Category: General

A workshop in the beautiful Pyrenees anyone? Can life get any better for a quantum computing scientist than spending time in the mountains doing quantum information science?

BENASQUE 2007
Dear Colleague,
We are pleased to inform you that following a very successful editions of Benasque 1998, 2000, 2003 and 2005 we are organizing another workshop of the similar type in June 2007. This is to invite you to apply using
the electronic form that you can find on the website specified below. We encourage you to apply as soon as
possible and not later than the end of March 2007. The number of participants at the Benasque Centre at any given time is limited to about 50. We will do our best to accommodate most of the applicants, however, in some cases we may be unable to find suitable time slots for all of them, i.e. we cannot guarantee acceptance. Budget permitting, we expect to offer a modest allowance to some participants. Preference will be given to those staying for the whole
duration of the workshop.
We do hope to see you in Benasque next year!
Ignacio Cirac and Artur Ekert
_________________________________________________________
BENASQUE 2007
Title: Quantum Information
Venue: Benasque in the Spanish Pyrenees.
Date: The 3 week period 10– 29 June 2007.
Website: http://sophia.ecm.ub.es/
Registers at: http://benasque.ecm.ub.es/2007qi/2007qi.htm
_________________________________________________________

I grew up in a small town. Whenever I go home, one of the first things I do is turn to the Police Department report in the local newspaper. Why? To see if my friends have ended up in jail? Nope. For gems like this

Possible dead male in wheelchair. Emergency personnel were dispatched. Officier advised, subject was fine, wheelchair was dead. Wheelchair and subject was transported to his residence.

or, how about this,

Report of a dog causing a traffic problem in the area. Officer arrived and located the dog. After a game of fetch the dog was loaded into the car taken to the kennels.

or, maybe this

Report of a man carrying dead turkey down Main Street. Turkey determined to be recent kill and hunting season open.

Quant-ph people have some interesting comments, but those cond-mat people just one-uped everyone:

cond-mat/0608492
Title: Do superconductors violate Lenz’s law?
Authors: J.E. Hirsch
Comments: Readers are invited to place a wager on the outcome of the proposed experiment, this http URL
Subj-class: Superconductivity; Strongly Correlated Electrons

Wagering? On the ArXiv?

This last week has been a big week. I guess I’ll start at today and work backwards.
Today, we closed on purchasing a home in Seattle and get the keys in a few hours. Yep, it’s sold!

One requirement we had when searching for a house was that it had to be house which we could name. Well this house certainly has a uniqueness that makes qualifies it. The street address for the home is 2459. 2459? Yep 2459. “Why that’s a prime number!” you say. Why, yes, yes it is a prime number. Not only is it a prime number, but it is a Sophie Germain prime number. A prime number is called a Sophie Germain prime if twice the prime plus one is also prime. Not only is the number a Sophie Germain prime number, but it is also a safe prime number. A prime number is called safe if half one minus the number is also prime. (Safe primes are useful for the discrete logarithm problem because they have subgroups of large order.) Pretty cool, no? (1229, 2459, 4919, 9839 form a Cunningham chain of the first kind)
Here is a picture of the home:

Yep, that front yard needs a lot of work! But the bones are good. We’re not sure on the name of the house yet, but given all the numerology above and the character of the house, I’m thinking maybe “Villa Sophia.”
So buying a home means that on Thursday we acquired a substantial debt. Welcome to the American dream!
But wait, who is this “we” of which I speak? Hmm.
Well last Friday, I got engaged! That there is a woman out there crazy enough to say “yes” when I said “Will you marry me?” surely astounds all readers of this blog. And that this crazy woman is wonderful, wise, creative, brilliant, and beautiful makes me feel like I’m the luckiest guy around.
Yep, it’s been a big week 🙂
(As regards my engagement, my apologies to Pontiff Benedict VIII)

In October I get to go to London for the 7th European QIPC Workshop Quantum Information Processing and Communication which is being hosted by the Royal Society of London (Which is cool, because the original society was founded, IIRC, as a meeting to discuss the ideas of one Sir Francis Bacon!) The theme of this workshop is “Physicists and Computer Scientist Reunite!” Here is a blurb which Scott Aaronson produced after taking a huge verbose statement I wrote about this theme (those computer scientists have fine compression algorithms, I do say):

In the early days of quantum information science, physicists and computer scientists could make great progress by just sitting down at the same table and explaining the basic concerns of their respective fields. But those halcyon days are gone. Today the major discoveries of the mid-nineties have essentially morphed into separate disciplines. One can now work on quantum error correction without knowing anything about, say, quantum complexity or ion traps. Whereas the early days were distinguished by conferences in which computer scientists were forced to listen to physicists and vice versa, today the field is large enough that cross-disciplinary traffic has been reduced to a trickle. Yet quantum information is still just a fifteen-year-old teenager, so it would be astonishing indeed if the borderlands between physics and computer science were already picked clean. What connections remain to be discovered? What recent work in physics should computer scientists know about, and vice versa?
Quantum information scientists of the world, unite!

