Quantized Thoughts

Happy New Year from Singapore

2012-01-01T13:48:00.003Z

A glimpse of our new year's eve.

Fukushima: A nuclear physics primer

2011-03-12T14:28:00.004Z

As I am sure everyone has heard by now, there has been an enormous earthquake off the coast of North-East Japan, which (together with the tsunami caused by the quake) has lead to widespread distruction and loss of life. At the moment, however, there is concern over trouble at two nuclear power station. The amount of information coming out through the media is quite limited, and of course isn't easy to decrypt what experts are saying if you don't know what the terminology means.

Caveat: Although I am a physicist, I am the wrong type of physicist to be paricularly expert on nuclear safety. I am writing this simply so this to try to help non-physicists decipher what is going on at the moment in Fukushima.

The first thing you need to know is what a nuclear power plant actually does, and what radiation is. All atoms are composed of a cloud of electrons which surround a nucleous composed of neutrons and protons. The stability of the nucleus is what determines radioactivity, and is determined by the number of protons and neutrons contained in the nucleus. The interaction between these particles determine how tightly they are bound together.

The above diagram shows the relative stability of different atomic elements, running from lighter to heavier elements. As you can see, iron (Fe) has the highest binding energy (meaning that its nucleons are the most tightly bound). Nuclear reactions in which larger nuclei split apart are known as fission reactions (moving towards iron from the right), while reactions where smaller nuclei are combined to form a larger nucleus are called fusion reactions (moving towards iron from the left). All commercial reactors are at present fission reactors. These work by capturing the energy released by large nuclei splitting, usually using uranium as fuel. The reactors at Fukushima are boiling water reactors, which capture this energy by using it to boil water to produce steam used to drive a turbine, which in turn generates an electric current (producing electricity).

Different nuclei come apart in different ways, depending on their composition. Which element a nucleus is is governed by the total number of protons only, and this determines it's chemical properties. The nuclei of the same element can have different numbers of neutrons, and these different varieties are known as isotopes. The chart I showed above is of the most stable isotope for each element. How a particular radioactive element comes apart depends not on only on which element it is, but rather which isotope of that element. Below is a diagram showing how different nuclei decay.

Here the important unexplained types of decay are

β^- corresponding to the emission of an electron (this is a neutron changing into a proton in the nucleus),
β⁺ corresponding to the emission of an positron, which is a positively charged version of an electron (this is a proton changing into a neutron in the nucleus)
α which corresponds to the emission of a group of helium nucleus (2 protons and 2 neutrons tightly bound together), and happens because of the huge spike in binding energy for helium nuclei which can be seen in the first diagram.
Fission, where the nucleus splits into several large parts

These ejected byproducts (together with γ-rays which can also be emitted) are what is usually what nuclear radiation is used to refer to. This what is known as ionising radiation, particles sufficiently energetic to knock electrons free from other atoms and molecules, which can in turn lead to chemical changes. Such radiation is dangerous for humans primarily because it can cause chemical changes within our body which can lead to any number of problems. In general ingestion or inhalation is much more dangerous than other types of exposure.

As I mentioned earlier, both Fukushima I and II user boiling water reactors. They use what is called 'light water' which simply means they use purified water to cool the fission reactions. The word 'light' is used to distinguish them from 'heavy water' reactors which use water where the hydrogen is replaced by a heavier isotope called deuterium (which can be used to regulate reactions in some reactor designs).

At Fukushima I, it appears that when the earthquake struck some problem occured with the cooling system for one of the reactors failed. The nuclear reactions produce a lot of heat, and needs to be kept cool by adding water. Unfortunately, even though you can slow down the fission reaction, some byproducts of the decay of uranium are themselves radioactive, and (according to one expert who just appeared on the BBC) can contribute as much as 10% of the energy produced in the reactor, which is essentially impossible to stop. Without the cooling system working, there is a build-up of steam. It is also possible for the fuel to react with the water to produce hydrogen. These gases have to be vented in order for the pressure inside the reactor to be kept within safe limits (so that the reactor doesn't come apart). As long as the reactor is intack, the amount of radiation released should be low. Hydrogen is not radioactive, even if it absorbs a neutron (producing deuterium), the nucleus is stable. Tritium would be bad, but I can't see anyway for that to have been produced. However, Nitrogen 16 will also have been produced, which is extremely radioactive. This may sound bad, but it is infact so radioactive that it decays very quickly, meaning that it doesn't pose a danger any distance from the plant. The half-life is 7 seconds, meaning that 7 seconds after production half of the radioactive nitrogen has converted to safe oxygen. So after after 11 minutes there is on millionth the radiation. Give that wind speeds are relatively slow, the nitrogen will decay before it can cause much trouble (except perhaps for people actually in the plant). This is why we are hearing about high radiation levels in the control room, but little additional radiation right outside the perimeter.

There has also been an explosion at the plant which is causing significant, since it is not entirely clear what has happened. It sounds like this was probably caused by the hydrogen igniting, which has damaged the building, but it seems like the reactor core is still intact. If this is true, and they can keep the reactor cool enough that the fuel does not all melt (a meltdown, which makes it much harder to cool, and which would likely result in the release of much more nasty isotopes) then the amount of radiation released shouldn't pose to much of a health risk. Fortunately the wind seems to be blowing out to see, which also improves the situation.

The latest I have heard is that the authorities are considering using sea water to cool the reactor core, which they will be reluctant to do since it will make the reactor unusable in future, but which should cool the reactor core. Apparently the incident is currently rated as 4 ("Accident with local consequences") on the International Nuclear Event Scale, which is still one level below the Three Mile Island incident in the US, and 3 levels below the maximum level which corresponds to a Chernobyl-like event.

If anyone has any further information they would like to contribute, or any corrections to what I have written above (as I say, I am the wrong type of physicist), then please let me know, wither in the comments or by email.

Theoretical Physics Q and A site progress

2010-11-24T10:31:00.002Z

The proposed Theoretical Physics stack exchange site has finished its definition phase and has now entered a commitment phase. What this means is that we need as many physicists as possible to agree (by signing up here) to participate in the beta and hopefully ask or answer 10 questions in the first 3 months. This shouldn't be a huge time commitment, but it is really important to get as many research physicists as possible early on. The reason for this is that the democratic nature of Stack Exchange sites means that the direction of the site is set by the participants. Obviously there are a lot more people interested in some aspect of theoretical physics than there are people who have some level of expertise in the field, and so it is important to get as many TP grad students, postdocs and faculty involved at an early stage to insure that the site becomes a TP version of MathOverflow and CSTheory, rather than becoming a site for people to post their pet crackpot theories or discuss pop science topics.

To help convince you to sign up, below are a list of the top 5 examples of both on-topic and off-topic questions chosen during the definition phase.

On-topic:

Are there entangled states which do not violate any Bell inequality?
Are XXZ spinchains with uniform couplings exactly solvable?
Has [specific toy model] been studied in the literature?
What are the justifying foundations of statistical mechanics without appealing to the ergodic hypothesis?
Within Twistor String Theory (ala Within), what is currently seen as the significance of the superconformal algebra realized on supertwistor space?

Off-topic:

Why is the sky blue during the day, red during sunrise and sunset and black at night?
I have found an error in general relativity/quantum mechanics/the second law of thermodynamics. Can someone help me work out the maths?
Is Dr. Quantum's Double Slit Experiment video scientifically accurate?
Why do hot things glow?
What is the current thinking about Lisi's "Exceptionally Simple Theory of Everything"?

A theoretical physics Q and A site

2010-11-13T18:53:00.002Z

I've become totally enamored with the CSTheory stack exchange site. It's proving very addictive, but in exchange for the time I spend on the site I am finding that I am learning a lot of new things, and a few new tricks.

I had hoped that the Physics stack exchange site might become a similar resource for physicists (and I still very much self-identify as a physicist). Unfortunately this has turned out not to be the case. There was never a policy dictating that questions should be research level (as there was both for CSTheory and MathOverflow), and this has led to the majority of questions either being basic undergrad type questions or pop-sci question. As a result, there are also very many poor answers which contain common misconceptions, but which get up-voted. Consequently, I don't think the site is likely to be an attractive propositions for active researchers.

However, I don't want to just complain and not offer a solution, so I have set up a proposal for a Theoretical Physics stack exchange site. The aim of the site would be to provide a question and answers site aimed at research level questions only, akin to the CSTheory stack exchange site and MathOverflow. Personally I find both sites to be phenomenal resources, and I think it's high time we physicists had something similar.

I proposed the site as being for theoretical and mathematical physics and not physics in general only because I think that spanning both theory and experiment might make the scope of the site too broad, making it harder to get good answers to specific questions in any one area. Experimentalists with theory questions (or better yet, theory answers) are of course encouraged to participate.

The process of defining the site is entirely democratic, so you don't need to worry about whether you trust my judgement or not. If the site reaches beta temporary moderators are elected by the community. This is also why it is important to have a solid group of physicists early on, to set the level and tone of the site.

So, if you are a physicist and this sounds like something that might interest you, why not visit and help shape the scope and level of the site by submitting sample questions or voting on whether you think the questions submitted by others would be consistent with such a site?

CS Theory Q&A site in beta

2010-08-23T18:11:00.002+01:00

The mathoverflow-like site for theoretical computer science which I blogged about earlier is about to go into public beta. The site aims to allow users to ask and answer research level questions in TCS, and I must say that my experience with the private beta has been excellent. I have received excellent answers to the 2 questions I asked, and have been able to give reasonable answers to 8 questions so far. It really is an excellent resource. Anyway, if you have an interest in TCS it is well worth participating in the site. It needs as many users as possible to make it a success.

To join the public beta, simply visit http://cstheory.stackexchange.com

P vs NP finally resolved?

2010-08-09T03:24:00.002+01:00

A new paper has appeared from Vinay Deolalikar in HP Labs claiming to prove P is not equal to NP (in fact P≠NP is the title). Normally I ignore the constant stream of papers on the subject, but this work looks like a serious attempt and is being taken seriously by a number of people I respect, so it has jumped straight to the top of my reading list.

For more details see posts by the Pontiff, Greg Baker, and R J Lipton.

I really hadn't expected to see this proved within my life time, so I am of course skeptical. Still, even if there is an error, perhaps it opens up a new approach.

TheoryOverflow

2010-07-02T22:08:00.003+01:00

If you're a physicist, mathematician or computer scientist and haven't already seen MathOverflow then stop reading this post and go check it out. It is one of the best resources for research level math I have ever seen. It is absolutely shocking the speed and quality of responses to potentially very technical questions.

