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Ask HN: What has quantum computing achieved so far?

164 points by jack_riminton 3y ago

As a lowly web developer I struggle to understand what concrete progress has been made in quantum computing. I understand there are papers that have shown results that no classical computer could achieve but what has translated into practical applications?

thinkstorm 3y ago
It's early. And companies and governments achieving some sort of competitive advantage would be playing these applications close to their chest to keep their advantage. QC has led to significant prevention of loss-of-life, loss-of-equipment, and territory gains in battlefield applications. Encrypt/ Decrpyt was already mentioned as a use case. None of these dual-use practical applications are public. QC is good at "analog" computing: applications where you are more interested in potentials than in 0s and 1s. That lends itself to material design problems. There are applications in battery design and catalytic converter. F1 teams have some interesting fluid dynamics and laminar flow problems where QC was instrumental to test hunches fast. It's not so much about exact compute of solutions, but how to verify a first guess fast to then use traditional software. One could argue this is a niche application, but not if you consider marketing and streaming rights and advertisement impact. A similar approach is used for drug discovery. None of these "practical" applications are talked about - they are a competitive advantage of commercial enterprises. But if you care for a proxy you could look at any significant hires 1-2 years ago with PhDs, compute, math experience in relevant QC fields. And you would be surprised to see some companies hiring more than 20-30 people in that field (and not just Google or Amazon etc.). That's an FTE expense that could just be hedging of a large company; but could also be product design; and is definitely more than a test balloon or R&D pet project. Some of these companies are known for industrial adhesives, specialty cement, or "green" base oils for lubrication and cooling and cutting. so not all tech companies or big pharma.
sidcool 3y ago
So far it has factored the number 21 to its constituent primes.
- mikercampbell 3y ago
  Honestly, you also have to consider the sculptures they are. I’m joking, but they absolutely had a different designer than the colliders
  - JoachimS 3y ago
    They really are quite beautiful. At least when they aren't submerged in liquid nitrogen. I like this picture since you probably can see what it also looks like when enclosed: https://spectrum.ieee.org/media-library/less-than-p-greater-than-a-researcher-at-ibms-thomas-j-watson-research-center-examines-some-of-the-quantum-hardware-being-constructed-there-less-than-p-greater-than.jpg?id=32303847 https://spectrum.ieee.org/media-library/less-than-p-greater-...
- yaantc 3y ago
  Yes, using the Shor algorithm and this was achieved in... 2012 ([1], from Wikipedia). Larger cases of quantum factorization since then used non-scalable algorithms. [1] https://arxiv.org/abs/1111.4147 https://arxiv.org/abs/1111.4147
  - Woansdei 3y ago
    no, there has not been a single run of shor for even the number 6 as far as I know, in the link you give apendix A shows they did not in fact use the 5 bits needed for factoring 21. Every experiment I know about used short cuts to get an answer, you'd think 6 would be easy enough, it fits in the 4 bits they did use!
  - NooneAtAll3 3y ago
    Intel reported being able to factor 35 three out of ten times or thereabouts in spring, iirc noise is hell in QC, sadly
bramathon 3y ago
Quantum computers have not yet achieved any practical application. What they have achieved is performing highly specialized tasks like random circuit sampling or quantum simulation which would be too difficult for even the largest classical computers. While these tasks are highly tailored to the machines and effectively useless in the real world, they are exciting as they are demonstration that these devices can perform computations beyond classical. Turning this computing power towards practical use-cases is more challenging, but something we are likely to see in the next few years. The first applications will likely be ones like quantum chemistry where the problem is inherently quantum mechanical and thus maps more naturally to a quantum computer, or quantum-enhanced classical algorithms which lean heavily on classical solvers combined with quantum. The most important quantum algorithms require error-corrected qubits, which are some ways away but current devices are starting to demonstrate this at a small scale.
- smegsicle 3y ago
  [flagged]
  - Koshkin 3y ago
    Might as well be
- golol 3y ago
  Could one say that they are basically performing certain physical experiments with particles, and obtaining measurements which would be extremely hard to obtain via classical simulations? Or is that a mischaracterization?
  - ghaff 3y ago
    Not really wrong but using quantum effects to basically model real-world quantum systems is only a subset of potential applications.
