Talk:Quantum computing

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Former featured article Quantum computing is a former featured article. Please see the links under Article milestones below for its original nomination page (for older articles, check the nomination archive) and why it was removed.
Article milestones
Date Process Result
January 19, 2004 Refreshing brilliant prose Kept
May 9, 2006 Featured article review Kept
May 13, 2007 Featured article review Demoted
Current status: Former featured article

Contradictory statements regarding space?[edit]

The introduction suggests that simulating an n-bit quantum computer on a classical TM requires 2^n discrete states. But doesn't this contradict the later statement that QBP is a subset of PSPACE? (Erniecohen (talk) 15:50, 14 October 2012 (UTC))

It's just an example of how a classical computer could simulate a quantum computer. It doesn't mean that it's the only way to do so. --Robin (talk) 15:55, 14 October 2012 (UTC)
The problem is that the way that it is written, it strongly implies that quantum computing provides a space advantage, which is just false, so the 2^500 crap should just be removed. The relevant connection between the models is just that a classical TM can simulate a quantum computer with a polynomial blowup in space, but is strongly believed to require an exponential blowup in time. — Preceding unsigned comment added by Erniecohen (talkcontribs) 16:04, 14 October 2012 (UTC)
I wasn't aware of this. Do you have a reference? Skippydo (talk) 19:27, 14 October 2012 (UTC)

Has this been resolved? It seems odd to me in any case to say that 2500 complex values is equivalent to 2501 bits (does this mean that there are only four complex values available)? W. P. Uzer (talk) 12:27, 2 February 2014 (UTC)

Given these two objections, I've commented out the sentence in question for the moment. W. P. Uzer (talk) 08:50, 4 February 2014 (UTC)

How does it work... really![edit]

It seems like this article would benefit from explaining how quantum computers work physically. I assume they manipulate individual atoms, but how?

It seems to me that nobody really knows how it (sort of) works. It seems the researchers in the lab are playing with atomic scale phenomena that they don't fully understand. Since these researchers were trained to believe in quantum theory as the undisputed truth they preach their religion as fact. In the end they create mechanisms that can do some sort of awkward computing and they call these mechanisms "Quantum Computers". — Preceding unsigned comment added by (talk) 15:39, 15 June 2016 (UTC)

Comment so that archiving will work. (Answer already in article.) — Arthur Rubin (talk) 12:28, 31 May 2015 (UTC)
and where is the critique section of this article? — Preceding unsigned comment added by (talk) 05:12, 4 September 2015 (UTC)
Agreed. In the overview we find the statement: "Quantum computers share theoretical similarities with non-deterministic and probabilistic computers." Wow. Do you seriously suppose that the normal Wikipedia reader has any clue about determinism or probabilistic systems? Why even write something like that at the top of an article. Anyone who already knows about determinism, etc., also (probably) has some knowledge about Quantum Systems. The author of that statement could not do any better at pushing casual readers away from this topic. If anything, we need to draw more people into Computer Science in general, and bleeding-edge research in specific. Bloviation like the statement I referenced does much more harm than good by immediately throwing out arcane, industry-specific terminology. It literally turns readers off. I'm a computer scientist / engineer by education and trade, and it turned me off Big Time. Come on people. Write something that actual people can read and comprehend. Use your words. And not the 3-dollar ones, either. Plain English will do just fine.
There's an old-saying about being able to explain something in simple terms ... If you can't, you probably don't understand the subject yourself. Cheers. — Preceding unsigned comment added by (talk) 03:44, 25 October 2016 (UTC)

Announcing new results[edit]


"..(-2,334)‎ . .(Sorry, Wikipedia is not the place to announce new results. See WP:OR) .." - and wghere, WHERE is such place, for new ideas, announcing and discuss them, developing them more, and .."brainstorming",maybe ?, or just constructive discussion.. yap, according that "WP:OR" document, if we all would strictly managed by it, it would be means, - all advancing, all scientific and technical development would be almost stopped, in fact.. bcos no one would know about any new ideas, new results, new.. anything.. :/(