So, if you are still reading, I will presume you actually know the site. So why do I bring it up? Well, there is currently a proposal for a TheoryOverflow, aimed at Theoretical Computer Science, on the StackExchange site. Basically the way this works is that the people that produce the engine that powers the MathOverflow and StackOverflow websites are looking to produce similar sites in different areas. First an idea is proposed and fleshed out (Stage 1), once this is done it moves to a commitment stage where potential users are asked to commit to using the new site initially if it were made (Stage 2), either posting questions or answers. Finally it moves to a Beta (Stage 3). TheoryOverflow is currently in stage 2, and so needs support.

Rep, if you don't know, is basically reputation, and so people who have contributed to other such sites carry more weight than users who haven't. Different users have different amounts of rep depending on their level of contribution to StackOverflow and sister sites. Unfortunately more users seem to be necessary than usual, because most potential users committing to it seem to either be new or are coming from MathOverflow, and the StackExchange site doesn't care about your MathOverflow rep (though it does about StackOverflow rep).

So basically, TheoryOverflow needs more support. If it turns out even a tiny fraction as useful as MathOverflow, then it will be a fantastic resource. So please help make it happen. You can sign up here.

Quantum Country

2010-04-18T21:35:00.001+01:00

Nice article (and a pretty cool photo) in The Record about my dear friend and collaborator Anne Broadbent.

Quantum verifiers

2010-04-15T01:16:00.003+01:00

If you have heard me talk in the last couple of months you may know that I have been working on trying to characterize the power of quantum interactive proofs with multiple provers. Well, I am delighted to say that our paper is finally on the arXiv here. I am quite chuffed with it since it is the first time I have been able to use an equation as the title of a paper, and is also the first time one of my results can be neatly captured by a single simple equation. Some how I feel it lends me more cred as a theorist!

Recently Jain, Ji, Upadhyay and Watrous proved the rather amazing result (here) that interactive proofs with quantum verifiers can only prove problems in PSPACE, and so are identical in power to interactive proofs with classical verifiers. Our result proves an equivalent statement for interactive proofs with more than one prover, basically showing that any interactive proof with potentially entangled (but non-communicating) provers can be simulated using only a classical verifier and some extra entanglement. The case for non-entangled provers had previously been proved by Kobayashi and Matsumoto (here).

Taken together these three results show something interesting, and quite counter intuitive: the availability of quantum verifiers does not change the power of any interactive proof system. Now, this result doesn't necessarily hold when we fix the number of rounds (our MIP* protocols requires polynomially more rounds than than the equivalent QMIP protocol), but I find the symmetry in these three results pretty remarkable.

As Oded Regev pointed out to me on SciRate, some authors have used QMIP* to denote the quantum equivalent of MIP* and QMIP to denote the quantum equivalent of MIP. Although we were aware of this, there are at least two conflicting notations used, and we simply followed the convention used on the Complexity Zoo, to try to minimize confusion. One nice property of the notation Oded suggests, however, is that the three results mentioned above can be expressed as:

QIP=IP
QMIP=MIP
QMIP*=MIP*

Neat, no? So, how should I feel about QMA now?

Engaged!

2010-04-15T01:02:00.002+01:00

If you know me personally or follow me on twitter then this may not be a big surprise, but I thought I would repeat the news here, since I am so happy. On the 2^nd of March I asked my wonderful girlfriend Amy to be my wife. I am delighted to say that she agreed!

We haven't set a date yet, but we are planning to get married in summer 2011. I will post more plans as we make them, in the mean time if you are bored, you can check out our new wedding blog here.

Post-FOCS post

2009-10-30T15:08:00.002Z

I'm back from the FOCS conference in Atlanta, and since Lance has pointed out the lack of blog posts about it, I thought I would try to say something about it.

For those of you who don't already know, FOCS is actually the IEEE Symposium on Foundations of Computer Science, and this year marks the 50th annual meeting. This was also my first time to attend FOCS, and it was a slightly odd experience. My background is in theoretical physics rather than theoretical computer science, so I am much more used to the physics model of conferences and publishing.

One thing I found particularly odd is that for such a prestigious conference with a rigorous review process they limited all the talks to 25 minutes including questions. Given the technical nature of many of the results this seems a little strange. Is there really a need to compress the conference into 3 days if it means having such little time to take in each of the results. This also seems to lead to a rather strange style of presenting, where some speakers seem to dive into the technical details without giving the intuition behind their approach. Maybe this is just a cultural difference between CS and physics, but I can't help thinking that the compact time frame for talks really limited how much I actually took in. There were a lot of very interesting results, and I really wish I had had more time to process these before moving on to a new topic.

The other thing I found strange, being used to physics conferences, was the lack of a conference dinner. I usually enjoy conference dinners as they tend to be a great way to meet other people in the field. While there were lunches on two of the days, these really did seem quite cliquey and so I mostly ended up meeting people who were connected to one of the other quantum speakers (we had our own clique!).

So now I've brought up two things I didn't like about the conference, perhaps I should focus on the things I really did enjoy: the talks. Keep in mind that I have a very different background to most of the attendants, so I am probably skipping over some other great talks. These are simply the ones that caught my imagination.

Day 0 of the conference was last Saturday. It wasn't part of the conference proper, and was open to the public. There were a series of public talks to mark the 50th anniversary of FOCS and the 20th anniversary of the algorithms, combinatorics and optimization program at Georgia Tech. Even though I ended up staying in the Hotel Palomar (which I thoroughly recommend) right beside the auditorium it took me nearly an hour to find the right place. In retrospect, it shouldn't have been hard to find at all, except that the map was somewhat inaccurate, and seemed to direct us to a building on the opposite side of the road.

There were four talks in total, from Richard Karp, Mihalis Yannakakis, Noga Alon and Manuel Blum. Unfortunately jet lag got the better of me, and I ended up missing the last talk. Of the first three, I particularly enjoyed Mihalis's talk on equilibria. Why? Well it seems that many of the equilibria problems he was discussing are of a similar form to the the equations that arise in dealing with closed timelike curves. This probably shouldn't be surprising, since Deutsch's consistency condition is effectively just enforcing equilibrium, but none the less I found the connection fascinating. Actually throughout the conference, I found that quite a number of talks dealt with issues that also arise in physics.

Sunday marked the star of the conference, and also the start of parallel sessions. As a result, I was constantly having to decide which session I wanted to attend, and so could only see half of the talks. In the morning I attended session 1B (see the program here), and got a good sampling of talks on complexity. I've been interested in a (quantum) communications complexity question for some time, so I particularly enjoyed Paul Beame's talk on multiparty communications complexity.

By far the highlight of the day for me, though, was session 2A, where we were introduced to the abstract tiling model model by David Doty, before Sandy Irani's excellent talk on the connection between this problem and Hamiltonian problems in quantum complexity. I really found this session to be eye opening, as I hadn't been aware of the abstract tiling model before, but it has really caught my interest. Sandy's talk in particular caught my interest, and I will be reading their paper in detail once I can get my current teaching backlog out of the way.

The other talk that I greatly enjoyed was on polynomial identity testing given by Shubhangi Saraf (particularly the colourful combinatorics!). Unfortunately by this stage I was pretty worn out, and didn't really take everything in. Another paper for the reading list.

The highlights of day 2 for me were talks by Alexander Sherstov on the intersection of half-spaces and by Vitaly Feldman on statistical query learning.

On Saturday myself and my co-author Elham had flipped a coin to decide who would give our talk, and I lost. On Monday evening we went out to my hotel to finish the slides and have a celebratory dinner to mark our first FOCS paper together. The Palomar, where I was saying, somehow seemed to be both cheaper than the conference hotel and much better. We sat beside a fire pit on the roof terrace, putting the last touches on the slides. Not a bad way to prepare for a talk!

Tuesday was the third and final day of the conference. The quantum session was in the morning, which unfortunately meant quite a low turnout. I have to say, I enjoyed all three of the other talks in the session. Our talk was first, at 9am, followed by André Chailloux talking about quantum coin flipping, then Sarvagya Upadhyay talking about quantum interactive proofs, and finally Ben Reichardt talking about quantum query complexity and span programs.

I found Sarvagya's talk particularly interesting, but also kind of strange. In his talk he was showing that two message quantum interactive proofs are in PSPACE. This was certainly a major result and I was very interested to hear the details fo the proof. What was strange, however, was that I know the same authors have proved the much stronger result that QIP=IP or equivalently QIP=PSPACE. It is a little strange to sit through what you know to be a talk about a weaker result, when you know the speaker has the stronger result ready to go. Oh well!

Unfortunately, after our session I realised that we could prove another result about interactive proofs, and spent the rest of the day working through the details with Elham, and so missed the later talks.

Despite my reservations about the structure of the conference, I very much enjoyed my first FOCS experience, and I'm hoping that we'll get the new results written up in time for STOC.

Twitter

2009-10-09T16:02:00.002+01:00

I'm now on twitter. It turns out to be a lot more interesting than I had been expecting, probably due to the relatively large number of QIPers/exQIPers (@dabacon, @mattleifer, @danbrowne77, @WaterlooIQC, @iqoqi, @coherence, @dwavesys, @rohde, @mickbremner, @michael_nielsen, @tobiasosborne and @seandbarrett).

First paper!

2009-08-03T18:08:00.002+01:00

No, not mine. My DPhil student Yuichiro Matsuzaki has just uploaded his first paper to the arxiv. It should appear in the quant-ph morning mailing. I might write something about it once it appears.

UK limiting freedom of expression for immigrants

2009-08-03T13:40:00.002+01:00

It seems that the UK government plans to limit freedom of expression for immigrants wishing to become citizens. The Guardian has the story. It seems if you voice opposition to government policy (and by this I mean the policy of the current party in power) you can be declined citizenship:

At the weekend stories attributed to government sources suggested that immigrants who took part in anti-war demonstrations could jeopardise their chances of qualifying for citizenship.
....
But, when it was pointed out that demonstrating was not illegal, Woolas suggested that an applicant could also lose points not just for breaking the law – but also for engaging in certain activities that were legal.
Sarah Montague, the presenter, asked: "Are you effectively saying to people who want to have a British passport, 'You can have one, and when you've got one you can demonstrate as much as you like, but until then don't'?"
Woolas replied: "In essence, yes. In essence we are saying that the test that applies to the citizen should be broader than the test that applies to the person who wants to be a citizen. I think that's a fair point of view, to say that if you want to come to our country and settle, you should show that adherence."

That's Phil Woolas, the immigration minister. Well, Phil, allow me to acquaint you with Article 10 of the European Convention on Human Rights:

Everyone has the right to freedom of expression. this right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority and regardless of frontiers. This article shall not prevent States from requiring the licensing of broadcasting, television or cinema enterprises.
The exercise of these freedoms, since it carries with it duties and responsibilities, may be subject to such formalities, conditions, restrictions or penalties as are prescribed by law and are necessary in a democratic society, in the interests of national security, territorial integrity or public safety, for the prevention of disorder or crime, for the protection of health or morals, for the protection of the reputation or the rights of others, for preventing the disclosure of information received in confidence, or for maintaining the authority and impartiality of the judiciary.

