And then there’s the Misconception of Misconceptions, about how a QC “analyzes all possible paths at the same time”—with no recognition anywhere of the central difficulty, the thing that makes a QC enormously weaker than an exponentially parallel classical computer, but is also the new and interesting part, namely that you only get to see a single, random outcome when you measure, with its probability given by the Born rule. That’s the error so common that I warn against it right below the title of my blog.

As for his nonsense about quantum computing, there’s so much promotional bullshit going on that it’s understandable that anyone wanting to do something about this has no particular reason to start with Kaku. Expertly describes and rectifies common misconceptions about quantum computing—a technology regarded by experts as one that is likely to have profound societal implications. . . . Kaku deftly navigates the relevant scientific landscape. . . . Lucid. . . . Kaku excels at developing understandable metaphors for the complexities of quantum mechanics and computing. . . . Well written and accessible, offering readers a comprehensive overview of quantum computing, its underlying principles, and its potential.” — Science In any case, for Kaku, knowledge is power. It’s part of the reason he’s moved from the lab to TV, radio and books. “The whole purpose of writing books for the public is so that [they] can make educated, reasonable, wise decisions about the future of technology. Once technology becomes so complicated that the average person cannot grasp it, then there’s big trouble, because then people with no moral compass will be in charge of the direction of that technology.”This is justified by a bizarre paragraph about lattice gauge theory, which explains that since we can’t solve QCD analytically, here’s what theorists do: That mind-blowing future is the focus of the final five or so hours of the audiobook, which explores the real-world impacts quantum computing could have: altering our immune systems to avoid cancer and Alzheimer’s, increasing crop yields, ending world hunger. As Kaku puts it, “the familiar laws of common sense are routinely violated at the atomic level”; but his lucid prose and thought process make abundant sense of this technological turning point. The runaway success of the microchip processor may be nearing its end, with profound implications for our economy, society and way of life, even leaving Silicon Valley as a new Rust Belt, its technology obsolete. Step forward the quantum computer, which harnesses the power and complexity of the atomic realm, and may be useful in solving humanity's greatest challenges from climate change, to global starvation, to incurable diseases. Humanity's next great technological achievement already promises to be every bit as revolutionary as the transistor and microchip once were. Its unprecedented gains in computing power and unique ability to simulate the physical universe herald advances that could change every aspect of our lives. I am just reading a book about Ronald Reagan’s “Star Wars” Strategic Defense Initiative program. It is horrifying how far Edward Teller was able to convince the President, Congress, Pentagon and the public into his hare-brained visions ( “Brilliant Pebbles”, “Excalibur”, and so on). Pure monomaniacal intensity can bring in billions.

Besides that, I think it would be good if journalists writing about this stuff would just ask people making such claims “and then what?”. I mean, let’s assume for a moment we actually manage to build a 7000 logical qubit quantum computer and actually simulate Maldacena’s whatever model on it. And then what? They’ll write papers and press releases. And then what? What will we learn from it? What will we do with it? If you ask a normal computer to figure its way out of a maze, it will try every single branch in turn, ruling them all out individually until it finds the right one. A quantum computer can go down every path of the maze at once. It can hold uncertainty in its head. An exhilarating guide to the astonishing future of quantum computing, from the international bestselling physicist

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When I was a teenager, I enjoyed reading Hyperspace, an early popularization of string theory by the theoretical physicist Michio Kaku. I’m sure I’d have plenty of criticisms if I reread it today, but at the time, I liked it a lot. In the decades since, Kaku has widened his ambit to, well, pretty much everything, regularly churning out popular books with subtitles like “How Science Will Revolutionize the 21st Century” and “How Science Will Shape Human Destiny and Our Daily Lives.” He’s also appeared on countless TV specials, in many cases to argue that UFOs likely contain extraterrestrial visitors. Estimates that I have seen say it’ll require about a million physical qubits for 110 to 150 or so logical qubits, though that depends on error rate and algorithm. I strongly doubt that you can do 7000 logical with only 1 million physical ones, it’s almost certainly considerably more. At the very least I’d like to see a source for the NS estimate.

One solves the equations for one tiny cube, uses that to solve the equations for the next neighboring cube, and repeats the same process for all that follow. In this way, eventually the computer solves for all the neighboring cubes, one after the other.Researchers have made great progress in developing the algorithms that quantum computers will use. But the devices themselves still need a lot more work. I am not sure what Feynman thought quantum computers could do, but they gain you no formal power over classical machines: any problem which can be solved with a quantum computer can be solved with a classical computer, and vice versa. What they do gain is an improvement in time complexity for some problems. That in practice makes some problems soluble which would not be soluble on a classical machine because they have some awful time complexity.