\( — Preceding unsigned comment added by Martin Hovorka (talkcontribs) 19:30, 2 September 2013 (UTC)

deleting of new idea announcing[edit]


hmm... not even just announce,a bit, any new idea (imho quite promising, relevant, and ..perspective.., this my multi-Sieves/Sifthering Q.C. Idea) ..even nor get,make a little advertisement,and spreading-out, for this new,constructive,fresh-brigth concept.. :\( (..but it is, and always was, my idea, trying make Q.Computing with this concept of sieve, /sifter approach,/concept(sieving) — Preceding unsigned comment added by Martin Hovorka (talkcontribs) 20:57, 2 September 2013 (UTC)

It's your fault for announcing the idea here. Doesn't everyone know by now that, if you want to patent an invention, you must do so within one year of publication. Under the new US patent law, publication may make it impossible to patent it at all. (And, yes, posting it on Wikipedia constitutes "publication".) — Arthur Rubin (talk) 21:07, 2 September 2013 (UTC)

other wiki for discussing quantum ideas[edit]

There is a common misconception that people who support the WP:OR policy are people who don't want to see any original research on any wiki.

Actually, some of us *do* want to see original research on a wiki -- but on an appropriate wiki where such research is on-topic, not just any random wiki.

There are over 10,000 English-language wiki. Pretty much any topic you can think of is on-topic at at least one of them. In particular, quantum computing seems to be on topic at several wiki including , Wikia: 3dids, , , , , , , etc.

--DavidCary (talk) 04:30, 15 January 2014 (UTC)

Quantum supercomputer[edit]

Is it really the case that a quantum computer is "also known as a quantum supercomputer"? I've never seen that usage before & suspect it should be deleted. -- (talk) 00:48, 6 January 2014 (UTC)

misc suggestions / solving chess - programming the universe - more intuitive intro[edit]

I think it would be great if the article mentioned solving chess as something that quantum computing would allow.

I also think Seth Lloyd's book "Programming the Universe" should be referenced somewhere.

The first sentence I think is too technical. It tells precisely what the term means in physics, it doesn't give any layman sense as to what quantum computing is. It almost sounds like: "Quantum computing is a process where computers use quantum systems to do computing". A layman will want to know something basic immediately like the fact that quantum computers are extremely fast and will soon be replacing standard computers.

...My 2 cents. Squish7 (talk) 00:40, 26 March 2014 (UTC)

Page title should be "Quantum computing"[edit]

To my sensibility, this page title is all wrong, or maybe not entirely - simply we have to create a more general page about more "general aspects and applications of quantum computing" like some quantum transistors that work partially as "quantum computers" but are cheaper to produce.

Computer science is no more about computers than astronomy is about telescopes.Edsger Dijkstra

Additionally, Google

 "quantum computing" -"quantum computer"

gives 2,440,000 results

 -"quantum computing" "quantum computer" 

gives 961,000 results, so one appears without the other significantly more often. — MaxEnt 05:10, 5 May 2014 (UTC)

 DoneRuud 18:01, 21 December 2014 (UTC)

Quantum games[edit]

A collection of IPs is adding an announcement of "the first quantum computer game". Even if this were sourced to a reliable source (it's not at all in the reference specified, which is a blog [not even a blog entry], and all I can find is a blog entry pointing to the announcement by the creator), would it be appropriate for the article? — Arthur Rubin (talk) 05:49, 21 May 2014 (UTC)

The announcement by the alleged creator is not a reliable source, either. — Arthur Rubin (talk) 10:39, 24 May 2014 (UTC)

strongly need th consider of change the title of this wiki-page from Q. "Computer" to "COMPUTING"[edit]

can be title of whole wiki-page re-turned to be Quantum COMPUTING, as it was before ? as "Computing" is far more fitting, more overal term for this wiki page´ topic, as just 1 concrete THE "computer") — Preceding unsigned comment added by (talk) 17:49, 23 July 2014 (UTC)

 DoneRuud 18:01, 21 December 2014 (UTC)

Invented When?[edit]

You should discuss when Quantum computing was invented and the purpose of Quantum Computing at the time.

