Quantum computing is one of the first great technologies of the 21st century, but the details are still shrouded in mystery. I can explain conventional digital computing down to the electron in a MOSFET, and with this newsletter, I have made it my mission to do the same for quantum computing.

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. Here you will 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: here we look closer at qubits and divide our understanding into solved and unsolved parts.

In my recent multi-week hiatus, I’ve been watching a lot of lectures by the late Richard Feynman, one of the 20th century’s top quantum experts, to reground myself at 20 issues in. I’ve also been collecting and editing issues 11 - 20 into the Quantum Computing Anthology, Volume 2. I plan to have that complete and ready for print and Kindle within a month or so of this writing.

My last newsletter issue talked about scale - big and small. The point of that issue wasn’t so much about the size of things as it was an exercise to get you comfortable with things that are really beyond human comprehension. There are many, many things that we deal with every day that are far outside of our scope of knowledge, but we just accept them and go about our day. Things like refrigeration, air travel, and wireless Internet all depend on science and technology that in many respects is indistinguishable from magic.

Quantum mechanics is a similar thing. It could easily be considered magic, but it does exist. It works. We need to accept that to move on the next stage in our journey.

The quantum world, of course, is super small. A lot of my discussion on quantum principles has revolved around what quantum things look like and act like.

I’ve been asking what is a qubit? The answer is actually more complex than that question alone allows. We also must ask “how do you make a qubit?” and “how does a qubit work?”

As I’ve done before, I can use a conventional computer as a frame of reference for these quantum computer questions.

Question part 1: What is a bit?

Answer: A bit is something that can represent two states: 0 or 1.

Question part 2: How do you make a bit?

Answer: A bit can be made of anything that switches on or off or either holds or does not hold an electric charge. Throughout history, bits have been made with hand operated mechanical switches, electromagnetic relay switches, vacuum tubes, diodes, resistors, capacitors, transistors, and a few other things. As long as it can distinctly represent the states 0 and 1, it can be used as a bit.

Question part 3: How does a bit work?

Answer: A bit controls an electric charge or voltage level. It can turn on and allow the charge to pass or be sensed. We call this a binary 1. A bit can also turn off and not pass a charge or voltage level. We call this a binary 0.

Question part 1: What is a qubit?

Answer: A qubit is something that exhibits the quantum properties of superposition and entanglement.

That is it? Hmmm. Easier than I thought. So far…

Question part 2: How do you make a qubit?

Answer: A qubit can be made out of anything that exhibits controllable superposition and entanglement. It can be made of a single trapped electron, a single photon, a trapped ion (an atom with an extra electron), a transmon (subatomic charged field), a group of a certain type of atom, and other atomic and subatomic level particles or groups of particles that exhibit the two key quantum properties. In most cases, the physical construct that makes a qubit must be cooled to near absolute zero before it will exhibit quantum properties. There are probably many ways to make qubits that haven’t been discovered yet.

Question part 3: How does a qubit work?

Answer: You tell me and we’ll both know.

Of the six questions above, we have an answer to five. That means we are left with just one unanswered: “How does a qubit work?” The big question.

We know that qubits work due to superposition (introduced in newsletter issue 10, book chapter 11) and entanglement. Superposition is the property of being able to seemingly exist in more than one state at the same time. Entanglement is the connection between two quantum particles that allows one to have awareness of the state of the other despite distance and no physical connection between the two.

So, qubits work due to superposition and entanglement. We know that, and if you search the Internet or library, that is the answer you will find. The problem is that that answer is meaningless unless we really know how superposition and entanglement work.

We have now circled back to the beginning of this newsletter endeavor. In newsletter issue 1 (book chapter 2), I gave a common public definition of a quantum computer:

A quantum computer is a computer that performs calculations based on quantum mechanics. Rather than bits, like a conventional computer uses, quantum computers use quantum bits - qubits. Quantum computers calculate based on superposition and entanglement amongst qubits. While a conventional bit can hold a value of either 1 or 0, a qubit can be 1, 0 or both values at the same time. Thus, a quantum computer can hold all possible answers to a problem at the same time and can solve really complex problems very fast.

Easy to find that definition, but it really doesn’t give much useful information. It’s pat and publishable but does not answer the big question. Let’s see how close we can get to a meaningful answer in upcoming newsletter issues.

See you soon.

New to the Quantum Edge newsletter?

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.

Coming soon: Volume 2, collecting newsletter issues 11 though 20 is in the works. Look for it on Amazon soon.

In the meantime, 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?)

If you received this newsletter as a forward and wish to subscribe yourself, you can do so at quantumedge.today/subscribe.

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.