  - samstave 3y ago
    You might like this interview on Lex Fridman with: Guillaume Verdon (aka Beff Jezos on Twitter) is a physicist, quantum computing researcher, and founder of e/acc (effective accelerationism) movement. https://www.youtube.com/watch?v=8fEEbKJoNbU https://www.youtube.com/watch?v=8fEEbKJoNbU
ghaff 3y ago
For the most part, commercially useful results weren’t expected at this point. Different techniques are being worked on, some real progress seems to be happening with respect to noise correction, larger systems are being built, etc. Could it all end up a bust? Possible but I wouldn’t bet on it. Things like breaking crypto are pretty far out but there will probably be commercially interesting results much sooner.
keithalewis 3y ago
[flagged]
- smegsicle 3y ago
  shhhhhhhhhhhhhhhhh
ganzuul 3y ago
Quantum annealing https://en.wikipedia.org/wiki/D-Wave_Systems https://en.wikipedia.org/wiki/D-Wave_Systems
- westurner 3y ago
  Quantum annealing > D-Wave implementations : https://en.wikipedia.org/wiki/Quantum_annealing#D-Wave_implementations https://en.wikipedia.org/wiki/Quantum_annealing#D-Wave_imple... : > In December 2015, Google announced that the D-Wave 2X outperforms both simulated annealing and Quantum Monte Carlo by up to a factor of 100,000,000 on a set of hard optimization problems.[35] Timeline of quantum computing and communication > 2023: https://en.wikipedia.org/wiki/Timeline_of_quantum_computing_and_communication#2023 https://en.wikipedia.org/wiki/Timeline_of_quantum_computing_... : > 14 June [2023] – IBM computer scientists report that a quantum computer produced better results for a physics problem than a conventional supercomputer.[365][366] : "Evidence for the utility of quantum computing before fault tolerance" (2023) : https://www.nature.com/articles/s41586-023-06096-3 https://www.nature.com/articles/s41586-023-06096-3 : > Quantum advantage can be approached in two steps: first, by demonstrating the ability of existing devices to perform accurate computations at a scale that lies beyond brute-force classical simulation, and second by finding problems with associated quantum circuits that derive an advantage from these devices. Here we focus on taking the first step and do not aim to implement quantum circuits for problems with proven speed-ups. Quantum Algorithm Zoo lists speedups by algorithm; https://quantumalgorithmzoo.org/ https://quantumalgorithmzoo.org/ https://westurner.github.io/hnlog/#q-tequila https://westurner.github.io/hnlog/#q-tequila ctrl-f "tequila" : From "Computational Chemistry Using PyTorch" https://news.ycombinator.com/item?id=36825353 https://news.ycombinator.com/item?id=36825353 : > Tequila wraps Psi4, Madness, and/or PySCF for Quantum Chemistry with Expectation Values: https://github.com/tequilahub/tequila#quantumchemistry https://github.com/tequilahub/tequila#quantumchemistry And from https://github.com/tequilahub/tequila#quantum-backends https://github.com/tequilahub/tequila#quantum-backends : > Quantum Backends currently supported by tequilahub/tequila: Qulacs, Qibo, Qiskit, Cirq (SymPy), PyQuil, QLM / myQLM tequilahub/tequila-tutorials: https://github.com/tequilahub/tequila-tutorials https://github.com/tequilahub/tequila-tutorials - tequila-tutorials/BasicUsage.ipynb: https://github.com/tequilahub/tequila-tutorials/blob/main/BasicUsage.ipynb https://github.com/tequilahub/tequila-tutorials/blob/main/Ba... - tequila-tutorials/Quantum_Calculator.ipynb : https://github.com/tequilahub/tequila-tutorials/blob/main/Quantum_Calculator.ipynb https://github.com/tequilahub/tequila-tutorials/blob/main/Qu... Practical Q12 QIS STEM learning exercise ideas: https://news.ycombinator.com/item?id=38687045#38801630 https://news.ycombinator.com/item?id=38687045#38801630
isoprophlex 3y ago
Line the pockets of greasy management consultants that deliver dumb ass think pieces to the C-suite about transforming organizations to a PoSt-QuAnTuM ReAdY sTAtE
- dazzawazza 3y ago
  This is true for all tech. New, old, imaginary, visionary or snake oil. Someone will seek to make a buck from fear, optimism or ignorance. That's what ChatGPT tells me, my Co-Pilot in life. No more thinking for me... no-sir-eee.
hcks 3y ago
Nothing. Also contrary to what the hype is trying to make people believe, the whole field is pretty much in the same place as in 1990
tho234u2o343 3y ago
Factoring 15 while using the fact that 15 = 5 x 3 to build the circuit. (IIRC this is still the best; all the hype-y 2^xxx+1 PR ones aren't really using Shor's algorithm and also use some number theoretic short-cuts).
