The Case Against Quantum Computing

MrAl

Joined Jun 17, 2014
11,389
I think, you think you are disagreeing with me, but you are not. As I see it, string theory can (maybe) describe and infinite number of universes (as you said too general) and there seems to be no hope of coming up with the particular solution that will describe ours.

Coupled with the fact that it requires supersymmetry and each new collider we build ups the lower limit on then energy of supersymmetric particles requiring modifications to the theory, and it looks like a dead end to me. What it predicts beyond the standard model has been pretty much disproven.

Bob

Bob
Hi,

Well thanks for clarifying that. However, i am not sure if you accept it or not, maybe you accept it for some things and not for other things. That's probably my view too. BTW when i say string theory i am including M Theory.

However, supersymmetry is not "required" for string theory. As with all mathematics, symmetry always simplifies the problem in some way. So it is used to form a more workable solution ... a simpler model to work with. We do this all the time in electronics, we create models that are not exact but can show us a lot of information it would have taken longer to get without the toy model. A transistor modeled by a dependent current source for example. It works to a certain point so we can get at least some information from it. We can always turn to the full blown model spice offers us.
In the purest sense though supersymmetry is not "required" i think a better word is "desired".

It's also interesting how it helped mathematics in general.
 

BobTPH

Joined Jun 5, 2013
8,813
Hi,

Well thanks for clarifying that. However, i am not sure if you accept it or not, maybe you accept it for some things and not for other things. That's probably my view too. BTW when i say string theory i am including M Theory.

However, supersymmetry is not "required" for string theory. As with all mathematics, symmetry always simplifies the problem in some way. So it is used to form a more workable solution ... a simpler model to work with. We do this all the time in electronics, we create models that are not exact but can show us a lot of information it would have taken longer to get without the toy model. A transistor modeled by a dependent current source for example. It works to a certain point so we can get at least some information from it. We can always turn to the full blown model spice offers us.
In the purest sense though supersymmetry is not "required" i think a better word is "desired".

It's also interesting how it helped mathematics in general.
Supersymmetry was added to string theory to allow it to model fermions and gravitons. Before that it could only model bosons. So you are technically correct, but, without supersymmetry it is not a theory of everything.

From Wikipedia:
'Superstring theory' is a shorthand for supersymmetric string theorybecause unlike bosonic string theory, it is the version of string theory that accounts for both fermions and bosonsand incorporates supersymmetry to model gravity.
Bob
 

MrAl

Joined Jun 17, 2014
11,389
Supersymmetry was added to string theory to allow it to model fermions and gravitons. Before that it could only model bosons. So you are technically correct, but, without supersymmetry it is not a theory of everything.

From Wikipedia:


Bob
Hello again,

I think the interpretation makes a difference but i guess it doesnt matter that much here.
My interpretation is that you can do it anyway. When they say "added to account for this or that" it is mainly because it is too difficult to do it without that modification or simplification.
I guess it doesnt matter that much though for this discussion. Maybe too much of a nit pick.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,081
https://profmattstrassler.com/artic...-stock-of-the-higgs-jan-2013/5-supersymmetry/
https://profmattstrassler.com/artic...ersymmetry/where-stands-supersymmetry-122013/

1652973284202.png
Our claim is that studies of the 2011-2012 data by ATLAS and CMS rule out almost all natural supersymmetry variants which have a gluino with mass below 1000 GeV/c^2. Very few assumptions are required and very few loopholes remain.

The lack of evidence for supersymmetry at the LHC does not signify a death knell for the idea. Nevertheless, “now the community is going off in a large number of different directions,” Peskin says. “We’re all pretty confused right now.”
https://www.symmetrymagazine.org/article/the-status-of-supersymmetry


https://www.symmetrymagazine.org/article/can-a-theory-ever-die

Can a theory ever die?
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,081
https://www.vox.com/23132776/quantu...rsecurity-artificial-intelligence-white-house
Quantum computers could change the world — provided they can work
Plenty of experts are skeptical that IBM or any of its competitors will ever get there, raising the possibility that the engineering problems presented by quantum computers are simply too hard for the systems to ever be truly reliable. “What’s happened over the last decade is that there have been a tremendous number of claims about the more immediate things you can do with a quantum computer, like solve all these machine learning problems,” Scott Aaronson, a quantum computing expert at the University of Texas, told me last year. “But these claims are about 90 percent bullshit.” To fulfill that promise, “you’re going to need some revolutionary development.”
 

MrAl

Joined Jun 17, 2014
11,389
https://www.vox.com/23132776/quantu...rsecurity-artificial-intelligence-white-house
Quantum computers could change the world — provided they can work
I guess we are all a little 'agnostic' toward QC and other technologies like self driving road missiles (har har) and fusion power.
IT is kind of interesting that several technologies are in the development phase where the development is long term. The only thing we have to go on is scientific research that suggests these things will work one day. Maybe super batteries and room temperature super conductors are in that group too to some extent.

