Quantum Supremacy: How the Quantum Computer Revolution Will Change Everything

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His book about QFT isn’t half bad, it doesn’t add anything to the Weinberg or Zee but has a very interesting historical foray into simmetries and all the work in the post war era, citing the japanese effort that i knew nothing about. At this stage, it’s worth introducing an important caveat. Quantum computers are very, very hard to make. Because they rely on tiny particles that are extremely sensitive to any kind of disturbance, most can only run at temperatures close to absolute zero, where everything slows down and there’s minimal environmental “noise”. That is, as you would expect, quite difficult to arrange. So far, the most advanced quantum computer in the world, IBM’s Osprey, has 433 qubits. This might not sound like much, but as the company points out “the number of classical bits that would be necessary to represent a state on the Osprey processor far exceeds the total number of atoms in the known universe”. What they don’t say is that it only works for about 70 to 80 millionths of a second before being overwhelmed by noise. Not only that, but the calculations it can make have very limited applications. As Kaku himself notes: “A workable quantum computer that can solve real-world problems is still many years in the future.” Some physicists, such as Mikhail Dyakonov at the University of Montpellier, believe the technical challenges mean the chances of a quantum computer “that could compete with your laptop” ever being built are pretty much zero. Kaku’s] lucid prose and thought process make abundant sense of this technological turning point.”— The New York Times Book Review 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. How? The main thing to understand is that quantum computers can make calculations much, much faster than digital ones. They do this using qubits, the quantum equivalent of bits – the zeros and ones that convey information in a conventional computer. Whereas bits are stored as electrical charges in transistors etched on to silicon chips, qubits are represented by properties of particles, for example, the angular momentum of an electron. Qubits’ superior firepower comes about because the laws of classical physics do not apply in the strange subatomic world, allowing them to take any value between zero and one, and enabling a mysterious process called quantum entanglement, which Einstein famously called spukhafte Fernwirkung or “spooky action at a distance”. Kaku makes valiant efforts to explain these mechanisms in his book, but it’s essentially impossible for a layperson to fully grasp. As the science communicator Sabine Hossenfelder puts it in one of her wildly popular YouTube videos on the subject: “When we write about quantum mechanics, we’re faced with the task of converting mathematical expressions into language. And regardless of which language we use, English, German, Chinese or whatever, our language didn’t evolve to describe quantum behaviour.”

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.Because Teller (in Livermore) was able to bring in funding, Livermore’s director refused to rein him in and even prevented other scientists writing corrective letters. Competing labs–Argonne and Los Alamos–had to conduct their own tests to show that proposals don’t work and Teller just came up even more insane plans. Maybe he should have let ChatGPT write it? Something entirely different, could you comment on this paper, pretty please

Scott Aaronson has read the book and confirms that it’s every bit as awful as it seems. For a different look at out-of-control quantum […] Alternately admiring and critical, unvarnished, and a closely detailed account of a troubled innovator. Well, that’s the universal law of technology, that [it] can be used for good or evil. When humans discovered the bow and arrow, we could use that to bring down game and feed people in our tribe. But of course, the bow and arrow can also be used against our enemies.”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. Quantum computers aren’t just about doing things faster or more efficiently. They’ll let us do things that we couldn’t even have dreamed of without them. Things that even the best supercomputer just isn’t capable of. You’ll probably never have a quantum chip in your laptop or smartphone. There’s not going to be an iPhone Q. Quantum computers have been theorised about for decades, but the reason it’s taken so long for them to arrive is that they’re incredibly sensitive to interference.