[HN Gopher] The Google Willow Thing
___________________________________________________________________
The Google Willow Thing
Author : Bootvis
Score : 360 points
Date : 2024-12-10 16:34 UTC (6 hours ago)
(HTM) web link (scottaaronson.blog)
(TXT) w3m dump (scottaaronson.blog)
| mupuff1234 wrote:
| I just want to know if the stock movement is justified or not.
| Vecr wrote:
| Stock movements aren't generally justified.
| crazygringo wrote:
| Oh wow it was up 6.2% at one point this morning from yesterday,
| now 4.6%.
| dboreham wrote:
| You never know the reason for a stock move. Could be that
| people see Oracle's poor results today as reason GCP will make
| more money.
| crazygringo wrote:
| If you're a journalist and simply phone a few institutional
| investors who make up the bulk of this kind of trading and
| with who you have a trusting relationship, they'll tell you.
|
| If they all mostly agree, that's your answer.
|
| And it's almost always what you assumed anyways from the
| news, because this stuff isn't rocket science.
|
| So for all practical purposes, yes actually you _usually do_
| know, whenever a stock movement is large enough that it 's
| clearly outside the normal noise of day trading.
|
| I mean, can you _prove_ the reason with 100% mathematical
| certainty? No. But can you be 99% sure? Of course.
| praptak wrote:
| I want the ability to answer such questions with an accuracy
| slightly over 50%.
| melvinmelih wrote:
| Depends on which universe you're talking about.
| vasco wrote:
| You don't need a quantum computer to know everything from now
| until the end of times has already been priced in.
| aeternum wrote:
| >it would also take ~10^25 years for a classical computer to
| directly verify the quantum computer's results!!
|
| This claim makes little sense. There are many problems that are
| much easier to verify than to solve. Why isn't that approach ever
| used to validate these quantum computing claims?
| svachalek wrote:
| I think he was making that exact point in this blog.
| aidenn0 wrote:
| Right, Factoring and discrete logs both come to mind; is
| Google's quantum computer not able to achieve measurable
| speedups on those versus classical computation?
| fastball wrote:
| Google's chip is not general enough to perform any quantum
| algorithm.
| tmvphil wrote:
| It is perfectly general, but the error rate is too high to
| operate all qubits simultaneously for more than a few tens
| of gates without error. This is why error correction is
| needed but then you need orders of magnitude more physical
| qubits to deal with the overhead.
| pitpatagain wrote:
| That's exactly correct, this chip cannot do either of those
| things yet. Which is why they use this toy-ish random circuit
| sampling problem.
| Filligree wrote:
| Not a large enough speedup to factor something that couldn't
| be done on a classical computer.
|
| Well, really it can't run them at all, but a more-general
| computer this size which could, still wouldn't be large
| enough.
| pitpatagain wrote:
| Because we don't currently know a problem like this that both
| has a quantum algorithm we can run on this type of device with
| expected exponential speedup and has a fast classical
| verification algorithm. That's exactly the author's point/he
| has been advocating for quite a while the importance of
| researching such an example that would be better to use.
| qnleigh wrote:
| Depends on what you mean by "this type of device." Strictly
| speaking there are many efficiently verifiable quantum
| algorithms (including Shor's algorithm, the one that breaks
| RSA). But if you mean "this particular device," then yes,
| none are simple enough to run on a processor of this scale.
| gyrovagueGeist wrote:
| They likely mean on any of the current era of NISQ-like
| devices (https://en.wikipedia.org/wiki/Noisy_intermediate-
| scale_quant...) like this one or quantum annealers.
| hammock wrote:
| Do we have any proof or evidence that such a problem even
| exists?
| megiddo wrote:
| He argues this point exactly.
| JumpCrisscross wrote:
| > _Why isn 't that approach ever used to validate these quantum
| computing claims?_
|
| Hossenfelder's linked tweet addresses this head on [1]. We need
| four orders of magnitude more qubits before a QC can simulate
| anything real.
|
| In the meantime, we're stuck with toy problems (absent the sort
| of intermediate test algorithms Aaronson mentions, though the
| existence of such algorithms would undermine the feat's PR
| value, as it would afford cheap takedowns about the QC lacking
| supremacy).
|
| [1] https://x.com/skdh/status/1866352680899104960
| EvgeniyZh wrote:
| That's not true, there are enough interesting problems for
| NISQ. Quantum chemistry for example.
| throw310822 wrote:
| Could it be that it's not a chance if these kind of problems
| are chosen? Somehow we can get from a quantum system an amount
| of computation that goes well beyond what a classical system
| can perform, _but we can 't seem to extract any useful
| information from it_. Hmm.
| hiddencost wrote:
| For reference, Aaronson is widely regarded as one of the
| foremost members of the field.
|
| Try "I don't understand this claim"?
| adastra22 wrote:
| That's what the author is saying. Researchers in this field
| should, for credibility reasons, be solving test problems that
| can be quickly verified. As to why this isn't done:
|
| (1) They're picking problems domains that are maximally close
| to the substrate of the computation device, so they can hit
| maximum problem sizes (like 10^25). For many (all?) fast-
| verifiable problems they can't currently handle impressively
| large problem sizes. In the same way that GPUs are only really
| good at "embarrassingly parallel" algorithms like computer
| graphics and linear algebra, these quantum chips are only
| really good at certain classes of algorithms that don't require
| too much coherence.
|
| (2) A lot of potential use cases are NOT easy to validate, but
| are still very useful and interesting. Weather and climate
| prediction, for example. Quantum chemistry simulations is
| another. Nuclear simulations for the department of energy.
| Cryptography is kinda exceptional in that it provides easily
| verifiable results.
| qnleigh wrote:
| I would add one more to this, which I would argue is the main
| reason:
|
| (0) For a quantum algorithm/simulation to be classically
| verifiable, it needs additional structure; something that
| leads to a structured, verifiable output despite the
| intermediate steps being intractable to simulate classically.
| That additional structure necessarily adds complexity beyond
| what can be run on current devices.
|
| To pick an arbitrary example I'm familiar with, this paper
| (https://arxiv.org/abs/2104.00687) relies on the quantum
| computer implementing a certain cryptographic hash function.
| This alone makes the computation way more complex than what
| can be run on current hardware.
| vasco wrote:
| Isn't weather prediction extremely easy to validate? What am
| I missing other than looking out the window tomorrow?
| adastra22 wrote:
| At scale, yes. But this would still be solving toy problems
| with less variables, fewer dimensions.
|
| And they're not actually solving weather problems right
| now, I think. That was just an example. What they are
| actually solving are toy mathematical challenges.