- jncfhnb 3y ago
  Don’t forget 2x2=4
- iamawacko 3y ago
  Factoring 15 with quantum computers happened nearly 22 years ago[1]. The current record for factoring, with just Shor's and no minimization, is 21. Like you said, a lot of the hyped ones aren't practical. It's not that hard to pretend to factor large numbers on a quantum computer [2]. There have been a few newer algorithms can work with larger numbers, but they have scaling issues and so aren't useful for cryptography. [1]https://research.ibm.com/blog/factor-15-shors-algorithm https://research.ibm.com/blog/factor-15-shors-algorithm [2]https://arxiv.org/abs/1301.7007 https://arxiv.org/abs/1301.7007
rzl1235 3y ago
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TriangleEdge 3y ago
My understanding of quantum computers is that it's a "let's get the universe to solve our problem" type of approach. This being said, it _feels_ like a massive con to me. I'm 100% enthusiastic about fusion energy, and I get excited about most things physics related, but not quantum computers. What can be added to my set of physics knowledge to make quantum computers seem less imaginary?
- golol 3y ago
  I agree with you. Turing machines make sense and I can extend my intuition to a general idea of "dynamical systems can peroform computation", but I have no idea how quantum computing fits in there.
  - hnfong 3y ago
    Quantum computing makes a couple algorithms faster but doesn't allow solving problems that we don't already know how to solve with a classical Turing machine.
- bmer 3y ago
  You probably ought to be more skeptical about nuclear fusion than quantum computing, to be perfectly honest: https://lucian.uchicago.edu/blogs/atomicage/2022/12/17/clean-energy-or-weapons-what-the-breakthrough-in-nuclear-fusion-really-means-via-the-wire/ https://lucian.uchicago.edu/blogs/atomicage/2022/12/17/clean...
- philipswood 3y ago
  My take on the origins of the field is that defining Quantum Computers was an outgrowth of trying to get at a "quantum observer" to make some headway in "understanding" quantum physics. I also feel it's a way to make the many-worlds interpretation of Quantum Physics more substantial - I mean, when you have a working QC, if the results of the computation isn't arising from interference between the many worlds, where are the calculations being done?
- majoe 3y ago
  tl;dr: Quantum computers are not only interesting for their practical applications, but also for furthering our understanding of Quantum mechanics. I had a similar feeling until I took a course on 'Theory of Quantum Information'. It cleared up some reservations I had about problems of Quantum Computing, e.g. error correction, and showed, that these are solvable (at least in theory). But more important, the lectures made it clear for me, that information is a physical quantity not less real than e.g. energy and that treating it as a non-physical "auxiliary" variable is core to many of the perceived paradoxes of QM. Also Quantum Computers try to make Quantum coherence work outside of closed laboratory systems, which not only pushes the boundaries of experimental physics, but also leads to interesting theoretical problems, since open systems don't exhibit a unitary time translation and are therefore not governed by the Schrödinger equation. These things together helped to spark a new interest in looking at the foundational questions of Quantum mechanics after decades of "Shut up and calculate".
happytiger 3y ago
Think of quantum computing progress like this. There were fundamental problems keeping it from working, and those have been largely overcome. Now we have a path and we are really just improving the technology until it’s useful, and that path is very clear. It’s just a matter of going down it, which is what’s really happening. The general consensus is that there will be a fault tolerant quantum computer by 2035-2040. So like silicon, it is going to take us a while to get there, but we are only talking about 11-16 years or so according to the best experts in the field (remember AI has similar longer terms before it rapidly accelerated). And quantum computers are profoundly powerful — as in civilization changing computer power.
- Aardwolf 3y ago
  > and that path is very clear How is the time of this clear path measured? I actually have the exact same question about fusion reactors (such as ITER with results planned decades ahead of time) What could speed up those decades? Letting more people work on it at the same time? Throwing more money at it? (e.g. for ITER, are we just waiting for them to pour concrete faster?) Or are these decades of planning also waiting for other technologies to appear in 10, 20, ... years? (Which would be some kind of unclear uncertainty after all)
  - ghaff 3y ago
    One area in quantum that’s getting a lot of attention is dealing with noise. (Basically you want to decrease the number of qubits needed to make a reliable logical qubit to a reasonable number.) This has turned out to be a big problem (with some calling it potentially intractable.) But a lot of progress is being made in this area. There’s a good article in the current issue of Technology Review.) This is one area that could lead to outsized advances. More money and people can usually move but there’s a limit to which just throwing money at a problem can accelerate the outcome in part because of all the complex interconnection, some not even appreciated. Think ML with GPUs.
