Quantum Biology: The Fuzzy Connection Between Quantum Mechanics and Living Things

Here’s the story of how I stumbled upon a realization today: some of my scientific work overlaps with the emerging field of quantum biology. I used to refer to my academic research line as quantum chemistry applied to systems of biological relevance – a scientific journey to studying biological systems through the lens of quantum chemistry. In my previous life as an active academic researcher, I dived deep into the nitty-gritty of biothings, using ab initio calculations and beyond to explore the metal-based anti-cancer agents like cisplatin, NAMI-A, or how metal binding affects DNA structural characteristics. Oh, and let’s not forget about the hours I spent tinkering with catalysts that mimic naturally occurring enzymes and with photosystem II, the first protein complex involved in the light-dependent reactions of photosynthesis.

Enough with the bragging. Long story short, I realized that some of the work I’ve done falls under the umbrella of quantum biology. So, I asked myself the following question:

Artistic representations of waves and particles - quantum foam
Artistic representations of waves and particles © Gerd Altmann

What’s Quantum Biology?

Just think about it for a second: the universe itself is governed by the laws of quantum mechanics as is filled with particles that behave in ways that defeat our ordinary intuition. I am talking about electrons and quarks (well, let’s forget for a moment about dark energy and dark matter), which are like little ripples in the underlying quantum fields that make up the fabric of reality. And those particles, in turn, make up atoms and molecules – the building blocks of all life on Earth, at least, including us.

So, when you really get down to it, we humans – along with plants, bacteria, and all other living things – may ultimately just be an emerging phenomenon from excitations of the quantum fields. It’s a provocative thought, but it could mean that the principles of quantum mechanics are at work in our very bodies and possibly brains, influencing everything from our behaviors down to our own existence.

Objects in our everyday world – people, planets, puppies – are made up of atoms and molecules. Atoms and molecules, in turn, are made of elementary particles, interacting via a set of fundamental forces. And these particles and forces are accurately described by the principles of quantum field theory.

Sean M. Carroll 2021

Put simply, quantum biology is the study of how quantum mechanics and theoretical chemistry intersect with the slimy and wonderful world of biology. You see, many aspects of biology just can’t be explained by classical physics alone, so we must turn to the counterintuitive rules of quantum mechanics to make sense of it.

From the way energy is converted in biological processes, to the transfer of electrons and protons in photosynthesis and cellular respiration, there is mounting evidence that quantum mechanics shapes how living things function.

The influence of non-trivial quantum phenomena in biological processes is a complex and still speculative area of study, but one that’s absolutely fascinating to explore. At its core, quantum biology is about taking apart the mysteries of life and trying to understand the fundamental physics that drive it all.

So, are you ready to geek out with me and explore some examples of quantum biology?

Let’s go.

Visualization of a one-dimensional quantum wave function in 3D. Video Credit: Steve Spicklemire.
– Photosynthesis and superposition

Photosynthesis is a prime example of how quantum effects are at play in the biological world. Protein complexes within photosynthetic organisms absorb solar energy and transfer it as electronic excitation to the reaction center, where it’s used to power biochemical reactions. And the efficiency of this process? It’s off the charts, typically exceeding an incredible 90%.

So, what’s the secret behind this remarkable efficiency? Ultrafast excited-state dynamics, including energy transfer and charge separation. And quantum superposition and coherence dynamics may be what makes it all possible.

Recent experimental developments support this, by demonstrating excitonic coherence effects in photosynthetic complexes at both low and ambient temperatures.

– Animal navigation systems and quantum entanglement

It turns out that numerous organisms, from insects to fish, can sense the Earth’s magnetic field to navigate their way around. It is mind-boggling if you think about it. Imagine if you, just like homing pigeons, could detect weak magnetic anomalies.

How would that feel? How would it smell like? And how do these creatures perform this magic?

One possible explanation for how organisms sense the Earth’s magnetic field is through a light-initiated chemical reaction that occurs in a cryptochrome photoreceptor. This reaction involves radical pairs and can be influenced by alterations in magnetic field orientation. This mechanism is based on the idea that biological systems may contain ladders of electronic states, which can be utilized to sense external stimuli. The relative energies of singlet and triplet states can be then used to sense magnetic fields.

Quantum entanglement is believed to be a key factor in this ability.

– Cellular processes and quantum tunneling

Did you know that proton-coupled electron transfer, which involves the simultaneous transfer of a proton and an electron from different chemical groups, is a critical mechanism in various biological functions?

These nuclear quantum effects represent a distinct type of quantum phenomenon observed in biological systems. In enzymes that employ these processes, quantum effects may significantly contribute to catalytic rates, thanks to zero-point energy-induced energy shift and hydrogen tunneling. Perhaps surprisingly, proton transfers and quantum effects may drive DNA mutations, and therefore biological evolution.

Hybrid quantum/classical molecular dynamics simulations of proton transfer in the dihydrofolate reductase. Video Credit: Hammes-Schiffer research group

The Origin of Quantum Biology: Erwin Schrödinger’s What is Life?

Quantum biology is a relatively recent field, having gained traction only in the last few decades or so. However, the possibility that quantum mechanics could be at play in biological systems is a concept that’s been puzzling scientists for over a century now.

It all started with the pioneers, who paved the way for modern-day exploration of this idea.

