’t belong anywhere near classical systems. Interference isn’t anything mysterious or quantum, Karimi pointed out. It’s simply a feature of how waves behave.

Researchers want to gain a better understanding of when and how classical systems can mimic quantum math. That knowledge could be helpful for sorting out contentious claims about quantum effects in life — including in the brain.

Among researchers keen to connect life to the quantum realm, the brain has long been a focus of intense interest and plenty of heated debate. In 1989, for instance, Roger Penrose revived old ideas about quantum physics as the basis for free will; he proposed that consciousness arises from quantum effects in the brain, in networks of protein filaments called microtubules. Few neuroscientists take this view seriously.

Given that context, Wolf Singer, a neurophysiologist at the Ernst Strüngmann Institute of the Max Planck Society, was initially skeptical when Khrennikov invited him to a workshop on quantumlike modeling.

Singer and colleagues showed in 2025 that introducing oscillations into a particular kind of simple neural network makes them more efficient and robust. Singer said that using interference essentially gave the network a new dimension to work with: time. This was because the phase of an oscillation encodes information about how events are structured in time relative to each other. After the workshop, Singer said he was “impressed by the fact that some real-world phenomena are maybe better described using the description techniques they use in quantum physics.”

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Quantumlike states also provide a conceptual blueprint for intentionally engineering networks — which could be anything from electrical circuits to neurons to physical pendulums coupled by springs — that can take advantage of superposition and interference to compute. In follow-up work, Scholes and his colleagues showed that it’s possible to wire together quantumlike bits to produce bigger networks, which are also quantumlike states, and demonstrated how a network could be designed to mimic the quantum version of a “logic gate,” a circuit used to perform a simple computation.

Dickey and his doctoral co-supervisor, Kais, believe quantumlike states have “strong potential for practical applications” in quantum machine learning and in modeling complex systems. But those applications face limitations: The complexity of the underlying network blows up when you start wiring quantumlike bits together. To perfectly mimic quantum logic gates, “you need to have infinite resources, physical resources,” Scholes said.

Dickey has built on Scholes’ work to pin down network properties that produce quantumlike states and is working to find computationally efficient ways to produce them. He also published work in 2026 showing how networks can be designed to produce more kinds of quantum states than Scholes’ original framework allowed.

For his part, Scholes is interested in understanding the limits of quantumlike states in the classical world. He’s working to determine whether it’s possible for classical systems to meaningfully mimic entanglement.

Even if biology is ultimately not as quantum as researchers once hoped, there may still be interesting — and potentially illuminating — parallels between the living world and the quantum realm. Although quantum superpositions dissolve with increasing scale, aspects of the math that governs the smallest, simplest stuff of existence seem to resurface in the most sprawling, complex classical systems we know.