Maybe I'm missing something, but I don't see any clauses where it says that it's fine to limit these rights if the person is applying for citizenship.

This isn't just a bad thing for immigrants: if new citizens are biased towards that agree with a particular political party due to requirements for citizenship, then it also skews the electorate. Allowing this decision to go through is essentially allowing a single political party to manipulate elections by biasing the selection of eligible voters.

Frankly I think Mr Woolas should consider resigning for conflating party interests (i.e. the Labour party's interests) with the national good on such a massive and dangerous scale. But he won't. It seems the last honourable man left the party in 2003.

But at least I have something to comfort myself with. Being Irish, I am an immigrant, but I am also entitled to vote in parliamentary elections. Oh, and since I am entitled to live and work in the UK, and my passport allows me to travel at least as easily as a UK one, I don't really have to worry about his threats. Guess which party can't count on my support?

Did global warming stop in 1998? No!

2009-07-09T16:11:00.003+01:00

I just noticed a friend's status update questioning whether global warming has stopped since 1998. This shocked me a little, since it is a patently ridiculous claim, but apparently one being made by the group of nutjobs and the willingly ignorant who style themselves "global warming skeptics". I think I prefer the term "reality denialists". I've just done a quick search on Google News, amd this claim is everywhere. Fortunately most of these claims turn out to be in the Letters to the Editor section of newspapers, but it has managed to wiggle its way into articles too. A few years ago, in 2006, the Telegraph ran a story with the headline "There IS a problem with global warming... it stopped in 1998". I guess this isn't surprising, since it is after all the Telegraph, but even so I am shocked that such a claim is propogating.

So, I thought I should at least look at the data to see where the claim was coming from. This chart taken from Wikipedia seems to explain it all:

In 1998 there was an enormous spike in the average global temperature far exceeding the temperature in either 1997 or 1999-2001. As you can see, it is an outlying data point about as far from the 5-year average as any point on the graph. The problem with taking yearly temperatures is that the data is very noisy and the temperatures jump about quite a lot from year to year, obscuring the trend at least over short intervals. The running 5-year average makes it clear that the average temperature is increasing sharply. So where does this claim about no global warming since 1998 come from? Well, if you look at the temperature in 1998 and compare it to the average temperature from 1999 onwards then they are about equal. But this is complete nonsense since we've cherry picked the outlying 1998 data point as our starting position. If we start on the 5 year average, then we see a dramatic increase. In fact we could play the same game in reverse and say that the average global temperature has rocketed up since 1999 at almost double the actual rate. The claim that the average global temperature has not increased since 1998 is a flagrant abuse of statistics. It works simply by picking the hottest year on record as the starting point and then only considering a short time period so that the regression to the mean increase more or less cancels the increase in the average temperature. It's a trick that preys on an ignorance of statistics. In five years the trick won't work, because the increase in the 5-year average will have brought us far above the 1998 data point. So the claim is bullshit, pure and simple.

What is particularly incidious about this clasim is that it has almost certainly been composed deliberately to trick people. It often comes accompanied by an assertion that climate models fail to predict this halt to global warming, which is of course true. It's true that none of the main climate models predict a halt or pause in global warming for the last decade, but that's probably just as well, since there hasn't been one. Should a climate model predict how people will abuse statistics? For me, predicting the climate change is enough and we can leave the precrime detection for the movies.

The Canadians are coming

2009-07-02T17:38:00.002+01:00

The list of accepted papers for FOCS has just been published. There appear to be 6 quantum related papers.

Two-message quantum interactive proofs are in PSPACE
Rahul Jain, Sarvagya Upadhyay and John Watrous.
Span programs and quantum query complexity: The general adversary bound is nearly tight for every boolean function
Ben Reichardt.
Optimal quantum strong coin flipping
André Chailloux and Iordanis Kerenidis.
The Quantum and Classical Complexity of Translationally Invariant Tiling and Hamiltonian Problems
Sandy Irani and Daniel Gottesman.
Universal Blind Quantum Computation
Anne Broadbent, Joseph Fitzsimons and Elham Kashefi.
A Probabilistic Inequality with Applications to Threshold Direct Product Theorems
Falk Unger.

So what's notable about this list (aside from the fact that I'm on it)? Take a look at the authors. Four of the six accepted papers have Waterloo affiliated authors. I count 7 current affiliations to either IQC or PI, out of 12 authors, and Elham has spent time at IQC in the past. If any proof were needed that IQC lives up to its promise its the above list. Try to imagine one institute producing 2/3 of the papers in Nature or Science. Hard, no?

An appeal for reason

2009-06-20T22:42:00.003+01:00

Today Ahmadinejad's thugs murdered an unarmed girl peacefully watching the protests. I'm not going to repost the video or post a picture because I will throw up if I have to watch her die on camera again.

If you are an academic and experiencing even a tiny fraction of my outrage, please consider signing a petition organized by Elham Kashefi. Just email her to add your name to the list of signatories. Below is the current version:

WHERE IS MY VOTE

June 20, 2009

A week ago, Friday June 12, Ahmadinejad was declared the winner of the Iranian presidential election. Immediately after, all other candidates, Moussavi, Karroubi, and even the conservative Rezaei, disputed the official results. So did some people who started several demonstrations to express their anger. More news fueled the suspicion of fraud at an unprecendented scale. On Monday June 15, and to the amazement of the world, millions of people – of all ages, classes, and backgrounds – were in the streets of Tehran demanding another election in what was the biggest demonstration since the revolution in 1979. A week later, despite the threats and beatings issued and ordered by the government, millions of people are still demonstrating, and the movement is growing and spreading to other cities. Observers might find the situation confusing, since Iran has long been an isolated country and the everyday Iranian is unknown to the outside world. One cannot even prove that there was a fraud. There remains the fact that millions of people are protesting in the streets of Iran.

These are traditional, religious, modern, young, old, rich and poor, academics – some of them our colleagues – going out in the streets and risking their lives with a form of innocence in their aims and tactics. Some of them may stand on their roofs at night shouting “God is great” to keep the movement alive. They are braving the power because they insist that the Islamic republic is a republic.

The government is imposing a ban on the foreign press, shutting down all means of communication within their reach, arresting hundreds of prominent activists, politicians and religious figures opposing the results, and terrorising demonstrators. Every day fewer videos and reports escape from Iran. The state media is depicting the protests as incited by the West, accusing the movement of being a party of hooligans and traitors. After a week of uncertainty, the head of the state, Khamenei, just issued yesterday strong and explicit threats against participants in the protests and rallies.

This text is an urgent request to academics to fight the misrepresentation of this movement. This is not only about showing support to the courage and determination of people on the streets of Iran. It also means reaching for the many people in Iran who would like to participate but are frightened or know of the movement only through the state media. It means informing these people of the scale and nature of the movement, and thus widen its support within Iran. To all academics, please sign this appeal to support this movement in its call for a new election and oppose any violent intervention on protesters.

Dr. S. Aaronson (MIT) – Prof. S. Abramsky (University of Oxford) – Dr. R. Alleaume (Telecom ParisTech) – Prof. W. Arendt (University of Ulm) – Dr. E. Barker (University of Oxford) – Prof. S. M. Barnett (University of Strathclyde) – Dr. D. Browne (University College London) – Prof. P. Buneman (University of Edinburgh) – Prof. A. Cabello (Universidad de Sevilla) – Prof. T. Calarco (University of Ulm) – Prof. B. Chandrasekaran (Ohio State University) – Dr. B. Coecke (University of Oxford) – Prof. S. B. Cooper (University of Leeds) – Prof. D. W. Corne (Heriot-Watt University) – Dr. N. Datta (University of Cambridge) – Prof. V. Danos (University of Edinburgh) – Dr. J. Degorre (CNRS) – Dr. J. Desharnais (Universite Laval) – Prof. M. Dezani-Ciancaglini (Universita di Torino) – Prof. E. E. Doberkat (Technische Universitt Dortmund) – Dr. P. Dumais (Universite de Montreal) – Dr. K. Etessami (University of Edinburgh) – Dr. A. Feito (Imperial College London) – Prof. F. Ferreira (University of Edinburgh) – Prof. W. Fontana (Harvard University) – Prof. B. Foroughi (St. Francis Xavier University) – Dr. B. Farzad (Brock University) – Dr. J. Feret (INRIA) – Dr. J. Fitzsimons (University of Oxford) – Dr. D. Green (The City University of New York) – Dr. R. Harmer (CNRS) – Prof. J. M. Henderson (University of Edinburgh) – Prof. L. Hendren (McGill University) – Dr. M. Huth (Imperial College London) – Prof. H. J. Jensen (Imperial College London) – Dr. E. Kashefi (University of Edinburgh) – Dr. H. Koeppl (EPFL) – Dr. J. Krivine (IHES) – Prof. R. Laflamme (University of Waterloo) – Prof. B. Leimkuhler (University of Edinburgh) – Prof. N. Lutkenhaus (University of Waterloo) – Dr. D. Markham (CNRS) – Prof. H. Mairson (Brandeis University) – Prof. M. Mislove (Tulane University) – Prof. E. Mjolsness (University of California) – Prof. C. Moore (University of New Mexico) – Dr. M. Owari (Imperial College London) – Prof. C. Palamidessi (INRIA) – Prof. P. Panangaden (McGill University) – Prof. M. B. Plenio (Imperial College London) – Dr. O. Radulescu (University of Rennes 1) – Prof. Y. A. Ryan (University of Luxembourg) – Dr. A. Serafini (University College London) – Dr. P. Series (University of Edinburgh) – Dr. S. Severini (University of Waterloo) – Dr. M. P. da Silva (U. de Sherbrooke) – Prof. L. Smolin (Perimeter Institute) – Prof. F. Taddei (Universite Paris Descartes) – Prof. A. Tapp (Universite de Montreal) – Dr. L. Tortora de Falco (Universit Roma Tre) – Dr. D. Varacca (Universite Paris Diderot) – Dr. S. Virmani (University of Strathclyde) – Prof. P. Wadler (University of Edinburgh)

In solidarity with the people of Iran

2009-06-15T22:41:00.003+01:00

Tonight my heart hangs heavy. There can be little doubt now that the Iranian elections were rigged and that the population is being suppressed by a brutal dictatorship. It truly breaks my heart to see the violence dealt out on a people who want nothing more than for their voice to be heard. I don't know who the woman in this photo is, but I am truly touched by her courage and her defiance. I wish I had half her courage.

