Yesterday at the Perimeter Institute, while I was attending FTQC II, I developed a tremendous headache (conveniently it arose just before the panel discussion I was on started its session) which lasted into the night and is only now disipating. This headache was, I’ve concluded, the result of a perfect trifecta of downers. And because I have nothing better to do while waiting for my ride to the Toronto airport to fly back to Seattle, I thought I’d catelog these downers, for posterity, and for my own egotistical record. No one likes to hear anyone complain, heck I myself particularly hate to hear whining complaints come from someone as lucky as I’ve been, so if you’re not interested in such purging, please stop reading now. I meant it! Proceed at your own caution.
(Downer Numero 1) Being surrounded by people who are absolutely a trillion times smarter than I am. Can I ever hope to keep up with Aram Harrow, Barbara Terhal, and Daniel Gotesman? Nope, I most certainly can’t! Most of the time my wonded ego simply keeps its head down and silently wanders through the backrooms of its own extremely minor accomplishments, but yeseterday it seemed my own shortcomings decided to take refuge directly in between my temples. Ouch! Why does this matter, that I’m that much slower than everyone around me? Well certainly in a big picture it doesn’t, but it reminds me of how little I’ve actually done, and the small probabilities that I actually have of doing anything of major merit. Headache pain meter increase “plus one.”
(Downer Numero 2) Hearing about fault-tolerant quantum computing reminded me how far we are from building a quantum computer and how little we realize that we have no clue how far we are from building a quantum computer. The threshold theorem for fault-tolerant quantum computing seems, to me, a soothing balm which we can spread over our proof of principle exposed skin, but it certainly, to me at least, doesn’t seem like anything we’d remotely like to really do. And being at a conference where the whole point of the conference was to explore the realm, and only the realm, of fault-tolerance, began by the time my headache started, to drive me crazy. I think this was exacerbated by the fact that, while there were a few experimental talks (and they were excellent, of course) I have a hard time thinking about fault-tolerance without thinking about experiments. And then I start thinking about experiments and I start wishing I myself could work in a lab, because what I so desire is lots and lots of qubits, which I can tinker with and come up with new ideas for fault-tolerance in these systems. Because I’m an arrogant theorist locked up in an ivory tower, I find myself frustrated at not being able to participate in experimental progress. I want a quantum computer and I want it now, without another decade of fault-tolerant workshop to beat my head up against. Headache pain meter “plus one more.”
(Downer Numero 3) I’ve been reading The Black Swan: The Impact of the Highly Improbable 
hexamer friends where we would stand in a six sided circle arms outstretched.” Headache pain meter “plus one.”
Really most days trifectas like the ones above don’t spend their time haunting my heads. But yesterday they ate up my brain, kept me up at night, and, as you can certainly tell from reading this post, made me very very grumpy. Well, I guess there is, as the saying goes, always tomorrow. When I’m hoping only a few of the trifecta pose haunts my throbing head.
O brave new quantum world!
Maybe it was … just a headache.
Aww. Poor Bacon.
Dave,
ad 1) read your won graduation speech.
ad 2) read about quantum computers in a diamond (e.g. on Lubos’ blog).
ad 3) keep in mind that N.T. was less successful as an investor than you might think after reading his book(s).
Dave, that was the smartest, wisest quantum computing blog article I’ve read all year. I’m glad at least one smart person went to that conference
Maybe I should feel better after reading this entry, as I realize that even those who are far more advanced in their knowledge of CS-theory suffer from the same inferiority-complex I do. ALL HOPE IS NOT LOST!
Dave, I have to say that I find the timing of this despair a little odd. This year has had some pretty interesting experimental results. So far we’ve seen substantial progress with NVs (as wolfgang mentions), we’ve seen optical entanglement of two separate ion traps, and of course superconducting CNOTs are all over even the mainstream press at the moment. We’re not even halfway through the year yet.
If anything, it seems to me that we are seeing the next generation of QCs. Sure the fidelity is still nowhere near what we need for fault-tolerant computing, but thresholds rise, and robust pulse sequences and entanglement distillation continually increase our control.
I don’t think that we’re anywhere near scalability yet, but I think there is a lot of reasons to be hopeful.
Oh, and re numero uno, I’m currently a big fan of your supercoherent qubits.
