QM: A couple of defensible statements. Also, a bit on their implications for the QC.

A Special Note (added on 17th June 2018): This post is now a sticky post; it will remain, for some time, at the top of this blog.

I am likely to keep this particular post at the top of this blog, as a sticky post, for some time in the future (may be for a few months or so). So, even if posts at this blog normally appear in the reverse chronological order, any newer entries that I may post after this one would be found below this one.

[In particular, right now, I am going through a biography: “Schrodinger: Life and Thought” by Walter Moore [^]. I had bought this book way back in 2011, but had to keep it aside back then, and then, somehow, I came to forget all about it. The book surfaced during a recent move we made, and thus, I began reading it just this week. I may write a post or two about it in the near future (say within a couple of weeks or so) if something strikes me while I am at it.]


A Yawningly Long Preamble:

[Feel free to skip to the sections starting with the “Statement 1” below.]

As you know, I’ve been thinking about foundations of QM for a long, long time, a time running into decades by now.

I thought a lot about it, and then published a couple of papers during my PhD, using a new approach which I had developed. This approach was used for resolving the wave-particle duality, but only in the context of photons. However, I then got stuck when it came to extending and applying this same approach to electrons. So, I kept on browsing a lot of QM-related literature in general. Then, I ran, notably, into the Nobel laureate W. E. Lamb’s “anti-photon” paper [^], and also the related literature (use Google Scholar). I thought a lot about this paper—and also about QM. I began thinking about QM once again from the scratch, so to speak.

Eventually, I came to abandon my own PhD-time approach. At the same time, with some vague but new ideas already somewhere at the back of my mind, I once again started studying QM, once again with a fresh mind, but this time around much more systematically. …

… In the process, I came to develop a completely new understanding of QM!… It’s been at least months since I began talking about it [^]. … My confidence in this new understanding has only increased, since then.

Today’s post will be based on this new understanding. (I could call it a new theory, perhaps.)


My findings suggest a few conclusions which I think I should not hold back any longer. Hence this post.

I have been trying to locate the right words for formulating my conclusions—but without much satisfaction. Finally, I’ve decided to go ahead and post an entry here anyway, regardless of whether the output comes out as being well formulated or not.

In other words, don’t try to pin me down with the specific words I use here in this post! Instead, try to understand what I am trying to get at. In still other words: the particular words I use may change, but the intended meaning will, from now on, “always” remain the same—ummm…. more or less the same!

OK, so here are the statements I am making today. I think they are well defensible:


Notation:
QM: Quantum Mechanics, quantum mechanically, etc.
CM: Classical Mechanics
QC: Quantum Computer
QS: Quantum Supremacy ([^] and [^])


Statement 1: It is possible to explain all quantum mechanical phenomena on the basis of those principles which are already known (or have already been developed) in the context of classical mechanics.

Informal Explanation 1.1: Statement 1 holds true. It’s just that when it comes to explaining the QM phenomena (i.e., when it comes to supplying a physical mechanism for QM), even if the principles do remain the same, the way they are to be combined and applied is different. These differences basically arise because of a reason mentioned in the next Informal Explanation.

Informal Explanation 1.2: Yes, the tradition of 80+ years, involving an illustrious string of Nobel laureates and others, is, in a way, “wrong.” The QM principles are not, fundamentally speaking, very different from those encountered in the CM. It’s just that some of the objects that QM assumes and talks about are different (only partly different) from those assumed in the CM.


Corollary 1 of Statement 1: A quantum computer could “in principle” be built as an “application layer” on top of the “OS platform” supplied by the classical mechanics.

Informal Explanation 1.C1.1: Hierarchically speaking, QM remains the most fundamental or the “ground” layer. The aspects of the physical reality that CM refers to, therefore, indeed are at a layer lying on top of QM. This part does continue to remain the same.

However, what the Corollary 1 now says is that you can also completely explain the workings of QM in terms of a virtual QM machine that is built on top of the well-known principles of CM.