Perhaps there should be other names that should be used to reflect the time frame as well as the proposed technology.
For some semi comical examples:
Quantime Computers
Self Crashing Vehicles (SCV's)
Fuxion Power

Now some of these are comical, but to be serious there should be other names for technology that just isnt quite there yet so people will know right off that it is still in development.
Maybe just "Alpha" s in software:
Alpha Quantum Computers
Alpha Self Driving Vehicles
Alpha Fusion Power

Just some simple examples but im sure there are better ideas out there.
This way it would not be as misleading i think.
I guess i am saying this because if the technology isnt done being developed yet then it isnt yet technology and there may be a chance that it never will be, or could even be found to have secondary problems that make it too problematic to be continued in use (examples below).

An interesting example was the Wankle Engine. I read about this years and years ago. It took many years before they actually built one and put it in production line cars. The Mazda if i remember right. The Corvair i think. It came and went not sure if they make one anymore. But it did take a long time to get one into production so some things have a long wait time.
Today i think the engine isnt good enough for some government standards so it has to be improved. So while things are coming out that are new other things are also changing and that may affect the new tech in a negative way.
There is another engine similar too that is being developed cant remember the same though but it's supposed to be really reliable. Hope to see that come out also.

Also related...
Since i met up with a friend i knew long ago that now lives in Los Angeles i keep up with some news on California now too.
They are having an issue with EV's (electric vehicles). The issue, as expected, is the load on the electric grid in CA is just too much. They are expecting power outages now and then because so many EV's are on the road now. Also, i think the gov maandate to switch to EV's is 2025 or something like that so the load on the grid is going to be overwhelming.
So here we see a secondary problem that comes up that maybe wasnt anticipated at the time of the invention. This could happen with anything i think and so we wont know until after it's out there and running and becoming popular. Another example is bitcoin mining which is said to consume a lot of electricity.

So all this technology still in dev may come and go we wont know until we get there.

PS I noticed that CA does some really nutty stuff though with environmental laws. They restrict and restrict with the two most needed resources water and electric power. It's nuts.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,081
I can't read the article but QC error correction is much like Hamming and other error-correction codes with classical bits. There is a trade-off. If 'bits' are cheap, the trade for error correction is small, if 'qubits' are expensive it makes building a practical QC much harder.

https://www.scientificamerican.com/article/how-to-fix-quantum-computing-bugs/
There is another problem yet to solve. Codes living on two-dimensional planes and incorporating only nearest-neighbor connections have a large overhead. Correcting more errors means building a larger code, which employs more physical qubits to create a single logical qubit. The setup requires more physical hardware to represent the same amount of data—and more hardware makes it more difficult to build qubits good enough to beat the error threshold.

Quantum engineers have two options. We could make peace with the large overhead—the extra qubits and gates—as the cost of a simpler architecture and work to understand and optimize the different factors contributing to the cost. Alternatively, we could continue to seek better codes. For instance, to encode more logical qubits into fewer physical qubits, perhaps we should allow qubits to interact with more distant qubits than just their nearest neighbors or go beyond a two-dimensional grid to a three- or higher-dimensional lattice. Our theory team is pursuing both options.
If you hear anyone say that what is special about quantum computing is that you have superposition and entanglement, beware! Not all superposition and entangled states are special.
...
Overlooking the need for universal computation is also the root of misconceptions and misleading messages about logical qubits and quantum error correction. Protecting information in memory from error is a start, but it is not enough. We need a universal set of quantum gates, one that is sufficiently rich to perform any gate that is allowed by quantum physics. Then we need to make those gates robust to errors. This is where things get difficult.
 

MrAl

Joined Jun 17, 2014
11,389
Hi there,

I have been reading these kinds of articles for months now. Literally months running into years.
That bothers me because it always seems like we are "almost there" but never quite get there in reality.
So i hope this gets going soon.
I kinda started to ignore some of these articles now because they all quote advancements but nothing too concrete.

I did see some real life problems were solved with QC but not sure i they are relevant enough yet or not. Some are in number theory.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,081
Hi there,

I have been reading these kinds of articles for months now. Literally months running into years.
That bothers me because it always seems like we are "almost there" but never quite get there in reality.
So i hope this gets going soon.
I kinda started to ignore some of these articles now because they all quote advancements but nothing too concrete.

I did see some real life problems were solved with QC but not sure i they are relevant enough yet or not. Some are in number theory.
In theory advanced QC machines (if we can solve the decoherence problem) will be faster and cheaper that conventional computers on the same types of some computational problems but:
Quantum computing isn’t going to find new answers to fundamental physics problems, find your car keys, your cat or keep the checking account balanced. ;)
https://quantumalgorithmzoo.org/

https://hackernoon.com/decoherence-quantum-computers-greatest-obstacle-67c74ae962b6
Decoherence: Quantum Computer’s Greatest Obstacle

1653658026674.png
 

MrAl

Joined Jun 17, 2014
11,389
In theory advanced QC machines (if we can solve the decoherence problem) will be faster and cheaper that conventional computers on the same types of some computational problems but:
Quantum computing isn’t going to find new answers to fundamental physics problems, find your car keys, your cat or keep the checking account balanced. ;)
https://quantumalgorithmzoo.org/

https://hackernoon.com/decoherence-quantum-computers-greatest-obstacle-67c74ae962b6
Decoherence: Quantum Computer’s Greatest Obstacle

View attachment 268104
Hi,

Not sure what you are getting at here.