    - deleted 3y ago
      [deleted]
jowdones 3y ago
I think it's misleading calling these things "computers". They are no more "computer" than the analog computers, like MEDA: https://www.analogmuseum.org/english/collection/meda/43/ https://www.analogmuseum.org/english/collection/meda/43/ I've worked with analog computers, they were used in control systems. I understand that Moon landing used analog computers along digital ones as well. Basically you can do PID (proportional, integrative, derivative) calculus on them using plain analog electronics. Very specialized and nothing to get overexcited about. It's like calling these biological machinery "computers": https://en.wikipedia.org/wiki/File:Human_computers_-_Dryden.jpg https://en.wikipedia.org/wiki/File:Human_computers_-_Dryden.... Bottom line "quantum computing" has nothing to do with the classic field of digital computers (personal PCs), it's a stupid, deliberate misuse to borrow from the legitimacy and respectability of an established field. The term should die in a fire. "quantum crap putting" is a lot more appropriate given all the crap they put in the headlines to fool the guillible.
- ghaff 3y ago
  And yet you refer to analog computers in your very comment. There’s nothing special about Boolean logic as a way to solve problems that require, wait for it, computation of some sort.
- philipswood 3y ago
  It's not misleading: Quantum computers ARE computers. (Or WILL BE when we build proper ones...) David Deutsch formalized universal quantum computers -in analogy to a universal classical computers in the 80s. The starting point is basically noticing the mismatch between the classical theories of computing and quantum physics. From the abstract of 'Quantum theory, the Church-Turing principle and the universal quantum computer': >It is argued that underlying the Church-Turing hypothesis there is an implicit physical assertion. Here, this assertion is presented explicitly as a physical principle: ‘every finitely realizable physical system can be perfectly simulated by a universal model computing machine operating by finite means’. Classical physics and the universal Turing machine, because the former is continuous and the latter discrete, do not obey the principle, at least in the strong form above. A class of model computing machines that is the quantum generalization of the class of Turing machines is described, and it is shown that quantum theory and the ‘universal quantum computer’ are compatible with the principle. Computing machines resembling the universal quantum computer could, in principle, be built and would have many remarkable properties not reproducible by any Turing machine. These do not include the computation of non-recursive functions, but they do include ‘quantum parallelism’, a method by which certain probabilistic tasks can be performed faster by a universal quantum computer than by any classical restriction of it.
MattPalmer1086 3y ago
I'm not even sure that a quantum computer has incontrovertibly outperformed a classical one at this time on anything. Some have claimed it, on problems that have no practical utility. Classical results have also been improved on response. Arguably then the only concrete achievement of quantum computing to date has been improvements to classical algorithms. However, I fully expect that we will eventually have powerful quantum computers. Practical applications for those are things like modelling chemical reactions or quantum systems, or optimisation. No discussion on quantum computing would be complete without a link to Scott Aaronson's blog. Worth a read to get a better understanding of the subject. https://scottaaronson.com/ https://scottaaronson.com/
- asah 3y ago
  not promising: "For the 2022-2023 and 2023-2024 academic years, I'm on leave to work at OpenAI on the theoretical foundations of AI safety."
  - MattPalmer1086 3y ago
    Yeah true he has been on other things recently.
  - Koshkin 3y ago
    In the evolutionary sense, the intelligence emerged as, and has always been used as a weapon. Not sure what this can say about its “safety.”
    - fao_ 3y ago
      I don't think it's fair to frame intelligence solely in terms of a weapon when one of the single most important underpinnings of intelligence in terms of predator/prey interactions and group survival is "empathy".
      - bee_rider 3y ago
        It isn’t clear in the first place what a weapon means in evolutionary terms, I mean it is a competitive process, what isn’t a weapon? Plants tremble at the sheep’s ferocious teeth.
Sparkyte 3y ago
Nothing conventional or practical in your daily use. However there are scientific scenarios where superpositions and qubits come into play. They can also decrypt any form cryptology faster than any conventional computer system. The problem is that they are not as energy efficient as a conventional system.
fastneutron 3y ago
Some interesting science results, but essentially nothing in the way of economically-valuable computations. I think we'll eventually get there in the next decade or so, but even before that, there are immediately useful spinoff technologies coming out of the effort like quantum sensors and greatly improved RF and photonics products. Even if/when these things are working on a useful scale, quantum computing is going to be more comparable to special-purpose accelerators like GPUs, or perhaps akin having a re-programmable physics lab-on-a-chip. It will be advantageous for the subset of problems that can be cast in the form of Schrodinger's equation, of which there are many. For example, you can use the quantum computer to generate high-fidelity solutions of the electronic structure of some classically intractable molecule, and use those solutions as the training set for a classical AI model that then goes and performs the bulk of the computation on whatever it was you were trying to do.
