[HN Gopher] Quantum winter is coming
___________________________________________________________________
Quantum winter is coming
Author : nsoonhui
Score : 249 points
Date : 2022-11-05 13:24 UTC (9 hours ago)
(HTM) web link (backreaction.blogspot.com)
(TXT) w3m dump (backreaction.blogspot.com)
| sdgdfgsfdfgsdfg wrote:
| Two things can be true at the same time:
|
| We know that an ideal quantum computer provides an exponential
| speed-up in commercially relevant applications. There is a
| significant amount of smoke and mirrors in the quantum space.
|
| Unless there is some unknown fundamental reason why we cannot
| realize a good-enough quantum computer with sufficient knowledge
| and engineering, governments and business are well-advised to
| invest into R&D of quantum computers.
| tsimionescu wrote:
| By this logic, the ancient Egyptian pharaohs should have
| dedicated a sizeable portion of their treasury to researching
| manned flight, since they knew it was possible and they knew it
| would have significant economic and military advantages.
|
| Which is to say, just because something is possible in theory
| doesn't mean we have a clear idea how to get there, and if
| we're waiting on research breakthroughs, more money is unlikely
| to significantly speed up the process.
| dguest wrote:
| The US is spending around 1% of its national budget on
| science, and a minuscule part of that goes to quantum
| computing. That fraction of the pharaoh's treasury might have
| payed for one rather entertaining crackpot to build bird-like
| things, but it wouldn't put a dent in their other
| accomplishments.
| throwawaymaths wrote:
| But actually if you spend more money than can reasonably
| and effectively be spent on a given field, you run the risk
| of _setting back_ the field by advancing charlatans.
| boltzmann-brain wrote:
| That's an interesting comment. Have you seen this happen?
| throwawaymaths wrote:
| Yes.
| rini17 wrote:
| Psychedelics.
| sfpotter wrote:
| The amount of research funding is finite. Why spend it on
| something highly speculative when there are many other things
| it could be spent on which are not speculative?
| dguest wrote:
| It's finite but not explicitly conserved: science funding is
| around 1% of the US national budget and can change (a bit).
|
| In practice you're right, though, usually new funding in one
| place gets taken from somewhere else. But if the world really
| wanted scientific progress we could afford to fund some more
| speculative projects.
| binarycoffee wrote:
| > Two things can be true at the same time
|
| Yes, but it is not possible to assert that both are true at the
| same time with full certainty.
| sweezyjeezy wrote:
| > We know an ideal quantum computer provides an exponential
| speed-up in commercially relevant applications
|
| Do we know that though?
| reedf1 wrote:
| Yes, and you can test it yourself on already consumer
| available quantum hardware via AWS.
| tsimionescu wrote:
| AWS Braket is only, at best, useful for research in quantum
| algorithms. It gives you access to classical simulations of
| QCs (which run you linear-time quantum algorithm in
| exponential real time), or access to some noisy real QCs
| (the ones whose best achievements so far are proving that
| 21 = 3 * 7 using a version of Shor's algorithm specialized
| for certain numerical properties of the number 21).
| jnwatson wrote:
| Breaking RSA and ECC is commercially relevant.
| naasking wrote:
| > Breaking RSA and ECC is commercially relevant.
|
| Yes, but we don't actually know that we can build such a
| device.
| marginalia_nu wrote:
| If you can break RSA once using say a $34 billion machine
| that is a one-shot operation, is it really commercially
| relevant?
| Jweb_Guru wrote:
| With the number of qubits required to break RSA, there's
| no reason why general purpose computing wouldn't be
| possible.
| marginalia_nu wrote:
| Without assuming a spherical cow, that is well into the
| realm of science fiction-stuff we have no idea how to do.
| It assumes a degree of control over the variables that is
| far beyond anything we have access to.
|
| As a parallel, on a purely theoretical level, we know how
| to construct a warp drive as well[1].
|
| Solving a theoretical equation is one thing, replicating
| the prerequisite conditions experimentally is another
| entirely. Theoretically you can balance a perfect sphere
| upon another perfect sphere. In practice, you can't
| because setting up such an arrangement is practically
| impossible.
|
| [1] https://en.wikipedia.org/wiki/Alcubierre_drive
| civilized wrote:
| We don't. Here's a survey paper from quantum computing expert
| Scott Aaronson, posted to arXiv just a couple months ago:
| https://arxiv.org/pdf/2209.06930.pdf
|
| From the abstract:
|
| > I survey, for a general scientific audience, three decades
| of research into which sorts of problems admit exponential
| speedups via quantum computers -- from the classics (like the
| algorithms of Simon and Shor), to the breakthrough of
| Yamakawa and Zhandry from April 2022. [...] I make some
| skeptical remarks about widely-repeated claims of exponential
| quantum speedups for practical machine learning and
| optimization problems. Through many examples, I try to convey
| the "law of conservation of weirdness," according to which
| every problem admitting an exponential quantum speedup must
| have some unusual property to allow the amplitude to be
| concentrated on the unknown right answer(s).
|
| I am very confused at how so many people are absolutely
| convinced that quantum computing is known to do, or already
| does, all sorts of things it is not known to do. There's a
| sister comment here saying exponentially superior quantum
| computers are available in AWS!
|
| It's like an urban legend that circulates among software
| engineers.
| sdgdfgsfdfgsdfg wrote:
| You're wrong, we do know that, and the paper you cite
| doesn't refute that in any way.
|
| Integer factorization and quantum simulation would be two
| examples of commercially highly relevant applications where
| an exponential speed-up applies.
| civilized wrote:
| Integer factorization for codebreaking is a military or
| criminal application, not a commercial one. Someone will
| make money doing it, but it won't be contributing to
| society in the way we normally mean when talking about
| commerce. It would be like saying nukes have commercial
| applications.
|
| "Quantum simulation" is too vague to speak to
| applicability in any domain. There is no proven or
| empirically demonstrated exponential speedup on any
| simulation problem with known commercial applications.
| typon wrote:
| Switching a few key libraries like OpenSSL to using
| quantum-resistant cryptography is WAY WAY easier than
| constructing a viable quantum computer (in secret) that
| is able to break 512 bit or 1024 bit key RSA.
| geysersam wrote:
| Why would integer factorization be commercially relevant?
| Only practical use of that (as far as I'm aware) is
| breaking RSA. Hopefully people will just switch to known
| quantum secure algorithms. It'll be a nothing burger.
| typon wrote:
| The only thing I can think of is somehow speeding up drug
| discovery or materials research by accelerating atomistic
| simulation. However that's so far from reality it's hard to
| tell whether it will actually be faster in practice. (Pretty
| much the first application people like Feynman had in mind
| too)
| marcosdumay wrote:
| Well, those two small niches plus biological research are
| bottlenecks is pretty much any production process we have
| with real things.
| deepburner wrote:
| As a person who works in Quantum Computing, I can concur that
| there's hype in the field; one of the professors in my university
| has a quantum machine learning (TM) startup that seems to be
| performing well, even though most of the faculty and grad
| students can tell you that it's bullshit.
|
| However. This paragraph straight up displays a fundamental lack
| of understanding by Hossenfelder:
|
| > Last time I looked, no one had any idea how to do a weather
| forecast on a quantum computer. It's not just that no one has
| done it, no one knows if it's even possible, because weather is a
| non-linear system whereas quantum mechanics is a linear theory.
|
| Unitary evolution generated by the Schrodinger equation is a
| linear map on _probability amplitudes_, just like how classical
| (probabilistic) computing performs linear operations on
| _probability distributions_. The commonly used quantum circuit
| model is a superset of classical logic gates and can accomplish
| anything a probabilistic classical computer can, so if anything
| is possible in a classical computing scheme, it's also possible
| in the quantum circuit scheme.
|
| I don't have much sympathy for her since this is not the first
| time Hossenfelder has displayed a lack of understanding, recently
| she has published a paper criticizing another one [1], now
| replaced with a much shorter text due to being told [2] by the
| authors of the original paper.
|
| Yeah I get it, it's dumb when the president of BofA is talking
| about how QC is "the next big thing", I know it's not coming
| Soon^TM, but saying "we will never have a quantum computer
| because the current ones suck" has the same energy as "the world
| doesn't need more than 5 computers" imo.
| sfpotter wrote:
| > Unitary evolution generated by the Schrodinger equation is a
| linear map on _probability amplitudes_, just like how classical
| (probabilistic) computing performs linear operations on
| _probability distributions_. The commonly used quantum circuit
| model is a superset of classical logic gates and can accomplish
| anything a probabilistic classical computer can, so if anything
| is possible in a classical computing scheme, it's also possible
| in the quantum circuit scheme.
