Silicon Qubits

Well done video providing an overview of the research. Here is the original paper in Nature. For a more general explanation of the research, here is an article from The Register. See also the University of New South Wales's press release. Why is it that University press offices are loath to link to the original paper?

Quantum cryptography: yesterday, today, and tomorrow

Chris Lee's impressive overview of quantum cryptography. Arstechnica, to my mind, does the best science reporting on quantum mechanics.

A real world example of the future of secure computation is found in the Danish sugar beet industry. All the sugar beets in Denmark are purchased by a single company. The farmers buy the rights to sell a certain volume of sugar beets to the monopolist. However, individual farmers must buy these rights based on estimates of their own production. As a result they often find themselves in the market to buy or sell rights.

Now, the last thing they want to do is buy and sell these rights through auctions run by the monopolist—monopoly power must be limited after all—because the monopolist would have the production records of every farmer and be able to use that to bid the price of the rights down. The market is setup by sellers simply listing the number of units they are willing to sell at each price. Buyers make a similar list of how many units they are willing buy at each price. The results are put together into two graphs of price and volume. Business is conducted at the intersection of these two curves.

Key to the success of this market is that no one knows who is in the market, or how much any particular farmer wants to buy or sell. A more open auction would reveal too much information, leaving farmers vulnerable to market manipulation by the monopolist and each other. So, secure computation could enable a way to create markets that are less open to manipulation, creating a fair economic mechanism.

Salman Rushdie on being sentenced to death

A powerful, riveting, essay in the New Yorker by Salman Rushdie about how the fatwa, issued over the publication of "The Satanic Verses", tore his life apart.

“How does it feel,” she asked him, “to know that you have just been sentenced to death by Ayatollah Khomeini?” It was a sunny Tuesday in London, but the question shut out the light. This is what he said, without really knowing what he was saying: “It doesn’t feel good.” This is what he thought: I’m a dead man. He wondered how many days he had left, and guessed that the answer was probably a single-digit number.

If someone thousands of miles away suddenly – and very publicly – ordered my death, I don't think I would know how to react. A career in Physics does not prepare one for that. But neither does a career as a writer.

A few years back I read several Rushdie books back to back. "The Satanic Verses" is an impressive, nuanced, and sprawling work. For me, one of the most interesting parts of Rushdie's essay is where he discusses the story which inspired "The Satanic Verses". It is startling how badly the book was misinterpreted.

The book took more than four years to write. Afterward, when people tried to reduce it to an “insult,” he wanted to reply, “I can insult people a lot faster than that.” But it did not strike his opponents as strange that a serious writer should spend a tenth of his life creating something as crude as an insult. This was because they refused to see him as a serious writer. In order to attack him and his work, they had to paint him as a bad person, an apostate traitor, an unscrupulous seeker of fame and wealth, an opportunist who “attacked Islam” for his own personal gain. This was what was meant by the much repeated phrase “He did it on purpose.” Well, of course he had done it on purpose. How could one write a quarter of a million words by accident? The problem, as Bill Clinton might have said, was what one meant by “it.

As a physicist I have become used to popular accounts of my working being mangled when they are reported. This is not due to incompetence or maliciousness by the reporter, but is often because trying to explain what is happening at the cutting edge of quantum mechanics to the average person is an extremely difficult and subtle task. At worse we end up with misguided blog comments or the occasional angry rant laced with ad hominem attacks. When a writer like Salman Rushdie's words are mangled people die.

Slow motion video of cats flipping

Destin, from Smarter Every Day, uses slow motion video to explain the physics behind why cats land on their feet. I love the archival footage of Cats in zero G trying to right themselves.

Don't try this at home.

Midnight's Children

Midnight's Children

Midnight's Children Movie Poster

Walking by the Princess Cinema here in Waterloo I saw this poster for Deepa Mehta's new movie adaptation of Salman Rushdie's Midnight's Children. Midnight's Children, winner of the the Booker of Bookers prize, is the best book I have read. Rushdie seamlessly blends fantasy with history as he tells the story of India's independence, the partition of India and Pakistan, and the growth of two nations.

Given the scope of the book, it will be interesting to see how this is condensed and reworked for the silver screen. The film makes its debut at TIFF and then opens October 26th.

