I am confused, since even factoring 21 is apparently so difficult that it "isn’t yet a good benchmark for tracking the progress of quantum computers." [0]
So the "useful quantum computing" that is "imminent" is not the kind of quantum computing that involves the factorization of nearly prime numbers?
Factoring will be okay for tracking progress later; it's just a bad benchmark now. Factoring benchmarks have little visibility into fault tolerance spinning up, which is the important progress right now. Factoring becoming a reasonable benchmark is strongly related to quantum computing becoming useful.
Perhaps? The sort of quantum computers that people are talking about now are not general purpose. So you might be able to make a useful quantum computer that is not Shor's algorithm.
I don't think that's correct, the research projects the article is talking about all seem to aim at making general purpose quantum computers eventually. Obviously they haven't succeded yet, but general purpose does seem to be what they are talking about.
Simulating the Hubbard model for superconductors at large scales is significantly more likely to happen sooner than factoring RSA-2048 with Shor’s algorithm.
Google have been working on this for years
Don't ask me if they've the top supercomputers beat, ask Gemini :)
Like if you were building one of the first normal computers, how big numbers you can multiply would be a terrible benchmark since once you have figured out how to multiply small numbers its fairly trivial to multiply big numbers. The challenge is making the computer multiply numbers at all.
This isn't a perfect metaphor as scaling is harder in a quantum setting, but we are mostly at the stage where we are trying to get the things to work at all. Once we reach the stage where we can factor small numbers reliably, the amount of time to go from smaller numbers to bigger numbers will be probably be relatively short.
From my limited understanding, that's actually the opposite of the truth.
In QC systems, the engineering "difficulty" scales very badly with the number of gates or steps of the algorithm.
Its not like addition where you can repeat a process in parallel and bam-ALU. From what I understand as a layperson, the size of the inputs is absolutely part of the scaling.
But the reason factoring numbers is used as the quantum benchmark is exactly that we have a quantum algorithm for that problem which is meant to scale better than any known algorithm on a classical computer.
So it seems like it takes an exponentially bigger device to factor 21 than 15, then 35 than 21, and so on, but if I understand right, at some point this levels out and it's only relatively speaking a little harder to factor say 10^30 than 10^29.
Why are we so confident this is true given all of the experience so far trying to scale up from factoring 15 to factoring 21?
> Why are we so confident this is true given all of the experience so far trying to scale up from factoring 15 to factoring 21?
I don't think we have any "real" experience scaling from 15 to 21. Or at least not in the way shor's algorithm would be implemented in practise on fault tolerant qubits.
We haven't even done 15 yet in a "real" way yet. I susect the amount of time to factor 15 on fault tolerant qubits will be a lot longer than the time to go from 15 to 21.
Actually yes, how much numbers you can crunch per second and how big they are were among the first benchmarks for actual computers. Also, these prototypes were almost always immediately useful. (Think of the computer that cracked Enigma).
In comparison, there is no realistic path forward for scaling quantum computers. Anyone serious that is not trying to sell you QC will tell you that quantum systems become exponentially less stable the bigger they are and the longer they live. That is a fundamental physical truth. And since they're still struggling to do anything at all with a quantum computer, don't get your hopes up too much.
This is quite falatious and wrong. The first computers were built in order to solve problems immediately that were already being solved slowly by manual methods. There never was a period where people built computers so slow that they were slower than adding machines and slide rules, just because they seemed cool and might one day be much faster.
Once quantum computers are possible, is there actually anything else, any other real world applications, besides breaking crypto and number theory problems that they can do, and do much better than regular computers?
Yes, in fact they might be useful for chemistry simulation long before they are useful for cryptography. Simulations of quantum systems inherently scale better on quantum hardware.
The video is essentially an argument from the software side (ironically she thinks the hardware side is going pretty well). Even if the hardware wasn't so hard to build or scale, there are surprisingly few problems where quantum algorithms have turned out to be useful.
I believe the primary most practical use would be compression. Devices could have quantum decoder chips that give us massive compression gains which could also massively expand storage capacity. Even modest chips far before the realization of the scale necessary for cryptography breaking could give compression gains on the order of 100 to 1000x. IMO that's the real game changer. The theoretical modeling and cryptography breaking that you see papers being published on is much further out. The real work that isn't being publicized because of the importance of trade secrets is on storage / compression.
Suppose you're compressing the text of a book: How would a quantum processor let you get a much better compression ratio, even in theory?