|
| To predict weather on a computer, we need to run large CFD
| simulations. When we do this on a classical computer, this
| involves a discretization of a system of PDEs with millions or
| billions of degrees of freedom, requiring 4 or 8 bits per
| floating point number. It may be possible to do the same CFD
| simulations on a quantum computer, but this is several
| constrained by the small number of qubits currently available
| on quantum computers. And clearly, even if you _could_ run the
| same algorithm, presumably the point of using a quantum
| computer would be reap the "quantum advantage" in order to do
| something algorithmically superior to what's possible on a
| classical computer.
|
| I think this is a pretty small point to get hung up on. The
| rest of her article is perfectly reasonable.
| cma wrote:
| You left out the footnote links
| bodhiandphysics wrote:
| One thing to note is while there are not a lot of quantum
| algorithms (though wikipedia's list is very incomplete!), some of
| them are massively useful. Grover's algorithm provides a
| quadratic improvement in black box search (which is a subroutine
| in many many many many algorithms). Solving a system of sparse
| linear equations can be solved log(n) time on a quantum computer,
| compared to n on a classical computer. This is the single most
| important problem in scientific computing.
| lisper wrote:
| > Solving a system of sparse linear equations ... is the single
| most important problem in scientific computing.
|
| I think this is arguable. To be sure, a lot of linear-system
| solving goes on in science, but you cannot conclude from this
| that it is the "single most important problem", it's just the
| one that we happen to know how to solve, and so that's where
| the compute power goes. It's like looking for your keys under
| the street light because it's easier to see rather than because
| it's where you lost your keys. Protein folding and the Navier-
| Stokes equation are arguably "more important", we just have no
| idea how to solve those problems.
| bodhiandphysics wrote:
| The navier stokes equation is quite literally solved using
| the diagonalization of large matrixes!
| lisper wrote:
| As an approximation, because we don't know how to find
| exact solutions.
| NiceKeeb wrote:
| It constantly amazes me how much attention Hossenfelder, a simple
| research fellow, manages to attract.
| in3d wrote:
| She opines on a lot of things she has very little knowledge
| about and her writing style is terrible. But it's crack for HN
| readers who mistake skepticisms and snark for insight.
| guender wrote:
| Hossenfelder has been in Physics for more than 25 years and is
| a seasoned researcher and communicator. Her "academic rank"
| shouldn't and in fact doesn't have any bearing on her impact.
| kittiepryde wrote:
| Do you have an educational youtube channel? Will definitely
| take a look if you do.
| starkd wrote:
| Intelligently communicating complex topics to the masses is a
| valuable skill in itself. She gains a lot of credibility with
| her humble attitude and willingness to admit what she does not
| know.
| propter_hoc wrote:
| I studied experimental condensed-matter physics and this article
| is spot on. The PIs at my university were holding clouds of
| rubidium atoms with laser tweezers at microkelvins in ultra-high
| vacuum, agitating them with a laser beam, and publishing papers
| saying "look it responds sort of like a qubit!"
|
| If you have seen the kind of equipment required to perform these
| experiments, it's absolutely unimaginable that these concepts
| could be miniaturized enough that someone would be able to put
| them in a desktop size box, and to do so usefully and safely
| within a timeline that is competitive with the advancement of
| microelectronics.
| JBits wrote:
| The scalability of quantum computing tech is a major concern
| but no one is claiming that it'll be miniaturize to that extent
| nor that this is even a goal.
| boltzmann-brain wrote:
| If computational tech cannot be miniaturized then it is dead,
| as only at massive production quotas does the technology
| become useful enough to become inexpensive. This is exactly
| what happened with normal (non quantum) computers. Imagine if
| computers were still the size of a room... Terrifying thought
| JBits wrote:
| You're right that it does need to be miniturized to some
| extent but there's absolutely no need for it to be desktop
| sized. If in the future a quantum computer is built, taking
| up multiple rooms is not an issue at all.
|
| The value is in a quantum computer existing at all, not
| it's availablity to consumers.
| serverholic wrote:
| I can't help but think capitalism plays a part in encouraging
| this kind of pathological behavior.
| peteradio wrote:
| How much of that size is cryo-equipment though?
| propter_hoc wrote:
| That's my point; how do you propose to miniaturize cryogenic
| equipment (and make it safe for the general public to use)?
|
| The UHV equipment is pretty intense too, fwiw.
| peteradio wrote:
| I'm not sure, I wonder if there are some back of the
| envelope estimates that could be done to see how small you
| could theoretically shrink that portion. At least when you
| make it small the materials cost is minimized!! Could make
| it out of exotic materials and it might still be cost
| effective. I wouldn't worry too much about safety once its
| small, there is minimal amount of harm caused by ultra cold
| or ultra high vacuum.
| logifail wrote:
| > I wouldn't worry too much about safety once its small,
| there is minimal amount of harm caused by ultra cold or
| ultra high vacuum
|
| In a previous life I worked with NMR machines, the ones
| with superconducting magnets cooled by liquid helium
| which is itself cooled by liquid nitrogen.
|
| I would dispute "minimal amount of harm", part of the our
| training involved what to do if the magnet quenches, I
| recall "run for the exit before you suffocate" was
| basically the SOP...
|
| Anyway, they were loads of fun to work with, I won't ever
| forget that time I nearly had my house keys snatched out
| of my hand by one, but back then (25 years ago) they
| occupied entire rooms. AFAIK they still do.
|
| OT but I had an MRI a couple of weeks ago, and forgot to
| take off my gold wedding band. I could _distinctly_ feel
| the magnetic field pulsing in my ring as the scan
| started. After a brief moment of sheer panic I realised
| it wasn 't a problem ... and as I lay there I was idly
| wondering about just how much gold was in my ring :)
| peteradio wrote:
| > I would dispute "minimal amount of harm", part of the
| our training involved what to do if the magnet quenches,
| I recall "run for the exit before you suffocate" was
| basically the SOP...
|
| Yes, at current scale it would be very hazardous, but at
| miniature scale a gram of liquid helium could do how much
| damage considering it would have to make its way through
| the internals of a machine to contact skin?
| rich_sasha wrote:
| I once saw a cut out of a D-wave computer (not a "real"
| quantum computer but also cryogenic). The whole device is
| roughly the size of a old school mainframe - a few wardrobes.
| But it's mostly layers of insulation and cooling. The
| business bit inside fits in your hand. Or so I remember at
| least.
|
| Actual cooling (stuff that pumps liquid nitrogen and helium)
| was external to all this.
| starkd wrote:
| I think the most realistic goal was always a main-frame type
| computer that could perform computations for special purposes.
| Not necessarily to shrink it down to phone-size or even a
| desktop. But maybe the marketing did really have this
| objective.
| himinlomax wrote:
| First thing would be to figure what that special purpose
| could possibly be. We're not even there yet ...
| benreesman wrote:
| Grover has some plausible applications as well as Shor.
|
| And Shor is based on quantum superior FFT if I recall
| correctly, which could have applications outside of
| discrete log.
|
| Disclaimer: I'm not an expert on this stuff, I'm sure
| someone will correct me if I'm wrong because there are real
| pros on here.
| hailwren wrote:
| For civilian applications, sure. But Shor's seems like a
| good enough reason for defense and defense have deep enough
| pockets to get this somewhat rolling.
| return_to_monke wrote:
| The special purpose is figuring out what the special
| purpose is :)
| er4hn wrote:
| My friends in the industry tell me that predicting protein
| folding is a popular civilian use case.
| kazinator wrote:
| Seems like the easiest way to use quantum mechanics to
| predict how a protein will fold might be to actually
| build that protein and watch.
| jacobsimon wrote:
| Huh I'm not an expert but doesn't AWS already offer quantum
| computing as a service?
|
| https://aws.amazon.com/braket/
| krastanov wrote:
| They do not offer anything of use. This is just a demo for
| an API that in principle can be used as an "assembly
| language" for quantum computers, but it either runs on
| simulators that can not do more than 10 "perfect" qubits,
| or on hardware that has 100-ish "noisy" qubits. You need
| about a million "noisy" qubits, together with error
| correction codes, to encode 1000 logical "perfect" qubits.
| That is about the minimal number at which you can do
| something useful.
| sp332 wrote:
| All true, but in the context of the thread, the future of
| quantum computing will probably be remote. So the bulk of
| the machinery is irrelevant.
| __MatrixMan__ wrote:
| Unless the bulk required to be useful is infeasible to
| assemble anywhere.
| DonHopkins wrote:
| You'll need to build a Dyson Sphere to power your quantum
| chip factory!
|
| https://dyson-sphere-program.fandom.com/wiki/Quantum_Chip
|
| QUANTUM CHIPS Running low? Never Again! | Dyson Sphere
| Program Master Class
|
| https://www.youtube.com/watch?v=O-xAZj0C2yo
| moffkalast wrote:
| Problem is, practically any special purpose can probably be
| done more cost effectively by brute forcing with conventional
| computing.
