I can explain digital logic down to the electron in a MOSFET, but I can't come close to the same with quantum computing. This newsletter is a journal of my quest to learn the fundamentals of quantum computing and explain them on a human level.

Welcome to the Quantum Edge newsletter. Join me in my year-long journey into the weirdness that is quantum computing.

If you haven’t yet read issue 1, you can jump back to the archive and read it here: https://www.quantumedge.today/p/a-quantum-of-what

Issue 2.0, Feb 13, 2025

Last week, I introduced the concept of “quantum” and discussed quantum language a bit. Today, I’m going to talk about quantum particles - the little things at the heart of a quantum computer.

Quantum computers are, of course, built around quantum particles and they work because of the weird way that super small particles interact in the quantum world. The quantum world is described by the science of quantum mechanics.

Particle Basics

To understand quantum mechanics, you must understand something about particles. Particles come in many forms and sizes. For quantum computing, the most important type of particle is known as an elemental particle. Elemental particles are sub-atomic, meaning smaller than an atom, and elemental, meaning they can’t be broken into smaller particles.

The quantum exploration starts by taking a jump back to high school science class. We were taught that things are made of materials, like wood, steel, concrete, etc. Those materials are made of molecules. Molecules are made of groupings of atoms.

Atoms were once thought to be the smallest possible thing and were called the chemical elements, because with nothing smaller, atoms had to be the base elemental particles that make up everything. The “chemical” part of the name came from the alchemists who were doing the experiments at the time. Of course, we all now know that atoms aren’t elemental particles. They are made up of smaller things which we call sub-atomic particles.

So, anything smaller than an atom is called a sub-atomic particle. Atoms are made of three types of sub-atomic particles: protons, neutrons and electrons. Protons and neutrons are, grouped in the center, called the nucleus, and electrons surround the center.

Protons have a positive charge, electrons a negative charge and neutrons don’t have a charge. All of the known different types of atoms are listed in the periodic table of the elements and ordered based on their various properties (are they metal, reactive, gaseous, etc.).

Thus endeth high school science from 1979.

College physics of 1980 introduced more subatomic particles, including composite particles. At first, protons and neutrons were mostly thought of as elemental particles. It was thought that they couldn’t be broken into smaller parts. However, in the 1950s and ‘60’s, physicists started to think that maybe protons and neutrons could be broken into parts.

In 1961 and 1964, two folks (Murray Gell-Mann and George Zweig) independently came to the conclusion that protons and neutrons are not elemental but are, in fact, composites made up of three smaller particles. They did the math and then came up with an experiment to verify their math. In their experiment, they shot electrons at protons and recorded the bounce patterns on photographic film.

Soooooo, how does shooting electrons at protons let you see what is inside? This might best be answered with a larger world analogy.

A Thought Experiment - Seeing Inside a Proton

Imagine you are standing on the roof of your house looking down at your lawn. Below is a large beachball. You drop golf balls down on to the beachball and watch how they bounce. If you hit the beach ball on the center, the golf ball will pretty much bounce straight back up and eventually roll off on one side or the other. If you hit it on the left side, the golf ball will bounce to the left. Hit it on the right and it will bounce to the right. The farther from center that you hit, the farther to the side the golf ball will end up. Do this with 100 golf balls and you will have a pattern of golf balls on the ground.

Phase two: Instead of one beach ball, you take three basketballs and glue them together. The three basketballs form a triangle shape about the same size as the single beachball. We’ll call it a beachketball. The beachball is elemental in that it can’t be broken into smaller parts. The beachketball is composite, in that in can be broken into smaller parts.

Now go back up on your roof and drop your golf balls on the beachketball. This time, the direction of the bounce is determined by where on each individual basketball your golf ball hits. You can hit your beachketball on the right side, but if the point of impact is on the left side of one of the basketballs, your golf ball will bounce to the left, not right. Some of your golf balls won’t hit any of the three basketballs and go straight to the ground. Again drop 100 golf balls and you will get a very different pattern from the beachball experiment.

Finally, imagine that it is nighttime and you can’t see if the beachball or the beachketball is on the lawn below you. Your friend will put one or the other on the lawn and not tell you which. You drop all the golf balls, and when done, your friend removes whatever was on the lawn. When you come outside in the light of the next morning, your golf balls are still there. Do you think you could tell if you dropped your golf balls on a single beachball or a three-part beachketball based on the pattern?

This is basically how Gell-Mann and Zweig figured out that protons are made of three smaller particles. Instead of golf balls, they used electrons and instead of beach balls they bounced electrons off protons. The bounce pattern showed that a proton is made of three smaller particles stuck together like the beachketball. Both physicists independently did the same experiment and saw the same thing.

Another Case of Inventing the Language

Zweig wanted to call the three smaller particles “aces.” Gell-Mann came up with “quark”, which I like better. Maybe Zweig was a poker player and thought “ace” being the most important card in some games would be a fitting name. Gell-Mann claims to have taken some inspiration from Finnegan’s Wake by James Joyce. I’ve tried to read Finnegan’s Wake and quit four pages in. Given how difficult quantum mechanics is to understand, I’m good with the Finnegan’s Wake homage.

Getting More Specific - What is a Particle?

That’s a big question. Too much for this issue. I’ll cover that one in the future. For now, spend some time picturing the electron-proton / golfball-beachketball analogy.

Until Next week…

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See you on February 20th

About Positive Edge LLC

Positive Edge is the consulting arm of Duane Benson, Tech journalist, Futurist, Entrepreneur. Positive Edge is your conduit to decades of leading-edge technology development, management and communications expertise.