If you're mistakenly describing the density of information on some kind of physical object, that's not data compression, that's just a different storage medium.
One theoretical use case is “Harvest Now, Decrypt Later” (HNDL) attacks, or “Store Now, Decrypt Later” (SNDL). If an oppressive regime saves encrypted messages now, they can decrypt later when QCs can break RSA and ECC.
It's a good reason to implement post-quantum cryptography.
Wasn't sure if you meant crypto (btc) or cryptography :)
I will never get used to ECC meaning "Error Correcting Code" or "Elliptic Curve Cryptography." That said, this isn't unique to quantum expectations. Faster classical computers or better classical techniques could make various problems easier in the future.
From TFA: ‘One more time for those in the back: the main known applications of quantum computers remain (1) the simulation of quantum physics and chemistry themselves, (2) breaking a lot of currently deployed cryptography, and (3) eventually, achieving some modest benefits for optimization, machine learning, and other areas (but it will probably be a while before those modest benefits win out in practice). To be sure, the detailed list of quantum speedups expands over time (as new quantum algorithms get discovered) and also contracts over time (as some of the quantum algorithms get dequantized). But the list of known applications “from 30,000 feet” remains fairly close to what it was a quarter century ago, after you hack away the dense thickets of obfuscation and hype.’
I realize this is a minority opinion, and goes against all theories of how quantum computing works, but I just cannot believe that nature will allow us to reliably compute with amplitudes as small as 2^-256. I still suspect something will break down as we approach and move below the planck scale.
Fun fact: the Planck mass is about 22 micrograms, about the amount of Vitamin D in a typical multivitamin supplement, and the corresponding derived Planck momentum is 6.5 kg m/s, which is around how hard a child kicks a soccer ball. Nothing inherently special or limiting about these.
If you look at Planck units or any dimensionless set of physical units, you will see that mass stands apart from others units. There’s like a factor 10^15 or something like this, i.e. we can’t scale all physical units to be around the same values, something is going with mass and gravity that makes it different than others
After computing in 1899 for the first time the value of what is now named "Planck's constant" (despite the fact that Planck has computed both constants that are now named "Boltzmann's constant" and "Planck's constant"), Planck has immediately realized that this provides an extra value, besides those previously known, which can be used for the definition of a natural unit of measurement.
Nevertheless, Planck did not understand well enough the requirements for a good system of fundamental units of measurement (because he was a theoretician, not an experimentalist; he had computed his constants by a better mathematical treatment of the experimental data provided by Paschen), so he did not find any good way to integrate Planck's constant in a system of fundamental units and he has made the same mistake made by Stoney 25 years before him (after computing the value of the elementary electric charge) and he has chosen the wrong method for defining the unit of mass among two variants previously proposed by Maxwell (the 2 variants were deriving the unit of mass from the mass of some atom or molecule and deriving the unit of mass from the Newtonian constant of gravitation).
All dimensionless systems of fundamental units are worthless in practice (because they cause huge uncertainties in all values of absolute measurements) and they do not have any special theoretical significance.
For the number of independently chosen fundamental units of measurement there exists an optimum value and the systems with either more or fewer fundamental units lead to greater uncertainties in the values of the physical quantities and to superfluous computations in the mathematical models.
The dimensionless systems of units are not simpler, but more complicated, so attempting to eliminate the independently chosen fundamental units is the wrong goal when searching for the best system of units of measurement.
My point is that the values of the so-called "Planck units" have absolutely no physical significance, therefore it is extremely wrong to use them in any reasoning about what is possible or impossible or about anything else.
The "Planck units" are not unique, there also exists a very similar system of "Stoney units", proposed a quarter of century before the "Planck units", where the values of the units are different, and there are also other variants of dimensionless systems of units proposed later. None of them is better than the others and all are bad, the worst defect being that the huge experimental uncertainties from measuring the value of the Newtonian constant of gravitation are moved from that single value into the values of all unrelated physical quantities, so that no absolute value can be known precisely, but only the ratios between quantities of the same kind.
In a useful system of fundamental units, for all units there are "natural" choices, except for one, which is the scale factor of the spatio-temporal units. For this scale factor of space-time, in the current state of knowledge there is no special value that can be distinguished from other arbitrary choices, so it is chosen solely based on the practical ease of building standards of frequency and wave-number that have adequate reproducibility and stability.