| nine_k wrote:
| Cost of brute-forcing certain things (like NP-hard^W^W _NP-
| complete_ problems) on regular computers quickly exceeds
| the cost of building and operating a quantum computer.
| Hence all the trying to make these contraptions work on
| non-toy problems.
| brnaftr361 wrote:
| Just make an Amoeboa computer?
| tsimionescu wrote:
| We don't know of a single NP-hard problem where quantum
| computers would show any exponential speed-up (there may
| be some speed-up by using the O(sqrt(n)) brute search
| quantum algorithm instead of the classical O(n) search
| algo, but that will be quickly drowned out by the
| exponential factors).
|
| Even worse, there is no reason to think that there will
| ever be - as far as we know, QCs only show an exponential
| advantage on problems with very very specific structures,
| while the whole problem of NP-hard problems is that they
| have no structure in general.
| nine_k wrote:
| Indeed, NP-hard is wrong! NP-complete is the interesting
| class where quantum computers theoretically could help.
| tsimionescu wrote:
| From what I've read on Scott Aaronson's blogs, NP-
| complete is also wrong. The general suspicion seems to be
| that polynomial quantum algorithms (BQP) are separate
| from NP - they are suspected to be neither a subset nor a
| superset of NP.
|
| Some problems in BQP are suspected to be in NP (integer
| factorization, for which the best known classical
| algorithm is sub-exponential, but we have a polynomial
| time quantum algorithm), but there is no known NP-
| complete problem for which a quantum algorithm is known,
| or even suspected to exist.
|
| Edit - some links:
|
| [0] https://www.scottaaronson.com/papers/npcomplete.pdf -
| chapter 4
|
| > If we interpret the space of 2n possible assignments to
| a Boolean formula ph as a "database," and the satisfying
| assignments of ph as "marked items," then Bennett et
| al.'s result says that any quantum algorithm needs at
| least ~n/2 steps to find a satisfying assignment of ph
| with high probability, unless the algorithm exploits the
| structure of ph in a nontrivial way. In other words,
| there is no "brute-force" quantum algorithm to solve NP-
| complete problems in polynomial time, just as there is no
| brute-force classical algorithm.
|
| [1] https://youtu.be/0jrybODBUpA?t=30m28s "P versus NP"
| gaze wrote:
| No. Quantum computers are not known to provide any speed
| up to any NP problems.
| tsimionescu wrote:
| That is a bit too strong a claim (even taking "NP" to
| mean "NP - P", since all P problems are also in NP).
|
| First of all, while not proven, it is considered most
| likely that integer factorization is _not_ in P, so
| potentially we already know of 1 NP-P problem which can
| have an exponential speed-up from a QC (Shor 's
| algorithm).
|
| Secondly, there is one non-exponential speedup that can
| potentially apply to even NP-complete problems - using
| Grover's algorithm to find an element in an unordered
| list with complexity O(sqrt(n)) instead of the classical
| O(n).
| mirekrusin wrote:
| Isn't the whole problem in there - as n - somehow this
| assumes that n-qubits can magically grow without a fuss -
| what if to entangle more quibits you need to cool the
| whole system down exponentially/using exponentially more
| energy? All those O(...) notations flip over, don't they?
| tsimionescu wrote:
| Assuming the current version of Quantum Mechanics is
| correct, no. Given that we know QM is not compatible with
| General Relativity, which means one or both of them
| _must_ be wrong, we could potentially discover some
| limitation of QM while investigating this.
|
| Ironically, if that were to happen, it would probably be
| a much more important boon for humanity than if we
| successfully build a working QC.
| jeremyjh wrote:
| I thought there were concerns about public key
| cryptography - factoring large numbers much faster with
| QC at least sounds plausible, but maybe it's just
| speculation ?
| tsimionescu wrote:
| That is true, but integer factorization is not an NP-hard
| problem, as far as we know at least. A quantum algorithm,
| Shor's algorithm, is indeed known to be able to solve it
| in polynomial time if you have a QC.
|
| It is suspected to be NP but not even NP-complete,
| nevermind NP-hard. It is suspected not to be in P, but
| that is not yet proven.
| kragen wrote:
| Integer factorization is obviously in NP, though as you
| say, whether it is in the P subset of NP is still an open
| question.
| tsimionescu wrote:
| I was trying to be careful with my language specifically
| to avoid this mistake, but I still messed up...
| kragen wrote:
| It's tricky!
| zh3 wrote:
| I've actually pushed rubidium ions around in UQ's setup, and a
| bunch of us had a tour and Q&A with the founder. It's
| incredibly detailed stuff (insane optical tables, and weeks
| tracking down a stray hair that was contanimating the high
| vacuum system). I'm still on the sceptical side, but some of
| the tricks they use to move things with atomic-level precision
| make it hard to imagine there won't be something useful coming
| out of it.
|
| Whether it will ever justify the investment is, of course,
| another question.
| packetlost wrote:
| There's a bunch of different modalities that have varying
| possibilities of being miniaturized, but neutral atom is
| probably the hardest (that I'm aware of). It's important to
| remember that basically no one who takes QC seriously thinks
| we're going to have quantum in smartphone-sized devices any
| time soon. It's really better to think of them as specialized
| co-processors than as general purpose computational units, of
| which we're more in the "mainframe" era than the "smartphone"
| era.
|
| > "look it responds sort of like a qubit!"
|
| And behave like them too ;)
| moralestapia wrote:
| I would argue against QC from a theoretical standpoint (i.e.
| will the asymptote of EC be enough to beat the asymptote of
| noise?) not from a technological one, recall that not long ago,
| a single transistor was a whole experiment on its own and today
| there's single chips with a trillion (!) of them.
| sgt101 wrote:
| 60 years ago.
| tsimionescu wrote:
| On the other hand, from the moment the idea of computing was
| first used as a top secret weapon until it became a
| commercially available solution was around 10-15 years (in
| 1936 Turing wrote his thesis on computability, in 1938, the
| Polish mathematicians researching Enigma built their "Bomba"
| machines to help with decryption, by 1948 the first working
| electronic computer was created, the Baby, and by 1951, you
| had UNIVAC1 which was being sold to corporations). Quantum
| computing has not advanced anywhere near this fast (because
| it is a much much harder problem). Past pace of technological
| advance can't be used to predict future pace in a quite
| different field.
| sgt101 wrote:
| Also, for many of the things we would use a QC for we have
| digital computers, and they pick most of the low hanging
| fruit... this was not the case when digital computers
| started out.
| galaxyLogic wrote:
| Right, think of fission fast progress but fusion very slow
| progress. Fission and fusion are very much about the same
| thing so they should be as easy right? But they're not.
| empiricus wrote:
| Fission is just putting two rocks together, and you get
| energy. Fusion is a little more complicated in practice.
| edgyquant wrote:
| There were simple computational devices going back
| centuries and depending on the definition even millennia.
| The axioms of computation were also entirely formalized and
| proven long before electronic computers were born
| tsimionescu wrote:
| True, I forgot especially about Babbage and Lovelace's
| contributions...
|
| Still, my point still stands if we limit it to electronic
| computers, I think.
| lupire wrote:
| The original computers were big because they were mechanical,
| and they shrunk by being reduced to electric and due to more
| precise engineering.
|
| QC are big because the energy levels are so high that they
| require complex equipment to focus energy and remove heat,
| akin to the tyranny of the rocket equation.
| daniel-cussen wrote:
| Gotta admit the transistorization of the computer and the
| exponential decay of size required for the transistor, and
| exponential decay in duration of the transistor to FO4 (switch
| states, it's much less than the clock cycle) was beautiful
| while it lasted. Like now it's back to the drawing board.
|
| .
|
| Same as airplanes, basically the same since 1960, like we fly
| on Super Fortresses with the bomb bays replaced with cargo
| holds...like different dispenser, and the plexiglass fishbowl
| artillery in the front done differently. I would love to be in
| one of those fishbowls, like all exposed flying at the horizon
| like panoramic view. So suicidal, like all aviation.
|
| Like not getting shot at like in Catch-22 though. Hopefully.
| bhelkey wrote:
| > Same as airplanes, basically the same since 1960, like we
| fly on Super Fortresses with the bomb bays replaced with
| cargo holds
|
| Nit picking, the B-29 Superfortress was a propeller driven
| aircraft [1]. Modern commercial planes generally have jet
| engines. Jet engines represent a leap forwards in aerospace
| engineering.
|
| [1] https://en.m.wikipedia.org/wiki/Boeing_B-29_Superfortress
| zitterbewegung wrote:
| We see a similar thing with Ai / ML where there is a huge
| amount of hype but applications of quantum computation are only
| restricted to searching an unstructured database, finding prime
| factors of a number , solving a linear system of equations ,
| computing knot invariants and the obvious one which is quantum
| simulation. [1]
|
| It would be better just exposing this as a library of functions
| and then hooking it up to a cloud service to solve. Which
| Amazon, Microsoft and IBM have. Microsoft and IBM are using
| their own hardware And Amazon is reselling other providers.