| ChrisArchitect wrote:
| Related:
|
| _Willow, Our Quantum Chip_
|
| https://news.ycombinator.com/item?id=42367649
| 01HNNWZ0MV43FF wrote:
| > No doubt people will ask me what this means for superconducting
| qubits versus trapped-ion or neutral-atom or photonic qubits,
|
| I only wonder what it means for cryptography.
|
| The letters "crypt" don't appear in the text.
| Filligree wrote:
| Nothing, yet.
| NooneAtAll3 wrote:
| quantum computing is entering "middle-late 1930s" - it's still
| quite some time away from Turing&Enigma moment
|
| but it already passed "1920s" with "only radios" - analog, non-
| digital devices
|
| stability tech is almost here (check quanta magazine), next is
| the scaling up
| adastra22 wrote:
| As noted in the article, it could be a very sharp transition
| from "largest factorization performed so far is 3x7=21" to
| "we can factor real-world RSA."
|
| If you want to make a classical computing analogy, it's like
| we're struggling to make transistors with more than a single
| 9 of reliability, and _obviously_ you can 't do complex
| computation with a circuit where every step gives garbage
| 1-in-10 times.
|
| Except it's not's obvious. 90% reliability could probably be
| made to work with silicon transistors with bog standard error
| correcting logic at the hardware level. Quantum error is a
| little bit more troublesome to work with, but there are also
| no known theoretical reasons error correction wouldn't work
| at existing error rates. We just need better algorithms,
| which might very well exist.
|
| Or, the next generation of chips would offer more 9's
| reliability, and even with existing error correction just a
| few more sigma in reliability would put us over the tipping
| point of being able to make reliable large-scale systems.
| fluoridation wrote:
| There were mechanical computers before the 20th century that
| had more complexity (in terms of total information) and were
| more useful than quantum computers are.
| blast wrote:
| Damn he's funny.
|
| _For 20 years I've been trying to teach the world how to fish in
| Hilbert space, but (sigh) I suppose I'll just hand out some more
| fish._
| munchler wrote:
| The argument in favor of the Everettian multiverse ("where else
| could the computation have happened, if it wasn't being farmed
| out to parallel universes?") seems illogical to me. Aren't these
| parallel universes running the same computation at the same time,
| and thus also "farming out" part of _their_ computations to _us_?
| If so, it 's a zero-sum game, so how could there be an overall
| performance gain for all the universes?
| Filligree wrote:
| That's not really how MWI works. There isn't some fixed number
| of universes; actually, there aren't really distinct universes
| (or timelines) at all. Attempting to count them is about like
| trying to measure the length of a coastline; they blend
| together once you zoom far enough in.
|
| Running the quantum computer _causes_ 'new timelines' to be
| created. Though so would ordinary atoms just sitting there; the
| tricky thing about quantum computers is making it so the split
| is temporary.
|
| So the quantum computer gets split into multiple versions of
| itself, does some computation in each, and merges the results.
| This isn't map-reduce; there's a strictly limited set of ways
| in which you can do the merger, all of which are weird from a
| classical perspective.
|
| You can argue for MWI based on this, because the computations
| that got merged still had to happen _somewhere_. It 's
| incompatible with Copenhagen, more so the bigger and longer-
| lasting the computation gets. It's not, strictly speaking,
| incompatible with pilot wave theory; but pilot wave theory is
| MWI plus an additional declaration that "Here, you see this
| timeline here? That's the real one, all the others are fake.
| Yes, all the computation needed to instantiate them still
| happens, but they lack the attribute of being real."
|
| Though that makes PWT incompatible with computationalism, and
| hence with concepts such as mind-uploading. Which is a bullet
| you can choose to bite, of course...
| munchler wrote:
| Thank you. This makes sense.
| monero-xmr wrote:
| I'd prefer to say we just go back in time the moment it
| collapses. How can you disagree with me? No proof of anything
| and we can all contrive untestable solutions.
|
| No wait, it's actually God who exists in the wave collapse,
| and His divine intervention does the computation.
| fidotron wrote:
| The easy comparison for devs is quantum computing is like git
| branching.
|
| The big question being the PR approval process.
| whimsicalism wrote:
| no that's not a good comparison for MWI, it's more
| continuous
| fidotron wrote:
| That sounds like you having a narrow understanding of git
| - there is no way it is not continuous.
| whimsicalism wrote:
| git branches are not continuous
| fidotron wrote:
| You mean as opposed to discrete? (And not in the usual
| sense of continuous)
|
| There is nothing stopping you putting probability
| distributions in git and branching them.
| whimsicalism wrote:
| i think we are just not connecting in what we are saying,
| nbd
| dartos wrote:
| Git operates on commits (branches are really nicknames
| for specific commits with some extra features), which are
| discrete steps.
|
| That's what's stopping you from doing anything continuous
| in git.
| amelius wrote:
| Maybe our consciousness also branches, and all branches are
| approved.
| adastra22 wrote:
| I don't think this is accurate. There is no classical
| computation happening here, and there is no reason you have
| to have "room" for the classical computation to happen. That
| seems to be assuming that the universe is a classical
| substrate and a classical algorithm has to be instantiated
| somewhere.
|
| Quantum computing isn't classical computing. It isn't a
| Turing machine. It is a fundamentally different kind of
| information processing device, making use of non-classical
| physical phenomena.
|
| I'm not a defender of Copenhagen, but the wave collapse
| interpretation has no difficulty explaining quantum
| computation. A quantum computer creates extremely large,
| complexly entangled wave functions that upon collapse result
| in states that can be interpreted as solutions to problems
| that were encoded in the sequence of operations that setup
| the entangled wave function. The Everett interpretation is
| easier to think about in my opinion, and I prefer thinking in
| terms of MWI when I try to make sense of these results. But
| it is not necessary.
|
| Computer science is the study of universal Turing machines
| and their application. But Turing machines are only
| "universal" in the sense that they can represent any
| statement of mathematical logic, and that can (we believe) be
| used to simulate anything we can dream up. But there are
| intrinsic performance limitations of Turing machines, studied
| by algorithmic theory, which are artifacts of the Turing
| machine itself, not physical limitations of the universe we
| live in. That searching an unordered list with a serial
| processor takes O(n) time, for example. Grover showed that
| there are non-Turing machine quantum processes that could be
| used to perform the same computation in O(sqrt(n)) time. That
| doesn't mean we need to go looking for "where did that
| computation actually happen". That doesn't even make sense.
| slowmovintarget wrote:
| According to this ( https://arxiv.org/pdf/2302.10778 ),
| there are no branches, just decoherence (minus the
| "collapse").
| lisper wrote:
| > Turing machines are only "universal" in the sense that
| they can represent any statement of mathematical logic
|
| That's not quite right. TM's in general are not universal.
