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Quantum computers move closer to the assembly line

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Re: Quantum computers move closer to the assembly line

#11

Post by varelse »

n4r9 wrote: post #9
bowsamic wrote: post #5

Earlier quoted context omitted.

As a quantum physicist myself, this is a very good question. I remember going to a quantum control conference (a topic very relevant to quantum computing) a few years ago and there were a couple of quantum computing startups. I asked their engineers, what exactly are quantum computers useful for? They had no concrete ideas. I don't think the situation is much better today. Now, I understand building quantum computers…

As I understand from Wikipedia there are four fundamental quantum algorithms that perform better in some way than the best-known classical counterparts, and many more algorithms in total. The four fundamental ones are: * HHL algorithm for solving (sparse & insensitive) systems of linear equations * Grover's search algorithm for determining black-box inputs * Shor's algorithm for factoring primes * Quantum fourier tra…

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Re: Quantum computers move closer to the assembly line

#13

Post by zero_k »

I am very tired of this quantum computing nonsense. I have been hearing about it overtaking everything for almost 20 years (when I did my PhD). While the EU and the US has been pumping money into quantum for all these years, they completely missed the AI revolution, and have been chronically underfunding basic research (e.g. what I'm partial to, formal methods). You can still get tons of money from funding agencies by _somehow_ incorporating "quantum" into your funding proposal. It's a joke.

I remember being at the SAT conference 2 years ago (co-located with all other formal methods conferences), and I raised my concern about the BS that was accepted as a research paper again doing some nonsense quantum stuff, and the person from Intel was like, we are almost at 100 qbits, end of the year! Pinky Promise! Of course none of that happened. They promised 1000s of qbits in just a decade 20 years ago.

Best part is that even when they have 10s of thousands of qbits they can't show me a single, actually useful, revolutionary application other than breaking RSA, which is laughable (yada-yada some optimization problems, sorry, but no, the more you dig, the more it's obvious it is nonsense). Billions of EUR into this fever dream and they got completely blind-sided by deep learning (which they _also_ under-funded until industry picked it up and made it work). It's the same idiots who demoted Katalin Kario who recently got the Nobel recently for mRNA vaccines. I sometimes really get tired of Academia.

Re: Quantum computers move closer to the assembly line

#14

Post by okintheory »

n4r9 wrote: post #9
bowsamic wrote: post #5

Earlier quoted context omitted.

As a quantum physicist myself, this is a very good question. I remember going to a quantum control conference (a topic very relevant to quantum computing) a few years ago and there were a couple of quantum computing startups. I asked their engineers, what exactly are quantum computers useful for? They had no concrete ideas. I don't think the situation is much better today. Now, I understand building quantum computers…

As I understand from Wikipedia there are four fundamental quantum algorithms that perform better in some way than the best-known classical counterparts, and many more algorithms in total. The four fundamental ones are: * HHL algorithm for solving (sparse & insensitive) systems of linear equations * Grover's search algorithm for determining black-box inputs * Shor's algorithm for factoring primes * Quantum fourier tra…

You should be very skeptical of all those applications except Shor.

HHL: Here's a quote from Ewin Tang [1]: "We know that quantum computers can “efficiently solve” high-dimensional linear algebra problems; however, this assumes that we have some way to evolve a quantum system precisely according to input data, a much harder problem than the linear algebra itself."

[1] https://ewintang.com/blog/2019/01/28/an-overview-of-quantum-...

Grover's search: This is a speed-up from 2^n to 2^sqrt(n). Impressive, but there's not a lot of exp-time algorithms that people ever run. They go for heuristics instead.

Quantum fourier transforms: This is a tool, it's cool, but needs an application. I haven't seen a serious proposal for using it somewhere where a classical algorithm wouldn't do better.

Re: Quantum computers move closer to the assembly line

#15

Post by bowsamic »

garyiskidding wrote: post #7
bowsamic wrote: post #5

Earlier quoted context omitted.

As a quantum physicist myself, this is a very good question. I remember going to a quantum control conference (a topic very relevant to quantum computing) a few years ago and there were a couple of quantum computing startups. I asked their engineers, what exactly are quantum computers useful for? They had no concrete ideas. I don't think the situation is much better today. Now, I understand building quantum computers…

I did not understand what real world computing use would quantum computers have over the current generation of compute in terms of architecture/efficiency or a measurable metric. Thanks for explaining.