| [2,3,4,5]
|
| Researching post quantum cryptography algorithms are already on
| their way [7] but most likely feasible quantum computers are 80
| years away when I was reading a great deal of quantum algorithm
| papers as a class and I asked the professor how long it would
| take.
|
| The interesting strategy if you were to hack a organization
| which has encrypted backups would be to exfiltrate the backups
| and then wait for a quantum computer that could break it which
| is why post quantum encryption needs to be researched but the
| algorithms involved are still in their early stages.
|
| Post [1] https://en.wikipedia.org/wiki/Quantum_algorithm
|
| [2] https://quantumai.google/hardware [3]
| https://azure.microsoft.com/en-us/solutions/quantum-computin...
| [4] https://aws.amazon.com/braket/ [5]
| https://www.ibm.com/quantum [6]
| https://en.wikipedia.org/wiki/Post-quantum_cryptography?wpro...
| [7] https://pqcrypto.org/conferences.html
| mirekrusin wrote:
| State of quantum computing is much worse than AI/ML.
|
| AI/ML easily demonstrates superiority - from playing games,
| classification, translation, generative art etc.
|
| QC is stuck at no practical use with claims that it'll stay
| this way for decades, some claiming forever as there may be
| physical walls that can't be broken.
| zitterbewegung wrote:
| Totally agree should have played that much more up in my
| comment.
| sgt101 wrote:
| My current ML project is funded because the bank regulator
| said it would have to be done or there would be a big fine.
|
| I do not think that there will be a QC project done on the
| same basis for 40 years.
| seydor wrote:
| Because there was a spring?
| DebtDeflation wrote:
| The obligatory:
| https://scottlocklin.wordpress.com/2019/01/15/quantum-comput...
| BoppreH wrote:
| Unfortunately I work in cryptography, and breaking our algorithms
| is one of the tasks that requires the least number of qubits. And
| that doesn't depend on having a desktop quantum computer either,
| but only that a single state actor anywhere has a sufficiently
| large quantum computer.
|
| I'm a bit bitter that physics handed us this magical tool, and
| the best we managed so far is using it to invalidate decades of
| security research.
| JanisErdmanis wrote:
| It's rather easy to produce qubits and place them in a box. The
| hard part is to make them interact with each other in a
| controlled fashion thus, adding one qubit to a large system is
| substantially harder than adding it to a small one.
|
| The only true benchmark is a factorisation of numbers. Number
| 21 has been factorised with nudging. Let's wait for a number 45
| in the coming next decade.
| hannob wrote:
| > Unfortunately I work in cryptography, and breaking our
| algorithms is one of the tasks that requires the least number
| of qubits
|
| I don't think that is true (or maybe I'm underestimating how
| many qbits other uses of QCs take). Estimates are still in the
| many millions: https://cacm.acm.org/news/237303-how-quantum-
| computer-could-...
| BoppreH wrote:
| That's from three years ago, and for error-corrected RSA
| breaking. ECC has keys an order of magnitude smaller, and
| minimizing the number of quits to run Shor's is a hot area.
|
| And compared to other uses (quantum AI anyone?), it's
| surprisingly compact.
| tromp wrote:
| You only need a few thousand error-free qubits to implement
| Shor's algorithm for 256-bit Elliptic Curve Discrete Log,
| that will for instance break nearly all crypto. The
| "millions" is trying to account for the several orders of
| magnitude error correcting overhead.
| tsimionescu wrote:
| The difficulty of adding qubits increases super-linearly
| with the number of qubits (especially because of
| communication delay vs time to decoherence) , so "only" a
| few thousand is already very optimistic. Worse, the idea of
| "error-free qubits" is essentially like cold fusion - you
| can say the words and we understand what you mean by them,
| but they don't describe anything that can exist in
| practice.
| billti wrote:
| > The difficulty of adding qubits increases super-
| linearly with the number of qubits
|
| Is that true? Hardware from the likes of IBM and IonQ has
| already gone from < 10 to >= 20 "algorithmic qubits" [1]
| in the space of a few year.
|
| [1] https://ionq.com/quantum-systems/aria
| naasking wrote:
| Error-free qubits are a fantasy, error correction is a
| must. I'm not particularly worried about quantum computers
| breaking crypto anytime soon.
| hannob wrote:
| Sure, I just don't think error-free qubits are a thing (or
| will be in the future). I don't think anyone seriously
| expects quantum computing to work without error correction.
| lupire wrote:
| How many qubits vs larger keys?
| BoppreH wrote:
| I'm afraid the number of qubits doesn't grow fast enough.
| Here's[1] a tongue in cheek "Post-Quantum RSA" with 2 Terabit
| keys.
|
| [1] https://cr.yp.to/papers/pqrsa-20170419.pdf
| hackandthink wrote:
| Quantum Computers are a great research field. The physics and
| engineering problems are exciting.
|
| It's a case for research money. I wouldn't invest in it but
| billionaires could spend their money worse.
| galaxyLogic wrote:
| Yeah, they could buy Twitter :-)
| thom wrote:
| The main application of quantum computing is Cunningham's Law.
| Any time someone shows something is faster on a quantum computer,
| then you know it's worth spending some time proving that actually
| the classical algorithms could have been faster in the first
| place.
| robg wrote:
| Seems like true neuromorphoric computing has more of future than
| quantum computing. We assume processing power and iterations go
| together, but what happens when we get better at self-learning
| software like our wetware?
| tsimionescu wrote:
| A sfar as we know, the problem of solving the Schrodinger
| equation would be exponentially faster on a quantum computer
| than the fastest possible non-quantum computer. Given that
| "neuromorphic" computers are classical computers, we don't know
| of any way to achieve a similar speedup for this problem, so we
| can at least say that there are applications for which we need
| a QC if we want to solve them. Of course, it's possible that
| those are far fewer than "neuromorphic" computers, so it may
| make more sense to invest more in the latter.
|
| Note that I'm putting neuromorphic in quotes because it's
| mostly a marketing term, the resemblance between memirstors and
| neurons is at best symbolic.
| mabbo wrote:
| > They just produced a random distribution that would take a
| really long time to calculate by any other means. It's like this
| this guy stapling 5 M&M. That's a world record, hurray, but what
| are you going to do with it?
|
| And this is why I keep coming back to Sabine Hossenfelder.
| mrkramer wrote:
| I'm sick and tired of this pop science. Write research papers
| don't clot my YT feed.
| est wrote:
| This reads like some thing like IBM(r) Watson.
|
| There was indeed an AI boom at the moment, just not Watson.
| laurentoget wrote:
| "Problem is, a lot of CEOs in industry and the financial sector
| can't tell a bra from a ket"
|
| i do not know enough about quantum computing to judge whether
| this article is accurate or not, but it certainly is well written
| and entertaining
| atgctg wrote:
| I highly recommend "Quantum computing for the very curious"[0]
| for an introduction to quantum mechanics. I went through it
| years ago and can still remember the main ideas thanks to the
| built-in spaced repetition.
|
| [0] https://quantum.country
| powera wrote:
| It is remarkable how everybody only seems to comment on
| "spaced repetition" rather than anything involving quantum
| computing when they discuss that site.
|
| Regardless, memorizing a few facts won't help with reasoning
| about "is quantum computing even possible".
| mmplxx wrote:
| Maybe because it's pretty much the only essay that offers
| built-in spaced repetition?
| doliveira wrote:
| On a semi-related note, bra-kets are just magical. Programmers
| who deride mathematical notations, and claim we should abolish
| equations in favor of pseudocode, should try to get a glimpse
| of their power.
| lkoolma wrote:
| I agree that many in the financial sector do not know much
| about quantum computing, but it also does not seem that some in
| the quantum that do not understand the details of the problems
| that the financial sector has either. For instance, those in
| the capital markets/trading floors in Europe and North America
| do significant risk calculations with hundreds or a thousand
| variables on up to 100,000 positions with a certain confidence.
| Many of these risk calculations need to be reported nightly to
| regulators. These financial companies are paying many millions
| per year to AWS, Azure, or Google to do these calculations on
| classical computers. However, many parts of these calculations
| could be done with quantum computers relatively instantly,
| given enough qubits. I realize that the technology and
| reliability is not there today, but hopefully it will come
| soon. I would not be surprised if by 2035 using quantum
| computers to do many variable risk calculations would become
| (almost) mandatory for major European and North American
| financial companies.