If someone builds a QC on such a basis (which would be a virtual QC on top of CM), then it would be just a classical mechanically functioning simulator—an analog simulator, I should add—that simulates the QM phenomena.

Informal Explanation 1.C1.2: The phrase “in principle” does not always translate into “easily.” In this case, it in factt is very easily possible that building a big enough a QC of this kind (i.e. the simulating QC) may very well turn out to be an enterprise that is too difficult to be practically feasible.


Corollary 2 of Statement 1: A classical system can be designed in such a way that it shows all the features of the phenomenon of quantum entanglement (when the classical system is seen from an appropriately high-level viewpoint).

Informal Explanation 1.C2.1: There is nothing “inherently quantum-mechanical” about entanglement. The well-known principles of CM are enough to explain the phenomena of entanglement.

Informal Explanation 1.C2.2: We use our own terms. In particular, when we say “classical mechanics,” we do not mean these words in the same sense in which a casual reader of the QM literature, e.g. of Bell’s writings, may read them.

What we mean by “classical mechanics” is the same as what an engineer who has never studied QM proper means, when he says “classical mechanics” (i.e., the Newtonian mechanics + the Lagrangian and Hamiltonian reformulations including variational principles, as well as the more modern developments such as studies of nonlinear systems and the catastrophe theory).


Statement 2: It can be shown that even if the Corollary 1 above does hold true, the kind of quantum computer it refers to would be such that it will not be able to break a sufficiently high-end RSA encryption (such as what is used in practice today, at the high-end).

Aside 2.1: I wouldn’t have announced Statement 1 unless I was sure—absolutely goddamn sure, in fact—about the Statement 2. In fact, I must have waited for at least half a year just to make sure about this aspect, looking at these things from this PoV, then from that PoV, etc.


Statement 3: Inasmuch as the RSA-beating QC requires a controlled entanglement over thousands of qubits, it can be said, on the basis of the new understanding (the one which lies behind the Statement 1 above), that the goal of achieving even “just” the quantum supremacy seems highly improbable, at least in any foreseeable future, let alone achieving the goal of breaking the high-end RSA encryption currently in use. However, proving these points, esp. that the currently employed higher-end RSA cannot be broken, will require further development of the new theory, particularly a quantitative theory for the mechanism(s) involved in the quantum mechanical measurements.

Informal Explanation 3.1: A lot of funding has already gone into attempts to build a QC. Now, it seems that the US government, too, is considering throwing some funds at it.

The two obvious goal-posts for a proper QC are: (i) first gaining enough computational power to run past the capabilities of the classical digital computers, i.e., achieving the so-called “quantum supremacy,” and then, (ii) breaking the RSA encryption as is currently used in the real-world at the high-end.

The question of whether the QC-related researches will be able to achieve these two goals or not depends on the question of whether there are natural reasons/causes which might make it highly improbable (if not outright impossible) to achieve these two goals.

We have already mentioned that it can be shown that it will not be possible for a classical (analog) quantum simulator (of the kind we have in mind) to break the RSA encryption.

Thus, we have already made a conclusive statement about this combination of a QC and a goal-post:

  • Combination 1: CM-based QC Simulator that is able to break the RSA encryption.

We have said that it can be shown (i.e. proved) that the above combination would be impossible to have. (The combination is that extreme.)

However, it still leaves open 3 more combinations of a QC and a goal-post:

  • Combination 2: CM-based QC Simulator that exceeds the classical digital computer
  • Combination 3: Proper QC (working directly off the QM platform) that exceeds the classical digital computer
  • Combination 4: Proper QC (working directly off the QM platform) that is able to break the RSA encryption.

As of today, a conclusive statement cannot be made regarding the last three combinations, not even on the basis of my newest approach to the quantum phenomena, because the mathematical aspects which will help settle questions of this kind, have not yet been developed (by me).