| The "universality" of TMs has to do with the _existence_ of
| a universal TM which is capable of emulating any other TM
| by putting a specification of the TM to be emulated on the
| universal TM 's _tape_. The reason this matters is that
| once you 've built a universal TM, you never have to build
| any more hardware. Any TM can then be emulated in software.
| That result is due to Turing.
|
| The relationship between TMs and mathematical logic is of a
| fundamentally different character. It turns out that any
| system of formal logic can be emulated by a TM (and hence
| by a UTM), but that is a _different_ result, mainly due to
| Godel, not Turing. There is also the _empirical_
| observation (famously noted by Eugene Wigner [1]) that all
| known physical phenomena (with the exception of quantum
| measurements) can be modeled mathematically, and hence can
| be emulated by a TM, and hence can be emulated by a UTM.
| But it is entirely possible that a new class of physical
| phenomena could be discovered tomorrow that cannot be
| modeled mathematically.
|
| But here's the thing: no one has been able to come up with
| any idea of what such a phenomenon could possibly look
| like, and there is a reason to believe that this is not
| just a failure of imagination but actually a fundamental
| truth about the universe because our brains are physical
| systems which themselves can be modeled by mathematics, and
| that is (empirical) evidence that our universe is in some
| sense "closed" under Turing-equivalence (with quantum
| randomness being the lone notable exception). _That_ is the
| kind of universality embodied in the idea that TM 's can
| emulated "anything we can dream up". It's called the
| Church-Turing thesis [2] and unlike the universality of
| universal TM's it cannot be proven because a counterexample
| might be discovered at any time.
|
| [1] https://en.wikipedia.org/wiki/The_Unreasonable_Effectiv
| eness...
|
| [2]
| https://en.wikipedia.org/wiki/Church%E2%80%93Turing_thesis
| adastra22 wrote:
| I appreciate the detail, but for the record I don't think
| we disagree. There's a lot that I had to oversimplify in
| my already long comment, as I pointed out.
| fluoridation wrote:
| Hmm... Turing machines are "universal" in the sense that
| they can be used to model the behavior of any finite
| process that can compute a computable function. So if a
| process exists that can compute something, it _must_ be
| modelable as a Turing machine, and its operation must be
| analyzable as a finite series of elementary instructions
| that are analogous to those of a Turing machine. So I don
| 't see how it doesn't make sense to ask the question "if
| this process has a better asymptotic behavior than is
| theoretically possible, where did the computation take
| place?" I would be more inclined to believe that someone is
| not counting properly, than it being some kind of
| hypercomputer. Or even more simply that the process is just
| physically impossible.
| JumpCrisscross wrote:
| > _if a process exists that can compute something, it
| must be modelable as a Turing machine_
|
| Yes.
|
| > _and its operation must be analyzable as a finite
| series of elementary instructions that are analogous to
| those of a Turing machine_
|
| Analyzable, sure. MWI is fine as an analytic tool in the
| same way _e.g._ virtual particles and holes are. Nothing
| here requires that any of these analytic tools are
| physically corresponded to.
| fluoridation wrote:
| I didn't say I favored the MWI. My point is simply that
| the question of where computation took place shouldn't be
| dismissed. Like I said, I would be more inclined to think
| someone is not counting properly. As a simple example, a
| parallel program may run in half the time, but that
| doesn't mean it executed half as many operations.
| JumpCrisscross wrote:
| > _the question of where computation took place shouldn
| 't be dismissed_
|
| Sure. But it also shouldn't be glorified as adding
| anything to an old debate--every QCD calculation has this
| dynamic of lots of classical "computations" happening
| seemingly simultaneously.
| adastra22 wrote:
| There isn't hidden computation going on though.
| galaxyLogic wrote:
| A Turing Machine operates serially one instruction at a
| time. But you could obviously multiply its output by
| multiplying the machines.
|
| The question is then how could we efficiently multiply
| Turing machines? One way could be by using rays of light
| to do the computations. Rays of light operate in
| parallel. Light-based computers don't need to be based on
| quantum mechanics, just plain old laser-optics. They
| multiply their performance by using multiple rays of
| light, if I understand it correctly.
|
| SEE:
| https://thequantuminsider.com/2024/03/19/lightsolver-
| laser-c...
|
| So using multiple rays of light is a way to multiply
| Turing Machines economically, in practice, I would think.
|
| I assume quantum computers similarly just multiply Turing
| Machines -like computations, performing many computations
| in parallel, similarly to light-based computers. That
| does not mean that such computations must happen
| "somewhere else", than where the quantum processes occur.
| And that does not require multiple universes, just good
| old quantum mechanics, from Copenhagen.
| fluoridation wrote:
| Parallel computers don't "multiply their performance" in
| computation theoretic terms. If you took half as long by
| computing on two Turing machines simultaneously you
| didn't decrease the time complexity of the algorithm. You
| still churned through about the same number of total
| operations as if you had done it serially.
|
| The distinction between the total operations and the
| total time is important, because your energy requirements
| scale with the time complexity of what you try to
| compute, not with the total time it takes.
|
| An optical computer, for example, has a limit on how
| densely it can pack parallel computation into the same
| space, because at some point your lenses overheat and
| melt from the sheer intensity of the light passing
| through them. It's possible QCs are subject to similar
| limitations, and despite the math saying they're capable
| of computing certain functions polynomially, that doing
| so requires pushing exponential amounts of energy into
| the same space.
| adastra22 wrote:
| "Any process can be modeled by a Turing machine" is not
| the same as "Every process must be isomorphic to a Turing
| machine, and therefore share the same limitations."
|
| If I have a magic box that will instantly calculate the
| Nth digit of the busy beaver number of any size, that can
| be modeled by a Turning machine. AFAIK there is no
| constant time algorithm though, which is what our magic
| box does. So a Turing machine can't match the performance
| of our magic box. But no where is it written that a
| Turing machine puts a an upper bound on performance!
|
| That's what quantum computers are. They solve certain
| problems faster than a classical computer can. Classical
| computers can solve the same problems, just more slowly.
| athrowaway3z wrote:
| I recently had a good ChatGPT session about black holes
| swallowing information. This isn't my field, but I'm pretty
| sure this is wrong in the same way I was wrong.
|
| Here is an interesting exert from it:
|
| ----
|
| 5. The Big Picture
|
| Here's how to think about unitarity and collapse in terms of
| total information: Unitarity governs the
| full quantum system: The wavefunction evolution
| deterministically accounts for all possibilities across all
| time and space. Collapse is local and subjective: It
| reflects a single outcome within the broader unitary
| framework. For the observer, collapse resolves uncertainty,
| but this doesn't change the global state's total information.