| tsimionescu wrote:
| What makes you say this? Which particular quantum algorithm
| do you think gives an exponential speedup for multi-variate
| risk predictions? And why do you think there is any chance in
| hell that a quantum computer would exist by 2035 that could
| even store an input of the size you're talking about,
| nevermind have spare qubits to actually process it?
| vitiral wrote:
| I'm familiar with bras I think... what is a "ket"?
| capitalsigma wrote:
| It's physicist notation for inner products:
| https://en.wikipedia.org/wiki/Bra%E2%80%93ket_notation
| hprotagonist wrote:
| https://en.wikipedia.org/wiki/Bra%E2%80%93ket_notation
|
| a ket is |v>
| vitiral wrote:
| It seems I was NOT familiar with what a bra is...
| NiceKeeb wrote:
| It's the hermitian conjugate of the corresponding ket.
| adelarsq wrote:
| > director of research at Bank of America said that quantum
| computing will be "bigger than fire". The only way in I can see
| this coming true is that it'll produce more carbon emissions.
|
| I laugh so hard on this. But it's true.
| stephc_int13 wrote:
| The Quantum Computing fiasco is fascinating and underline quite
| few human nature flaws.
|
| - We're collectively less smart/rational than we think
|
| - People with money/power are not much better than average
|
| - We tend to be very gullible when we don't understand the
| underlying principles
|
| The same human flaws can be seen in UFO/Conspiracy theories and
| to some extent in the crypto/NFT scene.
|
| A lot of this is amplified to several orders of magnitude by
| incompetent journalism.
| logifail wrote:
| > - People with money/power are not much better than average
|
| I think it's way worse than that, the only things that people
| with money/power are better at ... is getting / hanging on to
| money and/or power.
|
| They're not better at anything apart from that, by any
| objective measure.
| stephc_int13 wrote:
| From my experience, people with higher social status (and
| thus money/power) tend on average to be somewhat smarter, but
| not by a large margin.
| SQueeeeeL wrote:
| A lot of that is correlated with more recreational time,
| better family lives (probably no one in jail), and higher
| quality education. This is the same logic the French
| aristocrats used to justify the oppression of the peasants,
| reading novels made them "better"
| seibelj wrote:
| Bitcoin is money the government doesn't control. I like it but
| statists don't.
| xaofnakj02 wrote:
| Plenty of anarchists (e.g. libertarian socialists) don't like
| bitcoin either.
| [deleted]
| seydor wrote:
| Rather simply, unfortunate coincidences. The people with money
| to invest happend to be computing-related people. "Quantum
| Computation" contains the word computation, which they
| understand, and Quantum, which stands for "mysterious, cool,
| ingenious". So they invested in. Something like "developmental
| neuroscience" is nowhere nearly as cool-sounding.
| quantum_mcts wrote:
| > weather is a non-linear system whereas quantum mechanics is a
| linear theory
|
| This lady have no idea what she is talking about.
| im-a-baby wrote:
| I believe the point is that quantum computers allow you to
| manipulate a linear combination of bits, whereas simulating the
| weather would require non-linear combinations. It's unclear how
| a QC would help simulate something like that better than a
| classical computer.
| quantum_mcts wrote:
| Quantum algorithms are nonlinear. If someone is saying
| "quantum mechanics is a linear theory" as a counterargument
| to anything QC related. Then that person has no idea what
| they are talking about. Because they likely never cared to
| learn event the basics of QC.
| raziel2701 wrote:
| Quantum mechanics is a linear theory. That's not an
| erroneous statement.
|
| Quantum computing and quantum mechanics, not the same
| thing.
| fauigerzigerk wrote:
| I don't think it's quite as simple as that:
|
| "New Quantum Algorithms Finally Crack Nonlinear Equations.
| Two teams found different ways for quantum computers to
| process nonlinear systems by first disguising them as
| linear ones."
|
| https://www.quantamagazine.org/new-quantum-algorithms-
| finall...
| mikewarot wrote:
| I believe that she was using the term "linear" in the
| computational/signal processing sense, not that of computing.
|
| In electronics, in a linear system, you can decompose a complex
| waveform and analyze its response to each frequency discretely,
| and when you recompose them, you get a correct answer.
|
| In a non-linear system, such as a mixer, no such analysis is
| possible, you have to consider all of the frequencies, and
| their levels at the same time.
|
| Also consider that most algorithms are founded on a
| deterministic computational method.
| Animats wrote:
| The "next big thing" isn't coming along well.
|
| * 2017 - the year of 3D TV.
|
| * 2019 - the year of VR
|
| * 2021 - the year of the Metaverse.
|
| All duds, or no more than niche products. Related duds include
| quantum computing, fusion power, and self-driving cars. (There
| are self-driving cars that work, from Waymo and Cruise, but
| they're a long way from being cost-effective.)
|
| On the other hand, there's lots of work to be done deploying the
| stuff that works. Solar. Wind. Batteries. Electric cars.
| Desalination plants. Automated manufacturing. Electrical
| transmission infrastructure to get power to where it's needed.
| All are profitable. None has either huge margins or
| monopolization potential. This discourages the Silicon Valley
| funding model.
| alerighi wrote:
| Let's add to the list crypto currencies and all the related
| stuff, such as NFT, that already made a lot of people loose a
| lot of money.
| legulere wrote:
| Sadly crypto currencies aren't dead yet like 3D television
| and is causing massive CO2 emissions.
| g42gregory wrote:
| Can somebody name one practical application of QC? Perhaps not
| right now, but within 3-5 years? It can't be prime number
| factorization in encryption, since people will just switch (and
| already have) to elliptic curves.
| photochemsyn wrote:
| Quantum computation plays a starring role in some of my favorite
| recent sci-fi novels (Hannu Rajaniemi's Quantum Thief, for
| example), but like the William Gibson's Neuromancer world
| (powered by Eastern Seaboard Fusion Reactors), it's just
| interesting and speculative sci-fi.
|
| Happily, there are many fields beside computing where quantum
| technology comes into play - better and cheap chip fabrication,
| semiconductor lasers and diodes, all kinds of materials science
| research, and of course, solar energy conversion systems modeled
| on the photosynthetic apparatus:
|
| https://sci-hub.se/10.1038/nature22012
|
| Romero, et al. (2017). Quantum design of photosynthesis for bio-
| inspired solar-energy conversion. Nature
|
| As far as what today's working scientists will pursue, the silly
| popular notion that researchers are free to explore whatever they
| find exciting and interesting is mostly nonsense; successful
| researchers in the modern science system are as keen as hounds on
| the scent for new funding disbursements from the major federal
| agencies (and some private sponsors). If the money dries up, they
| turn their attention to other things, except perhaps for a few
| back-burner projects handed off to some hopelessly naive yet
| charmingly enthusiastic grad student.
| benreesman wrote:
| Eastern Seabord Fission Authority ;)
|
| Gibson got some stuff wrong, but it's borderline scary how much
| he got right. Book is like 43 years old or something.
| nobodyandproud wrote:
| Can slow neutrinos, in principle, be used to build qubits?
| ouid wrote:
| The biggest obstacle to the realization of quantum computing is
| not technical, imo, but theoretical.
|
| it is well known, but not to laypeople, that a quantum computer
| is efficiently (quadratic overhead) simulable if it only operates
| on the eigenstates of the generalized Pauli matrices with the so
| called Clifford operators. This is a really fancy way of saying
| that this group action is not dense in the unitary operators,
| which is itself a fancy way of saying that it behaves like
| rolling a die, instead of like rolling a ball.
|
| In order to achieve density in the unitaries it suffices to
| construct a single state that is not one of these magic states
| (their language, not mine), to a sufficiently high level of
| purity.
|
| The much touted paper which claims to do this only succeeds in
| showing that the problem is equivalent to some other problem
| which we also do not know how to solve, (creating many, worse
| _separable_ copies of this state) and there is no particular
| reason to believe that it can be. Moreover given what it would be
| able to do, it seems much more likely to me that there is a
| proof, waiting to be discovered, that there is a fundamental
| obstruction to harvesting such a state without at least waiting
| as long as you would have to wait to do your computation the old
| fashioned way.
| raziel2701 wrote:
| No it definitely is technical, we need a lot of materials
| science and RF electronics to get things to work better with
| each other. We need better material growth and device
| fabrication techniques and better readout schemes.
| Strilanc wrote:
| Could you cite the "much touted paper" you're talking about?
|
| In my view, making the noisy physical magic states is the
| _easy_ part of the distillation process. You reset a qubit,
| then rotate it 90deg around the Y axis, then 45deg around the Z
| axis. That 's the magic state. Note that the tolerance on those
| rotations is forgiving: getting them to within 10deg, 95% of
| the time, is sufficient. All the error correcting code stuff
| that follows has fidelity requirements an order of magnitude
| stricter.