Chances are good that such a theory could be developed, at least in somewhat partly-qualitative-and-partly-quantitative terms, or in terms of some quantitative models that are based on some good analogies, sometime in the future (say within a decade or so). It is only when such developments do occur that we will be able to conclusively state something one way or the other in respect of the last three combinations.

However, relying on my own judgment, I think that I can safely state this much right away: The remaining three combinations would be tough, very tough, to achieve. The last combination, in particular, is best left aside, because the combination is far too complex that it can pose any real threat, at least as of today. I can say this much confidently—based on my new approach. (If you have some other basis to feel confident one way or the other, kindly supply the physical mechanism for the same, please, not just “math.”)


So, as of today, the completely defensible statements are the Statement No. 1 and 2 (with all their corollaries), but not the Statement 3. However, a probabilistic judgment for the Statement 3 has also been given.


A short (say, abstract-like) version:

A physical mechanism to explain QM phenomena has been developed, at least in the bare essential terms. It may perhaps become possible to use such a knowledge to build an analog simulator of a quantum computer. Such a simulator would be a machine based only on the well-known principles of classical mechanics, and using the kind of physical objects that the classical mechanics studies.

However, it can also be easily shown that such a simulator will not be able to break the RSA encryption using algorithm such as Shor’s. The proof rests on an idealized abstraction of classical objects (just the way the ideal fluid is an abstraction of real fluids).

On the basis of the new understanding, it becomes clear that trying to break RSA encryption using a QC proper (i.e. a computer that’s not just a simulator, but is a QC proper that directly operates at the level of the QM platform itself) would be a goal that is next to impossible to achieve. In fact, even achieving just the “quantum supremacy” (i.e., beating the best classical digital computer) itself can be anticipated, on the basis of the new understanding, as a goal that would be very tough to achieve, if at all.

Researches that attempt to build a proper QC may be able to bring about some developments in various related areas such as condensed matter physics, cryogenics, electronics, etc. But it is very highly unlikely that they would succeed in achieving the goal of quantum supremacy itself, let alone the goal of breaking the RSA encryption as it is deployed at the high-end today.


A Song I Like:

(Marathi) “kaa kaLenaa, koNatyaa kshaNee”
Music: Avinash-Vishwajeet
Singers: Swapnil Bondodkar, Bela Shende
Lyrics: Satish Rajwade

 


PS: Note that, as is usual at this blog, an iterative improvement of the draft is always a possibility. Done.

Revision History:

  1. First posted on 2018.06.15, about 12:35 hrs IST.
  2. Considerably revised the contents on 2018.06.15, 18:41 hrs IST.
  3. Edited to make the contents better on 2018.06.16, 15:30 hrs IST. Now, am mostly done with this post except, may be, for a minor typo or so, here or there.
  4. Edited (notably, changed the order of the Combinations) on 2018.06.17, 23:50 hrs IST. Also corrected some typos and streamlined the content. Now, I am going to leave this post in the shape it is. If you find some inconsistency or so, simple! Just write a comment or shoot me an email.

 

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My comments at other blogs—part 1

Introductory:

I sometimes post comments at other people’s blogs. Since a thread at these other blogs often is only partially related to the points I am interested in or am making, I don’t always have enough space to explain my points at that blog. Yet, simply in order to note something, I do infrequently post a few comments, thinking that I will return here (at this blog) and expand on those points later on. Yet, most often, what happens is that I simply forget the points once they are thus jotted down elsewhere. All in all, I have been wanting to improve on my “notes-keeping” techniques—it’s been getting messier and still messier!

While it would be ideal to provide some further explanation on the comments I thus make elsewhere, doing so would usually take enough extra effort that whenever I think of doing so, I immediately slip into that nice and comfortable and very cozy zone of… what else? procrastination.

I have, therefore, thought of a compromise solution: To provide (at least just) the links to the comments I have written elsewhere. This way, I will at least not forget the points which I need to expand on, later on. After all, this is my blog; I do take its back-up; and so, anything that I note here will stay somewhere at least in the backups (if not also in the mind); it won’t go permanently out of my mind, and therefore all lost to me.

