Zen and the Art of Spell Checking

In tonight’s quant-ph a keen eyed colleage finds a paper wrapped in an enigma wrapped in a koan:

Quantum Physics, abstract
quant-ph/0605070
From: Yu Shi [view email]
Date: Sun, 7 May 2006 12:02:44 GMT (16kb)
High Energy Quantum Teleportation Using Neutral Koans

Does this mean that Deepak Chopra was right? 😉
In this sprit:

Two students were watching an atom. One students said to the other: “look the electron is a particle, right?” The other said, “no most definitely a wave!” A wise master came along, so the students decided to ask the master his opinion on the matter. They both discussed with the master why each thought that the electron was what it was. The master thought for a while and then replied: “I’m not a physicist you damn fools.”

On a somewhat related note: This weekend we went to see Julia Sweeney and Ira Glass. Julia Sweeney does quite a routine about losing her religion (part of which is available from a “This American Life” show here here.) At one point in her routine she describes how after leaving her Catholic faith, she learns about all the new age mumbo jumbo. She is very excited by this: a blend of science and religion. But she makes the mistake of getting interested enough to actually go out and learn about quantum theory. Paraphrasing: “sure there is a lot about the behavior of atom particles and waves we don’t understand, but there is no quantum consciousness. Deepak Chopra is full of shit!” Ouch, new age slam!

The Universe's Machine Language

For those local to Seattle, Seth Lloyd is in town tonight giving a Seattle Science Lecture:

Monday, May 8 at 7:30 pm.
Seth Lloyd: ‘Programming the Universe’
Seth Lloyd is a professor at MIT who works in the vanguard of research in quantum computing – using the quantum mechanical properties of atoms as a computer. He believes once humans have a complete understand the laws of physics, quantum computing will allow a complete understanding of the universe as well. His new book Programming the Universe explains how the creation of the universe involves information processing. His hypotheses bear implications for the evolution vs. intelligent design debate since he argues divine intervention isn’t necessary to produce complexity and life. Downstairs at Town Hall, enter on Seneca Street.

Fifteen Year Plan

The Economist predicts that in 15 years time there will be quantum computers: “But quantum computing does now seem to be acquiring a momentum of its own. Give it 15 years, and who knows what will result.” Okay, not quite, but there is an article about building quantum computers which can be found here

Sophisticated Quantitation Assay

A rock star chemist sends me word of a company which has a product calledThe Qubit Quantitation System (You’ll have to say what country you are connecting from to see this page.) Those biologists have stolen our “qubit!” I wonder if they realize that their product will get horrible placement on search engines because they are using a very common and highly linked word. Doesn’t seem like the best strategy to me. (On another note, am I the only one who is annoyed by the word “assay?”)

Join QIP: See the World (or at least Canada and Japan!)

From my inbox some annoucements for some awesome summer schools and conferences:

———————————————————————-
6th Canadian Summer School on Quantum Information Processing
August 7-11, 2006, University of Calgary, Canada
http://www.equips.ca
———————————————————————-
Students and researchers are invited to attend the sixth summer school on quantum information processing held at the University of Calgary. The goal of the school is to introduce a general audience of computer scientists, physicists, and mathematicians with little or no background in quantum information processing to this exciting and growing field.
Quantum information processing lies at the intersection of computer science, physics, and mathematics and concerns information processing that depends on quantum mechanical effects. It aims at understanding the principles of quantum mechanics and how they can be used for computations and in communication. It is an
interdisciplinary area that brings together theorists and experimentalists.
Lectures will be given by excellent communicators and researchers in the area, including
* Andris Ambainis
* Richard Cleve
* David Feder
* Paul Haljan
* Peter Hoyer
* Ashwin Nayak
* Alain Tapp
* Wolfgang Tittel
* John Watrous
* Gregor Weihs
There are no fees for attending the school. Affordable, comfortable accommodation at the University of Calgary is available.
Registration: http://www.equips.ca
Contact information: equips [at] equips.ca
Summer school: August 7-11, 2006
Please see website for additional information on participation, registration, accommodation, and travel. Please do not hesitate to contact the organizers at equips[at]equips.ca.
The summer school is organized in conjunction with the third conference for graduate students in quantum information processing, held at the University of Calgary, August 14-19, 2006. For more information about the students’ conference, please visit http://www.iqis.org.

