Quantum technology is amazingly popular right now. The United States and the United Kingdom have made it a “national initiative” and the European Union has a “flagship” of quantum technology. India has a “national mission” and China has announced that it will include quantum technology in its next five-year plan. What is “quantum technology” and what impact will it have on our lives? That’s what we’ll talk about today.
The quantum initiatives vary somewhat from nation to nation, but usually include research programs on four key topics that I’ll cover in this video. That means: quantum computers, quantum internet, quantum metrology and quantum simulations.
We start with quantum computing.
Quantum computers are currently one of the most interesting developments in the fundamentals of physics. I talked at length about quantum computers in a previous video. More information can be found here. In short, quantum computers can dramatically speed up certain types of calculations. A quantum computer can do this because it does not work with “bits” that have values of 0 or 1, but with quantum bits – “qbits” for short – which can get involved and take any value between 0 and 1.
It is no coincidence that I say “between” instead of “both”. I think this describes the math more accurately. Either way, of course, these are just attempts to put equations into words, and the words, at best, give you a rough idea of what is really going on. The bottom line, however, is that you can process a lot more information with qbits than with normal bits. The result is that quantum computers can perform certain calculations much faster than conventional computers. However, this acceleration only works for certain types of calculations. Quantum computers are therefore special machines.
The theory behind quantum computing is well understood and undisputed. Quantum computers already exist and so far function as predicted. The problem with quantum computers is that you have to be able to get a large number of QBits into controllable quantum states in order for them to be commercially useful, and that’s really, really difficult.
It is estimated that we need to reach around a million. The details depend on the quality of the QBits and the problem you want to solve. The current state of research is around 50 qbit. Yes, this is a good start, but it’s a long way to go to a million and there’s no reason to believe that something similar to Moore is going to help us here as we’re already working on the limit.
So the main question for quantum computing is not “does it work”. We know it works. The question is “will it scale”?
For me, the situation for quantum computing today looks similar to what it did for nuclear fusion 50 years ago. Fifty years ago, physicists understood how nuclear fusion works well, and they had experimentally verified that their theories were correct. The problem was “just” making the technology big and yet efficient enough to actually be useful. And as you all know, that is still the problem today.
Now I am sure that at some point we will use both nuclear fusion and quantum computers in everyday life. Keep in mind, however, that technology enthusiasts are overly optimistic in their predictions about how long it will take for technology to become useful.
The quantum internet
The quantum internet refers to information transmitted using quantum effects. Above all, this means that the quantum internet uses quantum cryptography as a security protocol. Quantum cryptography is a method to make the transfer of information secure by exploiting the fact that in quantum mechanics a measurement irreversibly changes the state of a quantum particle. That is, if you properly encode a message with quantum particles, you can tell if it was intercepted by a hacker, as the hacker’s measurement would change the behavior of the particles. That doesn’t prevent the hacking, but it does mean you know when it’s happening.
I made a whole video on how quantum cryptography works. Check this out if you want to know more. Today I just want to draw your attention to two points where the headings are often wrong.
First, you can’t use quantum internet or any other quantum effect to transfer information faster than the speed of light. That quantum mechanics respects the speed of light limit is super basic knowledge that you think every science journalist knows. Unfortunately, this is not the case. You see this again and again in the headlines that the quantum internet can supposedly cross the speed of light limit. It can’t. That’s just wrong.
And no, it doesn’t depend on your interpretation of quantum mechanics, it’s wrong in every way. No, that’s not what Einstein meant by “creepy long-distance effect”. It’s really just wrong. With quantum mechanics, you can’t send information faster than the speed of light.
However, this is not the main problem I have with reporting on the Quantum Internet as this is obviously wrong and really what you want the Daily Mail to be. No, the main problem I have is that almost all articles mislead the audience about the relevance of the quantum internet.
It doesn’t lie explicitly, but it lies by omission. Here’s a recent example from Don Lincoln doing just that, and pretty much every article you read about quantum internet looks something like this.
First of all, they will tell you that once quantum computers reach a large enough number of QBits, they can quickly break the security protocols currently in use on the Internet, which is a huge problem for national security and privacy. Second, they will tell you that quantum internet is safe from hacking by quantum computers.
These two statements are now completely correct. But one important piece of information is missing between them: we have security protocols that do not require quantum technology, but are nonetheless safe from quantum computers. They just aren’t in use right now. These security protocols, which, to the best of our knowledge, cannot be broken even by quantum computers, are somewhat confusingly referred to as “post-quantum cryptography” or, in somewhat better terminology, quantum-secure cryptography.
This means that we don’t need the quantum internet to be safe from quantum computers. We just need to update the current security protocols and this update is already underway. For some reason, the people who work on quantum things don’t like to draw attention to it.
Quantum metrology is a collection of techniques used to improve measurements using quantum effects. The word “metrology” means that this research is about measurement; It has nothing to do with meteorology, something completely different. There have been some research developments lately in quantum metrology that I expect will soon be useful in areas like medicine or materials science. This is because one of the main advantages of quantum measurements is that they can get by with very few particles, which means minimal damage to the sample.
Personally, I think quantum metrology is the most promising part of the quantum technology package and the one that we are most likely to encounter soon in new applications.
I made a video earlier specifically about quantum metrology. So take a closer look at that.
Quantum simulations are a scientifically extremely interesting development that, in my opinion, has been somewhat underestimated. In a quantum simulation, you are trying to understand a complicated system, the properties of which you cannot calculate, by reproducing its behavior as best as possible with another quantum system that you can better control so that you can learn more about it.
This is actually something I’ve been working on myself for a few years, specifically the ability to allow you to simulate black holes using superfluids. I’ll tell you more about it another time because today I just want to say that I think this is a pretty dramatic change in the fundamentals of physics because it allows you to take math out as a mediator. Instead of modeling a system with math, either with pen on paper or with computer code, you model it directly with another system without having to write down equations in one form or another.
Quantum simulations are really cool from a basic science perspective because they allow you to learn a lot. For example, you can simulate particles similar to the Higgs or certain types of neutrinos and learn about their behavior that you couldn’t do any other way.
However, quantum simulations are unlikely to have a technological impact anytime soon, and what is worse, they have been oversold by some people in the community. Especially the talk about simulating wormholes is nonsense. These simulated “wormholes” have nothing to do with actual wormholes. In case you missed them, we have good reason to believe they don’t even exist. I highlight the wormhole myth because, to my shock, I saw it appear on a White House report. So quantum simulations are mostly cool, but when someone starts babbling about wormholes, it’s not a serious science.
I hope this brief summary helps you understand all of the quantum material in the headings.