# The quantum bacterium

## Or how nature still outsmarts humans

Allow me to introduce you to ammonia. It’s a remarkably simple and unassuming molecule, consisting of one nitrogen atom and three hydrogen atoms (NH3) connected in a pyramid-like structure. Pure ammonia is a gas at room temperature, but it can dissolve in water to form ammonium hydroxide (NH₄OH), which is most famously known for its use as a cleaning agent. Back in my childhood, my dad loved to use it for nearly everything in the household, from getting rid of stubborn grease on the grill to, well, poking holes in my goalkeeper gear while trying to get rid of the grass stains.

A lesser-known fact is that ammonia is a key ingredient in fertilizers. Without our ability to produce ammonia as a primary component for feeding crops, sustaining the global population of 7 billion would be a challenge. And yet, the so-called Haber-Bosch’s process behind the production of ammonia it is very inefficient, requiring very high temperatures, high pressure, and a long time. So much that ammonia production accounts for approximately 2% of the world’s energy consumption. One may argue that being so important for humans it’s energy well spent but: isn’t there a better way?

Enters cyanobacterium. This microorganism, with its single cell, produces ammonia spontaneously without having to heat hydrogen and nitrogen up to 500°C— Fascinating, isn’t it? So yes, we know there is indeed a better way, but haven’t found the secret recipe of how it’s done. And the reason why we haven’t is because it’s a **quantum process**.

The chemical reaction that goes inside cyanobacteria is a series of quantum evolutions, and to model them in a regular computer we would need a massive computation cluster, the largest you could possibly imagine. A perfect simulation would also need to account for the strength of the chemical bonds and the electromagnetic forces that happen between the sub-particles that make up ammonia, as well as the classical dynamics: geometry, mass, position, velocity…

Having unlimited resources, we would end up with an algorithm that accounts for millions of variables. Sadly, no matter how smartly we designed it, the number of possible combinations would be so large than any amount of computing force that we could cluster together would be dwarfed by the computation requirements.

So the hope is that a quantum computer helps us to resolve a problem like this. Let me roughly explain how.

## Quantum computers and ammonia production

In the context of simulating quantum systems on classical computers, the computational complexity for processes like ammonia production can become prohibitively high. For instance, simulating a quantum system of *n* qubits on a classical computer can have an exponential time complexity of *O(2ⁿ)*, given that each qubit can exist in a superposition of states. As the number of qubits *n* grows, the required computational resources to simulate such a system on a classical computer grow exponentially. This makes it computationally infeasible to simulate large quantum systems as the size *n* increases. In contrast, quantum computers, by design, operate on quantum principles. This allows them to potentially perform certain calculations with a polynomial time complexity, say *O(n² )* or *O(n³ )*, rather than the exponential time complexity faced by classical computers.

Returning to our cyanobacteria example, the quantum processes within these organisms involve a myriad quantum states. To simulate these states on a classical machine would involve computational complexities of the order *O(2ⁿ) *due to the multiplicity of superimposed quantum states. However, a quantum computer, leveraging quantum parallelism and entanglement, could potentially analyze such processes in fewer steps, with a much more favorable polynomial time complexity, making the task more tractable.

In the context of ammonia production, the quantum superposition property of qubits is essential. To simulate the quantum processes occurring in cyanobacteria, we need to consider numerous variables, including the strengths of chemical bonds, electromagnetic forces, and the behavior of sub-particles like protons, neutrons, quarks, neutrinos, and quasi-particles.

An ideal quantum computer can represent all these variables simultaneously in a superposition of states. It can explore different combinations of these variables in one step, which is something classical computers struggle to do efficiently due to the prohibitive computational power required. This means that a quantum computer can simulate the quantum evolutions taking place within cyanobacteria more effectively, providing insights into how ammonia production occurs naturally at room temperature.

Stretching the argument, one could say that it’s like if cyanobacteria had a miniature quantum computer built inside. Having access to this fault-tolerant device could aid us in identifying a more intelligent and environmentally friendly approach to ammonia production, which given the inefficiencies in the current process and its impact in society it would be a leap forward for our race. This is truly captivating, as it reminds us that the boundaries of human knowledge and innovation are ever-expanding, limited only by our curiosity and determination.

Please let me know if you’d like me to expand more in complexity theory or the quantum evolutions involved in the formation of complex molecules.