2601:C:5600:27B:C92A:EEBE:6758:C647 (talk) 17:52, 18 January 2015 (UTC)Johnnie DeHuff

The basic idea occurred as early as 1965, in Feynman Lectures on Physics,vol. 3 when Feynman mentioned that it was frequently faster to do the physical experiment than to do the mathematical computation. In other words, use a physics experiment as an analog computer. --Ancheta Wis   (talk | contribs) 17:56, 1 February 2015 (UTC)


Why is it 10? If we're going to archive, 5, or possibly 2, would be better. I already archived one thread which was (potentially) about the subject, rather than about the article. — Arthur Rubin (talk) 22:52, 4 May 2015 (UTC)

Changed to 5. I also "archived" 3 sections about alleged simulators of quantum computers, with no credible source. — Arthur Rubin (talk) 12:30, 31 May 2015 (UTC)

Three-bit Example?[edit]

It would be very helpful to see an example of a calculation or problem solved at the three bit level. Is there such a thing? JFistere (talk) 03:11, 15 October 2015 (UTC)

simplify intro![edit]

The technical expertise in this article is very good, but way too technical at the intro. The intro should be a thesis statement especially for newbies. I'll back-read the terminology you used and see if I can glean enough to simplify the intro for you. No promises though!

By the way, are the states referred to in the article the spin of the qbit?

I just found a good nuts 'n bolts explanation here... (talk) 18:57, 26 October 2015 (UTC)

misleading lede[edit]

  • "Given sufficient computational resources, however, a classical computer could be made to simulate any quantum algorithm, as quantum computation does not violate the Church–Turing thesis.[10]"

The whole article is currently very tech. Which is OK with me, even though I cannot understand it well enough to judge how correct it is... But it needs more content that is at a lower level. And it needs to be careful not to mislead readers who are not so tech. The above sentence currently concluding the lede is a prime example of content which is probably correct in theory but seriously misleading, particularly in the lede context. Most ordinary readers would not understand that "sufficient computational resources" includes unbounded quantities thereof, with no regard for feasibility. Yes, we may think quantum computers can only solve problems that a classical computer could solve if it was big enough and had enough time to solve. But there are many problems that would require using the entire universe to solve (organized as a classical computer) and still take longer than the expected life of the universe. If we think quantum computers will be able to solve some such problems (within feasible, limited, size and time constraints), we can fairly say there is a distinct difference in the problems these two classes of computers can solve, even if both classes of computers are only able to solve (all) Turing problems -- "given enough resources". I don't really know enough to know how the lede should be fixed -- but maybe I will Be Bold anyway, to get the ball rolling...- (talk) 19:11, 10 December 2015 (UTC)

I could not agree more. This article reads like an excerpt from a sub-par college textbook for a class called: "Hypothetical Quantum Computing Systems" or something. Text books are fine when confined to Academia. Wikipedia is supposed to be for the masses. And with so much jargon being tossed about, it makes it appear that this subject is well-defined and based on real-world working models; which is simply NOT the case. 99% of what I read is pure theory at this time (2016). (talk) 03:54, 25 October 2016 (UTC)

Do I have this right?[edit]

I've been trying to ground myself in this subject in order to attempt a good thesis statement. The way I understand it, those qbits would explore all possibilities for a given expression - between two clock ticks of the quantum computer. Is that right? Pb8bije6a7b6a3w (talk) 00:28, 11 December 2015 (UTC)

No, that's not right. "Exploring all possibilities" is not an accurate description of quantum computing. For comparison with the double-slit experiment, it is not correct to say that "a photon explores both slits and then chooses the right one". It is equally incorrect to say that "a quantum computer explores all possibilities and then chooses the right one". Think of quantum computing as operations that are meant to have a specific impact on correlated interference patterns. MvH (talk) 04:59, 14 January 2017 (UTC)

Quantum vials / cartridge entanglement[edit]

Large multi-mono-atomic groupings cannot maintain cohesion for long. An old idea is to replace each atom with a vial (cartridge), so now each vial plays the role of a single atom, then we entangle the vials among each other. The problem is that particles inside a vial may entangle with other ones of the same vial (so now the vial doesn't act as a single atom), in order to avoid that we use few atoms on each vial [seems clever but it isn't for other reasons/small mistakes become important] and we cool each vial to make it almost a condensate [seems clever but it isn't for other reasons/each person should have a quantum computers, so superconductivity at room temperature is the only solution, not extreme temperatures]. Some reverberative NON-MEASURED laser radiation (the laser should allow different quantum states of oscillation that will be not revealed to us) will increase cohesion inside the mini vats. Sounds great but until now the result is randomness. Crucial details are under development. Akio (Akio) 00:28, 13 May (UTC)

classical computer analogues[edit]