Oops, my comment about ion traps was inaccurate. Interference of photons coming from two traps has been shown. Even so, this is still very close to the goal of entangling separate traps.
doh! downer number one for me is that you’re already leaving waterloo and we won’t get to talk more!
i too periodically think that everyone else in the world is smarter than me. but i think this is sometimes a symptom of seeing people only every few months and having them tell you in a compressed time what took them (and their absent co-authors) forever to work out.
I think I’m more stupid than the people around me, too. I take some comfort from musing that this could be a personality trait rather than an accurate perception of reality. In any case, we should all derive some satisfaction from our meager accomplishments — we’re entitled to it.
As for black swans … they’re great, but they don’t appear by magic. We may need to slog away for a while, making incremental progress, to set the stage for the next black swan sighting. I saw enough evidence of incremental progress at the workshop to keep me going.
Here’s what’s weird, though. I’m hesitant to admit it, but I had a terrible headache that afternoon, too. Could it be what we ate for lunch?
Meanwhile, I am enjoying the view of the white swans. And I am sharing an apartment with Peter Shor, hopefully inhaling whenever he exhales (they say it works even if you don’t believe in it …).
Reading this paper
cond-mat/0609441
or watching this talk
http://online.kitp.ucsb.edu/online/qubit_c06/kitaev/
might go some way to treating all three conditions. If you manage to get your head round it, you might feel a little smarter and more optimistic (you still might feel dumber than the author of course… but you’ll be in pretty good company there!)
It was probably just a headache. Doh. All headache and wrong timezone make Dave grumpy grumpy.
I guess, having seen the whole series of announcements of exciting experiments before (i.e. in ion traps) makes me worry that we will be perpetually stuck in such announcements forever!
Reading Lubos’ blog is not going to make me happy. This I know with certainty!
Also finishing the “Black Swan” book made me almost throw it across the room considering he ends by fawning over Mandlebrot and makes a bunch of silly comments in a row (even though the only people who come out looking good in the end are statistical physicists.)
Dave, you are welcome to come work in my lab. Really. The best stress (and headache) relief I know.
Dear Dave,
This is an interesting post, in spite being a bit gloomy. I did not read the Black Swan book but heard a talk about it by Avital Pilpel. If I remember correctly black swans refer to events (like crashes of the stock market) which seem very improbable (or are, in fact, extremely improbable according to the mathematical models used at present). Yet they happen. Under various names, such phenomena drew a lot of interest (certainly in the context of stock markets, but also in machine learning and other areas) even before being titled and crowned as black swans.
To the extent that such “black swans” are not psychological/sociological/political effects but (at least in some of the cases) logical (mathematical) consequences of highly correlated stochastic systems, they are related to some concerns regarding decoherence and noise, we once discussed here.
I tend to think that the explanation of some “black swans” (say, in the context of the stock market,) is indeed that they are logical/mathematical a consequence of complicated highly correlated stochastic systems. A consequence not captured by current standard mathematical models.
And here are a few reasons to be cheerful.
a) To the extent that the assumptions behind FTQC are correct, it does not seem to be the case that progress in fault tolerance delay the QC endeavor but quite the opposite; fault tolerance is well ahead; maybe when it comes to fault tolerance quite a few black swans are already at place, waiting for an army of white swans and green ducks.
b) Progress in the skeptical direction concerning quantum computers (including my own) is slower than progress in building quantum computers. It may well be the case that quantum computers will be built even before they will be proved to be impossible :).
c) Clarke three laws
A reason to be skeptical regarding quantum computers skepticism is Clarke rules (I learned about it from a link in Terry Tao’s blog in another context, but it fits really nice to QC). Here are Clarke three laws (from Wikipedea):
1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
3. Any sufficiently advanced technology is indistinguishable from magic.
(Of course, it is possible to be skeptical also about Clarke laws themselves.)
Any sufficiently intricate magic is indistinguishable from technology.
Well, Dave, at least you were there, amongst the best and the brightest. There are those of us who toil away in relative obscurity most of the time and for whom just reading about (or, in my case sometimes, reporting on) meetings like this is enough to make us wonder if we wouldn’t have been better off as auto mechanics (hey, Tom Magliozzi of CarTalk went to MIT).