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: Continuing the discussion on quantum entanglement, and a new perspective on time and space.

A quantum computer has a set of qubits in a grid on a silicon chip. The chip, or quantum processing unit (QPU) is cooled to near absolute zero in temperature. Each qubit maybe a transmon, a single electron, photon, ion, group of ions, or other particle that exhibits superposition and entanglement. Each qubit has microwave (or optical) connectors to send photons in to the qubit and read the state back out.

The only substantial difference between the use of different types of qubits is that photon qubits are controlled with visible or infrared light photons and the others are controlled with photons of microwave energy. Light photon qubits use polarization states (horizontal or vertical), and the other types use spin state (spin up or spin down).

I’ll almost exclusively discuss spin state qubits, but you can assume that pretty much everything applies equally to polarization qubits.

Figure 1 shows a representative QPU with most qubits not in superposition, represented as 0. Qubits at A1, A2, B5, C1, D2, D4, and F6 are set to superposition. The Greek letter psi (ψ) represents a qubit in superposition. Qubits are A1 and A2 are entangled as are qubits at D2 and B5. A1 and A2 work together and D2 and B5 work together.

Entanglement connects quantum particles from a distance despite the particles having no physical connection between them. They can be close by or far apart. In our example in figure 1, the entangled qubits are only a very short distance apart. Some experiments have demonstrated quantum entanglement at farther distances. One experiment purports to have entangled a particle in Earth’s orbit at 750 miles with a particle on the ground.

Quantum math suggests that particles can be entangled at vast, even interstellar, distances. How to do that in practice, we don’t know, but in theory, it does work. And, no matter how far the distance between the particles, the entanglement is virtually instantaneous. You examine one, collapsing its superstition into a measurable spin up or spin down state and the other will collapse into the opposite state at nearly the same time.

My joint bank account holder, from the analogy in the prior issue, spends the money in the joint account. I’m in a different city on another continent. As soon as their transaction is registered with the banking system, my financial situation has changed despite there being no communication between them and me. No information was given to me. No energy or material passed between my banking partner and me, yet my situation (my “state”, if you will) instantly changed.

Bank account entanglement connects people at a distance. Quantum entanglement connects particles far apart and action on one impacts the other nearly instantaneously. That seems to violate the idea that nothing can travel faster than the speed of light. However, entanglement does not mean that anything is moving faster than light speed.

No.

The “speed of light is a universal speed limit” concept is an oversimplification. We do know that, from the perspective of a human standing on Earth, we can’t launch a rocket that will travel away from Earth at faster than the speed of light. We also know that all electromagnetic waves in a vacuum travel at the speed of light. We also know that, given equal conditions, all light travels at the same speed no matter where the observer is. It always comes at us at the same speed even if the star that created the light is a billion light years away from us and traveling away from us at a 100 million miles per hour. The light photons still reach us at the same speed as do the light photons from the sun, 93 million miles away and not getting any farther away.

As a generalization, “speed of light is a universal speed limit” is fine and acceptably accurate. However, when dealing with physics at the extreme, one must think beyond generalizations. Entanglement is definitely physics at the extreme. It does not make sense when using conventional thinking.

We tend to think of the speed of light as a number: 299,792,458 meters per second (186,000 miles per second). Roughly 300,000 kilometers per second. Most people take a brisk walk at about 5 kilometers per hour (Just over 3 miles per hour). Light is fast.

But light speed isn’t a simple number. It is not 300,000 kilometers. It is 300,000 kilometers per second. That means that the speed of light is not a number. It is a ratio of one thing to another. It is a ratio of space (meaning distance) to time, and it is a way to convert distance to time or time to distance.

In studying physics, you will often see the term “spacetime.” That is because space and time are different ways of looking at the same thing. Just like energy and matter are different ways of looking at the same thing. Energy and matter (measured as mass) are interconnected by the formula E=MC², space and time are interconnected by the formula C=300,000,000m/s. C represents the speed of light in a vacuum. E represents energy measured in Joules. M represents mass measured in Kilograms.

You can connect the two formulas. E = M (299,792,458)². In this formula, the “m/s” part isn’t necessary because the speed of light number is being used as a ratio in the calculation, not as a speed.

Back in newsletter issue 3 (book chapter 4), I used the E=MC² formula when discussing the mass of an electron. In physics, the mass small particles are generally recorded in electron volts (eV). An electron weighs about a half a million electron volts. (≈ 0.511MeV).

The E in E=MC² is energy in Joules (J). The energy used to represent an electron’s mass is MeV (million eV). Why not Joules too?

Because physicist is confusing - but not always as confusing as it may seem at first glance. It’s just that a Joule is a pretty large amount of energy and an eV is a pretty small amount of energy. eV matches up better with a subatomic particle because they are both small and J matches better with large numbers.

We can also use Joules with an electron, because Joules to eV is also a ratio. One J is equal to 6.242 X 10¹⁸ eV. (That is: 6,242,000,000,000,000,000 eV).

And…

We can also go back and forth between electron volts and wall/battery volts (call wall/battery volts “electric charge voltage”) and electron volts. 1eV means accelerating one electron to an electric charge voltage of one volt. If you apply that 1eV to 6.242 X 10¹⁸ electrons at the same time, you create one Amp of current flow.

You don’t need to remember any of these ratios. Just remember that space, time, mass, distance, and energy are all related to each other. You can convert back and forth with math. You can represent mass with energy or electricity. You can represent distance with speed or speed with distance. Most things are interrelated in our physical world.

Next time… Entanglement relies on these interrelationships.

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?)

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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.