Quantum computing is one of the first great technologies of the 21st century, and it will change everything someday.

Welcome to the Quantum Edge newsletter. Here you will learn more than just: “quantum computing works because of superposition and entanglement.” The Quantum Edge newsletter will tell you what goes with superposition and entanglement and what those terms actually mean.

Read about the physics, chemistry, and all sciences that create the foundation for quantum computing. Join me in my quest to translate the mysteries of the quantum world to the language of the dinner table and the coffee shop.

In today’s newsletter: Quasiparticles, Collective Excitation, and how they might impact quantum computing

I started this newsletter by covering atoms and particles. Composite particles are made up of smaller elemental particles. Elemental particles are the smallest possible (as far as we know today) things and can’t be broken down further. Elemental particles can’t be broken apart, but they come in different types and get different classifications.

The class of elemental subatomic particles called fermions make up all matter. These are all of the quarks, electrons, neutrinos, muon and tau particles. Each has a small mass and they collectively make up matter.

The elemental subatomic particles classed as bosons make up the forces that act on matter. Except the force of gravity. Maybe gravity too. No one knows yet. It’s complicated. Regardless, these are the particles that carry force consisting of energy or interactions between other particles: photons, gluons, Higgs, Z and W bosons. Photons and gluons do not have mass.

As we know it today, fermion particles are matter and bosons are force carriers/interactions. There are (as of this writing) 16 basic elemental particles. 16 is an oversimplification, though. Most particles have an equal and opposite anti-particle and there are more properties than mass, charge, and spin. Many also have what is described as a color attribute. It has nothing to do with red, blue, and green type color but the physicists discovering the property ran out of words, so they decided to call the attribute “color.”

I’ve heard physicists expand the basic 16 elemental particles as I first described in newsletter issue 3 (Figure 2. Table of subatomic particles) up to nearly a thousand variants by including antiparticles, color, and other attributes. If you want to get pedantic, yes, there are more than 16 elementary particles. But it is fine for me to call out 16 elemental particles, as long as you know that 16 is only a part of the story. It’s the only part of the story we need to know for now.

When you dig into electricity and chemistry you might hear of something called a “hole.” Simple electronics texts may describe how electrons flow from negative to positive and holes flow from positive to negative. Chemistry texts sometimes speak of holes replacing electrons. But if you look at the table of subatomic particle from issue 3, you will not find holes.

Go ahead and look. I’ll wait.

Nothing called a hole.

Electrons, quarks, photons. No holes.

The term “hole” does, in fact, refer to the absence of an electron in a place where an electron belongs. But it’s not just a place holder. Holes actually do exhibit some particle-like properties. The empty spot can be used in physics to simplify math calculations. It can be used in electronics to simplify visual explanations. And it can be used in quantum computing to do things. It also can be a source of instability in quantum computing.

Holes are placed in a classification called quasiparticles. The are not particles, but they act a bit like they are. Holes are joined in the set of things that act-like-particles-but-are-not-particles by phonons, plasmons, magnons, and maybe a few others that I’m not aware of.

Holes come from fermions - they are matter related. Phonons and plasmons do not. They come from force-related interactions. They are sometime also called quasiparticles. But a more accurate and increasingly common label is: “collective excitation.“ The reason for the distinction is that, while they all exhibit particle like behavior, quasiparticles have an electron - a fermion particle - at their root. Collective excitations are not so directly related to the behavior or absence of a single physical particle. They come from force interactions and are thus more related to bosons, even though you probably can’t pin down a specific boson subatomic particle at their root.

Phonons are derived from vibrations of atoms in solid material. Plasmons come from oscillations of atoms in a plasma state. They all are wave or wave-like states that exhibit quantum properties. A phonon is typically created when a particle, like a cosmic ray or background radiation passes through something. If the particle does not actually hit anything in the solid, it still affects the solid by creating a wave of disturbance, which we call a phonon.

To recap:

Fermions are the particles that make up mass. Electrons, quarks, and a few other particles make up the set of fermions. When the absences of a fermion particle causes particle-like behavior, we call it a quasiparticle.

Bosons are the particles that cause interactions or carry force. Photons, gluons, the Higgs particle, and a few others make up the set of bosons. When particle-like quantum properties show up due to force interactions, we call it a collective excitation. The concept is one of the newer in today’s physics (dating to around the 1950s), so not all of the terminology is settled.

Early work in quantum computing focused a lot of research on individual particles such as electrons and photons. Electrons and photons may, in the long run, be the primary qubits of choice, but they are difficult to capture, control, and shield from interference. Thus, much current work is being directed to collective excitations as qubits.

Superconducting transmons, as I wrote about in newsletter issue 19, are collective excitations utilized as qubits. A transmon is a group-caused set of coherent oscillations of billions of paired electrons that act as one (they all move together). A big collection like that is easier to create, easier to control, and less susceptible to interference than a single particle qubit. Google and IBM are two of the largest quantum computing companies that are focusing on transmons as qubits.

Other companies are looking at different types of quasiparticles and collective excitations. As long as a quasiparticles or collective excitation exhibits the quantum properties of superposition and entanglement, and can be effectively managed, it can be used as a qubit.

Quasiparticles and collective excitations can also be bad news for qubits. They can be created by natural phenomena and can interfere with quantum operations. For example, cosmic rays and other radiation particles passing through the QPU chip create phonons in their wake that disrupt the coherence of the qubits.

That’s all for today.

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Thinking about re-reading it but want a more transportable format?

I’ve wrapped the first ten issues of The Quantum Edge newsletter into book form. The collection, called “The Quantum Computing Anthology, Volume 1”, is now available in Kindle and paperback on Amazon. The book collects newsletter issues 1 through 10 and has some additional material and edits for continuity and clarity.

You can order the Volume 1 Kindle or paperback editions on Amazon today: The Quantum Computing Anthology, Volume 1

Check your email box Thursday - probably. (Okay, some of these weekly issues have come out on Friday, or not at all. But, in a quantum world, how can you tell?)

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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.