- Gooblebrai 3y ago
  The physics lab-on-a-chip sounds interesting. Never heard to it. Do you have any good resources to read more about it?
ksjskskskkk 3y ago
it got people to finally move away from RSA. besides that, it's mostly quackery by pretending code to impossible low temperature calibration and sensors don't exist.
- upofadown 3y ago
  The RSA thing requires further exposition. If someone invents a quantum computer that can do Shor's algorithm, exponential curves would be the most at risk. Exponential curves are fairly popular right now. Not that there is anything really wrong with RSA...
- Valodim 3y ago
  This isn't intuitive to me. Isn't RSA actually more difficult to break with quantum computing than comparable ecc key strengths, simply due to the larger amount of data involved? Put differently, I assumed that factorization of a 3072 bit number has a higher security margin than discrete logarithm on a 256 bit point on a curve. Is that not so?
  - NooneAtAll3 3y ago
    given that in either case it's a polynomial scaling, difference in a couple years between both isn't that important
    - deleted 3y ago
      [deleted]
westurner 3y ago
Quantum supremacy: https://en.wikipedia.org/wiki/Quantum_supremacy https://en.wikipedia.org/wiki/Quantum_supremacy "Scott’s Supreme Quantum Supremacy FAQ" (2019) https://news.ycombinator.com/item?id=21053405 https://news.ycombinator.com/item?id=21053405 https://www.scottaaronson.com/blog/?p=4317 https://www.scottaaronson.com/blog/?p=4317 /? quantum supremacy 2024: https://www.google.com/search?q=quantum+supremacy+2024 https://www.google.com/search?q=quantum+supremacy+2024 /? practical quantum advantage: https://www.google.com/search?q=quantum+advantage https://www.google.com/search?q=quantum+advantage
devnonymous 3y ago
This was posted recently here and i found it very interesting https://spectrum.ieee.org/quantum-computing-skeptics https://spectrum.ieee.org/quantum-computing-skeptics Related HN discussion https://news.ycombinator.com/item?id=38745970 https://news.ycombinator.com/item?id=38745970
philipswood 3y ago
I don't think Quantum Computing has any significant practical applications yet.* But then again I'd say that it doesn't need to. From a theoretical perspective QC improves our understanding of the physics of computation by bridging the gap between our classical theories of computation and our quantum theories of physics. QC gives us access to "quantum observers" to allow us to take our understanding of what Quantum Physics "means" further. QC lends some support to the many-worlds interpretation of Quantum Physics - Where else is the computation being done if we are retrieving answers from their interferences? From a physical perspective we are learning a lot tackling the hard challenges of realizing them. Even if we never build "practical" Quantum Computers, experimentally it would still be worth building them as physics experiments. And if we can build real practical machines they might have significant advantages in some practical fields like quantum physics simulations. * Unless somewhere the NSA (or their Chinese equivalent) are breaking cryptography using some moonshot machine.
sgt101 3y ago
I recommend this book: Q is for Quantum https://www.amazon.co.uk/dp/0999063502?ref=ppx_pop_mob_ap_share https://www.amazon.co.uk/dp/0999063502?ref=ppx_pop_mob_ap_sh... Direct answer, QC's are shown to exist at some scale in our universe. They may not get larger than 1000 qbits, but they also might. However so far the most practical thing that QC has done is inspire new classical algorithms for some problems, notably in recommendation.
nonrandomstring 3y ago
Post-quantum cryptography. Even if QC hasn't achieved anything tangible yet, the side effects of it looming are pushing things on.
doe88 3y ago
I may be a bit cynical in my assesment but to me quantum computing, is the revolution always 5 years away.
tappaseater 3y ago
I have been confused by Quantum Computing and have been reading and watching as much as possible on the topic. I can never seem to grasp the potential. I keep thinking about classical problems. Like what if I multiply a real number by a number consisting of qbits? Or what happens to bitwise operations with qbits? Then, something I read to the effect that we need to stop thinking of QC as solving classical problems but solving different problems at least reassured me I wasn't too dumb to get it.
- cwmma 3y ago
  From what I understand, there is at least one problem that is basically impossible to solve (in a useful amount of time) on classical computers, but theoretically solvable on a quantum computer (in a useful amount of time). That problem is breaking modern asymmetric encryption with shores algorithm. So there is at least that one concrete problem they can (theoretically) solve.
- margorczynski 3y ago
  The biggest application of quantum computers is simulating quantum processes - so physical and chemical simulations. Simulating superposition and entanglement on a classical computer is extremely demanding, on a QC it comes naturally. It most probably will never replace classical computers.
dxxvi 3y ago
I thought it could be used to crack private keys?
freetonik 3y ago
No practical applications yet, but the attention the quantum computing research has been getting helps to drive research in quantum mechanics and computer science.
daedlanth 3y ago
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CrypticShift 3y ago
Related question : What has optical (non quantum) computing achieved so far?