(note that the above summer school is followed by the Quantum Information Students’ Conference 2006, which sounds really cool and makes me wish I was a student.)
Also

The Eighth International Conference on
Quantum Communication, Measurement and Computing
“QCMC2006”
This is the First Call for Papers for QCMC2006, which will be held at
Tsukuba International Congress Center in Tokyo, JAPAN,
from 29th November to 3rd December 2006.
(Arrival Date: Tuesday 28th November,
Departure Date: Monday 4th December)
******************* Call for Papers *********************
The QCMC2006 Website is now accepting abstract submissions.
The deadline for abstract submission is Friday, 16 June, 2006
Authors will be notified of acceptance by the end of the August
All papers will be handled electronically.
Please go to the conference website for details;
http://www.qcmc2006.org/submission.html
QCMC2006 is seeking contributions in a
broad spectrum of topics relating to quantum information
and quantum communications, including:
-Quantum Cryptography
-Quantum Communication Systems
-Quantum Measurement and Quantum Metrology
-Quantum Optics for Information Processing
-Non-Classical Light Sources
-Quantum Repeaters
-Quantum Information Theory
-Quantum Computation
Invitation from the Chairmen of the Organizing Committee
Dear prospective QCMC2006 attendee
It is our pleasure to co-chair the Eighth International Conference on Quantum Communication, Measurement and Computing (QCMC). QCMC2006 is being held in Tokyo, to celebrate the 20th anniversary
of the initial meeting in this series, with a program that will focus on summarizing recent achievements in and looking ahead to the future of quantum communication, measurement and computing.
On behalf of the Organizing Committee we invite you to attend QCMC2006, and we encourage you to submit papers on any topic within the program scope.
We thank in advance all prospective QCMC2006 attendees for the high quality of their contributed papers, which we are
certain will add great value to the conference.
We would also like to thank the members of the Organizing Committee, the Program Committee, and Award & Advisory Committee for their kindness in committing to make QCMC2006 a great success.
Sincerely yours,
Osamu Hirota (Chair) and Jeffrey H. Shapiro (Co-Chair)
Chairmen of the Organizing Committee
The 8th International Conference on Quantum Communication, Measurement and Computing

and

Dear Colleagues-
This is the announcement and call for papers for the Second Conference on Quantum Information and Quantum Control, to be held in Toronto, Canada, 7-11 August 2006. More information, together with a list of invited speakers can be found at http://cqiqc.physics.utoronto.ca/CQIQCII. This conference is intended to follow on successful meeting held in 2004, and is intended to bring together the quantum information and quantum control communities.
The deadline for abstract submission is 19 May.
We look forward to seeing you in Toronto this summer,
Sincerely,
Aephraim Steinberg (chair)
Paul Brumer
Daniel James
Hoi-Kwong Lo
Harry Ruda
CQIQC II Organizing Committee

Smaller or Larger Hilbert Space: A Religious Debate

Quantum Quandries has founded a new church: The Church of the Smaller Hilbert Space. Humor that appeals directly to quantum physicists: priceless. I am greatly looking forward to the theological debate between members of the Church of the Larger Hilbert Space and Church of the Smaller Hilbert Space. And can we look forward to the Church of the Infinite Hilbert Space, or the Church of the Empty Hilbert Space (that last one feels a little Zen, doesn’t it?) And why aren’t their any Churches for Banach Spaces? Members of all Hilbert Space Churches would be welcome, of course.