And indeed the workshop will have an interesting format with each one hour time slot consisting of one topic as seem by a more physics perspective and a more computer science perspective. It will be interesting to see if the audience will be able to withstand this dual sided barrage of perspectives!

Turns out that of the mother and father protocols which have helped illuminate the field of quantum information, only the mother is necessary: quant-ph/0606225:

Title: The mother of all protocols: Restructuring quantum information’s family tree
Authors: Anura Abeyesinghe, Igor Devetak, Patrick Hayden, Andreas Winter
We give a simple, direct proof of the “mother” protocol of quantum information theory. In this new formulation, it is easy to see that the mother, or rather her generalization to the fully quantum Slepian-Wolf protocol, simultaneously accomplishes two goals: quantum communication-assisted entanglement distillation, and state transfer from the sender to the receiver. As a result, in addition to her other “children,” the mother protocol generates the state merging primitive of Horodecki, Oppenheim and Winter, a fully quantum reverse Shannon theorem, and a new class of distributed compression protocols for correlated quantum sources which are optimal for sources described by separable density operators. Moreover, the mother protocol described here is easily transformed into the so-called “father” protocol whose children provide the quantum capacity and the entanglement-assisted capacity of a quantum channel, demonstrating that the division of single-sender/single-receiver protocols into two families was unnecessary: all protocols in the family are children of the mother.

Yesterday I was at Bell Labs for a one day meeting on quantum computing. Bell Where, the young ones ask? You know, the place where the transistor was invented! (Can you name the three who won the Nobel prize in physics for the invention of the transistor? How many people that you meet walking down the street can name any of these three?)
Amazingly this meeting was covered by local media: see here. Any investors might be interested in the last few paragraphs of the article:

At least one audience member was impatient.
Jan Andrew Buck heads Princeton Group International, which backs biotech ventures. He said he is itching for a bare-bones quantum computer for plotting complicated routes and schedules.
“I think I can get a squeaky, scratchy quantum computer to market in two or three years,” Buck said. All he needs, he said, are investors with deep pockets and short deadlines.

Now I consider myself an optimist, but I think Jan Andrew Buck has just out optimismed even my cheery outlook.
Back to the topic at hand, the meeting was fun! The first two talks, by David DiVincenzo and Isaac Chuang, were interesting in that they both made some arguments about whether the “sea of qubits” type architecture for a quantum computer is really feasible. Loosely, the idea of a sea of qubits is to have, say, a two dimensional dense grid of qubits which you can control with nearest neighbor interactions. One difficulty with this approach is that if you have a dense sea of qubits, it is hard to imagine how to get all of the elements you need to control these qubits from a classical controller outside of the quantum computer to each individual qubit. This is particulary worrisome for some solid state qubits, where high density is often needed in order to get controllable strong two qubit interactions (like say in some quantum dot approaches), but applies to many other types of implementations as well. David DiVincenzo talked about work he performed with Barbara Terhal and Krysta Svore on threshold for two dimensional spatial layouts (see quant-ph/0604090.) Because the cost of this spatial layout was not huge, along with his work with a particular implementation of a superconducting qubit at IBM, David reconsidered, in his talk, whether the sea of qubit was really that bad of a problem. He concluded by discussing how perhaps techniques developed in making three dimensional circuitry could be used to overcome the sea of qubits problem. Ike, on the other hand, talked about the issues of designing a quantum computing made out of ions, where the issue of getting your classical control may not be as severe (other talks focused on the MEMS mirror arrays which will be used to control, in parallel, many thousands of ion trap qubits.) Ike was one of the original people to point out the difficulties in the “sea of qubits” ideas, and I can’t help but think the reason he started working on ion traps and not solid state implementations was in some part motivated by this problem.
To me, the debate about what the architecture for a future quantum computer will look like is very intersting. Mostly because this debate has to do, I think, with quantum computing people taking very seriously what “scalable” means. I personally can’t stand the word “scalable.” Why? Well mostly because it is put in front of every single proposal in which the authors can reasonably imagine some far fetched way to scale their proposed quantum system up. Call me jaded. But what is fun to watch is that, now that there is serious discussion of many qubit quantum computers, the real difficulties of scalbility are beginning to emerge. Scalability is about money. Scalability is about ease. Scalability is about architecture. Which physical implementation will scale up to our future quantum computer and what will the architecture of this computer look like? Depending on the day you ask me you’ll get a different answer. Which, I suppose, is one of the reasons why I remain but a lowly theorist…too scared to jump on the bandwagon I trust the most.

When I’m feeling particularly stupid, I always, like any good citizen, look around to see what or who I can blame for my stupidity. Lately the leading candidate of my excusing has been my age. I mean, according to Nintendo’s Brain Age game, the optimal age is 20. And we are all trained as graduate students that your best work can only be done in your twenties (I’ve long suspected that this is just a way for advisors to get more work out of their graduate students. Certainly the elders who promulgate that meme are pretty damn smart.) So today I was happy to find another good candidate for my excusing. Seattle is America’s Smartest Large City (Large city has a population over 200,000 adults.) Well, of course rankings like this are really silly (this sentence inserted to avoid ranting comments about how silly they are. Of course they are silly. As are most things in life.) But, eat that San Francisco!