One of the big players in the game, Erwin Schrödinger, about 20 years after his famous equation, wrote What is Life?, a book that is still considered the genesis of quantum biology.

– The giants who inspired Schrödinger

So, back in the day, Niels Bohr, another influential giant and one of the fathers of the Copenhagen interpretation, had some doubts about using quantum mechanics to explain biological processes. Despite his initial skepticism, he came around and in 1932, at the International Congress on Light Therapy, he talked about the concept of complementarity – the well-known (and huge) topic of wave-particle duality, according to which quantum entities exhibit both wave-like and particle-like behavior. But for Niels Bohr, this concept went beyond quantum mechanics, as he argued that there is an analogous complementarity between the functionality of life and our ability to understand it.

This idea inspired Max Delbrück, a young German physicist who visited Bohr’s research group in Copenhagen, and became engrossed in biophysics and molecular biology.

Delbrück co-authored a paper in 1935 that ended up being the starting point for Erwin Schrödinger’s What Is Life?

Incredibly small groups of atoms, much too small to display exact statistical laws, do play a dominating role in the very orderly and lawful events within a living organism

Erwin Schrödinger 1944
– The legacy of Schrödinger’s What is Life?

Back in the 1940s, our ingenious friend Schrödinger was pretty impressed by how accurate genetic inheritance is. Of course he was! Think about it: the probability of a mutation taking place in a given gene is less than one in 10 million during each reproductive cycle.

Schrödinger concluded that classical laws couldn’t account for this level of precision and developed a hypothesis based on the order-from-disorder principle. To understand this, consider diffusion. It can be modeled as a highly ordered and predictable process, and yet it originates from atoms and molecules randomly bouncing around.

Schrödinger then suggested that the quantum-driven dynamics of a small group of atoms could propagate and influence the macro-events within a living organism. He therefore proposed that genetic information had to be stored in a complex organic molecule: an aperiodic crystal that encoded at the atomic level life’s structure and dynamics.

I know what you are thinking: Watson and Crick in 1953!

Yes and no.

Yes, Schrödinger’s hypothesis was instrumental in inspiring Watson, Crick and Franklin’s discovery of DNA; and no: the aperiodic crystal is not exactly the same thing as DNA.

Nevertheless, despite Schrödinger’s groundbreaking ideas, biology developed without much reference to quantum mechanics, as physicists were skeptical about quantum effects playing a role in biological systems. In addition, the difficulty of achieving the necessary level of control in a hot and wet system like a living cell further compounded the challenge.

But that’s not to say that all of Schrödinger’s ideas went to waste. There have been attempts to connect biology and quantum mechanics, like Löwdin’s suggestion that quantum tunnelling of protons could cause mutations.

Schrödinger’s ideas were in fact pivotal in penetrating the skepticism of 20th-century academics and offered valuable insights into the relationship between quantum mechanics and biological systems.

Today, Schrödinger’s legacy lives on in the field of quantum biology.

Quantum fluctuations - Quantum Biology
Quantum “fuzziness” – wikipedia

Quantum Biology Today

Despite the work of Schrödinger and other pioneers of quantum mechanics, physicists of the 20th century believed that quantum effects had no significant impact on biology. That was, if you ask me, an obvious conclusion.

Since living systems are so messy and never completely cut off from their surroundings, quantum effects should vanish very quickly. Known as quantum decoherence, this phenomenon is also a real bummer for quantum computing today – but this is another story.

In simple words, quantum decoherence refers to the process by which a quantum system that was previously in a superposition state (able to exist in multiple states at once, like the famous cat), becomes entangled with its environment, such as particles in the air, a camera, or a human observer, and collapses into one well-defined state.

And here comes the twist.

Fresh research is suggesting that living things might actually need just a few well-localized, ultrafast-moving molecules to enable quantum effects. As we discussed earlier in this story, scientists are finding proof to back this hypothesis, such as observing quantum superposition in photosynthesis, quantum tunneling in enzyme action, and quantum entanglement in animal navigation systems.

There is no doubt that quantum biology is still in infancy. Quantum effects in these and other processes like (human) vision, sense of smell, DNA mutations, are still hard to study theoretically or measure precisely. However, after a hundred years of research, we may finally see whether all these fuzziness can truly benefit living organisms and help them thrive.

As stated by McFadden and Al-Khalili: Life has learned to manipulate quantum systems to its advantage in ways that we do not yet fully understand.

Quantum biology may help with that.

A final personal touch

When I first launched From Atoms To Words, I believed that the only subject truly worthy of discussion was physics and the exploration of the universe. I mean, let’s be real, what’s more humbling than the vast expanse of the Big Bang and the dawn of chemistry, alien life in the cosmos, or the enigmatic fabric of space-time?

But as I penned more stories, I realized that any scientific breakthrough can be spellbinding if viewed from the proper perspective.

If you’re curious about delving deeper into today’s topic, the Royal Society Review by McFadden and Al-Khalili is an excellent starting point (and the inspiration for this article).

As you read these pages, I hope you’ll come to the same realization that I did: Science isn’t merely about data and statistics, but the individuals behind the discoveries – the intrigue, the mishaps, and the triumphs.

Science is a treasure trove of extraordinary tales waiting to be unearthed.


From Quantum Chemistry To Stories

From Atoms to Words

A collection of my thoughts and musings on science, writing, and the intersection of the two.

Arturo Robertazzi - Me, my room. My books.