The main benefit of quantum computers is that they're (in principle) very precisely controllable quantum systems. In a sense, if you do a "quantum simulation", it's actually physically real since you are actually working with the same quantum states and interactions you would have in the "real thing".

Apart from some strange cases (usually using quantum fourier transform, such as prime number factorisation) they are not good replacements for classical computers at all.

Re: Quantum computers move closer to the assembly line

#16

Post by zero_k »

tambourine_man wrote: post #8

The recent changes in iMessages and Signal for PQC made me think there may be something imminent going on in this realm

The imminent nonsense of fear-mongering and money wasting, mostly. Academic funds spent billions on PQC and academia has been paid to shill nonsense for long enough to convince some of these players to "ah, let's just integrate PQC, whatever". It's nothing more than a waste of money and resources.

Re: Quantum computers move closer to the assembly line

#17

Post by bowsamic »

n4r9 wrote: post #9
bowsamic wrote: post #5

Earlier quoted context omitted.

As a quantum physicist myself, this is a very good question. I remember going to a quantum control conference (a topic very relevant to quantum computing) a few years ago and there were a couple of quantum computing startups. I asked their engineers, what exactly are quantum computers useful for? They had no concrete ideas. I don't think the situation is much better today. Now, I understand building quantum computers…

As I understand from Wikipedia there are four fundamental quantum algorithms that perform better in some way than the best-known classical counterparts, and many more algorithms in total. The four fundamental ones are: * HHL algorithm for solving (sparse & insensitive) systems of linear equations * Grover's search algorithm for determining black-box inputs * Shor's algorithm for factoring primes * Quantum fourier tra…

The most well known of those is Shor's algorithm and yet it's still extremely difficult to scale. The problem is that quantum computers, like any quantum system, are so difficult to control without introducing massive decoherence (EDIT: mixing with the environment and thus destroying any relevant "quantumness"), that they are almost impossible to scale.

It is indeed interesting that it's even theoretically possible to create quantum algorithms that are better than classical ones, but that doesn't mean it's practically useful. The latter is the relevant metric for bothering with "the assembly line". What you are talking about is still firmly within the realms of academia.

Re: Quantum computers move closer to the assembly line

#18

Post by bjoli »

tambourine_man wrote: post #8

The recent changes in iMessages and Signal for PQC made me think there may be something imminent going on in this realm

Related: i was under the impression that AES was safe (even aes-128). If it is so, why did Apple go for full pqc and not just the key exchange?

Would it be a good idea for signal to double the key size?

Re: Quantum computers move closer to the assembly line

#19

Post by dbrgn »

tambourine_man wrote: post #8

The recent changes in iMessages and Signal for PQC made me think there may be something imminent going on in this realm

The main thing that changed "recently" is that NIST standardized ML-KEM (aka Kyber) for post-quantum cryptography, which was important for implementors. However, ML-KEM is still quite new, so it is mostly used in hybrid schemes with the "store-now-decrypt-later" threat in mind.

Other than that, I don't think anything fundamentally changed during the last 10-20 years.

Re: Quantum computers move closer to the assembly line

#20

Post by dgacmu »

zero_k wrote: post #13

I am very tired of this quantum computing nonsense. I have been hearing about it overtaking everything for almost 20 years (when I did my PhD). While the EU and the US has been pumping money into quantum for all these years, they completely missed the AI revolution, and have been chronically underfunding basic research (e.g. what I'm partial to, formal methods). You can still get tons of money from funding agencies b…

Quantum is absolutely over-hyped. But so are many "really exciting but far off" projects. And so is AI (he says, having gotten a lot of funding to work in machine learning systems).

But that doesn't mean that it's bad to continue funding research into it at some level, in the same way that we fund fusion research, and all-optical computing, etc. It's just a question about balance. Unlike, say, blockchain, we know there _are_ useful applications for a quantum computer; cryptography, as you noted, but also things like quantum chemistry, and possibly some optimization problems. But they're also quite far off and many require stable qbits way beyond what we can build today.

It's a shame that funding at some levels requires excessive hype. It's as much a condemnation of our science funding system as anything.

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