A classical computer analogue, uses a noise generator to introduce noise when needed and entangled quantum rotation statistics. Then we run trillions of times the wavefunctional collapse in order we average the result (most tasks though do not require large averagings, so even a billion or a million might work for simple tasks). That quantum analugue is 10^7 times slower than an ideal quantum computer, but it works, also we don't have large arrayed quantum entangletrons (computer). Human averaging algorithms might not be perfect, but a good noise generator is way better than the natural noise if we add some mistakes of measurement of a future actual large entangletron (quantum computer). Yoritomo (Yoritomo) 04:01, 15 May (UTC)

Each digit should be partially connected (at variable rates that change for each task) with all other digits (at a unique percentage to each other digit), but also to separate non-interconnected randomness (at variable rates that change for each task, at a unique percentage to each other digit). This is called "tensor computing". That works fine for many tasks, you might not get the absolute answer but you will get close after a trillion trials. If you want the absolute answer (well to get even closer, because even getting the absolute answer is something probabilistic), you then should allow partial variable dynamics take action, a combinatorics method of "communicating vessels" (well partially communicating at different rates for each digit and partially introducing variable separate-noise rates to each digit). These combinatoric communicating vessels use as their grain an algorithmic module that acts as the smallest particle. An actual quantum computer uses as a grain-module an infinitely small module and we cannot, but we can get very close and minimize our grain-module enough to perform each task with a classical super computer. Nowadays a classical pseudo-entangletron is better than an entangletron (quantum computer) simply because we can already build a very complex one! Ieyasu (Ieyasu) 04:32, 15 May (UTC)
your first digit is totally random, all other digits are probabilistically separately random (not of the same random series) with some statistical probability of indruducing the initial random digit— Preceding unsigned comment added by 2A02:587:4103:2300:C8D5:96C1:1BF2:71A7 (talk)

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No mention of China?[edit]

Claims of quantum computing superiority (including launching of a quantum satellite) in second-half of Sept. 2016 interview at: (talk) 18:17, 17 September 2016 (UTC)

Error in "Basis" section?[edit]

"A double qubit can represent a one, a zero, or any quantum superposition of those two qubit states; a pair of qubits can be in any quantum superposition of 4 states, and three qubits..."

Should presumably read "A single qubit..." etc. Northutsire (talk) 19:24, 4 October 2016 (UTC)

Error in usage of the term non-determinism[edit]

The term non-deterministic was used twice in the article, the first time properly, in the sentence "Quantum computers share theoretical similarities with non-deterministic and probabilistic computers.", and the second time in a wrong way in the sentence "Quantum algorithms are often non-deterministic, in that they provide the correct solution only with a certain known probability." It is highly misleading as the term non-deterministic computing and the term probabilistic computing are very different in computer science. I corrected the error and clarified that the term non-determinism must not be used in that context. Of course, an alternative is simply to replace non-deterministic by probabilistic in the previous version, yet I find this to be a very good place to clarify to the physicists among the readers that the term non-determinism cannot be used for describing the probabilistic nature of (regular) quantum computers. Tal Mor (talk) 08:10, 29 November 2016 (UTC)

Sorry - I meant to clarify the issue to all the readers that are not computer scientists (not just to the physicists). Tal Mor (talk) 08:13, 29 November 2016 (UTC)

Make paragraph, but also new page: Quantum computing and deep learning[edit]

No human being can generate some complicated questions to ask a quantum computer about molecular statistics of mixed materials, so we define the parameters of our questions, but the final question is a result of computing! You don't need a computer only to get an answer, but even to finalize hard questions. We must be more analytical about how a quantum computer might act as a neural network, or how a neural network might control a quantum computer. Don't write random stuff. Collect some information for 4 years, and then write here. — Preceding unsigned comment added by 2A02:587:4116:2200:A123:2E94:AB7B:DF1 (talk) 11:10, 17 April 2017 (UTC)