Thus, from this post onwards, I will occasionally be lumping together a few links to my own comments elsewhere, via a post specially dedicated to such links, here.

Further, I have also decided to highlight some other interesting blogs or posts from time to time. Thus, though this blog was heavy on my own writings thus far, in future, it would also have a bit of a mix of other people’s blogs.

* * *

My Comments on a Blog Post about Animation of Quantum Manner:

Recently, I have made a few comments at a CalTech+PhDComics blog post on animation of quantum matter. The post in question is here: [^].

Among the many comments I made there, I think my more notable comments are: this [^], this [^] and this [^]. Let me tell you why I think so.

But before that, the right time to visit that blog-post and to go through all comments—mine as well as others’—is: right now.

From this point onwards, I assume that you are familiar with both the post and all the comments it received.

OK.

The first of my comments [^], though deliberately long, basically tries to take away that “quantum” kind of an aura which invariably engulfs any mainstream QM-based explanation of any QM phenomenon. Here, Prof. John Preskill and Dr. Painter had (probably though not at all very deliberately) introduced precisely this element of a mystery, by highlighting the asymmetry part of it, without providing any clue as to why the asymmetry might be arising. As soon as I saw the video and read their answers, I thought they were going overboard in emphasizing that asymmetry part.

In laying emphasis on the fact that this was not a simple, passive mechanical oscillator but one that was being actively (nay, aggressively) being kept cooled down to the near-absolute zero temperatures, I tried to remove that usual “quantum” sort of a fog surrounding the issue.

BTW, though it’s a minor point, in my comments, I also tried to indirectly emphasize the fact that starting from a non-absolute zero K temperature, you cannot ever hope to reach 0 K. This is not an issue pertaining to an ignorable kind of a small number; it’s not a matter of a relatively insignificant experimental error; it’s a matter of an important principle—of a law of thermodynamics. You don’t begin to violate laws of thermodynamics in your presentation just in order to make the matter look sexy to some clueless American high-school students or their equivalents there or elsewhere (regardless of their age, education,  alma mater, the obtainment of a tenure or a VC funding, fellowships obtained from professional societies, instances of their otherwise competent PhD students being unethically flunked during qualifiers, etc.). You don’t do that. You don’t have to, in order to either highlight the achievements of science or even to make it attractive.

The second and third of my above-mentioned comments (i.e. this [^]  and this [^]) introduce what in that context perhaps is a novel idea. Apparently, people haven’t pursued the single-quantum versions of the experiments which study the transfer of a quantum state from light to a mechanical oscillator (or vice-versa). Perhaps, before I introduced the idea, they hadn’t even thought of doing so—not in this context. (Such things are easily possible.) In any case, they should pursue such experiments. Why?

The reason is twofold.

Firstly, these days, there seems to be a new and special streak of QM skepticism gaining some traction, esp. in the American science circles.

For instance, no sooner does a private sector Canadian company D-Wave introduce some new version of their hardware than a small army of the NSF/American public R&D-funded skeptics launch scathing attacks on all its claims. For instance, see the nature of the comments at Prof. Scott Aaronson’s blog [^]. Being extra critical of extraordinary claims is perfectly OK, nay, it is even demanded by the rigours of science. But being skeptical never is: skepticism, even an informed skepticism, is not a route to knowledge. Skepticism only destroys knowledge.

Now, coming to Prof. Aaronson, inasmuch as he does maintain that extra rigour of criticism, he is to be encouraged and applauded. In fact, when he apparently isn’t too busy (or too passionately in the thick of the thrust and parry, i.e. “debate”), Prof. Aaronson himself seems to be pretty well-balanced about the issue. (He obviously has a tilt against D-Wave, but he also, equally obviously, has absolutely no axe to grind here—that much is clear. And, when it comes to summarizing, it’s good that he forgets the more shallow among many of all those con points (sometimes his own, too!), and thereby ends up presenting a pretty well-balanced viewpoint. Not necessarily the most comprehensive picture, but still, a pretty balanced one in terms of what all it does consider, anyway (and he does cover an impressive lot of the territory.))

