25

Mar

2011

Physics Fridays with Fuchs: The Quantum is Alive and Well

 

Every Friday during the month of March, This Side of the Pond will feature correspondence drawn from Coming of Age With Quantum Information: Notes on a Paulian Idea, a collection of more than 500 letters between physics luminary Christopher A. Fuchs and his friends, mentors, and other pioneers in the field. Our final installment is a double feature in which Fuchs writes to his “academic big brother” about Paul Simon and one strange dream.

Letters to Greg Comer

 

27 January 1996, “Philo”

The philosophy of it all my friend. I just heard a song on the radio that I had not heard since the Chapel Hill days – it drew my thought to you. I remember writing you almost exactly three years ago about my arrival in the land of the quantum. I’m writing you from the very same machine that I did then. So much is the same and so much is different.

Philosophy in every turn I used to say. Can you believe I’ve secured a full time job playing with quantum mechanics. I get paid to explore it and pick it apart in any way I wish. I get paid to keep dreaming about this lovely little structure.

The present project is finding bounds on the minimal resources required to transpose a quantum state from here to there. It’s just another way to explore how quantum a set of little quantum thingies are. Paul Simon is the moral guide.

When I get back to Montréal two projects are on the burner. Another calculation to gauge the tradeoff between information gain and disturbance in quantum measurement. And another attempt to derive much of quantum theory from information theoretic principles – an extension of Bill Wootters work as John Wheeler’s graduate student.

So many ways to profiteer from the madness of trying to build a quantum computer. That’s OK though – there really is hope that all the efforts won’t be wasted along the way.

I’m having a cup of coffee; it’s a little after 8:00 in the evening. Kiki is in Montréal just going to bed about now. The world is turning beneath me and I feel it; it all seems very mystical tonight.

Where am I going with this? I don’t know. I just wanted to say that the quantum is alive and well. And that coming out here panned out. And that in some ways it’s just the way it was three years ago.

I turn within myself.

27 February 1996, “Kant Cola”

Just thought I’d take a little coffee break before I get started up for the morning. I’ve got to start going through (with a fine-toothed comb) a first draft of a paper that Howard Barnum, Ben Schumacher, Richard Jozsa, and I are coauthoring. (Ben wrote the first draft of this one.) The subject is on the full fledged converse to the quantum coding theorem; namely, if less than a von Neumann’s entropy worth of qubits are sent per transmission, then a quantum signal can be reconstructed with vanishingly small error. ←− I know that doesn’t mean much to you, but that’s the subject.

The weather up here is very nice today. It’s a little below freezing, but the sun is out and there’s not a bit of wind.

Kiki and I went into the Outrèmont area Friday evening in search of an interesting restaurant . . . and what a find we made! Let me tell you a strange little story. During the summer of 1985, I was reading a book by C. F. von Weizsäcker titled The Unity of Nature. Most of the book was about quantum mechanics and Kantian philosophy. Apparently it spurred me to have the following dream. I was in a little hole-in-the-wall joint somewhere in Austin; my old friend David was there, also John Simpson and Marshall Burns. The place really stood out in my mind because of the Bohemian feel to it: dark, smoky, mystical almost. The night wasn’t filled with much of interest: David only wanted to talk about getting drunk, John only wanted to talk about finding a girl, and Marshall only wanted to talk about philosophy. In those days John didn’t drink alcohol, so, at some point, when he asked for a drink, I thought we’d be out of luck. But upon looking around, I saw a refrigerator in the middle of the bar near the pool table. We walked over to it and took a look. It was filled with all different sorts of vegetable drinks. John grabbed one, and I looked through it for something more interesting. At the very back, I found one lone can of “Kant Cola.” That was written on the label, along with a small portrait of Immanuel Kant. I opened the can, took a drink, . . . and, for a miraculous moment, I understood all the intricacies of the world – I understood the necessity of quantum mechanics. When I came out of my trance, the can was empty and I knew that I would never see the light again. Then I awoke. I was so taken with this dream that the next day I sketched out the layout of the joint and made a record of the dream. That was over ten years ago.

So back to the restaurant of Friday. The place was called “City Pub”; it was such a strange little place: dark, smoky, mystical almost. The food was excellent – far better than it should have been for the price. Each option in the place was only $4.99. I had steak, fries, and a vegetable. Kiki had potato soup, quiche, fries, and veggie. They had a special on beer, three for the price of one (so we had six). The music was some sort of strange mesh of things that I suspect you’d only hear in some little bar in Germany where everyone wears black. Anyway, we had quite a time there. However, just a little while before leaving I started to note how similar this place was to the place in my dream 10 years ago. I told Kiki the whole story. Then I looked around and – strangely enough – there was a refrigerator in the middle of the room near the pool table! I was so taken by this that upon my way to the restroom, I took a look into it. What a disappointment: it only contained beer. However, the restroom did have a surprise for me. In the middle of all the graffiti (about Québec’s hoped-for independence) was something written in bold black letters:

De nobis ipsis silemus

(E. Kant)

That made my evening. I wrote down the words so that I wouldn’t forget and went home to look up my old notes on the dream. Sure enough, there were similarities in the layout of the two places, and moreover, I saw that the name of the original place in my dream was “Hole in the Wall Pub.” Very strange. I asked Rüdiger Schack to translate the words for me, and he came up with “About ourselves we remain silent.”

That’s the story. I suppose I should be off to work.

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