There have been huge street protests and riots. Men with iron bars riding motorcycles are attacking protesters in the street, and attacking students in their dormitories. This cannot be aloud to stand. But there is hope. The Iranian people have not taken this matted lying down. At this point there seem only two possible outcomes: a massacre or the overthrow of a dictator. Tonight it seems the latter may be possible.

While I have never been to Iran, have only ever flown over it, while my personal beliefs are far different from many Iranians, and while I know little of the other candidates, I am human and I understand the drive for freedom from tyranny. I stand in solidarity with the people of Iran, for tonight everyone is Iranian.

So I guess I have blown any chance of ever getting security clearance for anything, and probably can't go to Iran if the protesters fail, but that is meaningless. It is the people on the streets and in the universities that will suffer should the protests fail, which is why they must not fail. My heart is truely with the students in Tehran university tonight and throughout Iran.

The story seems to have been de-emphasised by many of the larger media organisations, so I will write this post in the hope that it reaches at least a few people.

The two best sources of information on this are liveblogs by Andrew Sullivan and at the Huffington Post. Also, tweets from those inside the protests: persiankiwi and Change_for_Iran, and hashtag #iranelections.

It seems that the government has been cutting off communication lines, and that twitter is one of the few ways for people to organize and get word out of the country. Access is being cut off, so the demonstrators are heavily reliant on outsiders setting up open proxies and relaying the details over twitter. I know many who read this will be tech savy, so I leave it to their judgement what they wish to do.

Let me close by saying that the people have spoken, and they have spoken for change:

Communication's new Wave

2009-05-30T00:10:00.002+01:00

I've just seen the future and it is wavy.

I've already applied for sandbox access, since it seems a much more natural solution for my Social Notebook project that the current cludge of Elgg and flash. I've been working on a tablet interface (in Silverlight of all things), but rather than adding it to the existing site, I think it is probably worth trying to turn the whole idea into a set of Wave extensions via robots and gadgets.

Video Abstracts

2009-05-13T22:56:00.003+01:00

I've just received an email from Martin Plenio to tell me about a new initiative to exploit YouTube to promote science on the internet. Martin writes:

I am writing to you to bring to your attention some new tool that we (Daniel Burgarth and myself) have developed that has the aim of making science papers just a little more accessible. Its called Videoabstracts and consists of 'homemade' videos in which an author of the paper explains the key point of the paper in front of a whiteboard. The videos should not be longer than 5 minutes to force people to get to the point efficiently. We feel that these 5 minutes clarify the content and relevance of a paper much better than any abstract can do.

We have produced several examples that you may see on http://www.quantiki.org/video_abstracts. We did not strive for perfection as we feel that anybody should just be able to do these with a webcam and then upload them on QUANTIKI. The videos will then be stored on YouTube and at the same time a link will be created on the arXiv.

Viewers can leave comments on the content of the video and in that way stimulate discussions.

I've looked through the videoabstracts currently available (there are 11), and I can already see what a fantastic tool this can be. If only every arxiv paper had a five minute discussion of the key points it would save me a huge amount of time deciding what to read and what to skip. Scirate does a reasonable job of highlighting important papers, but its utility depends on how many people are actively citing papers. This new tool gives authors a way to introduce and promote their own work, in a very helpful and informative way. Given how opaque some papers can be, I certainly welcome the idea of a five minute run through from the authors. I'll leave you with two video abstracts, one from Martin and one from Daniel to show how this works.

$5 I can never spend

2009-05-10T02:41:00.002+01:00

I've just won $5 dollars form Scott Aaronson and Seth Lloyd, and I'm feeling pretty pleased about it. I'm splitting $15 dollars with Anne Broadbent and Elham Kashefi for a partial solution to the Aaronson $25 Challenge: Does BQP = IP_BQP. Dorit Aharonov, Michael Ben-Or and Elad Eban share $12 dollars for their independent work on interactive proofs. We don't have a full solution to the problem yet, but we do know that an almost classical verifier can participate in an interactive proof of any problem in BQP. I'll try to write a post on the problem soon.

What happened at QIS?

2009-04-26T22:45:00.002+01:00

The QIS workshop in D.C. should be over by now. Can anyone tell me how it went? I really wish I could have gone, but I have very limited travel funds and it was arranged very short notice. I know a few quantum bloggers went. Can anyone be persuaded to post a summary?

Is a fault-tolerant economy possible?

2009-03-29T14:56:00.002+01:00

Let me explicitly warn you now, I am obviously not an economist and so the speculation contained in this post may be completely naive.

In the current climate, this is a question I find myself asking more and more often. Initially, prior to the recent global economic downturn I had been playing with the idea of whether it would be possible to apply fault-tolerance ideas to investments, but I never really reached any firm conclusions. Applying such ideas to an entire economy might be much easier, since you could consider substantial changes to the regulatory apparatus which would be impossible for a single investor.

So what do I mean by this? Well, basically one way to look at the economy is as a computation. Every trade, every bailout, every lay-off or expansion constitutes a step in the computation, essentially a logic gate. So what are we computing? Well, the unemployment level is clearly a function of birthrate, emigration, hires and fires/redundancies. The Dow-Jones is a function of the stock price of 30 blue chip companies, which are themselves dependant on recent trades.

It seems to me that bail-outs and interest rate adjustments can be viewed as a rather crude attempt at error correction. So we translate the processes which constitute the economy (financial, employment, policy, external events, etc.) into gates within a computation, we can start to bring computer science results to bare on the problem. One question we can ask is whether error-correction is sufficient to stop the computation going off-track. The resounding answer to this question appears to be "no", given that the cause of the recent economic crisis traces back to sub-prime mortgages. Indeed this is what we would expect viewing the process as a computation. Trades in mortgage derivatives spread throughout the system, and so when people started defaulting on their mortgages, the impact was felt throughout the economy. This is exactly the situation fault-tolerance is designed to avoid.

In a fault-tolerant computation the computation is performed in such a way that an error in one area does not propogate throughout the system. We can certainly data mine past transactions to determine a noise model for the computation (coming from external factors and our inability to predict exactly what anyone is going to do in any given circumstance), and so should be able to determine what noise factors are correlated, and which are independant. As an example, the stock price of companies within the same sector will likely be correlated in their reaction to external events. This noise model is fundamentally important to designing fault-tolerant operations.

So how could we apply fault-tolerance to the economy? Well, first we need to identify the subspace we wish the computation to remain within. Now, our initial state must be within the stabilized subspace. This means we can't really use fault-tolerance to maintain low unemployment and high stock prices, since that is not the regime we are currently in, but we can certainly design the system so that noise will not significantly raise or lower certain economic indicators we have decided to protect, allowing only intentional actions to manipulate these indicators. Faortunately, almost any indicator we can choose will depent on a range of factors, essentially acting as an error correction code. Now, unfortunately we don't get to choose our encoding, but it is fortunate that a fairly decent one already exists due to the complexity of the economy.

So if we have an error correction encoding (we essentially want a form of self correction), what else do we need? Well, one thing we need to do is to formulate a set of fundamental operations which does not lead to correlation in noise. One way to do this is to impose strict rules on how investment can be made in such a way that not only do we require investment be spread across many sectors, but also that individual investors be required to invest in a sense independently. I know that this requires a huge regulatory aparatus, but if it could free us from the fear o economic downturn, it would surely be worth while. Now I suspect that my libertarian friends are going to find this a horrifying prospect, if we can identify a universal set of operations for computation of the factors individual investors care about, then we haven't asked anyone to give up any freedom in their goals, we would only have required them to go about them in a much more responsible way. The end results should not actually be much different. The way things are at the moment, we are actively propogating risk within the economy and the financial markets, and it seems that this can be halted relatively easily.

So what would we need to do if we wanted to take a more rigorous look at this problem? Well, a few things we would need to determine:

What economic indicators do we really care about?
What constitutes a universal set of operations for what governments want to accomplish?
What constitutes a universal set of operatons for what investors want to accomplish?
What is a reasonable noise model? What's correlated and what's not?
How much this will piss off Peter?

Thoughts?

Sean Carroll @ Google

2009-02-15T19:59:00.002Z

I was just watching some of the @Google talks, when I came across one given by Sean Carroll who is one of the bloggers at Cosmic Variance. The video seems to be new, but I can see no mention of it on CV. The talk basically is an overview of dark matter and dark energy. Anyway, I really enjoyed it, and the chances are that if you read this blog you may too.

Workshop on the Logical Aspects of Fault Tolerance

2009-02-09T17:06:00.003Z

Since I'm on the program committee for this workshop, I should probably give it a plug on my blog. It's an interesting mixture of disciplines, so it won't just be quantum loonies.

Event Title: Workshop on Logical Aspects of Fault Tolerance (LAFT)
co-located with LICS 2009.

Date: 08/15/2009

Location: University of California, Los Angeles

URL: www.aero.org/support/laft

Description:

We are soliciting papers on logical aspects of fault tolerance. The concept of "fault" underlies essentially all computational systems that have any goal. Loosely speaking, a fault is an unintended event that can have an unintended effect on the attainment of that goal. "Fault tolerance" is the term given to a system's ability to cope in some way with a fault, either inherently or through design. Fault tolerance has been studied for its application to circuits, and then branching out to distributed systems and more recently to quantum computers, where the concern with fault tolerance is almost the paramount issue. The relevance to biological computation is also obvious. Papers must be concerned with the logic of fault tolerance, not simply fault tolerance.

IMPORTANT DATES:
Papers due: April 17, 2009
Notification: May 22, 2009
Final papers: July 10, 2009
Workshop: August 15, 2009

Please send all workshop correspondence, including submissions, to marcus [at] aero [dot] org

HDR Singapore

2009-01-26T09:39:00.005Z

I'm visiting the Centre for Quantum Technologies in Singapore at the moment. Last night was began lunar new year, so I went out and snapped some photos. Inspired by Jane's HDR experiments, here are some HDR shots of Clark Quay and Boat Quay.

I didn't have a tripod, so these aren't as good as they could be, but bracing against a wall and enabling autobracket on my camera worked quite well.

His granddaddy's daddy came from Moneygall ...

2009-01-20T06:58:00.001Z

Most productive day ever

2008-10-21T00:14:00.002+01:00

I've just had what must have been my most productive day ever, having just finished submitting the last of 4 papers to QIP. Overkill? Probably, but I've had a reasonably productive summer, and haven't seen Santa Fe before.

On the other hand, I'm back in Ireland for the week to go to a wedding, so it's not like the week will average out as particularly productive.

Oxford Colleges on 'The Restraunt'

2008-10-06T00:53:00.003+01:00

I have just arrived back in Oxford only to discover that the latest installment of the BBC series 'The Restaurant' has serving dinner at formal hall in various Oxford colleges as its challenge. It even features my last college, Oriel.