Yet, if you go through all of those hundreds of comments (sometimes even 600+ comments) that each of Aaronson’s posts generates, you would certainly come out getting a definite feeling that something deeper is at work here than what meets the eye at the surface. Not just a feeling, not even just an evidence of sociology, but more: you will come out also with a lot of links pointing towards hard evidence too.

It’s almost as if someone or some influential group in that giant, American government-sponsored, R&D machine has decided to throw the monkey wrench into any QC works, esp. that elsewhere, by “showing,” sometimes even via dishonestly thin argumentation, that any new results favoring scalable QC is either unbelievably unreliable or that there is nothing QM-ness about it, that the result is what should be expected on the basis of classical mechanics alone. (BTW, “government-sponsored,” or, better still, “government-controlled” is what the phrase “public science” actually translates into.)

Of course, the “public science” in America is not the only party against any of these scalable QM kind of claims (or even experiments). Dr. Roger Schlafly [^], a more or less completely independent researcher, too, has flatly denied any possibility of ever building a scalable QC. He doesn’t have any specific evidence or a principle to cite in defence of his position. Apparently, he just feels that way. Oh, BTW, Prof. Scott Aaronson (himself) has (justifiably) criticised Schlafly.

(BTW, I otherwise have a significantly good opinion of also of Schlafly’s judgment, much of it formed in reference to his book on Einstein. I haven’t read this book completely, but from whatever portion of it that I read, it seems to be a very well written, and an even better researched a book. (BTBTW, the Google Books Preview (still) allows you to read this book in its entirety. It’s just that I haven’t found the time to complete my reading. (TBD!)))

Anyway, coming back to the issue at hand: With this background, I thought that Dr. Mankei’s comments at the above-mentioned (CalTech+PhDComics) blog post came perhaps a bit too early, and perhaps they were not sufficiently thought through. (He also immediately posted an independent paper to arXiv, for this purpose!)

Secondly, in any case, what I wanted to point out and emphasize was the possibility of a way that should convincingly show the quantum nature of the mechanical oscillator in this kind of an experimental arrangement. Overall, I am happy about suggesting the single-photon version of this QM experiment.

I sincerely believe that not only is the single-photon regime interesting in its own right but that in systematically reducing the flux by some 15 orders of magnitude, we could perhaps also be covering some interesting intermediate regimes as well.

Of course, the main point still concerns the single-photons regime. If you see the red-shift even in the single-photon regime, but no blue-shift, I believe that no one will be able to come up with a very rational argument interpreting such a result in a classical mechanics framework. And, a systematic reduction of light flux should provide additional clues to the way that the quantum nature of matter emerges gradually.

It’s true that our intuitions can so easily go wrong once in the quantum realm. Yet, my own intuition is that even if not in this particular experimental set-up (i.e. with this big a beam for the mechanical oscillator) then at least in a different but similar experimental set-up, the quantum blue-red asymmetry would continue to show up even in the single-photon regime. (TBD: write a post to indicate the reason behind keeping this intuition.) It should make the critics skeptics fall silent (for a while!!).

One final note. If you wish to see more comments on this matter, see Sean Carroll’s coverage of the same experimental development (and the same PhDComics-produced video) at his blog, here: [^].

* * *

I have quite a queue of (even very recent) comments I made elsewhere. I should be back with a couple of them pretty soon. Also, a few interesting links.

* * *

One more series! … What happened to the earlier series on tensors?:

I will resume my series on tensors once I get settled in Karjat. As of today, I am too busy organizing my stuff for the relocation to Karjat. And, I anyway don’t have a scanner at home. (Have been jobless, remember?). Friends whose scanner I could have used also all seemed to be too busy these days. So, I have decided to postpone the tensor-related series for a month or so. I will do the experiment myself and resume the tensors-related series in or after mid-July.