|
| In essence, unitarity doesn't just allow for all possible
| collapses--it encompasses them, treating every possible
| outcome and its constraints as part of the overall
| deterministic evolution of the wavefunction. Collapse is a
| refinement of possibilities for the observer, not an addition
| or destruction of information.
| 3form wrote:
| Why does the computation have to "happen somewhere"? I
| understand the desire to push the boundary of the classical
| reasoning, but I don't think it's something to be taken as an
| axiom, and I haven't heard about any proof either.
| adastra22 wrote:
| I'm not sure the sibling comment is correct, so I'll take
| another stab at it.
|
| First, I also think the "this favors the Everett
| interpretation" argument is incoherent, but for different
| reasons. I won't be defending that view. But I can try to
| answer your question about the nature of computation and
| "where" that computation is taking place.
|
| A quantum computer is essentially a random number generator,
| but with a non-uniform distribution that can be
| programmatically controlled.
|
| Let's start with the random part: a qubit can be either a 1 or
| a 0. When first initialized, when you then read it you will get
| either a zero or a one with 50% probability. (I am
| oversimplifying to the point of error! This is technically
| incorrect, but please excuse me for the purpose of a simplified
| explanation that makes sense to computer scientists rather than
| quantum physicists.) In the Copenhagen interpretation the wave
| function randomly collapsed in a way that can be measured as a
| 0 or as a 1 with 50% probability for either outcome. In the
| Everett interpretation there are two universes (really, two
| disjoint sets of universes): one where you see a 0, and the
| other where you see a 1, and your likelihood of ending up in
| either is 50%.
|
| For example, with three qubits you can read a random value
| between 0 to 7, where each qubit provides a 0 or 1 of a
| classical 3-bit binary value. If you're making a D&D simulator,
| you can take three of these registers (9 qubits total) and read
| them to get three values between 0 to 7, then increment each
| and add together to get the simulated value of three 8-sided
| dice, for the attack value of some game weapon.
|
| But so far we're assuming even and independent odds for a 0 or
| 1 in each qubit. A quantum gate operation lets you modify that
| probability distribution in interesting ways. Specifically you
| can take multiple qubits and entangle their state such that the
| eventual outcome (still random) is constrained to a non-uniform
| probability distribution. (The details don't matter, but it has
| to do with the fact that you can add wave amplitude, which is
| complex-valued and therefore can constructively or
| destructively interfere.)
|
| So instead of reading three separate 1d8 registers and adding
| them together, we can use quantum gate operations to perform
| the addition: entangling the state of a _new_ 4 qubit register
| (large enough to hold the sum of two 3 qubit registers) such
| that it represents the sum of two separate, randomly chosen
| with independent probability values between 0..7. The combined
| sum will be a random value between 0 and 14, but with the value
| 7 being most likely, 6 or 8 next most likely, etc. (You can see
| the probabilities here: https://anydice.com) We then add in the
| third 3-bit register, getting a 5-qubit result. For good
| measure, we then add a constant 3 value using quantum gate
| operations so the result will be what we expect for adding 3
| dice rolls, which start counting at 1 rather than 0. Now we
| have a great random number generator for D&D games. It's a
| 5-bit register that when you read it will give you a value
| between 3 and 24, with exactly the probabilities you would
| expect of three rolls of a fair 8-sided die.
|
| You can interpret what this means in Copenhagen vs Everett, but
| there isn't a way in which it makes material difference. I will
| say that the Everett interpretation is easier to think about:
| you setup the entangled operations such that there simply isn't
| a universe in which the register reads 31, or some value not
| representative of a 3d8 dice roll, and if you count the number
| of possible universes under the born rules and holding the rest
| of the multiverse constant, the counts match the 3d8 dice
| probability distribution. So you don't know which universe you
| will end up in when you finally read the register and, under
| the many worlds interpretation, split off into one of many
| possibilities. But you know it will be a good 3d8 dice roll for
| your D&D game.
|
| Now imagine you have two 1,024 qubit registers (each with
| random probability for each bit), and you run a full set of
| shift-adders to multiply them together into a 2,048 qubit
| register. If you read the result, it'll be a random non-prime
| number. Why? Because it's necessarily the product of two 1,024
| composites. What's interesting is that you can kinda do the
| reverse, as Peter Shor figured out how to do in the 90's: start
| with a 2,048 bit register, run the shift-adder in reverse
| (really, the method of continued fractions, but I'm going for
| an intuition pump here), then read the two 1,024 registers.
| What you will get is two values that when multiplied together
| will result in the input, the factors. If you put "60" in the
| input, you will maybe get the outputs (15, 4), or (5, 12), or
| (2, 30), or (1, 60). It's random which will pop out, but what
| you get WILL be a factorization of 60.
|
| Now put your bank's SSL public key in the register, and read
| the factors out. The factors are the private key.
|
| I don't think any talk of multiverses is needed to understand
| this. It's simply mucking around with the probability
| distribution of a random number generator in clever enough ways
| that the random number generated, whatever it is, will be _A_
| solution (perhaps one of many) to your problem. You do this by
| destructively interfering the register with wave functions that
| represent non-solutions, and keep doing this until only
| solutions are left as possible values. Then you read your
| random number register and know the result is drawn from the
| solution set.
| whimsicalism wrote:
| the larger the devices we are able to build where quantum
| effects still dominate, the more it hurts any notion of a
| 'physical collapse' suggested by some copenhagen branches.
|
| Other, weaker forms of Copenhagenism scarcely even qualify as
| a real metaphysical interpretation of what is going on. I do
| think building big things in superposition does seem
| suggestive that there is no 'collapse upon interaction with
| observer' effect in metaphysical reality.
| adastra22 wrote:
| > the more it hurts any notion of a 'physical collapse'
| suggested by some copenhagen branches
|
| Why? The mathematics of quantum mechanics describes
| perfectly well what is going on in these systems, to
| exactly the same level of accuracy. There is no predictive
| difference between Copenhagen and Everett interpretations.
|
| This is a philosophical argument, not a physical one.
| whimsicalism wrote:
| I'm not saying it is a purely empirical argument, hence
| my extensive mention of metaphysics. There are many,
| many, many theories that can match existing observation,
| such as superdeterminism or superdeterminism where there
| is a human-form God right outside of our causal
| observable universe that is using some magical force to
| determine where all particles are.
|
| The principle of parsimony, imo, favors an everettian
| explanation - and constructing larger contraptions with
| QM effects puts increasing parsimony pressure on why
| observers like humans are not simply getting entangled
| with the system they are observing when we see
| 'collapse.' The mathematics of QM does not describe
| collapse or how that occurs from wavefunction evolution
| or why observers are relevant.
| layer8 wrote:
| > and your likelihood of ending up in either is 50%.