The only historical value of the "Planck units" is that they provide a good example of how one should NOT choose a system of units of measurement. The fact that they are still frequently mentioned by some people in any other context than criticizing such a system just demonstrates the very sad state of physics education, where no physics textbook includes an adequate presentation of the foundation of physics, which is the theory of the measurement of physical quantities. One century and a half ago, Maxwell began his treatise on electricity and magnetism with a very good exposition of the state of metrology at that time, but later physics textbooks have become less and less rigorous, instead of improving.
I particularly like the end of the post where he compares the history of nuclear fission to the progress on quantum computing. Traditional encryption might already be broken but we have not been told.
In a world where spying on civilian communication of adversaries (and preventing spying on your own civilians) is becoming more critical for national security interests, i suspect that national governments would be lighting more of a fire if they believe their opponents had one.
tbh they could just be pushing for people to adopt newer, less-tested, weaker algorithms. switch from something battle-hardened to the QuantResist2000 algorithm which they've figured out how to break with lattice reduction and a couple of GPUs like those minecraft guys did.
I really doubt we are anywhere close to this when there has been no published legit prime factorization beyond 21: https://eprint.iacr.org/2025/1237.pdf
Surely if someone managed to factorize a 3 or 4 digits number, they would have published it as it's far enough of weaponization to be worth publishing. To be used to break cryptosystems, you need to be able to factor at least 2048-digits numbers. Even assuming the progress is linear with respect to the number of bits in the public key (this is the theoretical lower bound but assume hardware scaling is itself linear, which doesn't seem to be the case), there's a pretty big gap between 5 and 2048 and the fact that no-one has ever published any significant result (that is, not a magic trick by choosing the number in a way that makes the calculation trivial, see my link above) showing any process in that direction suggest we're not in any kind of immediate threat.
The reality is that quantum computing is still very very hard, and very very far from being able what is theoretically possible with them.
Zero money take: quantum computing looks like a bunch of refrigerator companies.
The fact that error correction seems to be struggling implies unaccounted for noise that is not heat. Who knows maybe gravitational waves heck your setup no matter what you do!
As someone that works in quantum computing research both academic and private, no it isn't imminent in my understanding of the word, but it will happen. We are still at that point whereby we are comparable to 60's general computing development. Many different platforms and we have sort of decided on the best next step but we have many issues still to solve. A lot of the key issues have solutions, the problem is more getting everyone to focus in the right direction, which also will mean when funding starts to focus in the right direction. There are snake oil sellers right now and life will be imminently easier when they are removed.
Wouldn't the comparison be more like the 1920s for computing. We had useful working computers in the 1940s working on real problems doing what was not possible before hand. By the 1950s we had computers doing Nuclear bomb simulations and the 1960s we had computers in banks doing accounting and inventory. So we had computers by then, not in homes, but we had them. In the 1920s we had mechanical calculators and theories on computation emerging but not a general purpose computer. Until we have a quantum computer doing work at least at the level of a digital computer I can't really believe it being the 1960s.
I'm not going to pretend that I am that knowledgeable on classic computing history from that time period. I was primarily going off the fact the semi conductor was built in the late 40's, and I would say we have the quantum version of that in both qubit and photonic based computing and they work and we have been developing on them for some time now. The key difference is that there are many more steps to get to the stage of making them useful. A transistor becamse useful extremely quickly and well in Quantum computing, these just haven't quite yet.
Not to be snarky, but how is it comparable to 60's computing? There was a commercial market for computers and private and public sector adoption and use in the 60s.
There is private sector adoption and planning now of specific single purpose focused quantum devices in military and security settings. They work and exist although I do not believe they are installed. I may be wrong on the exact date, as my classical computer knowledge isn't spot on. The point I was trying to make was that we have all the bits we need. We have the ability to make the photonic quantum version (which spoiler alert is where the focus needs to move to over the qubit method of quantum computing) of a transistor, so we have hit the 50's at least. The fundamentals at this point won't change. What will change is how they are put together and how they are made durable.
Eh, quantum computing could very well be the next nuclear fusion where every couple of years forever each solved problem brings us to "We're 5 years away!"
Yet, for sure we should keep funding both quantum computing and nuclear fusion research.
In the 60's we actually had extremely capable, fully-developed computers. Advanced systems like the IBM System360 and CDC 6600.
Quantum computing is currently stuck somewhere in the 1800's, when a lot of the theory was still being worked out and few functional devices had even been constructed.