* * * * *   * * * * *  * * * * *  

 

Update (June 23, 2013, 11:38 PM)

A Song I Like:
(Marathi) “ghar thakalele sanyaasi, haLu haLU bhint hee khachate…”
Music and Singer: Hridaynath Mangeshkar
Lyrics: Poet “Grace”, i.e., (Marathi) MaNikrao GoDghaaTe

 

[As usual, may be I will come back and edit this post a bit—or, may be, I will not!]

[Update June 23, 2013: Added: The “A Song I Like” section. May be, I will come back and edit and streamline this post, once, again!! OR, May be, I will NOT!!!]]

[E&OE]

So, it is a QC (at least this week!)

I wanted to write on tensors etc., but a few very fresh inputs concerning the D-Wave device have appeared, all barely within the past 24 hours or less.

First, it was Prof. David Poulin commenting at Prof. Scott Aaronson’s blog once again [^], alerting some new work from Prof. Troyer. Unlike in his last comment (on the same post, when he thought that it was not a QC), Poulin has now come closer towards (or has started) supporting the position that the D-Wave device is a QC:

“…the problem instances that are easy for the D-wave device can sometimes be hard for the SS model. This is interesting new evidence supporting the quantum nature of the D-wave device.”

Next, a very valuable comment by one Bill Kaminsky appeared on Aaronson’s blog, very neatly explaining the Smolin and Smith model [^], and then contrasting it with the new result by Troyer. [Guess this Bill Kaminsky is the same as one William Kaminsky, who, in turn, is a PhD student in QIS at MIT. (… Just a Google search, that’s all!)] … Incidentally, more explanatory material concerning the adiabatic quantum optimization, quantum annealing, and classical annealing, written by Kaminsky, had already been put up last week at Henning Dekant’s blog; see here [^].

Finally, while idly thinking about all these things, even as idly browsing Prof. Poulin’s home page, I just idly happened to hit the “New on quant-ph” link [^] at its bottom, and thereby landed at the arXiv site; and once there, I noticed a new paper by Troyer (and (eight!) pals): [^].

Essentially, what Troyer et al. now say is that the D-Wave device does something that the classical devices apparently don’t, and so, the D-Wave device must be quantum! … If not all the classical devices, then at least the two devices: one, considered by they themselves, and the other, considered by Smolin and Smith. The D-Wave device behaves unlike both.

Further, Troyer et al. offer the following conjecture to account for the difference between the D-Wave chip and the [semi-]classical models:

“…The question of why SQA and semi-classical spin models correlate so differently with the D-Wave device is obviously important and interesting. We note that while SQA captures decoherence in the instantaneous energy eigenbasis of the system, so that each energy eigenstate—in particular the ground state—is itself a coherent superposition of computational basis states, semi-classical spin models assume that each qubit decoheres locally, thus removing all coherence from the ground state. We conjecture that the fact that the D-Wave machine succeeds with high probability on certain instances which the semi-classical models finds hard, can be understood in terms of this difference.”

[emphasis mine]

So, looks like, it is a quantum computer, after all. … At least, for this week!

* * *

Clearly, more studies required. So, here are a few questions to the QC research community:

What needs to be done to study the above conjecture more closely? Would some simple and special-purpose simulations that directly allow for a parametric control of the degrees of decoherence, help at least to illustrate (if not to fully support) the above conjecture? Such simulations could be highly simplified (say involving just a linear graph) but, still, sufficiently complete so as to be able to isolate, study, and possibly help settle, this issue.

How do you square off the quantum-ness of the D-Wave chip, and the “absence” of a speed-up, as discussed on Aaronson’s blog?

What measures would you suggest to capture the “percentage quantum-ness” of a QC? of an adiabatic quantum device such as D-Wave’s?

On these measures, how quantum are the current two D-Wave chips (D-Wave One and Two)? What is your estimate?

* * *

May be, more, later. (Who knows, it might once again collapse back to being a simple classical computer, next Monday!)