In Waterloo

2008-09-06T22:22:00.003+01:00

I am in Waterloo (the quantum one!) for the next month or so. I will be based at IQC for that period, although I will likely show my face in Perimeter at some point too. Once again I get to pretend to be a mathematician, since I am affiliated with the Combinatorics and Optimization department at UW.

I will still be contactable via my normal email addresses, or via jfitzsim [at] iqc [dot] ca.

It looks like there is going to be a really interesting discussion at a Nature Network meeting in Toronto tomorrow night on Science 2.0. I'm currently trying to figure out how I can get to it. I don't suppose anyone else is heading there? Or if anyone knows how best to get back to Waterloo on a Sunday evening, I'd also be grateful.

Wired, here I come

2008-08-26T13:26:00.002+01:00

An article has just appeared in Computer Shopper magazine about cryptography and cryptanalysis. Normally this isn't the kind of thing I would put on my blog, unless they had made a massive blunder somewhere in it, but this article is special, because they ask me about the quantum crypto. How cool is that? It is a little odd that I am the person they asked, especially since Artur Ekert is also a fellow at Merton. The request came through our group and since I am the only one who has published any crypto papers, I ended up being the one to respond. I am a little embarassed at how they describe me, but I am still pretty chuffed to see my name in a pop science article.

How to write a PhD thesis

2008-08-20T02:21:00.002+01:00

It is the time of year when grad students throughout the world are struggling to get their thesis finished in time to start that postdoc in October, or even to enter the real world. Recently I wrote up some tips on how to write a PhD thesis, and I thought I should transpose them onto my blog. So here are my thesis writing tips:

Use LaTeX
Latex can easily be learnt in an afternoon and will make your thesis look more professional. It will save you hundreds of hours of correcting formating and will be far more consistent than a word processor. It handles equations and vector graphics with ease and is extremely versatile. Latex also allows comments which do not appear in the document, which are extremely handy for keeping notes to yourself. It is also the prefered format for most preprint servers. If you are planning a career in the physical sciences or maths, then latex is a must.
Work out the structure first
Spending a day or two at the start working out exactly how you want to structure your thesis may seem like procrastination, but will prove incredibly valuable later on. As you near the end of the thesis you will undoubtadly get the urge to restructure things. Putting in a little time at the start can save a lot of time spent on rewrites.
Leave introduction and conclusions until last
Believe it or not, the introduction is the very last thing you should write. It might seem logical to work through in the order the reader will encounter chapters, but this is a big mistake. In the first chapter you will want to describe the structure of the thesis, and outline how you are going to proceed. Even though you may should a plan for this at the start, it will change as space and time constraints begin to take their tole. Believe it or not, you will almost definitely over shoot the word limit and have to axe material.
Break each chapter up into managable chunks
Everyone gets writers block. You come to a chapter and the thought of filling twenty pages with the intricacies of some mathematical technique or experimental setup seem overwhelming. In order to avoid this, it is a really good idea to break down the thesis into smaller and smaller named sections (\section, \subsection and \subsubsection in latex) even before you start writing. Break it down into chunks on the order of 200 words so that they are easily attacked. It makes it easy to work on lots of different sections simultaneously, and means you can write a section in less than half an hour. Even if you don't want your thesis to have such fine graining, add the headers at the start and remove them later.
Use at least one chapter to introduce techniques used
It is often a mistake to introduce a new mathematical or experimental technique in the same chapter you use it. Having a seperate chapter in which you introduce necessary techniques can help you from making chapters overly long, and gives the reader time to absorb this new information. This also provides a very clear cut line between your work and previous work from others upon which you intend to build. This is essential to avoid annoying examiners. Poor students often try to blur this line, and so it is a red flag for anyone reading the thesis.
Use a bibliography manager such as JabRef
It is scarily easy to create duplicate references. I spent almost a week weeding out duplicates and triplicates from my bibliography file. Using a reference manager from the start avoids all this hassle by automatically detecting duplicate entries.
Use BibTeX
Don't write in references by hand. It will be hard to give them a consistent look, hard to keep track of where references what, and hard to update. Use latex, use JabRef (or similar) and use bibtex. You'll avoid all sorts of formating issues.
One chapter per paper if you have them
Every paper you wish to include should have its own chapter. If you have several papers on one topic, then you probably need several chapters on it too. You may need to mix content between these chapters, but one paper one chapter is a good rule of thumb.
Neglect earlier work if it isn't to as high a standard as the rest
Let's face it, that paper we got in our first 6 months isn't really our best work is it? If you have some particularly weak material, don't feel obliged to include it. You absolutely do not have to include everything you did over the course of your PhD, so don't feel obliged to.
Keep to less than 80% of the word limit/page count
It's just a fact of life, examiners don't like long theses. Don't use the full word limit, even as a guide. Keep it short and punchy, rather than long and drawnout.
Add a page listing collaborative work
No man is an island, and that goes double in science. Almost everybody collaborates on projects, and this is certainly not a bad thing. It is however very important for you not to appear to be passing off others work as your own. To avoid this, add a page to the start of the thesis listing any collaborative work, describing honestly your role. This makes it much clearer to the examiners who did what. Again, poor students often try to blur the line, but such bluring raises an immediate red flag and will cause pain in the viva. Avoid it.
It is ok two have two themes
Sometimes our work is in more than one area. Mine quite distinctly focused on two different topics, which could be unified under the broader topic of the thesis title. It can be hard to see how best to mesh two seperate topics together into a readable document. In my experience having a common introduction followed by to distinct parts to the thesis was the answer. It's quite common to do this, and can save you quite a headache.
Don't fear THE FEAR
Are you freaking out because you have been procrastinating and now you have little time left and little progress made? Good. That's called THE FEAR, and pretty much everybody gets it. It will motivate you to do superhuman amounts of work in those last weeks. No matter how tight the deadline, THE FEAR will see you through.

Blood from stem cells?

2008-08-20T02:19:00.002+01:00

This seems really big news:

Scientists said today that they have devised a way to grow large quantities of blood in the lab using human embryonic stem cells, potentially making blood drives a relic of the past.

But experts cautioned that although it represented a significant technical advance, the new approach required several key improvements before it could be considered a realistic alternative to donor blood.

The research team outlined a four-step process for turning embryonic stem cells into red blood cells capable of carrying as much oxygen as normal blood. The procedure was published online in the journal Blood.

LHC Rap

2008-07-30T01:47:00.001+01:00

And it's remarkably educational.

Social Notebook: Identifying users

2008-07-13T00:48:00.002+01:00

The main criticism I have been getting so far about Social Notebook is that it is invitation only, and that the default access setting is to allow only registered users. Now, the whole point of the site is to allow user tracking so that the propagation of ideas is visible to everyone, member or not. Obviously if I allow pseudonyms then the user tracking is essentially useless, since it is no deterrent to scooping somebody. So I need users to register with their real name, and my current way of enforcing this is through the invitation only registration system. Ideally I would like to make it more open, but I'm not sure how. Michael Nielsen has made a very sensible suggestion about charging a nominal fee, so that credit cards can be used for registration. I don't really want to go down this route, as I don't want to render the site inaccessable to secondary school/high school students. Perhaps the answer lies in combining the two approaches in an either-or manner, but if there are any other options out there I would certainly like to know. Anyone?

Science Blogging 2008

2008-07-13T00:34:00.002+01:00

It seems that Social Notebook was enough to score me an invitation to Science Blogging 2008 at the end of August. I guess this means that I'll have to finish off the site and put a bit of polish on it. As I have said before, while the site is currently invitation only, if anyone thinks they would have fun playing with it, then just drop me an email, or leave a comment on my blog.

The conference looks fantastic, so I'm definitely going to make sure I go (even if it means a transatlantic flight). My blog isn't sufficiently notable in and of itself for me to really feel part of the whole science blogging community. I don't really know any science bloggers in real life outside of the QIP community. I have however exchanged emails with the keynote speaker (Ben Goldacre) over the Steorn debacle, so I am very much looking forward to hearing him speak. It seems I read the blogs of quite a few of the attendees so it will be nice to put faces to pseudonyms.

Unfortunately I have 5 unfinished papers waiting for me to get around to them, so progress on Social Notebook may be slow.

Do they even research their stories?

2008-07-02T16:27:00.003+01:00

Just spotted this on google news.

Notice the BBC headline directly above that of Fox News.

Do Fox News do any research on their stories at all?

Open notebook science

2008-06-30T17:54:00.003+01:00

Inspired by a recent blogpost on open notebook science, I've spent the weekend coding. I've setup a site (Social Notebook) with the idea of trying to remove the risks from open notebook science. Basically the site uses a social network model. The method behind this madness is that it requires users to logon, and since it uses an invitation only registration system, accounts are associated with peoples real identities, rather than pseudonyms. This allows user tracking, so you know who reads what. My hope is that by making it very easy everyone (even if not logged in) to see who has read what, it will remove the motivation to steal someones idea without credit, since anyone can see that you did. Clicking on the Knowledge Propagation Graph (http://elgg.jfitzsimons.org/demos.html) link at the bottom of any page leads to a directed graph of how ideas have propogated.

At the moment it's a little primitive. I'll add in page resolution to the graph over the coming week and dates, and I'll try to add latex support tonight.

Each user has their own mini-wiki and can restrick access to any information using groups. You can define your own groups or use one of the four built-in groups: public, friends, logged-in users or private. I'll try to come up with an embargo script which can automatically change these based on date based on Dave Bacon's idea.

I'm hoping that a few people will try the current beta version and let me know where it can be improved. There is no pressure to put up work. If you just want to be able to participate, play around with the system and look at other people's notebooks that's fine. Just drop me an email, or leave a comment here. The only requirement is that you sign up with your real name, so if you want to join please use an institutional email address.

Update: If you want a login for the beta site, you could just leave a comment here. As long as you fill in the email address field with a reasonable address, I'll mail you an invitation.

Farewell Peter

2008-06-26T11:42:00.002+01:00

Peter Rohde is leaving academia, and leaving Oxford. For most of the last year he has been occupying the desk directly beneath mine (on the floor below; although Oxford is tight on space we haven't taken to double decker desks). He has good reasons for wanting to switch paths, and I wish him all the best for the future. He is a smart guy, and I'm sure he'll be successful in whatever he decides to do, but like the Pontiff I am saddened by his departure.

In his post on the subject, Dave Bacon goes on to explain that sadness is probably the wrong reaction to have, and that we should be celebrating those members of the QIP community who contribute to the field and then choose to go and forge a new path. I largely agree with him, but I'm still unhappy.