- Too few researchers, as in my area of quantum computing. I would state there is one other group that has any academic rigour, and is actually making significant and important progress. The two other groups are using non reproducible results for credit and funding for private companies. You have FAANG style companies also doing research, and the research that comes out still is clearly for funding. It doesn't stand up under scrutiny of method (there usually isn't one although that will soon change as I am in the process of producing a recipe to get to the point we are currently at which is as far as anyone is at) and repeatability.
- Too little progress. Now this is due to the research focus being spread too thin. We have currently the classic digital (qubit) vs analogue (photonic) quantum computing fight, and even within each we have such broad variations of where to focus. Therefore each category is still really just at the start as we are going in so many different directions. We aren't pooling our resources and trying to make progress together. This is also where a lack of openness regarding results and methods harms us. Likewise a lack of automation. Most significant research is done by human hand, which means building on it at a different research facility often requires learning off the person who developed the method in person if possible or at worse, just developing a method again which is a waste of time. If we don't see the results, the funding won't be there. Obviously classical computing eventually found a use case and then it became useful for the public but I fear we may not get to that stage as we may take too long.
As an aside, we may also get to the stage whereby, it is useful but only in a military/security setting. I have worked on a security project (I was not bound by any NDA surprisingly but I'm still wary) featuring a quantum setup, that could of sorts be comparable to a single board computer (say of an ESP32), although much larger. There is some value to it, and that particular project could be implemented into security right now (I do not believe it has or will, I believe it was viability) and isn't that far off. But that particular project has no other uses, outside of the military/security.
I worked in this field for years and helped build one of the recognizable companies. It has been disappointing to see, once again, promising science done in earnest be taken over by grifters. We knew many years ago that it was going to take FAR fewer qubits to crack encryption than pundits (and even experts) believed.
the funny thing is that nobody will ever do that. The moment someone uses quantum computing or any other technology to crack bitcoin in a visible way, the coins they just gave to themselves become worthless because confidence collapses.
Well, they wouldn't go for the trillion dollar wale addresses.
They would hack random, long unused, dead addresses holding 5 figure amounts and slowly convert those to money. They would eventually start to significantly lower the value and eventually crash bitcoin if too greedy, but could get filthy rich.
Did anyone else read the last two paragraphs as “I AM NOT ALLOWED TO TELL YOU THINGS YOU SHOULD BE VERY CONCERNED ABOUT” in bright flashing warning lights or is it just me?
I don't think he is saying that. As I said in my other comment here I think he is just drawing a potential parallel to other historic work that was done in a private(secret) domain. The larger point is we simply don't know so it's best to act in a way that even if it hasn't been done already it certainly seems like it will be broken. Hence the move to Post-Quantum Cryptography is probably a good idea!
Very much so. But the specificity and severity of what he knows is not clear just from this. Not necessarily to the point of "bright flashing warning lights" as the top-level comment put it. Anyway, I certainly am glad that people are (as far as I can tell?) more or less on top of the post-quantum transition.
It is more, many companies can't do what they claim to do, or they have done it once at best and had no more consistency. I sense most companies in the quantum computing space right now are of this ilk. As someone that works in academic and private quantum computing research, repeatability and methodology are severely lacking, which always rings alarm bells. Some companies are funded off the back of one very poor quality research paper, reviewed by people who are not experts, that then leads to a company that looks professional but behind the scenes I would imagine are saying Oh shit, now we actually have to do this thing we said we could do.
I am confused, since even factoring 21 is apparently so difficult that it "isn’t yet a good benchmark for tracking the progress of quantum computers." [0]
So the "useful quantum computing" that is "imminent" is not the kind of quantum computing that involves the factorization of nearly prime numbers?
[0] https://algassert.com/post/2500
Factoring will be okay for tracking progress later; it's just a bad benchmark now. Factoring benchmarks have little visibility into fault tolerance spinning up, which is the important progress right now. Factoring becoming a reasonable benchmark is strongly related to quantum computing becoming useful.
Perhaps? The sort of quantum computers that people are talking about now are not general purpose. So you might be able to make a useful quantum computer that is not Shor's algorithm.
I don't think that's correct, the research projects the article is talking about all seem to aim at making general purpose quantum computers eventually. Obviously they haven't succeded yet, but general purpose does seem to be what they are talking about.
Simulating the Hubbard model for superconductors at large scales is significantly more likely to happen sooner than factoring RSA-2048 with Shor’s algorithm.
Google have been working on this for years
Don't ask me if they've the top supercomputers beat, ask Gemini :)
I always find this argument a little silly.