[UPDATE]: Apparently Salman Rushdie wrote the script. This movie is shaping up to be epic in scope.

When scientists talk smack

Funny piece by the New Yorker.

“You know the difference between the Mars rover and the Higgs boson?” said a NASA spokesman, his face red with anger. “You can actually see the Mars rover.”

Carleton horse trades academic freedom for $15 million dollars

Some great reporting by Bruce Cheadle on the $15 million dollar donation that Carleton University recently accepted for its school of political management–the single largest donation in school history. The donation comes with some serious strings attached:

Carleton quietly released the donor agreement on the Friday afternoon before Canada Day after stonewalling The Canadian Press for almost a year to keep it under wraps.

The contract reveals the Riddell Foundation effectively appointed three of five people on a steering committee. That committee was given sweeping power over the graduate program’s budget, academic hiring, executive director and curriculum.

This is some scary, back-room dealing, stuff. Universities are starving for cash right now, but is giving up this much freedom worth it? This eats away at the ideals and principles on which universities are based. Of course, in practice, universities still suffer the same lapses as other human enterprises, but these are principles and ideals that worth striving for. Carleton has horse-traded long term academic freedom for a short term cash infusion.

If what is happening in the US is any indication, we will start to see lots more of this here in Canada:

The Washington-based Centre for American Progress published a study in October, 2010 that exposed numerous problematic deals involving American universities and major energy companies.

The study, titled “Big Oil Goes to College,” examined 10 agreements worth almost $1-billion and concluded that almost all of them undermined the schools’ independence and integrity.

In addition, news reports exposed that the billionaire Koch brothers have been giving universities funds for entrepreneurial studies provided their staunchly Republican foundation could pick the faculty and set curriculum. And since 2005, U.S. banking giant BB&T has spent millions to get colleges and universities to develop programs on Ayn Rand’s books and right-wing economic philosophy.


Quantum interpretations can make a difference

I stumbled upon this 2010 post by Chad Orzel talking about the many worlds interpretation to quantum mechanics. Chad has this to say about his general feelings towards the field of interpretations:

My real view is, alas, kind of wishy-washy: I’m agnostic about quantum interpretations, mostly because as far as we know, they’re all meta-theories, not proper scientific theories. There is no experimental test known that clearly favors one interpretation over another, so which one you like is ultimately a question of taste. They’re kind of fun to talk about, but absent a way to distinguish between them, they’re not more than that.

Matt Leifer has a great reply in the comments section:

You know, I couldn’t disagree more about this. In fact, I find it truly bizarre that quantum theory is pretty much the ONLY scientific theory where people do not think the the interpretation of the theory is an integral part of the theory itself. At least, I can’t think of any other examples.

Whilst it is true that an interpretation must reproduce the confirmed predictions of QM, they can differ quite a bit outside of that. The obvious example is spontaneous collapse theories, but there is also nonequilibrium Bohmian mechanics. Some may argue that these are different theories rather than different interpretations, but I think the dividing line between different theories and interpretations is rather blurry. It is not guaranteed that the interpretations will all agree when we are outside the realms of established physics, e.g. in quantum gravity.

The other thing that I think interpretations do for you is that they give different intuitions for how to proceed theoretically on certain problems. For example, the approach one takes to the emergence of classicality or to quantum chaos depends heavily on whether you view the state vector as an epistemic state (state of knowledge) or an ontic state (state of reality). This is one of the key issues that interpretations differ on.

In other words, interpretations CAN make a very real difference to how one does physics, and on controversial issues they probably SHOULD make a difference.

I like the way Matt puts this. Different interpretations provide different perspectives and approaches to a problem. I have found this to be true in my own work.

I still do not have a preferred interpretation, but that is because I know enough now to know that I still do not know enough to make an informed decision. There are to many nitty gritty subtleties that remain. I wish that someone would write a clear textbook on the subject. The quantum foundations version of Michael Nielsen's and Isaac Chuang's Quantum Computation and Quantum Information. I think such a text would help the field communicate and share with other branches of physics more effectively. I would certainly buy it. Is anyone working on such a project currently?