- meroes 3y ago
  No idea but I heard Fiorina give a talk 15ish years ago and literally nothing from it has panned out.
alberth 3y ago
It’ll be like AI. Where it’ll be under active development for 50+ years, without any major application. Then “ChatGPT” will come along and be the big unlock for its area.
pard68 3y ago
Like war, "absolutely nothing".
amelius 3y ago
Does anyone have a picture of a quantum computer without all the cooling equipment around it?
barbegal 3y ago
A little bit old but I think this video https://vimeo.com/180284417 https://vimeo.com/180284417 nicely demonstrates how a quantum computer compares to a classical computer and shows how limited the hardware is (although it has advanced slightly since 2016)
htk 3y ago
I'm interested in this question as well. Anything reported close to practical seems analog to having a bucket of water and calling it a computer to calculate fluid mechanics.
odyssey7 3y ago
Consider what the bombe could do and how prized a secret it was. There is no non-existence proof of a quantum computer with an analogous role today.
- pclmulqdq 3y ago
  Bitcoin and Ethereum are a proof of non-existence of useful quantum computing (in terms of encryption breaking).
  - mportela 3y ago
    can you elaborate on this?
  - odyssey7 3y ago
    A 51% attack would cause enough pandemonium. A state actor could do that using technology the public already knows about.
    - pclmulqdq 3y ago
      A 51% attack doesn't help anyone. Cracking the discrete log problem gets you a lot of money right away.
      - deleted 3y ago
        [deleted]
    - NooneAtAll3 3y ago
      iirc, top 2 computing pools for bitcoin are already more than 51% when combined
  - dflock 3y ago
    The Bombe was used to break the encryption and read German army and navy cypher traffic. It was kept secret at all costs, up to and including sometimes _not using its results_ for fear of tipping off the Germans, even if this resulted in loss of life and shipping in the Atlantic. Anyone far enough ahead to have a functional quantum computer powerful enough to mine all the Bitcoin, would instead keep it secret and use it to read foreign government encryption etc... Emptying the blockchain into your bank account doesn't move the needle for anyone at that level.
meroes 3y ago
The 2022 Nobel confirms reality is non-local, the culmination of 50+ years of physics, and we seem to have diddly. Where are the breakthroughs? They’re not in QC. I feel something is amiss. There’s a mismatch. Einstein was the strongest opponent of non-locality, for what? Not sure where the mismatch is exactly. Believing Einstein you’d think science is now in peril due to its non-local nature being impossible to conduct experiments. But AFAICT there’s so little interest.
- layer8 3y ago
  > The 2022 Nobel confirms reality is non-local No, it doesn’t do that, the public presentations around it are a bit misleading. What Bell’s theorem says is that QM is incompatible with local hidden-variables theories. In the Many Worlds theory, however, local realism is retained despite Bell’s theorem: https://physics.stackexchange.com/a/573382 https://physics.stackexchange.com/a/573382. My guess is that Einstein would have come around to that view, as it fits his philosophical thinking. That being said, the 2022 Nobel price was for the experiments conducted over a time span from 1972 to 2015, confirming Bell’s 1964 theorem. As such, there aren’t any recent major new insights. The latest experiments closed some remaining loopholes, but basically only confirmed what had already been generally assumed for a long time. All of this doesn’t change what QM predicts. It just limits the space of possible underlying theories that would explain QM.