|
| I don't quite agree with this characterization. You end up in
| both universes with 100% certainty, but there will then be
| two of you, one in each universe. Where the likelihood again
| comes in, is when one of the two yous wonders in which branch
| they are located, and tries to predict (retrodict?) based on
| information collected prior to the branching, it will be a
| 50/50 likelihood. Of course, if they are able to look at the
| outcome of the experiment, it will become clear in which
| branch they are located.
|
| This concept of probability in the context of MW is known as
| "self-locating uncertainty":
| https://www.journals.uchicago.edu/doi/10.1093/bjps/axw004
| Robotbeat wrote:
| Finally, someone mentioning Shor and his algorithm.
|
| Shor's algorithm is where the rubber meets the road for me.
| Synthetic benchmarks like what Google made just aren't that
| useful imo.
|
| There's even a case to be made that all the work needed to
| make quantum computing reliable negates the supposed
| advantage and makes it no more unscalable than conventional
| computing. I don't subscribe to that, but a successful Shor's
| Algorithm attack on RSA (with enough bits) would certainly
| prove that wrong.
| vasco wrote:
| As a layman I really hope this is correct because it makes a
| lot of sense. The multiverse thing is supposed to help
| thinking about it but I just get stuck on some problems of
| intuition if I try to do it like that. Great comment!
| klabb3 wrote:
| > "where else could the computation have happened, if it wasn't
| being farmed out to parallel universes?"
|
| Right. I'm definitely a layman here but as a CS generalist this
| rings out as narrow-minded to me, biased towards the way we
| designed physically and then mathematically formalized
| "computation".
|
| Not that I have anything against multiverses but.. if I had to
| choose between "Turing-style computation happened, but needed
| parallel universes to do so" and "what happened is something
| counter-intuitive and insufficiently understood about the
| universe we inhabit" I would bet on the latter.
| adastra22 wrote:
| I'm an actual physicist here. Not in quantum computers, but
| that was my advisor's field and I've kept paying attention in
| the years since. Your intuition here is correct, I believe.
| Classical computer science deals with information processing
| limits of devices constructed using the classical physics
| laws of Newton and Maxwell. Quantum physics introduces new
| elements that permit new kinds of information processing
| machines, which have no obligation to be constrained by
| classical law.
| ayewo wrote:
| > Quantum physics introduces new elements that permit new
| kinds of information processing machines, which have no
| obligation to be constrained by classical law.
|
| Question then becomes, how do you build such non-
| constrained machines? Also, how do you confirm that such
| machines--or even small scale prototypes--are not
| constrained by classic laws of physics?
| rlupi wrote:
| > Question then becomes, how do you build such non-
| constrained machines? Also, how do you confirm that such
| machines--or even small scale prototypes--are not
| constrained by classic laws of physics?
|
| You mean, like... transistors? ;-)
|
| https://en.wikipedia.org/wiki/History_of_the_transistor
| (search for quantum)
| adastra22 wrote:
| By doing the math of many physics calculations to design
| a setup that will make these quantum phenomena stable
| enough to be useful, then building it and seeing if
| prediction matches reality.
| AyyEye wrote:
| Rule #1 is that technologists must pretend that they
| understand what they are doing. Woo-woo is fine as long as
| you can get your peers to play along with you.
| qnleigh wrote:
| But to emphasize one quote from the blog: "the new experiment
| doesn't add anything new to this old debate" about multiverse
| interpretations vs. something else. An equally viable and
| perhaps conceptually simpler interpretation of the experiment
| is that the qubits are temporarily put in a 'superposition' of
| many different bitstrings, some operations are performed, and
| then measurement collapses this superposition back into a
| single definite bitstring. No multiverse required.
| superq wrote:
| > No multiverse required.
|
| True, but no exciting plot twists either. :(
| galaxyLogic wrote:
| Multiple Universes is a "Deus ex Machina" applied by
| Hollywood a lot these days.
| fizx wrote:
| The Everettian multiverse is a bit like seeing some bubbles and
| foam in the surf and concluding that there are "many oceans."
| Yes, there are many surfaces of water, but calling each bubble
| an ocean is a bit disingenuous.
|
| Like the bubble analogy, new Everettian universes are local,
| small, and the total amount of probability density (water in
| this analogy) is conserved.
| Strilanc wrote:
| The main issue with this line of argument is that you don't see
| people who like other interpretations claiming quantum
| computers won't work. Saying quantum computers imply many
| worlds is the classic mistake of wanting to show A=>B and
| arguing B=>A instead of ~B=>~A. If quantum computers were
| inconsistent with collapse interpretations, you'd expect people
| who think collapse interpretations are correct to be
| confidently predicting quantum computers will never work. But
| they don't; they just think the state inside the computer isn't
| collapsing.
|
| I'm often tempted to argue quantum computers at least clearly
| favor ontic interpretations (ones where quantum states are
| real). Because good luck computing things by subjectively
| having a computer instead of actually having a computer. But,
| as far as I know, you don't see quantum-bayesianism-ists having
| any qualms with quantum computers. I think because if you're
| already biting the bullet of interpreting diagonally polarized
| light as subjective, and Bell tests as subjective, then
| interpreting a computation as subjective isn't fundamentally
| different. It's just more in your face about it.
| adastra22 wrote:
| Quantum computers do defeat hidden-variable models, which
| would have to hide the computation somewhere. But yeah, Bell
| and EPR ruled those out years ago anyway.
| Strilanc wrote:
| I don't see people who believe hidden variable models, like
| pilot wave, claiming quantum computers won't work. So I
| don't think quantum computers disprove hidden variable
| models.
|
| I do agree quantum computers disprove _local_ hidden
| variable models. Because they can run Bell tests, and local
| hidden variable models can 't violate the Bell
| inequalities.
| adastra22 wrote:
| Last time I checked pilot wave theory was not developed
| enough to permit modeling of quantum computers, or at
| least no one had done the work yet to apply the theory to
| that use case. It is very undeveloped.
| S_A_P wrote:
| I am also curious if Mark Everett, Hugh's son, has an account
| here.
| munchler wrote:
| EELS!
| blueprint wrote:
| It's not necessary for there to be parallel universes when all
| possible paths are already taken within this universe.
| kokanee wrote:
| Parallel universes enter the conversation because we (non
| physicists) can't identify any scenario explainable with
| classical physics that allowed those paths to be taken in the
| allotted time and space.
| AnotherGoodName wrote:
| You just need to devise a system where the vast majority of
| universes give the right answer for this to work.
|
| Start by at least having a universe for each possibility so
| that every code path is computed. Then add a mechanism to
| create many more universes when a correct result is hit.
|
| So each wrong result has 1 universe and the correct result
| alone has 2^300 a universes. Run this. You now end up with the
| correct result 99.99999% of the time.
