# Quantum Bayesian Networks

## November 18, 2014

### Houston, Tranquility Base here, the Dragonfly has landed

Filed under: Uncategorized — rrtucci @ 9:18 pm

Houston, Tranquility Base here, the Dragonfly has landed.
(image based on NASA photo from here)

Pacific Spiketail Dragonfly (Photo from here)

The new Artiste logo reminds me of a dragonfly. Like many people, I’ve been fascinated by dragonflies since I was a child. Here are some interesting facts about dragonflies (taken from references at the end of this blog post):

Dragonflies and damselflies are often called the “jewels of the pond”.

Damselflies rest with their wings closed like butterflies. Dragonflies, on the other hand, keep each wing pair at opposite sides of their thorax when at rest.

Flight
Dragonflies are among the fastest flying insects. (which, however, is not that fast). In general, large dragonflies like the hawkers have a maximum speed of 10–15 meters/sec (22–34 mph) with average cruising speed of about 4.5 meters/sec (10 mph).

Dragonflies can fly in all 6 directions: front, right, left, up, down and backwards. They can fly upside down, and can change direction quickly. They can hover for as long as a minute.

Each of their 4 wings has a separate muscle and can be maneuvered independently.

They can eat and mate in midair without need to alight.

Food Chain
They have a voracious appetite, especially for mosquitoes. They will use a person or other mammal (e.g., horses or cows) as bait. They will hover right above their bait, and when the bait attracts a mosquito, they will pounce on it.

Besides mosquitoes, they eat other small insects like flies, bees, ants, wasps, and very rarely butterflies.

Though dragonflies are predators, they themselves are subject to being preyed upon by birds, lizards, frogs, spiders, fish, water bugs, and even other large dragonflies.

Life cycle
From egg to underwater gilled larva (called a naiad or nymph) to adult flying stage. Larval stage may last anywhere from 2 months to 5 years depending on species. Adult flying stage can last anywhere from a few weeks to 6 months depending on species.

Bite
Adult dragonflies do not normally bite or sting humans. They don’t have a stinger at the end of their tails; they use that to lay eggs. If you trap one in your hands without crushing it, it will try to bite you with its mouth, but it will fail to break your skin. Nymphs, however, are capable of delivering a painful but harmless bite.

Hunting Effectiveness
African lions capture prey about 25% of the time

A dragonfly comes equipped with very sophisticated target acquisition and Kalman filtering capabilities. It is able to focus on a single target prey amid a cloud of similarly fluttering insects. It is able to make very subtle mid-course corrections to intersect that moving target.

Senses
They have a nearly full (4pi) field of vision. Each eye has about 30,000 facets. But they can’t hear at all and they can’t smell very well either.

Evolution
Their order is Odonata, which means “toothed ones” — because of their noticeably serrated mandibles. Infraorder Anisoptera (from the Greek for “uneven wings”)

They first arose in the Carboniferous period, about 300 E6 years ago. For comparison, the Earth is 4.5 E9 years old, and the six animal classes are this old:

1. Invertebrates- 600 E6 years
2. Fishes – 510 E6 years
3. Amphibians – 370 E6 years
4. Reptiles – 315 E6 years
5. Mammals – 200 E6 years but exploded 65 E6 years ago after great extinction
6. Birds – 150 E6 years

Migration
Some dragonfly species migrate long distances each year, a still mysterious phenomenon not unlike the celebrated flight of the monarch butterfly. Recent studies have shown that green darner dragonflies migrate in sizable swarms each fall and spring between the northern United States and southern Mexico, while the globe skimmer dragonfly lives up to its name: it has been tracked crossing between India and Africa, a round trip, multigenerational pilgrimage that may exceed 10,000 miles.

References

## November 9, 2014

### Are Feynman Path Integrals Useful In Quantum Computing?

Filed under: Uncategorized — rrtucci @ 5:20 am

Contemporary High Energy physicists seldom formulate their new theories in the Schroedinger picture (or associated operator pictures like the Heisenberg or Interaction pictures). They prefer instead to formulate their theories in terms of Feynman path integrals because such integrals exhibit the symmetries of the theory more explicitly without having to worry about operator ordering. So an important question to ask is, are Feynman path integrals useful in Quantum Computing too? I would say, yes, absolutely. This is how I personally see it:

operator pictures ~ quantum circuits

Feynman path integral picture ~  quantum Bayesian networks

The analogy is not perfect, but it’s very close, in my opinion.

A related post is:
Quantum Circuits in the Dirac, Quayle and Bayes Conventions

## November 8, 2014

### I’m a Born-Again Group-Pest

Filed under: Uncategorized — rrtucci @ 9:23 am

Trying to learn Newtonian mechanics without a priori or concurrently learning Calculus is not a good idea, in my opinion. (I mean here Calculus taught in a non-rigorous, applied way; I don’t mean rigorous Mathematical Analysis). Indeed, non-rigorous Calculus is extremely helpful and insight-giving in doing Newtonian mechanics. It’s not surprising that both disciplines were invented concurrently by the same guy, Isaac Newton.