Like if you were building one of the first normal computers, how big numbers you can multiply would be a terrible benchmark since once you have figured out how to multiply small numbers its fairly trivial to multiply big numbers. The challenge is making the computer multiply numbers at all.
This isn't a perfect metaphor as scaling is harder in a quantum setting, but we are mostly at the stage where we are trying to get the things to work at all. Once we reach the stage where we can factor small numbers reliably, the amount of time to go from smaller numbers to bigger numbers will be probably be relatively short.
From my limited understanding, that's actually the opposite of the truth.
In QC systems, the engineering "difficulty" scales very badly with the number of gates or steps of the algorithm.
Its not like addition where you can repeat a process in parallel and bam-ALU. From what I understand as a layperson, the size of the inputs is absolutely part of the scaling.
But the reason factoring numbers is used as the quantum benchmark is exactly that we have a quantum algorithm for that problem which is meant to scale better than any known algorithm on a classical computer.
So it seems like it takes an exponentially bigger device to factor 21 than 15, then 35 than 21, and so on, but if I understand right, at some point this levels out and it's only relatively speaking a little harder to factor say 10^30 than 10^29.
Why are we so confident this is true given all of the experience so far trying to scale up from factoring 15 to factoring 21?
> Why are we so confident this is true given all of the experience so far trying to scale up from factoring 15 to factoring 21?
I don't think we have any "real" experience scaling from 15 to 21. Or at least not in the way shor's algorithm would be implemented in practise on fault tolerant qubits.
We haven't even done 15 yet in a "real" way yet. I susect the amount of time to factor 15 on fault tolerant qubits will be a lot longer than the time to go from 15 to 21.
The fact that it does appear to be so difficult to scale things up would suggest that the argument isn't silly.
Actually yes, how much numbers you can crunch per second and how big they are were among the first benchmarks for actual computers. Also, these prototypes were almost always immediately useful. (Think of the computer that cracked Enigma).
In comparison, there is no realistic path forward for scaling quantum computers. Anyone serious that is not trying to sell you QC will tell you that quantum systems become exponentially less stable the bigger they are and the longer they live. That is a fundamental physical truth. And since they're still struggling to do anything at all with a quantum computer, don't get your hopes up too much.
This is quite falatious and wrong. The first computers were built in order to solve problems immediately that were already being solved slowly by manual methods. There never was a period where people built computers so slow that they were slower than adding machines and slide rules, just because they seemed cool and might one day be much faster.
Once quantum computers are possible, is there actually anything else, any other real world applications, besides breaking crypto and number theory problems that they can do, and do much better than regular computers?
Yes, in fact they might be useful for chemistry simulation long before they are useful for cryptography. Simulations of quantum systems inherently scale better on quantum hardware.
https://en.wikipedia.org/wiki/Quantum_computational_chemistr...
More recently it's turned out that quantum computers are less useful for molecular simulation than previously thought. See: https://www.youtube.com/watch?v=pDj1QhPOVBo
The video is essentially an argument from the software side (ironically she thinks the hardware side is going pretty well). Even if the hardware wasn't so hard to build or scale, there are surprisingly few problems where quantum algorithms have turned out to be useful.
I believe the primary most practical use would be compression. Devices could have quantum decoder chips that give us massive compression gains which could also massively expand storage capacity. Even modest chips far before the realization of the scale necessary for cryptography breaking could give compression gains on the order of 100 to 1000x. IMO that's the real game changer. The theoretical modeling and cryptography breaking that you see papers being published on is much further out. The real work that isn't being publicized because of the importance of trade secrets is on storage / compression.
Pretty sure quantum algorithms can't be used for compression.
Someone just has to figure out how to actually implement middle out compression on a quantum computer.
> compression gains on the order of 100 to 1000x.
This feels like woo-woo to me.
Suppose you're compressing the text of a book: How would a quantum processor let you get a much better compression ratio, even in theory?
If you're mistakenly describing the density of information on some kind of physical object, that's not data compression, that's just a different storage medium.
One theoretical use case is “Harvest Now, Decrypt Later” (HNDL) attacks, or “Store Now, Decrypt Later” (SNDL). If an oppressive regime saves encrypted messages now, they can decrypt later when QCs can break RSA and ECC.
It's a good reason to implement post-quantum cryptography.
Wasn't sure if you meant crypto (btc) or cryptography :)
I will never get used to ECC meaning "Error Correcting Code" or "Elliptic Curve Cryptography." That said, this isn't unique to quantum expectations. Faster classical computers or better classical techniques could make various problems easier in the future.