|
| I'm not arguing on the above take or not fwiw, it's just that
| it easy to see how this could happen in many worlds.
| Effectively error correction just becomes a mechanism to create
| more universes for correct answers than incorrect answers and
| it all works. In fact it's very reasonable to think of quantum
| error correction this way (it really is a mechanism to favour
| correct answers being observed and in many worlds that means it
| creates more correct answer universes).
| skirmish wrote:
| > add a mechanism to create many more universes when a
| correct result is hit
|
| Simple count has not much to do with the outcome observed,
| IMU each branch in a split is not equally likely. If you
| finely sub-divide a low-probability branch into 2^300 sub-
| branches, so what. Instead, you need to merge multiple high
| probability branches back into a single outcome that is
| observed "99.99999% of the time".
| AnotherGoodName wrote:
| In many worlds the probability observed can absolutely be
| thought of as the ratio of worlds with that outcome vs
| another. Any specific numbers here are just as an example.
| JKCalhoun wrote:
| What does quantum computing need to move forward? Will just
| throwing a lot of money at the thing allow it to scale? Or are
| there fundamental problems blocking it that require new physics
| or new material sciences?
| ryandamm wrote:
| I was told by a Microsoft researcher that it will unlock
| currently unsolvable problems in chemistry, weather modeling,
| materials science, fusion and plasma physics, drug
| development... the list went on but it was really long. Most
| advances he cited would result from improved simulations, iirc.
|
| I don't recall enough of the conversation (circa 2019) to
| remember anything about the properties of the problems it helps
| solve, so I can't help generalize. Sorry.
| gauge_field wrote:
| Here is a perspective from another MS researcher: https://www
| .youtube.com/watch?v=WY3htdKUGsA&t=1564s&ab_chann...
|
| Essentially, they argue that unless strong algorithmic
| breakthrough happens (e.g. having cubic speedup, instead of
| quadratic), the only practical problem for which quantum
| computer will be useful, are those where you get exponential
| speed up:simulation of quantum systems (and breaking of RSA
| encyrption if you count that). Even those are challenged by
| other (approximate) simulation by Classical Deep Learning.
| There will be some quantum models for which quantum supremacy
| will be useful and Deep Learning wont. The question what
| classes of systems.
| EvgeniyZh wrote:
| It's hard to say. For example the Google's paper talks about
| some rare (once an hour) strong errors. Are they fundamental or
| have some easy fix? We don't know.
|
| One obvious problem is cooling. We can't cool million qubits in
| a single fridge, so we will need to split them between fridges
| and communicate. Also, the wiring is really complicated already
| and hard to scale (one reason IBM has heavy hex is to have more
| space).
|
| Another problem is connectivity. For transmon qubits
| connectivity is fixed. Applying gate to two far qubits requires
| a lot of swaps, which is expensive. This is less of a problem
| for ions or cold atoms because they can couple any two qubits;
| but they likely wouldn't be able to for large amount of qubits.
|
| Another thing is classical control, because the classical data
| needs to be processed at high speed. Some companies develop
| specialized hardware for that.
|
| None of these is necessarily fundamental, but these problems
| need to be solved, in addition to usual scaling (it is hard to
| manufacture these devices and it becomes harder with each
| qubit).
| bawolff wrote:
| I think we are well at the point where it is just time and
| money. Its not a physics problem its an engineering problem.
|
| I'm sure there are lots of complicated problems ahead, but i
| don't think we are waiting for someone to discover "new"
| physics.
| andrewla wrote:
| What does homeopathy need to move forward? What does perpetual
| motion machinery need to move forward?
|
| This is not totally fair; it is possible given certain
| independence assumptions. But they are likely not physically
| realizable.
|
| It is almost certain that even within our understanding of
| quantum systems it is simply not possible to have a quantum
| computer (much less create one). The assumptions necessary to
| produce a completely uncoupled system are likely invalid; we
| have yet to produce a compelling experiment to indicate
| otherwise. [1]
|
| [1] https://arxiv.org/pdf/1908.02499
| wasabi991011 wrote:
| From the paper:
|
| > Goal 3: Create distance-5 surface codes on NISQ circuits
| that require a little over 100 qubits.
|
| > The argument presented in the next section asserts that
| attempts to reach Goals 1-3 will fail.
|
| Goal 3 is exactly what Google has recently achieved with
| Willow. Actually, they did even better, reaching a distance-7
| surface code (with a little over 100 qubits). Q.E.D.
|
| To be clear, I do think your article is interesting and was
| valid at the time, but it goes to show how fast the field is
| advancing.
| daft_pink wrote:
| I just want to know when this thing is going to put me out of
| work forever with it's insane and crazy math skills.
| talldayo wrote:
| I don't think it has crazy math skills at all. That's what
| classical computing is really good at - give it a problem of
| arbitrary length and a computer should be able to string
| together instructions to yield you a sum.
|
| Quantum computing, especially right now, is simply focused on
| getting reliable input/output idempotency. It will be a really
| long time before it has insane and crazy math skills, and when
| it does, traditional CPU architectures will probably outperform
| it.
|
| TL:DR - if the Texas Instrument calculator didn't put you out
| of a job, neither will quantum computers.
| eastbound wrote:
| Aren't matrix calculations a perfect field for quantum
| computing? i.e. AI would progress extremely fast, wouldn't
| it?
| tmvphil wrote:
| No, not really. There is no speed up for general matrix
| multiply, and generally it won't be practical for any
| problem with large amounts of input and output data.
| Closest thing is HHL algorithm for solving big linear
| systems, which requires a bunch of caveats on the matrix,
| and even then, it needs to be a subroutine of another
| quantum algorithm, since it outputs a quantum state, and
| not the full vector.
| bawolff wrote:
| Unless your job involves factoring numbers into primes (or a
| few other limited math problems) probably never.
| galaxyLogic wrote:
| There's two great lanes of progress happening in engineering
| these days: 1. Quantum Computing, and 2. AI.
|
| If they can find some synergies between the two, that could be
| THE major development. Make better AI by using Quantum
| Computers, and make better Quantum Computers by applying AI.
| machina_ex_deus wrote:
| Before invoking parallel universes, how about comparing the
| system to nature's mind-boggling number of particles in the
| macroscopic world? A single gram contains 10^23=2^76 particles.
| Google's random circuit sampling experiment used only 67 qubits,
| Which is still order of magnitude below 76. I wonder why, the
| chip had 105 qubits and the error correction experiment used 101
| qubits.
|
| Did Google's experiment encounter problems when trying to run RCS
| on the full 105 qubits device?
|
| Before saying that the computation invoked parallel universes,
| first I'd like to see that the computation couldn't be explained
| by the state being encoded classically by the state of the
| particles in the system.