Analogously, I think that trying to learn Quantum Mechanics (QM) without a priori or concurrently learning Group theory (GT) is a terrible idea. (Again, I mean here GT taught in a non-rigorous, applied way). Non-rigorous GT is extremely helpful and insight-giving in doing QM. GT and QM were not invented concurrently by the same physicist, but they could easily have been. Mathematicians like Schur, Frobenius, Young, Galois, etc., had already developed GT to a high degree before QM came along, but there is no doubt that the invention of QM has spurred the invention of many new tools in GT.

As one can see from the Wikipedia “Timeline of Quantum Mechanics”, most of the fundamentals of QM were discovered during the miraculous decade 1920 to 1930. Note, for example, that in
1923 – Louis de Broglie extends wave–particle duality to particles,
1930 – Dirac’s textbook “Principles of Quantum Mechanics” was published

Note also that Hermann Weyl (1885-1955) came out with his book “The Theory of Groups and Quantum Mechanics” (available as a Dover edition) in 1930 and Eugene Wigner (1902-1995) with his book “Group Theory and its Application to the Quantum Mechanics of Atomic Spectra” in 1931. So already during the miraculous decade, and certainly long thereafter, Weyl and Wigner were common household “group-pests” who never lost a chance to point out to anyone within earshot how closely related QM and GT are.

As you can see, the observation that a knowledge of GT greatly helps one to understand QM is an observation that is almost as old as QM itself, and this observation has been widely publicized by some of the patron saints of QM.

I learned QM from some books that I think are very good (for example, the 2 volume set by Cohen-Tannoudji, Diu and Laloe), but, unfortunately, those books don’t use GT explicitly. Then I learned a bit of GT from some books that I think are pretty lousy. Either because of the shortcomings of my first GT books or due to my own shortcomings, or both, it took me a long time to feel comfortable with GT. The tide first started to turn for me when I read the two volume set by Elliot and Dawber entitled “Symmetries in Physics”, two books which I find truly wonderful and excellent. Using the Dawber and Elliot books as my “base camp”, I was able to explore GT further and read other more recent and specialized GT texts. You might prefer different books than I do. The field of GT is so vast, I think no single book or author can cover everything in detail and satisfy the topic selection and stylistic tastes of everyone.

Nowadays, I feel much more comfortable with GT, and I feel compelled to analyze in GT language everything that I do in QM, and I mean everything, be that physical chemistry, AMO (atomic-molecular-optical) physics, condensed matter physics, nuclear physics, particle physics, or relativity. It’s amazing how widely applicable GT is in physics.

Of course, finding applications of GT to quantum computation and quantum Bayesian networks is high in my agenda. My latest patent, number 12 in this list, is about GT. Two previous blog posts of mine on GT are

## November 4, 2014

### Self-Reparing Androids And Quantum Computers

Filed under: Uncategorized — rrtucci @ 6:33 pm

Henning Dekant (author of the WaveWatching blog) and I (and some others) are in the process of refurbishing the old Artiste company, a quantum computing software company. Henning and I decided we would keep the old website (http://www.ar-tiste.com) intact, plus start a new Artiste website (http://www.artiste-qb.net). The old website is “Artiste classic” with antiquated HTML technology and the new one is “Artiste modern” (or art deco, or futuristic).

I’ve always thought of Artiste as a company that combines Science and Art, the way Leonardo DaVinci was fond of doing. That is partly why I chose Artiste for the name of the company. Recently, I started using at the old Artiste website a logo of Leonardo DaVinci’s Vitruvian man (a nice picture of a cadaver doing jumping jacks) circumscribed by an italic letter “$a$“.

Henning came up with the brilliant idea of using for the modern website the same logo as the one in the classic website, but with the “Vitruvian man” replaced by a “Vitruvian robot”. Not only that. In a fit of brilliant artiste inspiration, Henning added a special effect to his Vitruvian robot that I find totally awesome. He modified some JavaScript code that he got from here and a picture of the robot “Maria” from Fritz Lang’s 1927 movie Metropolis. (Italian and German children seem to have different icons). The final result is a Vitruvian robot that when touched by the cursor, it explodes at the point of contact, but then the explosion is time reversed and the robot self-repairs and heals itself, like the Terminator robots. I find Henning’s masterpiece mesmerizing. It reminds me of alien technology, like quantum computing software. Check it out.

http://www.ar-tiste.com/vitruvian-robot.htm

The animation is located at the old Artiste website rather than directly in this blog post, because one can’t put Javascript in a wordpress.com blog. Henning informs me that his animation doesn’t work on browsers that are behind the times in implementing the DOM API (this is especially true of Internet Explorer.).

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