The need for quantum computers remains small

https://www.theregister.com/2022/07/21/quantum_computing/

by hunglee2 • 4 years ago

89 106 4 years ago

soganess• 4 years ago

Barring the sky falling, our best bet for NP hard problems is approximate solutions that have provable lower bounds on approximation ratio.

From that purview, a general heuristic for approximating combinatorial optimization problems would be a godsent. Even if algorithms like the QAOA do not improve(or tightly match) approximation ratios beyond that of a carefully crafted classical algorithm... A turn key algorithm on a coherent high-qubit-count quantum computer would change the industrial use landscape forever. The number of developer hours saved would be uncountable.

We're just aiming way too dang high.

elcritch• 4 years ago

I mean that sounds a lot like what DWave and Google are pursuing with the adiabatic QCs.

pyinstallwoes3• 4 years ago

Kind of like how instead of modeling the entire economy and figuring out how to influence the behavior, you just identify a key parameter such as inflation or interest rates and modify that to affect every possible outcome.

rektide• 4 years ago

The need is high... for bad people doing bad things to everyone else (trying to de-secure the world)?

There's some hypothetical travelling salesperson style questions we might ask. But we don't seem incapable of doing this work today. 98% the needs seem like: can we break the world's crypto. How is this anything beyond a chaotic evil mis-use? How will this do anything but de-secure & instigate risk across the planet?

At least when 99.5% of the engineers were working on ads, they were just wasting their time doing amoral shit. This seems actively immoral.

I really struggle to understand what this all is good for. There probably are some valid & good uses. But it's all hyper-abstract, with little grounding. The attempt to hipster-ize the facilities, to make the physical systems themselves look cool, to present an impressive front: it all works counter to the very essence that made computing cool for so much of my growing-up period: computing in my era was personal. It empowered people. I don't see how this will help actual people at all. It seems mostly like a big hard problem for which the winner reaps some eventual explotative spoils. At likely cost to general world order & peace. Hiss boo.

amelius• 4 years ago

Computational chemistry (e.g. protein folding) is one useful application.

femto2• 4 years ago

Which leads onto computational medicine.

The advent of SPICE [1] meant that with the right models electrical engineers could simulate complex electrical systems, do sensitivity analysis and make integrated circuits that had a high probability of working.

Imagine a (quantum) simulator that can rapidly simulate all or part of the human body. The effects of medicines could be rapidly simulated, or the simulation could guide the design of treatments. Eventually, if the simulation becomes as accurate as SPICE can be today, it would be possible to go directly from the design of a treatment to its administration, secure in the knowledge that it is unlikely to cause problems.

[1] https://en.wikipedia.org/wiki/SPICE

denton-scratch• 4 years ago

I really struggle to understand what this all is good for.

Defence?

If your secrets (or more likely, your nation's secrets) might be exposed by a quantum attack, then you'd better understand how such an attack might work, so you can defend against it. Nations (some) do research into chemical/biological weapons to learn how to defend against them (purportedly).

That's a "devil's advocate" answer. I lean to the view that, for very big secrets, it's better not to have a secret at all. At least, don't have secrets that need to be kept long-term. That sounds glib and handwavy, and it is; but most secrets seem to get out, sooner rather than later, and usually not as a result of someone cracking the cryptography.

rank0• 4 years ago

If you subscribe to game theory the end game means that you MUST develop this technology in case your adversaries are doing the same.

Humanity will never hold hands and sing kumbayah together.

z3phyr• 4 years ago

The need is to understand quantum systems and advance our understanding of theoretical computer science.

We do not dissuade particle physicists from performing physics because some bad people want atomic bombs; We do not dissuade Archimedes from doing his thing, for the fear of better siege engines;

vanviegen2• 4 years ago

Breaking a coin's crypto doesn't sound all that amoral to me. People holding those coins have specifically chosen to put their financial faith in tech, instead of society (which they are arguably undermining).

A have less respect for those hacking the minds of the general public.

marcosdumay• 4 years ago

Only people that deal with stuff created by chemical reactions have a need for quantum computers... None else.

mtlmtlmtlmtl8• 4 years ago

I wonder if quantum computing is just a mirage that results from looking too much at the time complexity of quantum algorithms versus the cost in qubits, which are still wildly expensive. Maybe qubits will just never scale to the number of qubits needed to meaningfully outperform classical computers.

dataflow2• 4 years ago

Yeah lots of people think decoherence will prevent QC from becoming practically useful. Some researchers seem to think differently, but I never found an explanation for why I should be as optimistic as they are.

ramraj07• 4 years ago

Which side is Scott Aaranson on? Just curious.

mtlmtlmtlmtl8• 4 years ago

I had some shower thoughts.