What do you want it to mean?
From TFA: ‘One more time for those in the back: the main known applications of quantum computers remain (1) the simulation of quantum physics and chemistry themselves, (2) breaking a lot of currently deployed cryptography, and (3) eventually, achieving some modest benefits for optimization, machine learning, and other areas (but it will probably be a while before those modest benefits win out in practice). To be sure, the detailed list of quantum speedups expands over time (as new quantum algorithms get discovered) and also contracts over time (as some of the quantum algorithms get dequantized). But the list of known applications “from 30,000 feet” remains fairly close to what it was a quarter century ago, after you hack away the dense thickets of obfuscation and hype.’
It turns out they're not so useful for chemistry. https://www.youtube.com/watch?v=pDj1QhPOVBo
I realize this is a minority opinion, and goes against all theories of how quantum computing works, but I just cannot believe that nature will allow us to reliably compute with amplitudes as small as 2^-256. I still suspect something will break down as we approach and move below the planck scale.
Fun fact: the Planck mass is about 22 micrograms, about the amount of Vitamin D in a typical multivitamin supplement, and the corresponding derived Planck momentum is 6.5 kg m/s, which is around how hard a child kicks a soccer ball. Nothing inherently special or limiting about these.
If you look at Planck units or any dimensionless set of physical units, you will see that mass stands apart from others units. There’s like a factor 10^15 or something like this, i.e. we can’t scale all physical units to be around the same values, something is going with mass and gravity that makes it different than others
After computing in 1899 for the first time the value of what is now named "Planck's constant" (despite the fact that Planck has computed both constants that are now named "Boltzmann's constant" and "Planck's constant"), Planck has immediately realized that this provides an extra value, besides those previously known, which can be used for the definition of a natural unit of measurement.
Nevertheless, Planck did not understand well enough the requirements for a good system of fundamental units of measurement (because he was a theoretician, not an experimentalist; he had computed his constants by a better mathematical treatment of the experimental data provided by Paschen), so he did not find any good way to integrate Planck's constant in a system of fundamental units and he has made the same mistake made by Stoney 25 years before him (after computing the value of the elementary electric charge) and he has chosen the wrong method for defining the unit of mass among two variants previously proposed by Maxwell (the 2 variants were deriving the unit of mass from the mass of some atom or molecule and deriving the unit of mass from the Newtonian constant of gravitation).
All dimensionless systems of fundamental units are worthless in practice (because they cause huge uncertainties in all values of absolute measurements) and they do not have any special theoretical significance.
For the number of independently chosen fundamental units of measurement there exists an optimum value and the systems with either more or fewer fundamental units lead to greater uncertainties in the values of the physical quantities and to superfluous computations in the mathematical models.
The dimensionless systems of units are not simpler, but more complicated, so attempting to eliminate the independently chosen fundamental units is the wrong goal when searching for the best system of units of measurement.
My point is that the values of the so-called "Planck units" have absolutely no physical significance, therefore it is extremely wrong to use them in any reasoning about what is possible or impossible or about anything else.
The "Planck units" are not unique, there also exists a very similar system of "Stoney units", proposed a quarter of century before the "Planck units", where the values of the units are different, and there are also other variants of dimensionless systems of units proposed later. None of them is better than the others and all are bad, the worst defect being that the huge experimental uncertainties from measuring the value of the Newtonian constant of gravitation are moved from that single value into the values of all unrelated physical quantities, so that no absolute value can be known precisely, but only the ratios between quantities of the same kind.
In a useful system of fundamental units, for all units there are "natural" choices, except for one, which is the scale factor of the spatio-temporal units. For this scale factor of space-time, in the current state of knowledge there is no special value that can be distinguished from other arbitrary choices, so it is chosen solely based on the practical ease of building standards of frequency and wave-number that have adequate reproducibility and stability.
The only historical value of the "Planck units" is that they provide a good example of how one should NOT choose a system of units of measurement. The fact that they are still frequently mentioned by some people in any other context than criticizing such a system just demonstrates the very sad state of physics education, where no physics textbook includes an adequate presentation of the foundation of physics, which is the theory of the measurement of physical quantities. One century and a half ago, Maxwell began his treatise on electricity and magnetism with a very good exposition of the state of metrology at that time, but later physics textbooks have become less and less rigorous, instead of improving.
I particularly like the end of the post where he compares the history of nuclear fission to the progress on quantum computing. Traditional encryption might already be broken but we have not been told.