Explain quantum mechanics in five words

John Preskill, while talking about taking a quantum mechanics class with the late John Wheeler, mentions this story:

Later, at a student-faculty lunch, Wheeler seemed troubled. He had been asked to explain the essence of quantum mechanics in five words or less, and was stumped. Frank Calaprice, a nuclear physicist within earshot, interjected helpfully, “What we expect to measure?” I was silent.

The question was absurd. It was fascinating. I still think about it. I can’t answer it.

This idea–explain quantum mechanics in five words–has captured the imagination of people. In the the blog comments, a number of people chime in with their thoughts:

My attempt at non-technical answer is: Quantum mechanics is nature's casino.

Sean Carroll, via Michael Nielsen, picked up on the idea and posted this Twitter challenge:

Which has led to a flood of tweets trying to summarize quantum mechanics. Here are my favourites so far:

How would you explain quantum mechanics in five words or less?

Relativistic Baseball

It looks like Randall Munroe of XKCD fame has a new project: "what if?". Every Tuesday he answer a hypothetical question with an illustrated essay. The first question tackled is "what would happen if you tried to hit a baseball pitched at 90% the speed of light?".

Suppose you’re watching from a hilltop outside the city. The first thing you see is a blinding light, far outshining the sun. This gradually fades over the course of a few seconds, and a growing fireball rises into a mushroom cloud. Then, with a great roar, the blast wave arrives, tearing up trees and shredding houses.

Everything within roughly a mile of the park is leveled, and a firestorm engulfs the surrounding city. The baseball diamond is now a sizable crater, centered a few hundred feet behind the former location of the backstop.

A careful reading of official Major League Baseball Rule 6.08(b) suggests that in this situation, the batter would be considered "hit by pitch", and would be eligible to advance to first base.

I am looking forward to the future questions/answers.

My CTV News interview on the Higgs Boson

My CTV News interview on the Higgs Boson

CTV News Higgs Boson

On Tuesday, before the LHC made its announcement of the Higgs Boson, I went on CTV News to talk about what the Higgs is up, why physicists are excited, and why it should not be called the God particle.

The Higgs Boson result presented in Comic Sans

Billions of dollars spent on a 50 year quest to find the elusive Higgs Boson, and the best font they can come up with is Comic Sans? I am surprised they did not dress Peter Higgs up in a clown suit for the seminar.

The reaction to the use of Comic Sans in such a prestigious announcement was akin to many as a social faux-pas on a scale of open flies or a small amount of faecal matter on one's cheek and threatened to overpower the statement on the very centre of our existence.

Sean Caroll's live blog of the Higgs announcement

After nearly half a century of looking, a particle that looks an awful lot like the Higgs Boson has been discovered. Sean Caroll live blogged the press conference. My favourite two quotes:

Peter Higgs is visibly moved at the final results. I hope people understand, and perhaps this helps make clear, how invested scientists are in this work.


A couple of people have mentioned supersymmetry. As Rolf Heuer just said, straightforward SUSY models have a remarkable feature: not a single Higgs boson, but five Higgs bosons. So we may have only have found 20% of the Higgs conglomerate.

A physicist's work is never done.

CMS result for four leptons

She shook me all night long

This spring I went to see the season opener for the Tri-City Roller Girls. It being my first time at a roller derby, I brought along my camera. After shooting over an hour of footage I put together this short movie. These girls are tough (and awesome).

Shot on my hacked Panasonic GH1 at 60fps. The footage was (mostly) retimed to 24fps in FCPX to achieve the slow motion.

LEGO Turing Machine

From Wikipedia:

A Turing machine is a device that manipulates symbols on a strip of tape according to a table of rules. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a computer.

Given enough LEGO blocks, you could play Angry Birds on this.

Five moments that changed modern Lindy Hop

Jerry Almonte wrote a great post about some of the pivotal moments that have shaped Lindy Hop. I have been dancing long enough to have been around for all but one of these moments.

My favourite is Todd and Naomi's spotlight in the ULHS 2005 Liberation final. At the time I had never seen footwork executed this fast and crisp. Frida Segerdahl, sitting right behind where Todd and Naomi are dancing, starts fist pumping with excitement during their second spotlight when they do the tandem variations.