Over the past year Peter has been not just a colleague, but also a friend. With his imminent departure from Oxford, it's unlikely that I will see much of him. No more primary parties, no more high table and no more Kobb. It seems that the pyramid structure of academia means that every year more and more of my friends leave. The go on to bigger and better things for the most part, but the feeling of being left behind is depressing. In a university town this is particularly bad, since the population is skewed. The scope for making new friends reduces as you get older, and people rarely stay more than a few years. I bet I'm not the only physicist with a quantitative finance text book on my shelf...

Good luck Peter!

Subtle as a brick

2008-06-05T21:55:00.002+01:00

I've just come back from watching Ironman for the third time. What can I say? I like going to the cinema.

Anyway it occurred to me that the film's makers have been less than subtle in basing Stark Industries on Lockheed Martin. Check out the company logos:

There is also a rather prominent shot of a YF-22 outside the Stark Industries headquarters.

Given the bad light in which Stark Industries is portrayed in the movie, I'm really very surprised that they would so clearly base it on a real company.

Oxford dinners

2008-06-05T05:06:00.002+01:00

Oxford is not part of the real world, it really isn't. Last Sunday week I went to dinner in college, as I do quite often. I tend to go to guest nights, which are three times a week, as these tend to be longer and more fun. You get to meet a lot of interesting people. Sunday is the best night. It's all black tie and gowns, which looks quite impressive. Fellows and their guests eat at high table, which is exactly what it sounds like: A high table which over looks low table (actually three long tables) where the students eat. If you've seen Harry Potter, then you probably have a fairly good idea of what I mean. The dining hall in Hogwarth' s is actually the Christ Church dining hall. After dinner we move into a private dining room for second deserts and port or desert wine. The pertinent point is that at second deserts you are not allowed sit beside you guest, so that other fellows may have the pleasure of their company.

I didn't bring a guest so I mixed more than most. At second deserts I was sitting beside a history professor from UCL, and we ended up having quite a long discussion about the history of quantum mechanics (it turns out he reads a lot of physicists' autobiographies). After second deserts we went to have coffee in the senior common room. Since I had no guest, I wandered over to the first physicist I saw and asked if I could join him and his guest. It took me about twenty minutes before I realised that the guest was Frank Wilczek, who won the Nobel prize in 2004. I ended up chatting to them and Betsy Devine, who's blog I've now started reading (I like to read stuff written by people I don't know about places I do). I had had a little too much port, so I may have ranted a little about my dislike for the Oxford Murders (both the book and the film). Oh well!

I'm really starting to enjoy the social side to college life here. If only I didn't work at night so much I might eat in hall all the time.

It's 5 am and I'm awake

2008-06-05T04:57:00.002+01:00

Ok, I know I should keep regular hours, but I don't. I've just finished working on a paper and passed the token to my co-authors. I'm still caffeinated so I can't go to sleep, so I've decided to blog.

I've been neglecting my blog lately, with no good excuse. I have been busy, but so is everyone this time of year. I've decided not to teach this year, since I'm not required to and I did a lot of teaching last year. As a result all of the work on my plate is of my own making. Unfortunately I enjoy research far more than writing up my results and so have built up a backlog of 6 papers waiting to be written up. This seems to be the critical level, so I'm spending all my time this weather working on one or another of these. Hopefully I'll have a productive few months, but the downside is that this really is not the fun part of a research career.

So, anybody else suffering from insomnia?

Quantum Cryptography is not broken

2008-05-20T12:32:00.002+01:00

There is a paper which has recently appeared in the IEEE Transactions on Information Theory which has been picked up by the media and inevitably by Slashdot. The arXiv version is quant-ph/0611009.

According to iTnews the paper does the impossible and breaks quantum key distribution:

Quantum cryptography – commonly lauded as an absolutely secure avenue of data transfer – has been broken.

The advanced technology was thought to be unbreakable due to laws of quantum mechanics that state that quantum mechanical objects cannot be observed or manipulated without being disturbed.

When I saw this turn up in my inbox I decided that there must be some mistake, that the authors were somehow misrepresented. It seems pretty clear that the authors, Jörgen Cederlöf and Jan-Åke Larsson, weren't misrepresented since the report matches up quite well with the faq on breaking quantum cryptography they have uploaded to their university server. So I sat down and read the paper.

In a nutshell, their paper claims that by altering both the classical and quantum channels it is possible for an eavesdropper to perform a man in the middle attack. The way this attack works is to target a subprotocol used to for verifying the identity of the sender and receiver. The specific protocol they target is known as Wegman-Carter authentication.

The attack uses information gained from eavesdropping on the key distribution stage of a previous round and combining it with knowledge gained from the authentication tab sent by the original sender. The way the authentication protocol works is to use a shared key to decide on a hash from some set of hashes and then to transmit the hash with the message to prove that the sender had access to the secret key, and so is who they say they are. In the proposed attack the idea is that the information gained from eavesdropping is on a round of key distribution can be used to reduce the number of possible hashes which could be used in the next round, by putting constraints on what the key can be. This yields some new set . Knowing the authentication tab then leads to a second constraint on the set of hash . As a result, the hash must lie within the set .

It is known that Wegman-Carter authentication is secure given the constraint , so what the authors are saying amounts to a statement about the additional information given by the constraint . The authors go on to discuss how the intersection of the two sets can be reduced and so can probabilistically yield a new tab for a message the eavesdropper wishes to insert.

This is where I have a problem with their paper. The purpose of quantum cryptography is detect an eavesdropper with arbitrarily high probability. If the eavesdropper cannot listen in without being detected, then and so . In this regime the protocol is still secure. So, how do the authors get around this point? Well, they make the channel noisy. They then assert that you can eavesdrop, as long as you don't do it too often, and hide in the noise. Essentially they seem to be assuming that some finite level of eavesdropping cannot be detected. But this assertion is incorrect. Even over noisy channels an eavesdropped can be detected with arbitrarily high probability (see for example quant-ph/9803006). This means that the sender and receiver can reduce the amount of information that can be undetectably gained by the eavesdropper so that .

How close do you really need to be to ? Well suppose for some function . Then . If , as is the case if we choose constant , then eavesdropping really doesn't help. So what's the lesson here? Well by using a reasonable sized authentication tag, and by setting bounds on noise sufficiently tightly, the attack is useless. Indeed, since the information gained from eavesdropping can be made arbitrarily small, quantum cryptography still appears to be perfectly secure.

The important issue that this paper highlights is that current systems, of the kind you can buy off the shelf, may not be perfectly secure. As current key distribution rates are low, there is significant incentive to compromise the security of quantum key distribution by setting high noise thresholds and using shorter authentication tabs. Ultimately, the paper represents an attack against poor implementations, rather than against the theoretical framework.

Summer in the city...

2008-05-20T12:16:00.002+01:00

... if by city you mean Oxford.

Missing out

2008-05-08T00:20:00.002+01:00

Seems I've been missing out on Ian Durham's blog, Quantum Moxie. I've just added it to my blogroll. It's well worth a look. I've spent a large chunk of an otherwise productive day reading back-posts.

Thesis finally online

2008-04-29T00:09:00.002+01:00

If anyone is interested, I've finally uploaded my D.Phil. thesis. It's still not on the arXiv, but I'll eventually get around to doing that. It's taken me the best part of a year to get it on-line, so I wouldn't hold my breadth. In the mean time, enjoy!

DWave visit

2008-04-28T20:10:00.002+01:00

Last Thursday our group had a visit from Herb Martin and Mohammad Amin of D-Wave. The point of the visit appeared to be largely to give our group a presentation on D-Wave's progress towards building a commercially viable quantum computer. Although I had heard Dr. Amin speaking before at QEC 07, this talk was a little more expansive, and there was plenty of time for a question and answers session after the talk. Dave Bacon and Scott Aaronson have both been quite vocal in their criticism of D-Wave, so (Geordie's blog aside) I've been waiting to hear the other side of the story.

Following the meeting I scribbled down my impressions of the current state of D-Wave's efforts:

D-Wave have constructed several device consisting of up to 28 noisy quantum bits (or qubits). Their internal roadmap apparently puts them at approximately 2000 qubits by the end of 2008. It is reasonable to expect that commercial applications will require on the order of 10,000 qubits or more.
D-Wave have done a significant amount of theoretical work on understanding effect of noise on their system. While I find their noise model to be somewhat incomplete, they appear to have made reasonable approximations. It is not, however, clear to me that this tells us anything particularly useful about whether they should expect a speed-up over classical approaches.
D-Wave appear to be ignoring the need to make adiabatic quantum computers fault tolerant. While their theoretical results show that a certain amount of noise be present without significant adverse affect, it has been known for years that such noise must scale proportional to the inverse of the total number of qubits. Above this threshold the device will give an incorrect answer. A part of the system noise will no doubt come from the fact that the system is operating at finite temperature. In order to continue to suppress errors, it is likely that the operating temperature of the device will have to drop proportional to approximately 1/N, where N is the number of qubits in the device. As the system is occasionally yielding incorrect results already, it seems unlikely that the noise can be sufficiently suppressed to allow systems of thousands of qubits to operate. Even if this can be achieved for large numbers of qubits, it will eventually fail, as field stability and other problems become the dominant sources of error. For this reason, systems which require the noise rate to scale as a function of the numbers of qubits are considered to be not scalable. Recently there has been a significant amount of work done on making adiabatic quantum computers fault-tolerant, however it is not clear that D-Wave has any plans to attempt to reach the required noise thresholds or adapt their architecture as necessary for fault-tolerant implementations.
D-Wave have publicly demonstrated their system being used to solve a number of optimization problems, but have not yet made sufficient information available to determine whether their system is operating in the quantum regime. It is important to note here that getting the correct result is not an indication that the device is functioning as a quantum computer. Each of the problems they solve can be solved with a classical technique known as simulated annealing. As it turns out, replacing all of the qubits with classical bits (as happens if there is sufficiently high noise) converts an adiabatic quantum computation into classical simulated annealing, and should still yield the correct result with high probability. The main difference here is the time required to reach the final state. It is expected that adiabatic quantum computing offers a substantial saving (square root of the classical case) in scaling of time required as a function of the total number of bits/qubits. It is however impossible to tell which regime the device is operating in simply be measuring the time required to solve problems of a given size. (It would be necessary to know how that time changes as a function of input size). As a result, from the few experimental results made publicly available, it is impossible to tell whether D-Wave has produced a functioning adiabatic quantum computer or rather an expensive classical computer. The decoherence times given for their qubits are sufficiently small compared to the length of computation that it is seems very likely that their device is operating in the classical regime, rather than the quantum regime, and so is not a quantum computer.
The device D-Wave has built is not a general purpose quantum computer, even if the effects of decoherence is ignored. Their current architecture is not capable of simulating the circuit model of quantum computation and so can not be used as a factoring machine, for example. D-Wave, however, do appear to have plans to extend their architecture to plug this gap.
It appears that the current device solves problems by expressing them in terms of an NP-complete problem (this is essentially the hardest type of problem for which you can verify your answer quickly). For problems which are not actually this hard, expressing them as an NP-complete problem may slow down the process of finding a solution.
It is clear from talking to Herb Martin and Mohammad Amin that D-Wave would be quite happy with producing a device which offers a factor of, say, 1000 speed-up versus a similarly priced classical computer. If this is the case, then the quantum advantage in scaling is beyond what they actually require, and so concerns about noise and fault-tolerance are less important. It should be clear, however, that if this is what D-Wave are aiming for, it is not a quantum computer but rather a special purpose classical computer. With a special purpose classical computer, it seems unlikely that they will be able to keep pace with Moore's law, regarding the increasing speed of conventional semiconductor architectures.