In a world where spying on civilian communication of adversaries (and preventing spying on your own civilians) is becoming more critical for national security interests, i suspect that national governments would be lighting more of a fire if they believe their opponents had one.
They absolutely are. NSA is obsessed with post-quantum projects atm
tbh they could just be pushing for people to adopt newer, less-tested, weaker algorithms. switch from something battle-hardened to the QuantResist2000 algorithm which they've figured out how to break with lattice reduction and a couple of GPUs like those minecraft guys did.
But is this because they are already needed or because they want to preserve encryption for past and present data post-quantum?
The latter
NSA is pushing for PQ algos.
I really doubt we are anywhere close to this when there has been no published legit prime factorization beyond 21: https://eprint.iacr.org/2025/1237.pdf
Surely if someone managed to factorize a 3 or 4 digits number, they would have published it as it's far enough of weaponization to be worth publishing. To be used to break cryptosystems, you need to be able to factor at least 2048-digits numbers. Even assuming the progress is linear with respect to the number of bits in the public key (this is the theoretical lower bound but assume hardware scaling is itself linear, which doesn't seem to be the case), there's a pretty big gap between 5 and 2048 and the fact that no-one has ever published any significant result (that is, not a magic trick by choosing the number in a way that makes the calculation trivial, see my link above) showing any process in that direction suggest we're not in any kind of immediate threat.
The reality is that quantum computing is still very very hard, and very very far from being able what is theoretically possible with them.
Zero money take: quantum computing looks like a bunch of refrigerator companies.
The fact that error correction seems to be struggling implies unaccounted for noise that is not heat. Who knows maybe gravitational waves heck your setup no matter what you do!
As someone that works in quantum computing research both academic and private, no it isn't imminent in my understanding of the word, but it will happen. We are still at that point whereby we are comparable to 60's general computing development. Many different platforms and we have sort of decided on the best next step but we have many issues still to solve. A lot of the key issues have solutions, the problem is more getting everyone to focus in the right direction, which also will mean when funding starts to focus in the right direction. There are snake oil sellers right now and life will be imminently easier when they are removed.
Wouldn't the comparison be more like the 1920s for computing. We had useful working computers in the 1940s working on real problems doing what was not possible before hand. By the 1950s we had computers doing Nuclear bomb simulations and the 1960s we had computers in banks doing accounting and inventory. So we had computers by then, not in homes, but we had them. In the 1920s we had mechanical calculators and theories on computation emerging but not a general purpose computer. Until we have a quantum computer doing work at least at the level of a digital computer I can't really believe it being the 1960s.
I'm not going to pretend that I am that knowledgeable on classic computing history from that time period. I was primarily going off the fact the semi conductor was built in the late 40's, and I would say we have the quantum version of that in both qubit and photonic based computing and they work and we have been developing on them for some time now. The key difference is that there are many more steps to get to the stage of making them useful. A transistor becamse useful extremely quickly and well in Quantum computing, these just haven't quite yet.
Not to be snarky, but how is it comparable to 60's computing? There was a commercial market for computers and private and public sector adoption and use in the 60s.
There is private sector adoption and planning now of specific single purpose focused quantum devices in military and security settings. They work and exist although I do not believe they are installed. I may be wrong on the exact date, as my classical computer knowledge isn't spot on. The point I was trying to make was that we have all the bits we need. We have the ability to make the photonic quantum version (which spoiler alert is where the focus needs to move to over the qubit method of quantum computing) of a transistor, so we have hit the 50's at least. The fundamentals at this point won't change. What will change is how they are put together and how they are made durable.
Eh, quantum computing could very well be the next nuclear fusion where every couple of years forever each solved problem brings us to "We're 5 years away!"
Yet, for sure we should keep funding both quantum computing and nuclear fusion research.
In the 60's we actually had extremely capable, fully-developed computers. Advanced systems like the IBM System360 and CDC 6600.
Quantum computing is currently stuck somewhere in the 1800's, when a lot of the theory was still being worked out and few functional devices had even been constructed.
> it will happen.
If you were to guess what reasons there might be that it WON’T happen, what would some of those reasons be?
So in my view, the issues I think about now are:
- Too few researchers, as in my area of quantum computing. I would state there is one other group that has any academic rigour, and is actually making significant and important progress. The two other groups are using non reproducible results for credit and funding for private companies. You have FAANG style companies also doing research, and the research that comes out still is clearly for funding. It doesn't stand up under scrutiny of method (there usually isn't one although that will soon change as I am in the process of producing a recipe to get to the point we are currently at which is as far as anyone is at) and repeatability.
