Quantum Bayesian Networks

December 18, 2009

Why Quantum Computers—Little Dieter Needs to do Quantum Mechanics

Filed under: Uncategorized — rrtucci @ 10:53 am

In a previous blog post, I answered the question of “Why quantum computers?” by making an analogy between QCs and Galileo’s telescope. Let me take a different tack here.

The documentary film “Little Dieter Needs to Fly” by Werner Herzog, tells the story of an American aviator named “Dieter Dengler” whose aircraft was shot down during the Vietnam war. Dengler was captured by the Viet Cong, and detained in a POW camp, where he endured torture and starvation, until he escaped into the surrounding jungle. He then proceeded to make a long, perilous journey through the thick tropical jungle, a journey that nearly killed him. Miraculously, he was finally spotted and rescued by US helicopters, and lived to tell his tale. The title of the documentary refers to the fact that Dengler can recall the exact day he became obsessed with becoming an aviator. He was a child in Germany during WW II. One thrilling day, forever etched in his memory, an allied aircraft flew extremely close to his observation point, so much so that he was able to see the aviator’s goggles. From that day on, Dieter knew he had to fly.

It seems that quantum mechanics provokes a similar fascination in a large fraction of the human population. For many of us, a brief introduction to q.m. sparks a strong, life long interest in it.

I just came across the following example of the enticing power of q.m. From this excellent interview of Sir Anthony Leggett, we learn that even this 71 year old Nobel prize winner still has a childlike curiosity about some aspects of the foundations of q.m.. We also learn that in the last few years he has become keenly interested in topological quantum computers.

Little Dieter needs QCs because he needs desperately to do quantum mechanics. QCs will allow us to do q.m. like no device ever before. The Large Hadron Collider will certainly allow us to do q.m. too, but much more indirectly, and only on a single tremendously expensive machine. Explaining LHC data will require assuming many ideas beyond q.m. (e.g., gauge field theory, spontaneous symmetry breaking, perhaps even more far fetched ones like super-symmetry, string theory, extra dimensions, etc.). By comparison, very few fundamental physics ideas beyond q.m. are needed to explain QCs. And QCs will probably someday be available in large numbers.

QCs will allow the general public to deepen its currently shallow understanding of q.m., a theory which is the foundation of most of 20th century physics. Just like amateur radio electronics popularized electromagnetism, and personal computers did the same for digital electronics and programming algorithms, QCs will finally make q.m. accessible to the masses. QCs will allow us to extend, refine, and maybe even revise, our current thinking about q.m. This, on top of the fact that QCs will shine as a calculational tool.


  1. Right on that we’re gathering from the physicists we talk to that QC will validate/invalidate dark corners of QM.

    Don’t know that I’d describe Sir Anthony Leggett’s attitude to the foundations of QM “childlike curiosity”, compliment though that may be. In conversation that quality came across to me more like the rapid calculation and penetrating gaze of a lion about to pounce on a gazelle!🙂

    Comment by Jack Woehr — December 18, 2009 @ 6:27 pm

  2. Robert, as a physicist I’m certainly not an expert in this emerging field, but what I do understand from following announced developments, I completely agree that this field will be quite exciting. I’m am almost giddy with excitement at times by reports I’m reading in various journals.

    New q.m. developments now seem to be announced monthly, and I have the same feelings of excitement that I saw growing up with the early microprocessor industry during the last three decades. Will this one emerge at an even faster pace? If so, we had better prepare the next generation of science & engineering students!

    Since this is a new year, I have a prediction: With the huge semi industry worldwide, the pace can only be beyond standard expectations as we reach quantum limits in standard fabs. Everyone will eventually be pressing upon these quantum limits. But as Lord Kelvin once keenly observed, “when you’re up against a problem, you’re facing a discovery.” What emerges will indeed be an ‘applied’ quantum science & technology century like we can’t yet imagine!

    Comment by JChan — January 2, 2010 @ 4:42 am

  3. “when you’re up against a problem, you’re facing a discovery.”
    Excellent Lord Kelvin quote JChan. Thanks for telling me about it.

    I agree with your New Year prediction about the semiconductor industry, and I share your passion for the new “applied” quantum mechanics. I also agree with you that NOW is the time to start preparing our students for a golden age in applied quantum mechanics.

    A propos of this: I never tire of pointing out in this blog that almost anyone can (and should, if the passion stirs them) start writing software for quantum computers today, right now! Contrary to the equipment needed to work on QC hardware, the equipment needed to work on QC software is not very costly, mainly just a personal computer and internet connection. Ideally, software for QCs should have reached a state of reasonable maturity by the time a large scale QC is available.

    Comment by rrtucci — January 2, 2010 @ 12:49 pm

  4. Seriously funny and precisely on target like a Stuka about to make a drop.

    Ah the good old days when German movies still mattered.

    Comment by Henning Dekant — March 14, 2012 @ 12:35 am

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