I may have missed or misremembered something, as I only kept rough notes. The slides from the talk aren't publicly available at the moment, but they were very similar to those used in the QEC talk, available here.

LaTeX in Blogger

2008-04-28T20:02:00.002+01:00

I've just installed a GreaseMonkey script which should now allow me to post on Blogger using LaTeX. Below is a sample of the output:

Example equation:

Not perfect, but not too bad either.

Shor madness

2008-03-25T00:25:00.002Z

Bruce Schneier points to post on Emergent Chaos, which gives a very bleak outlook for quantum computers being used to break public key cryptosystems.

The crypto-obviating algorithms in question are Shor's algorithm for factoring and an algorithm he developed for discrete logs. I was surprised to learn that Shor's algorithm requires 72k³ quantum gates to be able to factor a umber k bits long. Cubed is a somewhat high power. So I decided to look at a 4096-bit RSA key, which is the largest that most current software supports -- the crypto experts all say that if you want something stronger, you should shift to elliptic curve, and the US government is pushing this, too, with their "Suite B" algorithms.
To factor a 4096-bit number, you need 72*4096³ or 4,947,802,324,992 quantum gates. Lets just round that up to an even 5 trillion. Five trillion is a big number. We're only now getting to the point that we can put about that many normal bits on a disk drive. The first thing this tells me is that we aren't going to wake up one day and find out that someone's put that many q-gates on something you can buy from Fry's from a white-box Taiwanese special.

So what's wrong with this? The Quantum Pontiff defends the faith.

There is however one point which he, and apparently everyone commenting on this story, missed. The slow part of Shor's algorithm is the modular exponentiation (which conveniently is also required by RSA itself). The claim that it is necessarily O(k³) is simply wrong. The Schönhage-Strassen algorithm can be used to implement modular exponentiation in O(k²) log(k) log(log(k)))!

But the really sad part of this is that Peter Shor says exactly this in his paper.

Asymptotically, the best classical result for gate arrays for multiplication is the Schonhage–Strassen algorithm [Schonhage and Strassen 1971, Knuth 1981, Schonhage 1982]. This gives a gate array for integer multiplication that uses O(l log l log log l) gates to multiply two l-bit numbers. Thus, asymptotically, modular exponentiation requires O(l² log l log log l) time. Making this reversible would na¨ıvely cost the same amount in space; however, one can reuse the space used in the repeated squaring part of the algorithm, and thus reduce the amount of space needed to essentially that required for multiplying two l-bit numbers; one simple method for reducing this space (although not the most versatile one) will be given later in this section. Thus, modular exponentiation can be done in O(l² log l log log l) time and O(l log l log log l) space.
While the Schonhage–Strassen algorithm is the best multiplication algorithm discovered to date for large l, it does not scale well for small l. For small numbers, the best gate arrays for multiplication essentially use elementary-school longhand multiplication in binary. This method requires O(l²) time to multiply two l-bit numbers, and thus modular exponentiation requires O(l³) time with this method. These gate arrays can be made reversible, however, using only O(l) space.

Does nobody read their references anymore?

Please stop using the term 'Darwinist'

2008-03-23T00:41:00.003Z

If you ever use the phrase 'Darwinist' to refer to people who accept that evolution is the best explanation for how complex organisms arose on Earth, please stop.

We don't use the phrase 'Einsteinist' or 'Newtonist' to refer to those who accept that gravity is the reason we stick to the ground. We don't use 'Leibnizist' or 'Maxwellist' to refer to people who are confident that no matter how cleverly you arrange the magnets you can't get more violate conservation of momentum. And we don't use 'Copernicist' or 'Keplerist' to refer to those who deny the Earth is what planets orbit. There are people who use these terms, and we do have a word for those people; 'crackpots'. The use of these phrases implies disagreement within the scientific community which is simply not there. It essentially equates these stances to subscribing to a philosophical school, implying that the there is no evidence to justify these positions. Reality has a well-known scientific bias! (With apologies to Stephen Colbert)

So why use 'Darwinist'? Using it implies that there is some reasonable controversy over the validity of evolution within the scientific comunity, and there simply isn't.

There is a reason we don't have terms for the consensus position of the scientific community on these matters, and it's the same reason we don't have a specific word for somebody who does not believe in the Flying Spagetti Monster. It's ridiculous to label everybody who is NOT in a specific microscopically small minority group.

With that in mind, I'm not too keen on 'evolutionist' either, but at least it avoids the connotation that we blindly follow the teachings of some guy called Darwin.

iTunes solving NP-complete problems

2008-03-10T01:33:00.002Z

While over in Singapore, I was sharing an office with Pieter Kok, and a rather amazing thing happened. When he connected his new ipod to his laptop, iTunes managed to fill it with music, and by that I mean 0kb free. I was utterly amazed at this, since it essentially requires solving the subset sum problem, which is NP-complete. Anyone know if and how iTunes cheats?

The Igs

2008-03-07T00:36:00.002Z

Earlier this evening I went to the first event of the Ig Nobel tour of the UK. I'd been once before, and so Peter Rohde and I made about 20 paper airplanes waiting for the event to start (it's a tradition!). We didn't want to be the first to throw one, and so we waited for someone else to start. No one did! My disappointment knows no bounds.

Barack@Google

2008-03-06T00:04:00.002Z

Scott Aaronson has just posted his views on the Democratic primary. I, too, like both Obama and Clinton and would be happy to see either of them as US president. I had been slightly in favour of Obama before I read his post, and Scott's post hasn't done much to alter that view. A video of Barack Obama talking at Google which he links to, however, has changed my position. In the video Obama manages to say pretty much exactly what I want to hear on every topic he talks or is asked about. (Except of course when about twelve and a half minutes in he talks about the need for the US to beat Dublin in innovation and technology.)

I am now massively in favour of him. If only I could vote in US elections...

25 minutes of inclement weather = 1 cm of snow = a 90 minute delay

2008-03-03T21:28:00.005Z

Aer Lingus have done it again. I'm stuck in Dublin airport, waiting for my flight. It's been pushed back again. It's not just me either, every flight has been delayed.

The really ironic thing is that I really love snow.

Singapore

2008-02-18T06:30:00.003Z

I'm currently visiting the National University of Singapore, hence the lack of blog posts. I'll try to post something more substantial soon, but for the moment, let me just say that Singapore is fantastic, and well worth a visit.

Undersea underhandedness?

2008-02-08T02:19:00.000Z

It seems that over the last week a total of 5 undersea data cables have been cut which serve the Middle East. Apparently this is being blames on ships anchors, but that seems an incredibly unlikely scenario. The ship hypothesis has already been disputed in the media.

Repairs are already underway, but the whole incident looks very suspicious.

It looks like something fishy is going on under the sea.

Bruce Schneier and Steve Bellovin have more.

Wii-ly Wii-ly cool

2008-02-07T23:55:00.001Z

The Nintendo Wiimote seems to be like a Swiss army knife. So far Nintendo are on
ly using the most obvious features, but fortunately Johnny Lee comes to the rescue. Below are a few applications he has come up with. They're fairly simple hardware hacks, and the necessary software is on his site, but to me they seem to represent a massive leap forward in affordable human-computer interfaces.

Isn't it cool to be living in the future?

Age of wonders

2008-02-07T01:07:00.000Z

Just noticed an interesting story on Google News. It seems that researchers in Newcastle University have managed to create a three parent embryo. From BBC News:

The Newcastle team have effectively given the embryos a mitochondria
transplant.

They experimented on 10 severely abnormal embryos left over from traditional fertility treatment.
Within hours of their creation, the nucleus, containing DNA from the mother and father, was removed from the embryo, and implanted into a donor egg whose DNA had been largely removed.
The only genetic information remaining from the donor egg was the tiny bit that controls production of mitochondria - around 16,000 of the 3billion component parts that make up the human genome.

New site up and running

2008-02-05T02:54:00.000Z

I’ve got my new website up and running at http://www.jfitzsimons.org. It includes a mirror of my blog with an updated blogrole at http://blog.jfitzsimons.org. It’s still a little rough around the edges, but I hope too get it all smoothed out soon.

SpaceShipTwo

2008-01-24T02:22:00.000Z

Virgin Galactic has just unveiled a model of SpaceShipTwo, building on the success of SpaceShipOne. SpaceShipOne was the spacecraft designed and used to achieve the first privately funded human spaceflight, and won its builders Scaled Composites the Ansari X Prize.

The Virgin Galactic website has all the press material together with lots of graphics and photos.

Here is an animation of what to expect:

Photo Gallery

2008-01-22T01:15:00.000Z

As part of an attempt to create a more unified website, I've registered jfitzsimons.org. There is nothing there at the moment, but I've completed a photo album here.

Greetings TCD mathematicians

2008-01-14T02:05:00.000Z

Seems someone has just added my blog to the Trinity College Dublin maths wiki. Greetings!

I like the summary of my blog so much that I'm going to change my tagline to it (at least temporarily).

Quantized Thoughts: A TP from NUIM who gets riled by the Steorn debacle. Some other topics too, but that's what stands out for me.

The only slight correction I have to make is to point out that I work in Oxford University, rather than NUI Maynooth, although I did begin my PhD there.

Oddly, since the University doesn't employ any QIP researchers (last time I checked), of the 8 blogs listed, two belong to QIP theorists. The second QIP blog is Scott Aaronson's Shtetl-Optimized.

Since they seem unable to categorize him, I should probably point out that he is a theoretical computer scientist who does lots of work on quantum computing and reacts to DWave in much the same way I react to Steorn.

If you like Scott's blog (and mine) then it's well worth your time taking a look at Dave Bacon's blog.

Cosmic Variance is also there. Seems I'm keeping good company these days.