- Too little progress. Now this is due to the research focus being spread too thin. We have currently the classic digital (qubit) vs analogue (photonic) quantum computing fight, and even within each we have such broad variations of where to focus. Therefore each category is still really just at the start as we are going in so many different directions. We aren't pooling our resources and trying to make progress together. This is also where a lack of openness regarding results and methods harms us. Likewise a lack of automation. Most significant research is done by human hand, which means building on it at a different research facility often requires learning off the person who developed the method in person if possible or at worse, just developing a method again which is a waste of time. If we don't see the results, the funding won't be there. Obviously classical computing eventually found a use case and then it became useful for the public but I fear we may not get to that stage as we may take too long.
As an aside, we may also get to the stage whereby, it is useful but only in a military/security setting. I have worked on a security project (I was not bound by any NDA surprisingly but I'm still wary) featuring a quantum setup, that could of sorts be comparable to a single board computer (say of an ESP32), although much larger. There is some value to it, and that particular project could be implemented into security right now (I do not believe it has or will, I believe it was viability) and isn't that far off. But that particular project has no other uses, outside of the military/security.
What makes you confident that it will happen?
The people who are inside the machine are usually the least qualified to predict the machine's future
What an idiotic take. The LEAST qualified? Should I go ask some random junkie off the street where quantum computing will be in 5 years?
Yes. Apply wisdom of the crowd.
I worked in this field for years and helped build one of the recognizable companies. It has been disappointing to see, once again, promising science done in earnest be taken over by grifters. We knew many years ago that it was going to take FAR fewer qubits to crack encryption than pundits (and even experts) believed.
another late signal will be a funding spike
once someone makes a widget that extracts an RSA payload, their govt will seize, spend & scale
they will try to keep it quiet but they will start a spending spree that will be visible from space
Cloud providers will love it when we will need to buy more compute and memory for post quantum TSL.
We'll know when all of the old Bitcoin P2PK addresses and transacted from addresses are swept.
the funny thing is that nobody will ever do that. The moment someone uses quantum computing or any other technology to crack bitcoin in a visible way, the coins they just gave to themselves become worthless because confidence collapses.
There are some Bitcoin puzzles or old wallets that give some plausible deniability.
Well, they wouldn't go for the trillion dollar wale addresses.
They would hack random, long unused, dead addresses holding 5 figure amounts and slowly convert those to money. They would eventually start to significantly lower the value and eventually crash bitcoin if too greedy, but could get filthy rich.
Did anyone else read the last two paragraphs as “I AM NOT ALLOWED TO TELL YOU THINGS YOU SHOULD BE VERY CONCERNED ABOUT” in bright flashing warning lights or is it just me?
He's making it sound that way, although he might plausibly deny that by claiming he just doesn't want to speculate publicly.
Either way he must have known people would read it like you did when he wrote that; so we can safely assume it's boasting at the very least.
I don't think he is saying that. As I said in my other comment here I think he is just drawing a potential parallel to other historic work that was done in a private(secret) domain. The larger point is we simply don't know so it's best to act in a way that even if it hasn't been done already it certainly seems like it will be broken. Hence the move to Post-Quantum Cryptography is probably a good idea!
Aaronson says:
> This is the clearest warning that I can offer in public right now about the urgency of migrating to post-quantum cryptosystems...
That has a clear implication that he knows something that he doesn't want to say publically
Very much so. But the specificity and severity of what he knows is not clear just from this. Not necessarily to the point of "bright flashing warning lights" as the top-level comment put it. Anyway, I certainly am glad that people are (as far as I can tell?) more or less on top of the post-quantum transition.
a crypto system is expected to resist for 30 years.
it doesnt need to be imminent for people to start moving now to post-quantum.
if he thinks we are 10 years away from QC, we need to start moving now
It is more, many companies can't do what they claim to do, or they have done it once at best and had no more consistency. I sense most companies in the quantum computing space right now are of this ilk. As someone that works in academic and private quantum computing research, repeatability and methodology are severely lacking, which always rings alarm bells. Some companies are funded off the back of one very poor quality research paper, reviewed by people who are not experts, that then leads to a company that looks professional but behind the scenes I would imagine are saying Oh shit, now we actually have to do this thing we said we could do.
Just you
I ran it through ROT13, base64, reversed the bits, and then observed it....The act of decoding collapsed it into ...not imminent...