| zh3 wrote:
| Somehow the universe knows how to organise the sand in an egg
| timer to form an orderly pile. Simulating that with a classical
| computer seems impossible - yet the universe "computes" the
| correct result in real time. It feels like there is a huge gap
| between what actually happens and what can be done with a
| computer (even a quantum one).
| onlyrealcuzzo wrote:
| > Somehow the universe knows how to organise the sand in an
| egg timer to form an orderly pile. Simulating that with a
| classical computer seems impossible
|
| Is it really?
|
| There's only ~500,000 grains of sand in an egg timer.
|
| I don't know anything here, but this seems like something
| that shouldn't be impossible.
|
| So I'm curious. Why is this impossible?
|
| What am I missing?
| GeneralMayhem wrote:
| The real issue is that the sand _isn 't_ orderly sorted. At
| a micro level, it's billions and trillions of individual
| interactions between atoms that create the emergent
| behavior of solid grains of sand packing reasonably tightly
| but not phasing through each other.
| zh3 wrote:
| Maybe it's not that hard to simulate, but let's start with
| looking at just two of the sand grains that happen to hit
| each other? They collide, how they rebound is all angles,
| internal structure, Young's modulus, they have
| electrostatic interactions, even the Van der Walls force
| come into play. Sand grains aren't regular, consider how
| determining the precise point at which two irregular
| objects collide is quite a challenge (and this isn't even a
| game, approximations to save compute time won't do what the
| real world does 'naturally').
|
| So while we can - for something as simple and regular as an
| eggtimer - come up with some workable approximations, the
| approximation would surely fall short when it comes to the
| detail (an analytical solution for the path of every single
| grain).
| galaxyLogic wrote:
| When the output looks the same as the original we would
| say that the simulation was successful. That is how
| computer games do it. We're not asking for the exact
| position of each grain, just the general outline of the
| pile.
| vasco wrote:
| The universe also computes Pi perfectly every time and nobody
| is surprised or calling side universes for help explaining
| it.
| galaxyLogic wrote:
| Universe does not calculate the digits of Pi. We do.
| amelius wrote:
| I think they mean that Pi is part of many formulas in
| physics.
| throw310822 wrote:
| > yet the universe "computes" the correct result in real time
|
| Does it? In what sense the result is "correct"? It's not
| because it's perfectly regular, or unique, or predictable, or
| reproducible. So what's "correct" about it?
|
| Completely out of my depth here, but maybe there is a
| difference between evolution of a physical system and useful
| computation: and maybe there's much less useful computation
| that can be extracted from a physical system than the entire
| amount of computation that would be theoretically needed to
| simulate it exactly. Maybe you can construct physical systems
| that perform vast, but measurable, amounts of computation,
| but you can extract only a fixed max amount of useful
| information from them?
|
| And then you have this strange phenomenon: you build
| controlled systems that perform an enormous amount of
| deterministic, measurable computation, but you can't make
| them do any useful work...
| zh3 wrote:
| It does seem to, and can anyone credibly say they aren't
| out of their depth in these waters? (the sandpile thing is
| not original, it dates back many years). Taking the idea
| that the "universe is a simulation" [0], what sort of
| computer (or other device) could it be running on? (and how
| could we tell we're living in a VM?)
|
| From the same school of thought, to simulate the path of a
| single particle seems it should require a device comprised
| of more than a single particle. Therefore, if the universe
| is a simulation, the simulator must have more than the
| number of particles in the universe.
|
| [0] https://en.wikipedia.org/wiki/Simulation_hypothesis
| dataflow wrote:
| Dumb question: can someone explain the following?
|
| Imagine a ball falling on the ground.
|
| Simulating the O(10^23) atoms in each one with a classical
| computer would take (say) 10^23 times the amount of work of
| simulating a single atom. Depending on the level of detail, that
| could easily take, you know, many, _many_ years...
|
| We don't call the ball a supercomputer or a quantum computer just
| because it's so much more efficient than a classical computer
| here.
|
| I presume that's because it can't do arbitrary computation this
| quickly, right?
|
| So in what way are these quantum computers different? Can they do
| arbitrary computations?
| qnleigh wrote:
| Great question. The device is fully programable. Arbitrary one-
| qubit operations and arbitrary two-qubit operations between
| adjacent qubits can be performed. Theoretically these are
| 'universal for computation', meaning that a large enough device
| could compute anything computable. You can't program Quantum
| Tetris or whatever on a bouncy ball :).
|
| But nevertheless, many of these 'beyond-classical'
| demonstrations feel a bit arbitrary in the way you describe,
| and there's good reason for this. Logical operations are still
| quite noisy, and the more you apply, the more output quality
| degrades. To get the most 'beyond-classical,' you run the thing
| that maps most readily to the physical layout and limitations
| of the hardware.
|
| As things improve, we'll see more and more demonstrations of
| actually useful computations. Google and others have already
| performed lots of quantum simulations. In the long run, you
| will use quantum error correction, which is the other big
| announcement this week.
| dataflow wrote:
| Thank you!
| fluoridation wrote:
| So isn't this the same as turning a classical computer on and
| letting it run on whatever garbage is on the RAM at that
| time, and when some nonsense shows up on the screen
| breathlessly exclaim that it would take several millennia to
| get the same result with an abacus, despite the fact that
| something was "computed" only by strict adherence to the
| definition of the word? It's not like it takes a quantum
| computer to produce a meaningless stream of data.
| qnleigh wrote:
| That's a great analogy, and I basically agree with it. But
| there would be some ancient, abacus-wielding mathematicians
| who would be impressed by this fast-but-useless computer.
| One might take it as a sign that once/if the computer can
| be controlled properly, it might be quite useful.
|
| This might have been part of the history of classical
| computers as well, except that it turns out to be pretty
| easy to do classical operations with very high fidelity.
| Strilanc wrote:
| The key difference is that the problem being solved is a math
| problem. It can be written down on paper.
|
| A ball falling on the ground can be converted into a math
| problem. To get the conversion exactly right you will need to
| write down the exact state of the ball. But you will invariably
| incur small inaccuracies while doing this. For example, maybe
| the mass you write down is off by 1 part in a trillion. The
| math problem is the ground truth, so any conversion
| inaccuracies are now errors _in the ball_. In practice these
| inaccuracies will prevent even the original ball from solving
| the written down problem much better than you could with a
| computer.
|
| In the case of random circuit sampling, the written down
| problem is a tensor network [1] (that happens to also be a
| shallow quantum circuit). Fundamentally, a tensor network just
| specifies a bunch of matrix multiplications to do. It's not
| even that big of a problem: only a few kilobytes of information
| (whereas the exact state of a ball would be gargantuan). All
| you have to do is perform the specified multiplications,
| interpret the result as a probability distribution, and sample
| from it. The obstacle is that these multiplications create
| intermediate values that are really really large. The quantum
| computer bypasses this obstacle by executing the tensor network
| as a circuit.