Let's assume decoherence won't be a problem.

How about a purely economic perspective. Something like the number of bits of DRAM you can get for the cost of a single qubit. Surely, for quantum computers to become usefulfrom a cost POV, this number needs to shrink, yes?

So it could then be interesting to graph this ratio over time and see where it's headed. My gut is that given the state of the art nature of QC, the cost of 1 qubit should be very high, whereas one bit of DRAM should be very low. Which mean 1 qubit is worth a crazy amount of DRAM.

Does anyone know if this has been analysed?

DebtDeflation• 4 years ago

I wonder if quantum computing is just a mirage

Or something else.

https://scottlocklin.wordpress.com/2019/01/15/quantum-comput...

glitchc• 4 years ago

Reminds me of this: https://ieeexplore.ieee.org/document/4051190

Back then a digital computer couldn’t hold a candle to an analog one and processed only a few bits at a time. It was slow and imprecise. Look at where we are now.

A general quantum computer is a fundamentally different kind of computer. Those who cannot imagine what can be done with one lack the imagination to understand foundationally new technology and are unable to invent their own.

tjr225• 4 years ago

It seems that nobody on the planet is able to invent their own quantum computer.

chasil• 4 years ago

Actually, a 65-qubit quantum computer has been created.

"IBM's current largest quantum computer, revealed this month, contains 65 qubits."

https://www.science.org/content/article/ibm-promises-1000-qu...

Barrin92• 4 years ago

We went from analog to digital computers because of the concrete and specific attributes of digital computers that made them useful. Saying we went from A to B, therefore we will go from B to C, regardless of what C is makes no sense. "Things change, therefore this new thing is good and you simply lack the imagnation to understand why" is about as bad of an argument as it gets.

It's also funnily enough mirrors the everlasting blockchain advocacy.

cc101• 4 years ago

I remember when the Commodore 64 came out. "64K RAM?", I thought, "What could anyone do with so much RAM?" Power to do something new always generates new things to do with it.

jchw2• 4 years ago

You're only following the winners, but computer science has also had a lot of flops, too. Time will tell if quantum computers is one of those, but it sure isn't looking great so far.

reacweb• 4 years ago

At that time QL Sinclair was a loser. A good computer that never got programs. It was the computer of Lius Torwalds and the reason he had to write himself programs. Without QL Sinclair, we may never had Linux.

At my work, I was present when the research on ASAS (https://skybrary.aero/articles/airborne-separation-assurance...) led to the idea of PMS (https://www.eurocontrol.int/sites/default/files/2021-05/euro...).

Never underestimate serendipity

bpodgursky• 4 years ago

I think there is a world market for about five quantum computers.

O__________O• 4 years ago

Are quantum computers being used in economically significant ways that only are possible with quantum computers yet? If so, what is the best example?

Last time I checked few years ago, my understanding was the answer was still no; specifically, believe I asked Scott Aaronson as a follow up question to a talk he gave:

https://www.scottaaronson.com/

bowsamic5• 4 years ago

cycomanic2• 4 years ago

The short answer is no, I think Ising machines are much closer or even there for specific problems. They are somewhat similar to quantum computers, but entirely classical (Dwave was shown to be equivalent to an Ising machine IIRC).

lxe• 4 years ago

A great writeup about Shor's algorithm linked in the article: https://scottaaronson.blog/?p=208

blueprint• 4 years ago

No, per Susskind, we need entangled quantum computers of sufficient size to do wormhole experiments!

LeegleechN• 4 years ago

He's not wrong about the narrow algorithmic use cases (so far), but he's completely missing the utility for simulation of quantum phenomena (chemistry, microbiology, materials science). That use case alone completely justifies investing into them even if you don't care about advancing science.

bowsamic5• 4 years ago

Yeah the problem is in the name and the marketing. People think it is meant to replace normal computers, but that is totally wrong. The simulation use cases as well as probing fundamental physics are far more immediate and exciting

baby• 4 years ago

And there’s all the crypto FUD that quantum computers will scale enough to break crypto algorithms

credit_guy• 4 years ago

Out of curiosity, how many qubits would you need to simulate the molecule of water?

tokamak3• 4 years ago

Can QC simulate that?

xmcqdpt23• 4 years ago

To start, we'll neglect the bosonic degrees of freedom (the displacement of the atoms themselves) and look at only the fermionic DoF (the electrons).

Water has 8 electrons (which QC can treat exactly without any extra work) in a number of orbital. In general we need 2 qubits per orbital.