|
| As you note, there'd need to be some unforeseen obstacle for
| state prep to be the showstopper. Given how apparently easy it
| is to make these states, I think any obstacle like that would
| basically have to falsify quantum mechanics as we know it. It
| would be like finding out that light can't be diagonally
| polarized.
| ouid wrote:
| The ability to rotate 45 degrees is equivalent to the
| construction of a magic state, as you have correctly
| identified, as it is not a clifford operator, and adding it
| to your generators gives universal quantum computation on its
| own. You have pushed the problem sideways.
|
| This is the paper, https://arxiv.org/abs/quant-ph/0403025,
| and it is well understood by the paper that the independence
| of the noisy magic states is necessary for the distillation
| process to proceed. Note that the probability of having some
| entanglement between your partial states goes up rather
| dramatically with the number of them that you have, and not
| obviously in a way that you can do anything about.
| Strilanc wrote:
| Thanks for the reference.
|
| > _Note that the probability of having some entanglement
| between your partial states goes up rather dramatically
| with the number of them that you have_
|
| Entanglement is not binary, it is continuous. If you start
| with states like CPHASE(5deg)|TT>, a few rounds of
| distillation will have turned them into states like
| CPHASE(0.0000000000000001deg)|TT>. Sure the output states
| are "still entangled", but the amount of entanglement is so
| negligible that you don't have to care. Such small
| distortions won't prevent trillion step computations from
| working.
| [deleted]
| TheRealPomax wrote:
| is there a tl;dr? This is a very long post that doesn't seem to
| want to get to point by the time you made it halfway through.
| sandworm101 wrote:
| People also forget that analogue computers, mechanical devices to
| perform calculations, can also be faster than digital computers
| in some situations. That doesn't make them commercially viable.
|
| Seems to me that most all of the quantum computing community is
| trying to be in the right place when they can start cracking
| current encryption standards at a commercial scale. At that
| moment, anyone with a functional quantum computer will drown in
| money. Then a few weeks later new quantum-resistant algorithms
| will appear and the gold rush will end. All the other quantum
| projects seem like attempts to keep ones foot in the market while
| waiting for that day.
| charlieyu1 wrote:
| Quantum resistant encryption is already available
| JBits wrote:
| Would you be able to give any examples of quantum resistant
| encryption algorithms? I'm not familiar with the field and my
| most recent knowledge is a post on hn saying that some post
| quantum candidates had been broken by old laptops.
| GTP wrote:
| The whole symmetric key cryptography (e.g. AES) ia already
| quantum resistant. The problem only holds for public key
| encryption, but as the other commenter pointed out, there
| are already promising algorithms.
| kragen wrote:
| It's potentially quantum-resistant depending on how it's
| used. Grover's algorithm still reduces your effective key
| length by half in many situations.
| JBits wrote:
| That's nice, I didn't realise AES was quantum resistant.
|
| However, an algorithm being promising doesn't mean it
| works. Do you know how well the development of these
| other techniques is progressing?
| adrianN wrote:
| https://en.wikipedia.org/wiki/Post-quantum_cryptography
| crazygringo wrote:
| You've got me intrigued -- what are examples of mechanical
| devices being faster than digital ones? Assuming you're talking
| man-made.
|
| I'm trying to imagine and am totally stumped.
| 323 wrote:
| > _The Water Integrator was an early analog computer built in
| the Soviet Union in 1936 by Vladimir Sergeevich Lukyanov. It
| functioned by careful manipulation of water through a room
| full of interconnected pipes and pumps. The water level in
| various chambers (with precision to fractions of a
| millimeter) represented stored numbers, and the rate of flow
| between them represented mathematical operations. This
| machine was capable of solving inhomogeneous differential
| equations._
|
| https://www.techspot.com/trivia/97-1930s-which-countries-
| bui...
|
| https://en.wikipedia.org/wiki/Water_integrator
| robocat wrote:
| Here's an analogue computer called the MONIAC from ~1949
| that calculates monetary flow in an economy: https://www.en
| gineeringnz.org/programmes/heritage/heritage-r... with a
| fairly naff video of it operating but captures the essence:
| https://m.youtube.com/watch?v=rAZavOcEnLg
|
| I like the COMPAQ branding added to it!
| nine_k wrote:
| If your values are in the mechanical domain, doing a _simple
| and fixed_ computation in the mechanical domain may be more
| efficient. An example would be a mechanical differential in a
| rear-wheel drive car [1], or a swashplate in a helicopter
| [2].
|
| [1]: https://en.wikipedia.org/wiki/Differential_(mechanical_d
| evic...
|
| [2]: https://en.wikipedia.org/wiki/Swashplate_(aeronautics)
| kragen wrote:
| Those aren't examples of computation; they're examples of
| power transmission. If you found a way to compute the same
| information as a swashplate or a differential with a lower-
| cost, higher-speed, more reliable, lower-power device, it
| wouldn't replace the swashplate or differential. In fact
| we've had such devices for over a century, because the
| swashplate is just multiplying two quadratrue sine waves by
| constants and summing them, and the differential is just
| adding (or subtracting).
| naasking wrote:
| > You've got me intrigued -- what are examples of mechanical
| devices being faster than digital ones? Assuming you're
| talking man-made.
|
| You might be able to build a fluid device to test a property
| faster than you can simulate the fluid dynamics in full
| detail. Perhaps not on the first iteration, but iterating
| small changes to get a desired result could certainly be
| faster than simulating it, for simple systems.
| efferifick wrote:
| > Spanish Catalan architect Antoni Gaudi disliked drawings
| and prefered to explore some of his designs -- such as the
| unfinished Church of Colonia Guell and the Sagrada Familia --
| using scale models made of chains or weighted strings. It was
| long known that an optimal arch follows an inverted catenary
| curve, i.e., an upside-down hanging chain. Gaudi's upside-
| down physical models took him years to build but gave him
| more flexibility to explore organic designs, since every
| adjustment would immediately trigger the "physical
| recomputation" of optimal arches. He would turn the model
| upright by the way of a mirror placed underneath or by taking
| photographs.
|
| http://dataphys.org/list/gaudis-hanging-chain-models/
| alerighi wrote:
| Basically anything that has to do with processing an analog
| signal. It's always faster to do that with analog electronics
| rather than using a ADC, doing the computation in the digital
| domain, and then getting the result back to the analog world
| with an ADC.
|
| One example, if I need something that when two switches are
| triggered will turn on a light bulb (basically an AND gate)
| it's obviously faster doing that with an analog (mechanical)
| device, that is the two switches wired in series, than
| acquiring the signal with a microcontroller and outputting a
| signal to turn on the light bulb.
|
| Thinking about the industrial world, there are cases where
| you have constraints about speed and real time that make
| sense to do signal processing with analog components rather
| than digital ones. And that was always the case before
| computers where invented, by the way (missile guidance
| systems were purely analog, as one example, you can do a lot
| of stuff!)
| sandworm101 wrote:
| It all comes down to the definition of "faster". Standard
| testing is based on binary computations, the idea that there
| is a finite answer. Take a fire control computer on a ship.
| It has maybe 30 inputs, all essentially analogue dials. It
| combines them into a continuous analogue answer, a firing
| solution for the guns (elevation + azimuth). It doesn't do
| that "X times per second" or to a particular level of
| accuracy. The answer is always _just there_ , constantly
| changing and available to whoever needs it whenever they ask
| for it, measurable to whatever level of precision you want to
| measure. If you measure the output every microsecond, then it
| is a computer that can generate an answer every microsecond.
| But that speaks more to the method of measurement than the
| speed of the machine.
| kragen wrote:
| It's true that we measure the speed and precision of analog
| "computers" differently from how we measure them for
| digital computers, but it does not therefore follow that
| analog "computers" are all infinitely fast and perfectly
| precise. Any analog system has a finite bandwidth; signals
| above some cutoff frequency are strongly attenuated and
| before long are indistinguishable from noise. And analog
| systems also introduce error, which digital computation
| often does not. When digital computation does introduce
| error, you can decrease the size of the error exponentially
| just by computing with more digits, and there is no
| equivalent approach in the analog world.
|
| For mechanical naval fire control computers the cutoff
| frequency is on the order of 100 Hz and the error is on the
| order of 1%. You won't learn anything interesting by
| sampling them every microsecond that you wouldn't learn by
| sampling them every millisecond.
| galaxyLogic wrote:
| The simple sundial calculates the time based on Sun's
| position relative to Earth
| WorkerBee28474 wrote:
| Fire control computers, like on a navy ship, were faster than
| digital computers of the day. YouTube has a number of videos
| on them.
|
| An opamp performs multiplication faster than a digital
| computer (speed of light vs a few cycles). It's not super
| useful on its own, but it does fit the criteria.
|
| In Veritasium's video 2/2 on analog computers [0] they show
| some startup products near the end.