|
| [1]: https://en.wikipedia.org/wiki/Tensor_network
| nsxwolf wrote:
| Man, reading this makes me feel so small. Being a "software
| engineer" consuming APIs and updating database rows seems
| laughably childish compared to whatever the hell it is I just
| read. I can't even imagine why I should bother trying to
| understand it. It's completely inaccessible. Only an elite few
| get to touch these machines.
| gist wrote:
| Anything that someone else does that you don't understand or
| can't do always sounds super important, impressive, and
| enviable. Usually. But you have to realize that he spends his
| life doing and thinking about this. And will stipulate he's
| gifted in this area. I've never heard of him but managed to
| download his CV.
|
| I will also note that sometimes when I read HN links and think
| one thing then read the comments and people know enough to take
| issue with what is being said and even call it out.
| brailsafe wrote:
| > I can't even imagine why I should bother trying to understand
| it.
|
| Well, maybe you should just try for the hell of it and see how
| far you get? Becoming fit seems impossible to a morbidly obese
| 45 y.o, and it is if that person's expectation is unreasonable,
| but if they just change it to be more reasonable, break it down
| into manageable routines, then they can get somewhere
| eventually.
|
| Find some papers, fill many gaps, dedicate a few years in your
| spare time, in 6 months you'll be 6 months closer than you
| were.
|
| Whether there's a reason or not, idk, it's something to do, be
| curious. Don't forget that by dedicating their life to
| something, they're naturally not dedicating their life to other
| things, things that you might be able to do, like climbing
| mountains, making pizza, or coming up with witty banter in
| social situations.
| rkp8000 wrote:
| MSR has a very clear and accessible tutorial on quantum
| computing for anyone interested in getting up to speed with
| the fundamentals: https://www.youtube.com/watch?v=F_Riqjdh2oM
| .
| guilamu wrote:
| This is very rare, so much I can't remember when was the last
| time it happened, but I was inspired by your words.
|
| Thank you for writing them.
| absoluteunit1 wrote:
| Clicked on this article to learn a bit more about this newly
| released chip but instead got extremely motivated to pursue
| intellectual interests intensely
| nsxwolf wrote:
| I have a treadmill though. Even though I don't use it. I
| can't get a quantum computer.
| ojbyrne wrote:
| As with most novel hardware since the dawn of computing, there
| are ways to emulate it.
|
| https://www.ibm.com/quantum/qiskit
| rhubarbtree wrote:
| The theory of quantum computation is accessible with a good
| understanding of linear algebra. Anyone working in machine
| learning or computer graphics should feel encouraged by that,
| and take a look at the theory.
|
| Quantum error correction is one of those "wow" moments like
| euler's identity, it is worth making the effort to get there.
| gerdesj wrote:
| Start with the handy precis that Mr A leaves at the top in
| yellow. You can drop that into conversation right now with some
| confidence! Mr A has quite some clout hereabouts let alone
| elsewhere, so that seems reasonable.
|
| You can't know everything but knowing what you don't know and
| when to rely on someone else to know what you don't know and to
| confidently quote or use what they know that you don't know, is
| a skill too.
|
| "Critical thinking", and I suspect you do know how to do that
| and whilst this blog post might be somewhat impenetrable it is
| still might be useful to you, even as just general knowledge.
| Use your skills to determine - for you and you alone - whether
| it is truth, false or somewhere in between.
|
| Besides, a mental work out is good for you!
| hellojebus wrote:
| This was me yesterday after reading the official Willow
| release.
|
| Spent yesterday afternoon and this morning learning what I
| could. I'm now superficially familiar with quantum coherence,
| superposition, and phase relationships.
|
| In other words, you got this. Now I gotta learn linear algebra.
| brb.
| joak wrote:
| The hardware is progressing, we have a issue though: we don't
| have algorithms to run on quantum computers. Besides Shor's
| algorithm, useful to break RSA, we have nothing.
|
| Just vague ideas like: it could be useful for quantum simulations
| or optimisation or maybe ...
|
| If tomorrow we have a full running quantum computing what would
| we run on it? We are in a vacuum.
|
| The only hope is a breakthrough in quantum algorithms. Nothing in
| sight, not much progress on this side.
|
| Oh yes, Zapata Computing, the best funded company in quantum
| algorithms just went under this year.
| phoronixrly wrote:
| Sorry but you need to cite some sources... The fact that random
| adtech devs on HN have no algorithms useful to them to run on a
| QC does not mean much to me.
| reikonomusha wrote:
| No-nonsense roll-up of what algorithms a quantum computer can
| run in principle, along with their big-O speed ups (which
| don't necessarily reflect practical speed ups):
| https://quantumalgorithmzoo.org/
| griomnib wrote:
| You've provided me with a beautiful framing to understand
| some of the most obtuse and self-serving arguments I see on
| here: " _random adtech devs_ ".
| bambax wrote:
| > _Having said that, the biggest caveat to the "10^25 years"
| result is one to which I fear Google drew insufficient attention.
| Namely, for the exact same reason why (as far as anyone knows)
| this quantum computation would take ~10^25 years for a classical
| computer to simulate, it would also take ~10^25 years for a
| classical computer to directly verify the quantum computer's
| results!!_
|
| I don't understand that part, can someone explain? There should
| be plenty of problems that take a long time to solve, but are
| trivial to verify? Like for example factoring extremely large
| numbers that are the product of a few very large primes? Maybe
| not on the order of 10^25 years, but still?
| refulgentis wrote:
| This computation is... _handwaves, most handwaving I 've done
| in a while_...initializing a random state, and it's well-
| understood whether this state was randomly initialized isn't
| computable in a reasonable timeframe on classical computers.
| _ends extreme handwaving_
|
| This nerd sniped a bunch of us, because it sounds like "oh we
| proved P!=NP", the keys to understanding are A) hanging onto
| the _this_ in "this computation" (this is easier when you're
| familiar with the computation and it's contextual history in
| the field) B) remembering prime factors as a plausible
| application of QC.
|
| Then faced with the contradiction of B, it's neatly resolved by
| "yes, but the quantum computer isn't big enough to do prime
| factorization yet"
|
| As noted somewhat sideways in the blog, if someone has a
| computation that is A) not classically computable in a
| reasonable timeframe B) is computable on a miniscule quantum
| computer C) can be verified on a classic computer in a
| reasonable timeframe, a lot of researchers will be excited.
| flkenosad wrote:
| Could bitcoin miners use this to "guess" the next block?
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