Most QC demonstrations so far were performed using so-called minimal basis sets, which have a small number of orbitals and thus give inaccurate results. A better approach would be to take a large orbital basis, do a classical relatively expensive Hartree-Fock calculation then use the orbitals from that to do the QC. This technique when done on classical computers is called MRCI (multi-reference configuration interaction) and is the gold standard in Quantum Chemistry.

So, provided we can pay the cost of doing a large orbital HF calculation (and we can do that for fairly large molecules), we can get pretty good result using n electrons in n orbitals MRCI. So production electronic calculations of water molecules would take about 16 qubits per molecule.

The more frustrating problem is that the number of electronic interaction terms is N^4 the number of orbitals so that we would very rapidly need extremely deep circuits which are not feasible without error correction (which involve using like 8 actual qubits for every calculation qubit). There are proposal to use plane wave basis sets (N^2 interactions) but then we need many more orbitals and thus many more qubits.

We are in practice very far from QC having a significant impact on real-life quantum chemistry. It's not at all clear that we'll ever be able to do QC on a molecule the size of a typical drug, let alone a protein.

_80911495292• 4 years ago

What would be the example of an outstanding, reasonably-sized (even quantum computers of the future have finite resources) quantum simulation problem that is intractable today but would unlock some economic potential, if solved?

zbobet2012• 4 years ago

Drug molecule interactions, simulations for super conductors, etc. Etc.

nabla93• 4 years ago

That use case alone completely justifies investing into them

Not at very massive scale of investments required.

Take for example, GPGPU (general purpose graphics processing unit). The wast investment needed to get there was funded by gaming industry. Supercomputers as a investment target were tiny compared to gaming and general purpose computing.

AI boom was created on a tails of gaming industry and the benefits spilled into scientific computing as well.

throwawaymaths• 4 years ago

For chemistry, you usually care about the quantum mechanics of an ensemble. Simulating a single molecule is less useful and chemistry is already a very good heuristic system for this. We would care about say: we have a 2-dimensional membrane with lipids and cholesterols, and, say, two proteins interacting in this membrane. Now, give me a molecule that either enhances or inhibits the interaction, and please constrain your search to molecules that can cross the blood brain barrier and which we can synthesize in under five "undergrad ochem" steps[0] using a set of feeder molecules with low supply chain risk (let's not depend on glutamate from China, e.g.)

I'm not sure this is something that QC can easily solve.

[0] undergrad ochem is actually a pretty good heuristic for which reactions one can perform at industrial scale, though high scale reactions might require catalysts you don't learn about in ochem

tho2u43234• 4 years ago

That's probably because "real" quantum computing today can't even factor 4-bit numbers.

The coherent-bits are really not scaling fast enough (and this is to be expected given their entanglement IMO) for anyone to really care other than snazzy startups scamming investors of their money.

johnebgd• 4 years ago

Yeah, quantum computing is still basically experimental…

pyinstallwoes3• 4 years ago

Experimental, non-physical, completely theoretical. Yep.

feliyur• 4 years ago

From my limited understanding, a quantum computer performs computations over probability distributions, rather than over numerical values. Performing precise computations over probability distributions is a serious problem in many domains - physical simulations are just one. Another example is that could allow much more efficient and precise data fusion, and as a result - a leap in AI abilities, across domains where AI is used.

yccs27• 4 years ago

Unfortunately, even though a quantum computer "manipulates wavefunctions", you can still only measure the outcome once. The magic has to happen somewhere in between state preparation and measurement. It's more like a computer with an inbuilt RNG - but if you can reach the same result via multiple execution paths, the probabilities don't just add, but they can interfere like in-phase/out-of-phase oscillatins.

hit8run• 4 years ago

So did the need for computers before the revolution started. It’s just a matter of time

vanviegen2• 4 years ago

It’s just a matter of time

Why? Not every new tech solves a problem people actually have..

morelisp2• 4 years ago

"Computers" are named after the teams of humans previously tasked with doing what they now do, a relatively common job in the first half of the 20th century and even irregularly earlier. The need was clear.

seydor• 4 years ago

Quantum computers are a part of quantum mechanics that s more of a curiosity than something to be engineered at scale. There's so much more to explore in quantum mechanics outside computation that is not receiving commensurate funding. I guess it's because "computing" is what BigTech (who has the money to fund it) understands

throwawayffffas• 4 years ago

I was under the impression that it was because quantum computers would make the simulation of quantum mechanics significantly faster as well.

lizardactivist• 4 years ago

Is there any demonstration of practical, usable QC yet?

I'm thinking of some kind of common computational work, with a clearly defined input and verified output, shown to be carried out at least an order of magnitude faster than our conventional computers.

tokamak3• 4 years ago

Obviously not

nabla93• 4 years ago

Normal computers would have suffered the same fate if they were only good for scientific calculations.