|
| [0]https://youtu.be/GVsUOuSjvcg?t=898
| gaze wrote:
| What no. Opamps don't multiply and they don't operate at
| the speed of light. They have some timescale that goes like
| their bandwidth, which depends on their feedback path.
| Animats wrote:
| Yes, feedback op-amps definitely have bandwidth limits.
| Although you can get ones in the gigahertz range now.
|
| Analog multiplier ICs are available.[1] They're not
| common, and they cost $10-$20 each. Error is about 2%
| worst case for that one. There are several clever tricks
| used to multiply. See "Gilbert Cell" and "quarter square
| multiplier".
|
| [1] https://www.digikey.com/en/htmldatasheets/production/
| 1031484...
| boltzmann-brain wrote:
| The propagation time around the feedback loop is still
| (length of loop) / (speed of light*slowdown constant), so
| yes, "at the speed of light".
| osamagirl69 wrote:
| This is absolutely not true, the speed of analog circuits
| is (by a significant margin) determined by parasitic
| capacitance, inductance, and resistance of the
| components. To put numbers to it, a typical high
| performance analog multiplier might have a loop length of
| 1cm for the feedback path. This circuit should
| theoretically operate at 30GHz, but realistically such
| circuits operate with a bandwidth measured in megahertz.
| ahelwer wrote:
| Cracking encryption is basically irrelevant as a quantum
| computing application. Post-quantum encryption algorithm
| development proceeds apace and the messaging is already "if you
| want this to still be encrypted 30 years from now, start using
| post-quantum encryption today." Anybody caught with their pants
| down the day quantum computers can actually crack 4096-bit RSA
| simply isn't serious about security.
| less_less wrote:
| Yeah, people who are serious will have probably switched to /
| hybridized with PQC before a cryptographically relevant
| quantum computer is built. Unless some state agency has a
| secret one. So the main relevance might just be forcing
| everyone to switch / hybridize.
|
| At the same time, from history it seems almost certain that,
| if indeed a CRQC ever gets built, a significant number of
| users will not have secure PQC rolled out on day 0.
| tsunamifury wrote:
| "Anyone who doesn't have weaponized anthrax isn't serious
| about home defense."
|
| This forum gets more and more detached from reality every
| day.
| [deleted]
| thadt wrote:
| Not _this_ forum, but rather the US government:
|
| "NSA intends that all NSS will be quantum-resistant by
| 2035, in accordance with the goal espoused in NSM-10."
|
| Source: https://media.defense.gov/2022/Sep/07/2003071836/-1
| /-1/0/CSI...
| ahelwer wrote:
| The list of things that have to be encrypted 30 years from
| now is very, very small. I doubt any (many?) people here
| have contact with any of it. I don't understand your
| analogy at all, sorry.
| galaxyLogic wrote:
| What about my crypto-currency? Imagine a quantum computer
| could crash all them crypto-markets and bring about an
| economic collapse.
| sandworm101 wrote:
| The message I sent to my girlfriend last night. In 30
| years, when I am running for president, that
| email/text/signal message might come back to haunt me
| should anyone be able to decrypt the archived/encrypted
| copies held by state agencies.
|
| Anything that is private today is private for a reason.
| That reason doesn't automatically disappear over time.
| ahelwer wrote:
| This is indistinguishable from hoarder logic. Such things
| straight up don't matter on the scale of decades. The US
| DOJ has a policy of automatic declassification after 25
| years.
| sandworm101 wrote:
| >> hoarder logic.
|
| And the US intelligence community is the greatest data
| hoarder on the planet, rivaled only perhaps by the
| combined forces of facebook/google.
| crazygringo wrote:
| You do realize that because of #metoo, claims and
| evidence of people's actions 30, 40 years ago are being
| judged in the court of public opinion, if not in actual
| courts?
|
| I don't think you've been paying attention to the news.
|
| Also the US government isn't a great example. JFK was
| assassinated in 1963 and all records surrounding that
| _still_ haven 't been released.
|
| The idea that people don't care about secrets across the
| span of decades is utterly wrong.
| [deleted]
| charcircuit wrote:
| How does encryption impact #metoo? The person waking the
| accusation would have a decrypted version of the message
| and even if they didn't they could accuse without proof.
| less_less wrote:
| It's definitely not true today: for example, there are no
| NIST standards (and I'm not sure about standards from other
| governments) for quantum-resistant key exchange. Several
| such systems have been developed, and NIST has even chosen
| one to standardize, but they aren't standardized or widely
| deployed yet.
|
| But I expect that in 5-10 years, most security systems
| designed by competent professionals (up-to-date OS security
| services, TLS servers, SSH servers, VPN, firmware update
| systems etc) will have post-quantum crypto enabled by
| default. And I expect it will take longer than that to
| build a QC that can break classical crypto.
|
| More likely it will play out like the SHA-1 break: all
| professional security engineers should have switched off
| SHA-1 (at least for unkeyed hashing) years before any
| collision was found, and users who apply security patches
| should therefore by mostly up to date, but I'm sure some
| are still using the older crypto.
| kragen wrote:
| Analog computers have mostly been electronic rather than
| mechanical for 60 years. "Digital" and "electronic" are not
| synonyms; they are completely orthogonal. Analog computers 60
| years ago were mostly built with op-amps rather than shafts and
| gears, despite the survival of WWII-era mechanical naval fire
| control computers. That's in large part because human-scale
| shafts and gears max out with signals in the hertz to kilohertz
| range, while even the most ordinary op-amps can handle signals
| in the tens of kilohertz range (which has been true for 100
| years) and op-amps in the tens of megahertz range have been
| available for 60 years. Also, shafts and gears have inherent
| errors of around 1% from backlash, while op-amps can usually do
| better than 0.1% (again, for the last 100 years) and by 60
| years ago better than 0.001%.
|
| So with off-the-shelf electronics an analog computer can
| compute 1000 times faster with 1000 times better precision than
| if it were mechanical. Until the 01960s they used vacuum tubes
| and so used more power and were less reliable; since then
| electronics have used less power and been more reliable.
|
| Today we still use plenty of analog computation, but it's
| pushed to the margins. Every sound card has an antialiasing
| analog filter on its front end before switching to the digital
| domain. Even software-defined radios still use analog
| electronics to upconvert and downconvert signals between
| baseband or IF and the RF. Your Wi-Fi card can't sample that
| 2.4 GHz signal at its 4.8 Gsps Nyquist rate; doing that is not
| impossible but still requires high-end digital electronics.
| Submillimeter-wave communication is very much dependent on
| precise analog signal processing to modulate your desired
| signal into the hundreds of GHz range.
|
| ("Precise" in this case doesn't mean with linearity errors as
| low as 1%.)
| gaze wrote:
| Broad strokes this article raises some ok points. She's wrong
| about SC qubit coherence times and she's wrong about
| refrigeration being any kind of bottleneck. You could buy a
| dilution fridge from bluefors off the shelf. The microwave
| hardware and optics and all this stuff costs an order of
| magnitude more. Just kind of a low effort article. If you want to
| beat on SC qubits, bring up cosmic rays. She'd know that if she
| passed this by an expert, which I guess she's too smart to do.
|
| Either quantum computers pan out over the time investors stay
| interested or they don't. It's not unlike any other technology.
| As far as physicists feeling embarrassment, why should we? One,
| we're largely incapable of feeling it, and two, we tried and
| that's cool.
|
| You have these VCs who have a very narrow view of how the future
| should be (chiefly being that which makes them richer) so you can
| only pitch so many technologies that fit that mold. To be blunt,
| find me a better technology that could potentially push the
| boundaries of human capability or understanding or whatever that
| VCs will invest in. Beats the hell out of VR. Is it cooler than
| shooting stuff into orbit? Seems on par to me.
| JBits wrote:
| I would also say that Sabine is wrong on a number of points,
| like coherence times, but I thought that the problems with
| cooling were correct. Since I don't know much about cooling,
| would you be happy to elaborate?
| gaze wrote:
| See my other response
| raziel2701 wrote:
| Cooling is definitely a problem is your aim is to cool down the
| millions of physical qubits required to get the thousands of
| logical qubits needed to do an actually useful quantum
| computation. No one has scaled up their qubit technology to
| achieve millions of physical qubits, and this is going to be a
| very big computer with tons of thermal mass that needs to be
| cooled down sub-kelvin. That is a substantial engineering
| challenge.
| gaze wrote:
| Qubits are getting smaller at the same time their coherence
| times are getting longer. The millions of qubits figure
| assumes pretty crappy coherence times. I don't see any reason
| why you wouldn't fit a future QPU on a 4 inch wafer or some
| kind of stack of them.
|
| Finally, again, dil fridges are a solved problem. Not only
| are they solved but there's a ton of room for improvement.
| They're very inefficient. You can just make bigger ones with
| more dil units.