NooneAtAll3 3y ago
if one compares quantum computer progress to normal computer progress, then we a) just barely exited the era of theoretics-only (19th century, Babbage) b) just barely entered era of analogue devices-only (1900s, beginning of vacuum lamps) c) still a decade away from barely practical computers (1940s, Turing and germans) if you want to learn "what will be practical once usable quantum computer appears", look at https://quantumalgorithmzoo.org/ https://quantumalgorithmzoo.org/

antonvs 3y ago

Assuming it's true that there's some clear path in the quantum computing case, then ITER is rather different because there's currently no clear path to commercially viable nuclear fusion. ITER itself isn't even intended to achieve that. It's a research facility to test and demonstrate large-scale fusion in a tokamak. It's not even designed to generate electricity as output - just heat energy. If ITER ends up demonstrating that its approach could be further improved in the direction of a commercial design - which is not at all clear (see reference below) - they'll have to start a new project to achieve that. And you can expect that project to take even more money and quite probably a longer time, since there will be a lot of advances that will still need to be made. You might be interested to read "ITER is a showcase … for the drawbacks of fusion energy": https://thebulletin.org/2018/02/iter-is-a-showcase-for-the-drawbacks-of-fusion-energy/ https://thebulletin.org/2018/02/iter-is-a-showcase-for-the-d... . I recommend reading the whole article. > Letting more people work on it at the same time? Throwing more money at it? There are 6500 people all told that work on ITER, and its total funding is projected to reach as much as $65 billion. More people and money for ITER is almost certainly not the answer. But other groups are also working on it, including 30+ fusion startups (see e.g. https://app.dealroom.co/lists/25184 https://app.dealroom.co/lists/25184). However, ITER's funding is about 10-15 times that of all those startups combined. The problem with the startup approach is they're more likely to be killed if they don't achieve results. > Or are these decades of planning also waiting for other technologies to appear in 10, 20, ... years? For fusion, that's certainly the case. Despite the existence of startups, which perhaps reflect the existence of either altruistic and/or gullible VCs, fusion power is still very much a research project. It's not even certain that commercial fusion power will ever be viable - the article I linked helps explain that.

iainmerrick 3y ago

And quantum computers are profoundly powerful — as in civilization changing computer power. How so? The main promise/fear I hear about is breaking cryptography, but then it sounds like we can switch to new post-quantum encryption and we’ll be essentially in the same place as before.

regularfry 3y ago
It's not the same place because access to quantum computers is (and likely will be for a while) heavily asymmetric. People who want to break encryption will be able to do so, while people who want unbreakable encryption will, except for the tiny overlap with the former set, not have access to the hardware.
- iainmerrick 3y ago
  I don’t think you need a quantum computer to do post-quantum encryption. It’s just an encryption method that’s believed not to have any quantum shortcuts.
  - ghaff 3y ago
    Correct. At the moment seems to be mostly lattice-based approaches.
- dmurray 3y ago
  No, post-quantum cryptography is focused on methods where encryption can be done with classical computers. Post-quantum methods have other disadvantages, primarily that they haven't been studied as deeply as traditional methods (especially RSA) so they may be vulnerable to classes of attack we haven't thought of yet. https://en.m.wikipedia.org/wiki/Post-quantum_cryptography https://en.m.wikipedia.org/wiki/Post-quantum_cryptography
- JoachimS 3y ago
  AFAIK, this is basically the opposite of how it probably will pan out. Some organsations MAY someday have Quantum Computers capable of cracking some asymmetric keys (RSA). All of us will have access to cryptographic algorithms (inlcuding open source implementations) that can't be cracked by the Quantum Computers. These algorithms are executed on our normal, classical computers. We already have a first set of post quantum computer cryptographic algorithms. See the NIST competition for example. Their implementations still looks immature (some have fallen against classical attacks, including side channel issues). But we'll get there. We will also have to (yet again) deal with having algorithm agility, which adds complexity. Quantum Computers are not magical things. We can (and do) know type of problems, algorithms, operations they should be better than classical computers to solve (called quantum supremacy). Shor's algorithm, which provides exponential speedup of cracking RSA key is an example of such an algorithm. What we so far don't consider that much is the feasibility to perform these algorithms in reality. That is, we look at the asymptotic speedup, not the practical speedup. There is a really good paper by people from the MS PQ team that looked at this. Highly recommended: https://cacm.acm.org/magazines/2023/5/272276-disentangling-hype-from-practicality-on-realistically-achieving-quantum-advantage/fulltext https://cacm.acm.org/magazines/2023/5/272276-disentangling-h...
  - vitus 3y ago
    Shor's algorithm also solves the discrete logarithm problem, so it also theoretically breaks Elliptic Curve Diffie-Hellman. That is, it breaks both of the main types of key-exchange algorithms (as well as SRP) in use today with TLS. (Not PSK, although that in turn isn't usable in a limited-trust environment like the broader internet.) My understanding is that any use of post-quantum crypto today is layered on top of existing crypto (so breaking one is insufficient to compromise the channel), in large part due to the relative immaturity of the field that you've mentioned. The threat model here is not necessarily that we expect anyone to have sufficiently capable quantum computers (and/or algorithmic breakthroughs) in the immediate future, but that a potential adversary might store some encrypted comms that they can later decrypt. Perfect forward secrecy doesn't protect you against an algorithmic break.
dash2 3y ago
I'd also be interested to hear about applications beyond cryptography, which is a bit zero-sum.
chasil 3y ago
As I understand it, quantum computers will offer tremendous speed on the "traveling salesman" problem, and otherwise vastly improve questions of efficient resource scheduling and optimization. https://en.m.wikipedia.org/wiki/Travelling_salesman_problem https://en.m.wikipedia.org/wiki/Travelling_salesman_problem
- Jabbles 3y ago
  As that article says, approximate classical algorithms "can find solutions for extremely large problems (millions of cities) within a reasonable time which are with a high probability just 2–3% away from the optimal solution." Although faster quantum algorithms for the exact solution exist, I see no reason why this would result in "vastly" improved efficiency.