Why not physics problems?

Supposedly will be great for chemistry because it can test lots of combinations.

Find your keys or cat, we already have 'tags' to do that use with your cell phone.

Keeping the checking account balanced, we already have that. I wrote my own checking problem long ago that balances the book. All i have to do is check off what came into the bank up to that date. I will eventually eliminate that step also by having a web program that works with the checking program. I will have to sign on to my bank site then click a button in the app. Dont need quantum to do that.
A large bank may benefit though with so many transactions going on each second.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,081
Hi,

Not sure what you are getting at here.

Why not physics problems?

Supposedly will be great for chemistry because it can test lots of combinations.

Find your keys or cat, we already have 'tags' to do that use with your cell phone.

Keeping the checking account balanced, we already have that. I wrote my own checking problem long ago that balances the book. All i have to do is check off what came into the bank up to that date. I will eventually eliminate that step also by having a web program that works with the checking program. I will have to sign on to my bank site then click a button in the app. Dont need quantum to do that.
A large bank may benefit though with so many transactions going on each second.
How are we computationally limited in theoretical physics? What fundamental physics problem today is computationally bound? We need high-level "emergent" concepts to set up the problem in terms of fundamental particles/fields/etc.. The issue is with setting up initial conditions and interpreting the results, not the actual computations because most testable models can be simplified in mathematical complexity .

I'm sure a general QC will be a useful tool but most physics problems are not the sort of problems a QC will solve faster unlike a chemistry QC program looking for patterns for a cancer drug using known physics.

https://en.wikipedia.org/wiki/Worldwide_LHC_Computing_Grid

CERN computer network status.
https://wlcg.web.cern.ch/using-wlcg/monitoring-visualisation
http://wlcg-squid-monitor.cern.ch/snmpstats/
 
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Thread Starter

nsaspook

Joined Aug 27, 2009
13,081
Advanced? That term is a bit much. Its an experimental machine with a very limited computer capacity with a very narrow computer capability.

"So far, no one has been able to demonstrate quantum advantage for a “useful” computational task"
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,081
Looks like things are heating up on the QC investment side.

https://www.insidequantumtechnology...ners-respond-to-scathing-short-seller-report/

IonQ, Partners Respond To Scathing Short-Seller Report
IonQ late last week issued a cool-headed but generic response to a shrill report by short-seller Scorpion Capital earlier in the week that claimed that IonQ is an “academic side hustle,” that quantum computing advances claimed by IonQ are a “hoax,” and that IonQ CEO Peter Chapman “recklessly and compulsively” makes “bogus claims” about the company’s progress.
 

bogosort

Joined Sep 24, 2011
696
"So far, no one has been able to demonstrate quantum advantage for a “useful” computational task"
No one has been able to demonstrate quantum advantage for any computational task. We simply don't know if QC is more powerful, even in principle, than CC.

So far, the only evidence for quantum advantage is a handful of QC algorithms that can (in principle) beat the best currently available CC algorithms. And though Shor's QC algorithm for prime factorization is spectacular, we haven't been able to prove (despite much effort) that a classical algorithm can't perform just as well.

Given the enormous engineering challenges and the lack of clear theoretical advantage, the QC hype is definitely overblown. I wouldn't be surprised if quantum computers turn out just to be the most efficient (but still very expensive) way to simulate small quantum systems. That would certainly be useful in certain fields -- namely, quantum chemistry, materials science, and solid state physics -- but the idea that one day people will have personal QCs (for what reason? who knows) is a bit much.
 

cmartinez

Joined Jan 17, 2007
8,219
for what reason? who knows
My personal opinion, is that true AI will only be accomplished when QC finally goes mainstream. I think that calling current complex processing algorithms "artificial intelligence" is doing a disservice to the concept itself.
 

crutschow

Joined Mar 14, 2008
34,282
Roger Penrose has stated that a digital computer algorithm can never generate true consciousness, and suggested that the brain uses quantum processes in the brain cells microtubules to provide our consciousness, and the leaps in knowledge that allows.
 

cmartinez

Joined Jan 17, 2007
8,219
Roger Penrose has stated that a digital computer algorithm can never generate true consciousness, and suggested that the brain uses quantum processes in the brain cells microtubules to provide our consciousness, and the leaps in knowledge that allows.
But that suggestion so far amounts to mere speculation (albeit from a very respectable figure), right?
 
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