|
| That leaves the wiring, but you remove a lot of that with
| cryosilicon computers and multiplexers.
| c7b wrote:
| Not the first article on HN to make that point [0]. Feels a bit
| like whistleblowers starting to come out.
|
| [0] https://news.ycombinator.com/item?id=32722374
| rippercushions wrote:
| Did we even have a quantum summer? The hype is nowhere near what
| we've seen for (say) blockchain, AI or self-driving cars.
| indymike wrote:
| That hype was back in the 00's. This one could be like AI,
| where it had a huge hype cycle in the 80s, and exploded over
| the last decade. Or not.
| jhpankow wrote:
| There was as far as marketing. My family members stopped asking
| me about ads they saw on TV for IBM's quantum computers.
| CarbonCycles wrote:
| I've started to adopt a hedging strategy (i.e. short plays)
| with IBM marketing...seems like everything they touch dies
| (horrendously).
|
| ETA..in case anyone is interested, the author of the article
| is a theoretical physicist, which lends more credibility to
| the article.
|
| https://en.wikipedia.org/wiki/Sabine_Hossenfelder
| tambourine_man wrote:
| Oh yes, we did. Remember Google announcing quantum supremacy?
| At the very least a spring.
| mathattack wrote:
| The hype is smaller, though I've seen my share of grifters in
| the market. It's also not a vote of confidence to see IBM
| behind much of the research.
| rusticpenn wrote:
| I think that is a good thing. There are usecases being found
| for quantum computers, but nothing that can't be done with
| normal computers yet.
| moffkalast wrote:
| The problem with quantum computers is that every time someone
| thinks of a good application, there's a scientist dropping in
| with an "ackchyually that's not how any of this works". At this
| point I'm convinced that RNG is the only thing quantum effects
| are actually usable for.
| JanisErdmanis wrote:
| Already in winter mentality :)
| ahelwer wrote:
| As someone who has spent a fair bit of time figuring out how to
| explain quantum computing to people I've come to the conclusion
| that there are only two possible ways for people to understand
| it:
|
| (1) mathematically
|
| (2) as a finite list of things quantum computers can and cannot
| do
|
| and most people are not going to understand it mathematically,
| least of all money people who have to watch and evaluate 10
| powerpoint pitches in a day or whatever. Without the math you
| cannot possibly explain how superposition and entanglement work,
| and even _that_ explanation requires your audience already
| understand how _classical_ computers work. So you are often
| reduced to saying "Here is what we think quantum computers will
| be able to do. The timeline for accomplishing this is at least a
| decade out. Here are some other things that people have said
| quantum computers can do which they definitely will not be able
| to do." But then you're purely relying on your audience believing
| you based on your credentials rather than following their own
| reasoning from a place of understanding. Someone else can come in
| with different credentials and say different things, motivated by
| money or simple ignorance mixed with hope, and now your audience
| is playing the credential evaluation game rather than the quantum
| computing capability evaluation game. Mix in low interest rates
| and a few people who have learned what to say to get attention,
| and you get the current state of things.
|
| There is a quiet core of real quantum computing research
| happening, surrounded by a moat of noise and hype that is
| required to interface with investors and the public. My sincere
| hope is that this quiet core accomplishes real advances before
| the music stops.
| afiori wrote:
| The wrong explanation I like about QC works is to describe it
| as 2^n many computers doing the same computations on related
| data, with the caveat that you can only query one at random.
|
| Sprinkle some hand waiving around how you can "average them all
| together" or have them "check the answer with each other"
| before querying them.
| naasking wrote:
| I was just thinking about this analogy to parallel
| computation. It works well enough, and gives a better
| intuition than a list of things a QC can and cannot do, as
| long as they can understand that these aren't regular
| computers and so reading the result has some restrictions
| which is why it only provide exponential speedup on some
| problems.
| JanisErdmanis wrote:
| In my opinion, researchers are not honest when they do explain
| quantum computers mathematically. I have never seen an
| explanation with a narrative:
|
| - Here are matrices, this is how we multiply them and get a
| resulting vector.
|
| - Here are special kinds of matrices SU(N) which leave |\Psi|^2
| invariant, and here is an example for multiplying.
|
| - Quantum computers are just SU(N) matrix multiplication
| accelerators.
|
| At this point, no hype can survive and neither funding.
| ahelwer wrote:
| I don't think that's quite true. The product state has
| exponential size so you'd also need some kind of tensor
| oracle that could manipulate an exponential quantity of
| information in linear time.
| JanisErdmanis wrote:
| It's true that the product state is exponential in size.
| That's why the size of the quadratic matrix SU(N) matrix is
| N = 2^M, where M is the number of qubits. To my knowledge
| that's the only thing that is exponential there.
| ahelwer wrote:
| Hmm, that seems correct then. This is interesting, would
| you consider extending the explanation and posting it as
| an answer to this question?
| https://quantumcomputing.stackexchange.com/q/5459/4153
| JanisErdmanis wrote:
| The question of the precision of number representation in
| SU(N) is an interesting one. It's only a different
| question :)
| mgraczyk wrote:
| The video mostly seems reasonable, but the economic arguments
| toward the end seem off base to me.
|
| Hossenfelder describes a situation in which universities rent
| equipment from large companies, but fits this into a worldview in
| which quantum computing as an industry will not be commercially
| viable.
|
| But isn't this exactly what happened with the internet and other
| new forms of large scale computation? Initially demand came
| largely from academia (or government via defense), companies
| competed on cost and usability. After a few years or decades of
| competition and scaling, the technology became so commercially
| useful that it's now ubiquitous. Why won't that happen with
| quantum computers, why would that be a bad thing, and why
| shouldn't academics want to be working on that?
| rini17 wrote:
| Classical computers were solving all kinds of useful problems
| since the beginning.
|
| Quantum computers on the other hand, don't appear to be good
| for anything now and in foreseeable future.
| stevefan1999 wrote:
| Guys stop saying there is winter this and winter that, it's all
| part of the Gartner hype cycle:
|
| 1. it all started with a technology trigger (much to the like of
| early AI development by Turing and McCarthy)
|
| 2. then we reach the Peak of Inflated Expectations (trying to
| solve real world hard problems like Travelling Salesman)
|
| 3. and swamp through the Trough of Disillusionment (Death of LISP
| machine and overall major AI projects halts)
|
| 4. until the Slope of Enlightenment (accidental discovery of
| using GPU to accelerate AI computation)
|
| 5. and finally reaching the Plateau of Productivity (developing
| Tensorflow, PyTorch, and the overall AI democratization though
| the use of DL and AutoML).
|
| We have just barely in between the stage of Peak of Inflated
| Expectations and going to Trough of Disillusionment for Quantum
| Computing and very much likely to stay for a while. Don't you
| worry child, It's all part of the cycle.
| pessimizer wrote:
| Guys, stop saying Gartner hype cycle this and Gartner hype
| cycle that. Not every failing overhyped idea is secretly a
| future winner. Sometimes, there's actually a 3D TV winter.
| Animats wrote:
| From the article: _" The record breaking "useful" calculation for
| quantum computers is the prime-number factorization of 21. That's
| the number, not the number of digits. Yes, the answer is 3 times
| 7, but if you do it on a quantum computer you can publish it in
| Nature. In case you are impressed by this achievement, please
| allow me to clarify that doing this calculation with the standard
| algorithm and error correction is way beyond the capacity of
| current quantum computers. They actually used a simplified
| algorithm that works for this number in particular."_
|
| Oh. I thought things were further along than that.
| mirekrusin wrote:
| Apparently that's what it is and noise seems to be a huge
| problem - as it seems to be growing exponentially? Think crazy
| cool fridges that need to be orders of magnitude better, not
| just linearly better, if you want to entangle more qubits.
| time_to_smile wrote:
| It's wild that I've a seen a few linkedin invites and even job
| posting for "quantum computing AI". The tone is always along
| the lines of building up your quantum computing software
| development skills since it will be the next big thing in
| industry.
|
| I've worked with quantum computing researchers before (I mean
| in the same building not doing the work), it's interesting
| work, but we're still at the stage where a focused background
| in physics doing research in is the prereq, not skills with
| quantum algorithms and their implementations. "Programming
| quantum computers" is still physics not software engineering.
| csande17 wrote:
| There have been a lot of claims of larger numbers, but they all
| rely on some combination of (a) "classical preprocessing",
| where you find the answer on a normal computer first and use it
| as an input to the quantum algorithm, and/or (b) selecting
| numbers with extremely specific mathematical properties.
| UIUC_06 wrote:
| > Quantum computers are promising technology, yes, but the same
| can be said about nuclear fusion and look how that worked out.
|
| I've been following Sabine for quite a while. She's really
| working on her snark.
___________________________________________________________________
(page generated 2022-11-05 23:01 UTC)