Computer revolution was funded by demand in business, gaming and automation. It's the cash flow that funds long term R&D. Not potential benefit.

There is no such demand for quantum computers. Everyday problems have too small complexity for them to be useful even if algorithm exists.

I suspect that computational biochemistry will have funders from drug firms and companies doing materials science to keep funding the research for quantum computing, but the total sum will not be billions per year like it was in computer revolution.

varjag• 4 years ago

Classical computers appeared and for the first decade existed purely because of scientific demand. Gaming and business were secondary effects.

nabla93• 4 years ago

Scientific demand is enough to start something, not sustain huge annual investments.

Global supercomputer market is roughly $6-7 billion. Nvidia, AMD together spend more into R&D than the whole market has sales. Scientific use is minuscule compared to business and entertainment needs.

Quantum computers research gets millions or maybe few tens of millions funding. That's not enough.

budlebee• 4 years ago

It feels like I'm reading an article on Netscape browser that says, "AI is still useless."

derpherpsson• 4 years ago

If you are able of imagining the future, and capable of logical coherent thoughts, the statement "the need for quantum computers remains small" is just... damn narrow-minded and perhaps just plain stupid.

If you can shave off a factor n in O(n^3) then O-B-V-I-O-U-S-L-Y it will change the world. If you don't see the obviousness in this, then why are you working with computers?

Before you hate on me, did you even google "quantum computer"? Did you read the introduction section of the Wikipedia article?

trention• 4 years ago

The proportion of comp sci tasks that have practical importance for which a quantum computer can shave off a factor of ~000s seems to be sufficiently small to doubt it will "change the world".

morelisp2• 4 years ago

I've read the introduction (and, uh, a lot more). What specific algorithms do you have in mind where quantum supremacy seems a) likely (or even possible) and b) enough of an improvement to be world-changing?

xwdv• 4 years ago

Don’t we need quantum computers to crack cryptography in reasonable time? Could be useful for surveillance or espionage purposes.

alpineidyll3• 4 years ago

If error correction can be made to work they would revolutionize human life by allowing the microscopic world to be predictable. The recent result about error correction in surface codes from the Google group is encouraging, but still several OOMs away from anything meaningful.

yshvrdhn• 4 years ago

I would argue its similar to how we thought of computers when they first came out ?

wintorez• 4 years ago

"I think there is a world market for maybe five computers." -- Thomas Watson, president of IBM, 1943

rbanffy3• 4 years ago

I came here to say precisely that. We don’t know yet what they could be useful for because we don’t have a single one that’s as capable as conventional computers were in 1943.

rbanffy3• 4 years ago

“Apple is already dead.”

Nathan Myhrvold, former Microsoft CTO, 1997

rbanffy3• 4 years ago

“There is no reason anyone would want a computer in their home.”

Ken Olsen, founder of Digital Equipment Corporation, 1977

abeppu2• 4 years ago

He sort of glosses by the need to upgrade from current cryptographic algorithms. But I wonder if in 20-30 years, we'll look back on the bad timing of having designed blockchains before post-quantum cryptography was on solid footing. Even if there are few problems where quantum computers have a clear advantage, it seems at least unfortunate that a lot of people spent a lot of time and resources building up "value" explicitly protected by those problems ... and decentralizing them in a way that makes upgrades challenging.

We like to imagine that quantum computers will be creating value for society by doing simulations about cutting-edge scientific problems. What if it just lets rich companies impersonate long-dead bitcoin whales?

tromp• 4 years ago

I consider the odds of having quantum computers able to break discrete log within 3 decades to be rather minute. The challenges involved seem way larger than for something like making nuclear fusion commercially viable.

I also have a very hard time believing that

1) physical reality supports computing with a superposition of 2^{256} states each with an accurate amplitude of magnitude 2^{-128}, and

2) that we can engineer systems preserving such accuracies.

abeppu2• 4 years ago

Care to shed more light on your intuitions?

I get that the engineering challenges are hard (or we'd have figured it out by now). And everyone seems pretty bad at predicting how long it will take for us to build something fundamentally new.

But from the physical impossibility side, what would have to be true/what would we learn if we discovered that physical reality _doesn't_ support quantum computation with a large number of qubits and sufficient accuracy?

I did do a course which included some quantum computation material and the professor highlighted that it wasn't actually demonstrated whether nature would be so "extravagant" ... but I haven't heard anyone describe what the universe would need to be like to both support the quantum phenomena that we've already studied and demonstrated, but to disallow some larger/more complex arrangements of what seem to be the same principles.

The need for quantum computers remains small

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