How Quantum Computing Works

Take a byte out of quantum physics to go with your lunch.

A screenshot from a video that explains how quantum computing works

The folks at Munich-based design team Kurzgesagt — pronounced koorts-ge-ZA-kt, German for “in short” or “in a nutshell” — have put out another beautifully designed and executed explainer video, and this time they’re tackling quantum computers.

True to the name, Kurzgesagt videos start with the basics and climb purposefully to a conclusion. That’s a tall order for addressing anything quantum. Remember that Richard Feynman, one of the main brains behind the theory of quantum electrodynamics, famously quipped, “I think I can safely say that no one understands quantum mechanics.”

So Kurzgesagt is shouldering a heavy load here with admirable ease. Starting with a discussion of computing history, we learn how the size of an individual transistor has shrunk precipitously over the years, a result described by the grandiosely named Moore’s Law. But we seem to be leaving the days of shrinking transistors behind and approaching the physical limits of conventional transistors. For example, today’s transistors come in at around 14 nanometers. For comparison, the HIV virus has a diameter of 120 nanometers. A red blood cell is about 6,000 nanometers across.

Here’s one of the motivating factors for quantum computing research: If we can’t continue to pack more and more transistors into a smaller and smaller space — all while efficiently cooling the damn thing — we need to look for other ways to upgrade computing efficiency. Quantum computing would let us take advantage of a bizarre feature of quantum systems: They can be in multiple states at once. (At least, that’s one way to describe quantum superposition.)

The video is a little more upbeat than is warranted by the current state of quantum computing research and it, perhaps wisely, makes no mention of the difficulties involved in maintaining the quantum systems required for quantum computing. That being said, they’re probably not too far off with this: “Right now we don’t know if quantum computing will be just a very specialized tool or a big revolution for humanity. We have no idea where the limits of technology are and there’s only one way to find out.”

Kurzgesagt runs a YouTube channel dedicated to the team’s monthly videos, all of them worked out in that characteristic 2D animation style and voiced by the “serious” Steve Taylor. Check out their videos on how Facebook steals video content and, my personal favorite, their two-part series on the Fermi Paradox.

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