Quantum Bayesian Networks

December 10, 2018

Scotty: “Captain, the quantum entanglement wormhole tunnel that you requested is now operational”

Filed under: Uncategorized — rrtucci @ 9:13 pm

Many prestigious physicists believe that the phenomenon of quantum entanglement is at the very heart of quantum computing and quantum information theory. For example, John Preskill of Caltech uses the word entanglement in every title of every talk and paper he ever writes, or so it seems. Lately, other very famous particle physicists, for instance, Leonard Susskind and Ed Witten, have also begun to sing the praises of quantum entanglement. And it’s not only old timers that babble about it. It seems almost everyone does, young and old, knowledgeable and clueless.

If you Google “quantum entanglement”, and look at the images, you will find a plethora of attempts to illustrate q entanglement graphically. Some illustrations are very whimsical and cute, some are very wrong too, in my opinion. But I won’t be judgemental. Visual analogies are an important part of the fun of doing physics. We start with analogies that are a bit off, but, hopefully, as time goes on, we refine them. When I was a kid, I used to like to picture an alpha particle as a daisy with 4 petals, 2 proton ones and two neutron ones. Hey, not very sophisticated, but at least it allowed me to remember a few basic facts about the Helium nucleus. This morning, I got inspired to try my own hand at picturing quantum entanglement. Here is the doodle I arrived at:

BRIEF EXPLANATION OF IMAGE, only for the theoretically inclined: Starship Ada and Starship Bayes are in separate universes, pictured here as (half) diamond shaped areas called Penrose diagrams. A and B are both adjacent to a black hole which is also portrayed as a Penrose diagram, except that the space and time coordinates are swapped. The two walls of the black hole’s (half) diamond are its event horizon and the dashed line labelled singularity is all the times in the life of the center of the black hole. The two starships are exchanging “entanglement signals” across the event horizon of the black hole. A wormhole is normally defined as a tunnel that connects two Penrose diagrams that overlap at a single corner vertex. The wormhole occupies the single common vertex of the two universes. If you fold the above figure about its middle vertical axis, then the Penrose diagrams of Ada and Bayes sit on top of each other, and are identified as the same universe. Also, the original single black hole becomes two black holes with a wormhole connecting the bottom black hole to the top one. Now you can envision Ada and Bayes as existing in the same universe, but one Starship is close to the top black hole and the other Starship to the bottom one. This is all standard black hole physics. People actually believe these stoner speculations.

To paraphrase Mark Twain: “Everybody talks about q entanglement, but nobody does anything about it”. In particular, for me, a programmer with a Ph.D. in physics, I would like a nice software library for calculating various quantities related to quantum entanglement. Just calculations of down to earth, widely accepted theory. Nothing fringy. I looked around for such a library and found none that I liked so I wrote my own. My software library “Q Entanglement Lab” is now finished and it works like a charm. I suspect it could become some of the most influential work I’ve ever done. I had to invent several new, fairly clever if I may say so, algorithms for calculating entanglement. I am very pleased with how well they work. Of course, at first, they didn’t work at all, so I had to sweat bullets to refine and debug them until they did work.

I still haven’t decided when or how to release “Q Entanglement Lab”. I want it to be open source eventually, but first, I will seek to patent it in China, with the assistance of Dr. Tao Yin. Tao is a cofounder of our company artiste-qb.net, and he runs a separate company, an “affiliate” of artiste, based in Shenzhen, where he lives. If I get that patent in China, I will also try to convince some of our friends that work at Sunway Taihu Light to run an HPC version of my “Q Entanglement Lab”. I spoke about this in a previous blog post

1 Comment »

  1. For my non physicists friends reading this, I should explain what a Penrose diagram is. Easy Peasy. Start with a piece of graph paper with even grid sizes both horizontally and vertically. Originally the paper is infinite in both the horizontal space X direction and the vertical time T direction. Now choose any point and call it the origin X=T= 0 . Now shrink the X direction to a finite length -L to the left and +L to the right of the origin. The grid spacing along the X axis becomes closer and closer as you move towards the edges until at the edges the density of X points becomes infinite. Shrink the T direction to finite size the same way you shrank the X direction to a finite size. Now shrink all the top side of the square universe to a single point. This makes all the X’s of that top side become a single time , T= infinity. Now do the same to bottom side of square universe , shrink it to a single point. This makes all the X’s of the bottom side become a single point, T= minus infinity. When you shrink the top and bottom sides, deform the left and right sides so the left side becomes a corner, the X= minus infinity corner, and the right side becomes another corner, the X= plus infinity corner. Voilà. We have mapped an infinite plane representing X-T spacetime into a finite diamond shaped area. The worldline (history) of a particle whose X is fixed corresponds to an arc going from the bottom corner to the top corner.

    Comment by rrtucci — December 13, 2018 @ 8:28 am

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