Blabbering Bacon

For those local to Seattle: Next week, on Tuesday, I’m giving a talk here at UW:

Towards Robust and Powerful Quantum Computers
Colloquium
Tuesday, April 18, 2006
3:30 pm, EE-105
Abstract
Today, a massive effort, spanning many hundreds of research groups coming from multiple disparate disciplines, is underway to build a robust large scale quantum computer. These groups are undertaking this task because the payoffs for building a quantum computer are large and because of a remarkable set of theoretical insights, collectively known as the theory of fault-tolerant quantum computation, which assures them that building a robust quantum computer is possible. In this talk I will discuss my research into the theory of fault-tolerant quantum computation as well as into the study of the algorithmic power of quantum computers. On this first topic, I will highlight methods for achieving fault-tolerant quantum computation which are remarkably similar to how fault-tolerance is achieved in classical computers. Such “self-correcting” quantum systems are best thought of as being the equivalent of the classical transistor which jump started the classical computer revolution. On the second topic of quantum algorithms, I will highlight the similarities and differences between quantum and classical computers and describe how these differences have lead to new quantum algorithms for classically hard problems.

Free to Decide

Over at Michael Nielsen’s blog, Michael has a post telling us that he won’t be posting again until August. Personally Michael’s lack of posting scares the bejebus out of me: if he’s not posting, he must be working on some grand research which will make everything I do look even more trivial than before. Michael, you’re scaring me!
Anyway, along with the post Michael posts a comment by UW’s John Sidles trying to stir up some debate by asking about a paper by Conway and Kochen, “The Free Will Theorem”, quant-ph/0604069. Actually I had heard about this paper a while ago, via some non-arxiv channel (where I can’t remember, exactly) and had basically guessed from the brief description I had heard what the paper was about. This is how you know that you are getting old and curmudgeony when you can hear a title to a paper and a description of the results and can guess the way in which those contents were prove (There are rumors, which I myself have never verified, that at a certain well known quantum computing research group, the days starts as follows. A little before lunch, the researchers wander in, check their email and look at the day’s postings on the arxiv. Now they don’t do anything more than read the titles. The research group then proceeds to go to lunch. At the lunch they discuss, with great debate, the most interesting papers posted that day. Having never ever even read the papers! There is a similar story about a certain researcher in quantum computing, who, if you tell that researcher a new result, (s)he will, within a day, almost always be able to rederive the result for you. Of course, my personal nickname for this person is “The Oracle” and it is tempting to tell “The Oracle” that a certain open problem has been solved, when it has not been solved, and see if (s)he can come up with the answer!)
(A note: throughout this post I will use the words “free will” to describe something which, you may or may not agree is related to “free will” as you imagine it. In particular if an object is said to not have free will if its future evolution can be predicted from information in the past lightcone of the object. If it cannot be so predicted with certainty it is then said to possess free will. In fact, I find this definition already interesting and troublesome: can we ever predict anything by only knowing information in our past light cone? How do we know that in the next instance of our evolution a light ray will hit us and burn us up? Certainly we cannot see such a light ray coming, can we? We can, of course, use physics to explain what happened: but can we use it to predict our future behavior? Of course for the electromagnetic field, we could sheild ourselves from such radiation and reasonably assume that we can predict what is occuring. But what about gravity, which can’t be sheilded? For an account of this type of argument I recommend Wolfgang’s comments here here.)
Okay, back to the story at hand. What is Conway and Kochen’s free will theorem? The basic idea is quite simple. I will explain it in the context of Bell’s theorem and the Kochen-Specker theorem, since the author’s don’t describe it in this manner. Bell’s theorem, we known, tells us that there is no local hidden variable theory explaining what quantum theory predicts. The Kochen-Specker theorem is less well known (which leads, in my opinion, the proponents of this different result to suffer a severe inferiority complex in which they constantly try to argue that the KS theorem is more important than Bell’s theorem.) What the Kochen-Specker theorem says is that if there is a hidden variable theory of quantum theory, it must be contextual, i.e. the Kochen-Specker theorem rules out non-contextual hidden variable theories. The way I like to think about the Kochen-Specker theorem is as follows: suppose that there are some hidden variables associated with some quantum system. Now if you make a measurement on this system you will get some outcomes with differing probabilities. Now sometimes you get outcomes with certainty. You’d like to say that when you perform this measurement, this outcome is actually associated with the value of some real hidden variable. But what the KS theorem tells you is that this is not possible: there is no way that those measurement outcomes are actually associated with the hidden variables in a nice one to one manner. What does this have to with contextuality/non-contextuality? Well the “context” here is what other measurement outcomes you are measuring when you measure along with the outcome associated with a particular hidden variable. In non-contextual hidden variable theories, what those other measurement results are doesn’t matter: it is those types of theories that the KS theorem rules out.
(Note: From my personal perspective, I find the KS theorem fascinating, but not as disturbing at Bell’s theorem: that “what you measure” determines “what you can learn” is a deep insight, and one that tells us something about the way reality can be described. However it is not that difficult to imagine the universe as a computer in which accessing the memory of the computer depends on the context of your input: i.e. to get ahold of memory location which holds the value 01001010, you need to query the machine and it seems perfectly reasonable to me that the machine is set up in a manner such that I can’t get all of those bits, since my measurement will only get some of them and the context of the measurement will change some of the other bits. This was basically John Bell’s reaction to the Kochen-Specker theorem. Interestingly there is a claim in this Conway and Kochen theorem that this loophole has been filled! I have a bit to say about this below. Of course no matter where you come out in this arguement, there is no doubt that the KS is DEEP: it tells us that the universe is not a computer whose memory we can gain total access to. And if we can’t gain access to this memory, then does the memory have any “reality”?!!)
Well I’m rambling on. Back to the subject at hand, the free will theorem. In the free will theorem, Conway and Kochen set up an experiment in which you take two spin-1 particles and perform measurement on these spins. (Now for those of you in the know you will already be suspicious that a spin-1 particle was used (the 3 dimensional irrep of SU(2)) as well as an entangled quantum state…sounds like both KS and Bell doesn’t it?)) The free will theorem is then:

If the choice of directions in which to perform spin 1 experiments is not a function of the information accessible to the experimenters, then the responses of the particles are equally not functions of the information accessible to them

In other words if we have free will, then particles have free will! How does the theorem get proven? Well basically the proof uses the KS theorem as well as the perfect correlations arising from maximally entangle spin-1 systems. First recall that the KS theorem says that hidden variable theories must be contextual, i.e. if I give you just the measurement directions involved in a measurement, there is no way to map this onto yes/no outcomes in a manner consistent across a set of possible measurements. But suppose, however, that your map to yes/no outcomes (i.e. the particles response) also depends on a hidden variable representing information in the particles past light cone, i.e. that the particles have no free will (contray hypothesis.) Now because we are dealing with a maximally entangled spin-1 system, two spacelike separated parties, A and B, will obtain the same outcomes for their measurement results for measurement directions for which they measure along the same direction. So for fixed values of the information in the past of both parties, the particle response should be identical and can only depend on local measurement direction. But this is not possible when one chooses an appropriate set of directions corresponding to the Kochen Specker proof. One can thus conclude that we cannot freely choose the measurements directions, i.e. that not all choices of measruements are possible: there must be hidden variables associated with the measurement choice as well. Thus we have shown that particles having dependence on information in the past light cone implies that the measurement choice must have dependence on information in the past light cone. Having shown the contrapostive, we have shown the free will theorem.
Now the interesting thing about the free will theorem is that doesn’t tell us whether the universe alows us to have free will or not. It simply says that if we assume some form of free will, then the particles we describe will also have free will. Of course the “free will” we describe here is “independence of (classical) information in the past light cone,” so some would object to this definition of “free will.” In particular, by this definition, a system which is totally random has free will. But is seems to me that the interesting question about free will is not whether one can have such random systems, but whether one can have a mixture of determined and undetermined evolutions. I mean the fundamental paradox of free will seems to me to be that free will involves a lack of cause for an action, but we want this action to itself have causes. In this respect, the above theorem suffers a bit, in my opinion, for a simplistic version of free will which is too absolutist for my tastes. What I find fascinating is whether we can “quantify” different versions of free will and what such quantifications would tell us about our real world.
Well it seems that I’ve had the free will to ramble on quite a bit in this post. Hopefully you might decide that the subject is interesting enough to choose to read the paper on your own 😉