 

[May be I will come back (right today) and edit this post a bit, so as to make the write-up a bit more streamlined.]

 

[E&OE]

 

Is it a QC?

This post began its life as a supposedly brief update to my earlier post [^] on D-Wave’s paper, but the text soon grew long enough to become a separate post by itself. So, here we go.

Predictably, a controversy concerning the D-Wave paper (and its coverage in the media) came up soon later, at Prof. Scott Aaronson’s blog [^]. At 300+ comments (as of publishing this post), there is a lot of speculation, skepticism, and hilarity of the usenet/slashdot kind going on over there, apart from also some commentary.

However, as far as I am concerned, the most interesting part in (re) examining the paper and the related claims, was the following doubt which the controversy helped highlight: whether this particular D-Wave device had actually succeeded in exploiting, at least in part, the specifically quantum-mechanical effects, or not; whether there was an engineering success in controlling, at least in part (and to a practically significant extent), the quantum decoherence effects, or not.

The controversy was not entirely unexpected; recall this bit from the first New York Times story [^]:

““There is no sense in which this is the definitive statement about quantum computing,” Ms. McGeoch said. “I’m more interested in how well it works, not whether or not it is quantum.””

Though they called it a “quantum computer” (and I repeated the term), the term obviously was being used in a somewhat loose sense.

And, yes, I will admit it: without going through the paper well, I rather relied on the peer-review process, and so certainly thought, at least at the time of writing my earlier post, that D-Wave had a more impeccable and comprehensive result than what now seems to be the case.

But returning to who is interested in what: Well, as far as I am concerned, the issue of whether they got any speed-up or not, is strictly secondary—it’s “just” a consequence!

(In fact, I even don’t care if a QC research group cannot factor any composite beyond some single digit number, as of today. So long as they demonstrate a practically significant control of decoherence, and some clue about how they expect to scale it up, even their success in factoring only a small number would still make sense to me. Any future value of a QC in cracking open secret codes, or in designing better drugs through quantum chemical modeling, would be “just” a consequence, as far as I am concerned.)

To my mind, the real issue is: whether D-Wave succeeded in building a quantum computer (with some promise of some significant levels of a future scalability), or not.

So, from this angle, the most significant comment at Aaronson’s blog has been this one [^] by Prof. David Poulin, alerting the appearance of a paper by John Smolin and Graeme Smith, both of IBM, at arXiv, yesterday [^]. In case you are wondering whether to give this paper a read or not, let me remind you that IBM is a (corporate-sector) competitor to D-Wave. And, if that isn’t going to help, let me quote a bit from the main text of the paper:

“Since classical simulated annealing is intrinsically random and ‘quantum annealing’ is not…”

[emphasis mine]

and a line from their conclusions section:

“The deterministic nature of quantum annealing leads to rather different behaviors than the random processes of simulated annealing.”

[emphasis mine]

Interesting, no? (LOL!)

Of course, my own interests are in the foundations of QM, in providing a proper conceptual explanation for (and even mathematical expression to) the specifically quantum-mechanical effects/paradoxes/oddities, and not in the details of this or that quantum-mechanical process, whether it has some/a lot of/very great merit in building a scalable QC, or not.

So, I am not going to look too closely into this IBM paper either. Or provide a commentary on the position(s) it takes, its merits, or any polemical value it provides in this controversy (or in any other!). Or, add in any other way, to this D-Wave-related  controversy. … That way, I am not totally averse to controversies, but as far as this one goes, I find that it is a greater fun taking a ring-side view, here.

For another thing, these days, I am also thinking of quite different (and between them, somewhat unrelated) things: diffusion, small dams and water resources engineering/management, and tensors. Expect a post or two on these topics, soon enough.

So, all in all, even if I am having fun watching this controversy develop and grow, I guess I am going to sign off blogging about it. I won’t write any further on this topic, unless, of course something even more funny (or definitive, even if a bit serious) emerges from it.

[E&OE]