- zachf 3y ago
  Most quantum computer experts think that this is not the case, that it is very unlikely that quantum computers can solve NP-complete problems like travelling salesman more efficiently than classical computers. (In particular, the popular intuition that quantum computers “try a lot of solutions in parallel” is basically totally wrong, at least from the perspective of making a useful heuristic for what quantum computers are good for.) This is an older article, but its conclusions are still about right: https://www.cs.virginia.edu/~robins/The_Limits_of_Quantum_Computers.pdf https://www.cs.virginia.edu/~robins/The_Limits_of_Quantum_Co...

sandworm101 3y ago

The big project is decryption. There is a race to be the first country/agency to be able to decrypt data protected by pre-quantum encryption schemes. It is a very narrow use case but there are very deep pockets funding the race.

kossTKR 3y ago
Interesting. What are the motivations behind this funding? What is to gain? As far as i can see there is quite a lot of "quantum safe" encryption so what kind of historical data exists lying around with lots of value?
- gwnywg 3y ago
  Maybe whoever will break current state of encryption landscape will also gain privilege to build new and benefit from it? In my opinion if breaking AES is to serve military (and hunt for secrets) then it would be done in secret.
  - RandomLensman 3y ago
    As I understand it, AES isn't particularly susceptible to quantum computing (similar to classical computing).
  - Eisenstein 3y ago
    Why do you think quantum computing could help break AES?
- rashkov 3y ago
  Suppose for a moment that you’ve collected twenty years worth of sensitive but encrypted foreign communications. What kind of advantage can you get by having a peak at it?
  - fbdab103 3y ago
    Practically, how much real world value is there going to be? I assume all the big nations spy on each other. Have a very good idea on the broad strokes total number of personnel, planes, ships, bombs, and where they are all located. Potential for novel military insight seems low. There is probably lots of stupid human gossip to be found: mistresses, politically embarrassing failures, self-dealing schemes, etc. Maybe there are a few tantalizing useful nuggets: attached are the full schematics for the planetary weather control machine, where we buried that crashed ufo, location of the archive holding all the kompromat, etc. I have no doubt intelligence agencies would decrypt anything and everything, but it seems more like they would just because vs perceived need.
- tcmb 3y ago
  You can suddenly read all the encrypted emails, web traffic, instant messages and IP phone calls you have captured and stored for the past years (or even decades).
- bordercases 3y ago
  > As far as i can see there is quite a lot of "quantum safe" encryption so what kind of historical data exists lying around with lots of value? I find this statement funny, not at your expense. In public discourse, speak about quantum encryption too early – such as within the last five years – and the common opinion on say Stack Overflow/HN/Reddit/among the outer circles of cybersecurity is "don't model a threat before you get there". Now apparently there is a lot of quantum-safe encryption - not true, NIST barely came to a standard in the last year, which failed quickly, even though there are quantum-resistant strategies which have gained tentative adoption in companies like Signal and MullvadVPN. But interesting that this is a perception someone has now, and suddenly quantum computers are being put under popular scrutiny again, perhaps driven by advancements in inner circles and higher tiers of tech. It's tiresome to see these discourses out of sync
  - Eisenstein 3y ago
    I think 'quantum safe' needs to be qualified. Most encryption is inherently 'quantum safe' and does not need to be designed specifically to be so.
    - MattPalmer1086 3y ago
      Most asymmetric encryption is not quantum safe and has to be designed to be so. Symmetric encryption is safer, but you still need to double the key lengths at least.
- motohagiography 3y ago
  The utility of breaking old classically encrypted messages isn't really an existential problem for anyone, and there are no lost great secrets buried in encrypted intercepts that yield disruptive power if they are discovered today or anything like that. Think of it as a control plane vs. data plane, where you have the state as a control plane, and if data can escape its purview, or worse the data plane can generate control messages that subvert it - you get existential uncertainty and risk. It will never let itself be reduced to a dumb pipe. Encryption represents a limit on the absolute sovereignty of that control plane, so the resources to contain it are a constant need.
Nextgrid 3y ago
Keep in mind that whoever actually gets there is unlikely to talk about it and in fact would keep this ability under wraps and only use it it in extreme cases or where parallel construction can be used to conceal it.