Brown backs presumed consent for organ donation

2008-01-14T01:31:00.000Z

Apparently (via CNN) Gordon Brown backs plans to change the organ donation system in the UK so that consent for organ donation after death is assumed to be granted, rather than assumed not to be granted, although you can still opt out and your family can still refuse consent.

I can only see this as a tremendously good thing. Although I do have an organ donor card somewhere, I keep loosing it. I don't always have my wallet on me in any case. I'd like to think that in the event of my untimely death that my organs could be used to help people who would otherwise die, and I suspect that most people would agree.

To be brutally honest, I'm not even sure that people should be given a choice in the matter. After you die, your organs are of no use to you and it would be extremely selfish refuse to hand them over if a life is at stake.

The one part of the plan I don't like is the part where the next of kin are still allowed to make the decision about whether the organs are harvested or not. This may sound terribly cold hearted, but actually I'm trying to be compassionate. When a loved one dies, the last thing you want is for doctors to be going for the hard sell for organ donation. It would be a horrible decission to be faced with, made even worse by the fact that it is someone who you have loved, rather than you yourself. When I die, the last thing I would want is for my family to be faced with a decision like that. I would also rather that they were not given the opertunity to overrule my decision out of some desire to keep me intact.

I want to close by saying that my comments relate only to what happens after someone is dead. When someone is in a coma, for example, or has suffered severe neurological damage, the situation is completely different. Hopefully, though, the proposed scheme would be successful enough to alleviate the shortfall in organ donation to an extent where no pressure would be put on the families of patients on life support.

Album art meme

2008-01-12T17:20:00.000Z

Via Soylent Red comes the album meme. The rules are simple (quoting Rory):

The title of your album is the last four words of the last quote listed on this random quote page (I got “In a mad world only the mad are sane.”, from Akira Kurosawa).
Your band name is the first article you get by visiting the Wikipedia random article page (Anisogamy for me).
The album background is a (dubiously legal) derivative of the third image on Flickr's last seven days of interestingness (mine is this one).

Here's my attempt:

The quote from which the album title came was "I paint self-portraits because I am so often alone, because I am the person I know best.", from Frida Kahlo. The band name came from this wikipedia article on an episode of the Outer Limits. And the background came from this beautiful image.

UPDATE: Looks like the meme has propogated to Blake Stacey, and then into his comment section.

QEC photo and talks

2008-01-10T01:36:00.000Z

The slides from almost all of the QEC talks have been put online here. I apologize in advance for my use of a simpsons analogy with out the requisit youtube clip. Video of the talks is apparently on the way.

Four glasses puzzle

2008-01-09T02:26:00.000Z

Here's a nice puzzle via Soylentred:

Consider a table with a turntable in the middle, like you get in many Chinese restaurants. On this turntable are four glasses arranged in a square, all equidistant from the centre. Each of the glasses is either the correct way up, or upside-down. You task is to turn then all either the correct way up, or all upside-down, following this procedure:

You select two glass either along the edge of the square closest to you, or along one of the diagonals (only one diagonal is allowed, but which one you choose makes no difference to the puzzle. You can then feel the glasses to determine their orientation. Then you can choose to flip or not flip each of the glasses. If all the glasses are either up or down, then you will be told that you have won.

After this the turntable is rotated by some unknown angle (i.e. 0,90,180 or 270 degrees) and the above procedure is repeated. The process is repeated until you win.

The challenge is to find a scheme which gaurantees that you will suceed in a finite number of turns.

Turning the glasses randomly is not a solution (nor is turning each one you encounter upwards), as it is possible to never turn all the glasses either up or down (although it becomes extremely unlikely that you will fail).

I like this problem particularly because it can be viewed as a cellular automata problem. I think I'm going to have to start using it to judge prospective students. If you get stuck and feel you must find the answer, click through to the Soylentred link above and read my comment, which contains one possible solution.

Wikio and Steorn

2008-01-09T02:01:00.000Z

Seems Wikio thinks I'm the definitive source of news on Steorn. So much the worse for Steorn.

Holy Neuro Quantology, Batman!

2008-01-09T01:44:00.000Z

Just got this email today:

Dear Scientist, NeuroQuantology Journal accepted (January, 2008) to The Science
Citation Index Expanded, available as the ISI Web of Science, Neuroscience
Citation Index and indexed in (June, 2007) SCOPUS, EMBASE, DOAJ, Index
Copernicus database.

NeuroQuantology (An Interdisciplinary Journal of Neuroscience and Quantum
Physics), is a novel journal dedicated to supporting the interdisciplinary
exploration of the nature of quantum physics and its relation to the nervous
system.

We would like to ask you to kindly consider the NeuroQuantology in your future
publication plans. If you, an expert in your area, could kindly consider
reviewing a limited number of articles for NeuroQuantology. We will be glad if
you could contribute us.

Therefore, please visit our web page and feel free to browse through the full
texts of articles published in our journal and presented online in a PDF
format.

Should you have any questions, please do not hesitate to contact me at your
convenience. Sincerely yours

Journal web site:
http://www.neuroquantology.com/journal/index.php/nq/index

Sultan Tarlaci, MD
Editor-In-Chief
NeuroQuantology Journal

The pontiff has already proclaimed on this here. I wonder what list they got the email addresses from.

I'm actually considering signing up as a reviewer. Sure almost every article is likely to be quackery, but I've no problem with rejecting articles. If it puts people on the right track (and I have a feeling that no signalling is likely to feature heavily in many reviews) then it's probably worth putting in some time. On the other hand I certainly don't want to be the only one doing so.

So I have a proposition: If at least two other QIP people agree to referee (I'll take you word for it), I will too. Any takers? Dave?

Is quantology even a word?

UPDATE (09/01/07): I've just realised that I accidentaly titled this post 'Holy Quantum Metrology, Batman', rather than 'Holy Neuro Quantology, Batman'. My only defense is to say that reading or writing 'quantology' appears to break my brain. Probably not a good sign...

The Mysterious Adventures of Robin Langerton (Professor of Symbology)

2008-01-07T13:48:00.000Z

There is a new(ish) book in the form of a blog, written in the style of the DaVinci Code. The blog is called The Mysterious Adventures of Robin Langerton (Professor of Symbology) and contains one complete book so far, In The Phoenix’s Lair, and the start of another.

I hated the DaVinci Code almost as much as I hated Digital Fortress, which is probably why I love these parodies as much as I do. It would seem the author also disliked the DaVinci Code as you can read in his review of it here.

I should probably mention that to get the most out of the blog, it helps if you have lived in Dublin, where the adventures are set, but don't let that put you off.

Steorn: The madness continues

2008-01-06T12:42:00.001Z

This video has now appeared on youtube. Apparently it is an attempt to replicate Steorn's device (assuming there actually is something to replicate).

It is apparently discussed on the Steorn forum here.

Obviously the word skepticism doesn't even begin to describe how untrusting I am of this kind of thing.

XKCD parodies

2008-01-06T03:27:00.000Z

I got a little bored, so I decided to play around with some old xkcd comic strips.

2007 in cities

2008-01-03T14:54:00.000Z

Copying the idea from Rory, rather than writing a proper post, I just thought I'd run through a list of places I've visited over the past year, and see if I can beat his. In roughly chronological order they are:

Oxford
London
Zurich
Arosa
Dublin
Toronto
Waterloo
Kitchner
Montreal
Edinburgh
Cambridge
Los Angeles

Ok, technically Cambridge and Arosa aren't cities per say, so much as large towns, and Kitchner-Waterloo is probably a better defined region than either of the two components, but hey, how else was I going to beat Rory? So, what do I win?

Randall (XKCD) Monroe talk at Google

2008-01-03T14:35:00.000Z

Happy holidays

2008-01-03T05:38:00.000Z

Me and Amy! Amy gave my this cartoon on a t-shirt for Christmas, along with a really nice single comic cell she drew and framed, and some puzzles. I really like both of them, so I thought I'd stick this up here so even more people can laugh at how silly she made me look.

Physics and computer (in)security

2008-01-03T04:10:00.000Z

I've just bought Silence on the Wire by Michal Zalewski, and it is largely the reason I'm up at 4:12am. In fact it's also the reason I've spent most of the day messing around with a bag full of electronic components, an the jack off an old microphone and a bunch of DSP software trying to pick up information off a big pasma TV in my parents house. Despite what various sites say, it seems you can still pick up a reasonably strong signal from non-CRT monitors. Unfortunately for me, producing a useful signal from the noise is beyond an afternoons work. People kept asking my why I wasn't plugging anything in!

Anyway, the book has me thinking about a lot of different mechanisms for information leakage than I would generally consider. There is a really interesting discussion of timing attacks on various services (for example the keyboard interupt calls via the PRNG, /dev/random and /proc/interupts, and on RSA implimentations via the length of time required to decrypt chosen cipher texts). There is also a brief discussion of TEMPEST, hence the way I spent my afternoon. I really like this way of thinking about computer security that takes a more physical view of the system, and it got me thinking of a new attack:

All computer hashes and number theoretic one-way functions rely on logical operations which are not reversible. Many of the operations used are reversible (essentially everywhere you see a NOT or an XOR which is almost always really a CNOT). It's the AND gates that tend to lead to trouble. I do realise that everything is really made up of NANDS, but let's leave that aside for the moment. The problem, and hence the attack, comes about because physics is reversible.

Consider the following situation: The logical states of a bit correspond to basically to different energy levels within a computer. We can model this simply by thinking of a ball in a double well potential.

Every irreversible logic gate can be thought of as a reversible logic gate followed by some resetting of bits. In order to perform an irreversible gate, then we must erase some data. The trouble is that in order to erase a bit (by setting it to 0) we must expend different amounts of energy depending on what state it was in.
Thus by monitoring the amount of energy used during each gate it is possible to deduce the state of the computer prior to the irreversible gate being applied, or at least to reduce the number of possibilities. There is in fact a theoretical limit of k_Bln2 on the amount of energy required to erase a bit, although current processors are hundreds of times greater.

We can also ask whether reversible computing would help. In principle computation can be performed reversibly, but in practice this is not done, so this question is largely academic. Even so, if the computation is performed reversibly, we can assume the additional bits required for reversibility must be erased at the end of the calculation to result in an irreversible function over all. In this case information is still leaked about the initial state of the system before the irreversible function was applied.

In practice it seems the attack is not likely to pose a real threat, since monitoring the amount of power used to sufficient accuracy is not exactly something that can be done by looking at the kilowatt hours on the electricity bill. Even so, it might be possible to increase the energy usage, for example by increasing either the temperature of the system, or the distance between energy levels.

Lastly, it would appear that in some instances this could lead to a timing attack, since reseting a bit from 1 to 0 takes necessarily longer than not changing state. Certainly this won't affect clocked systems, since the time binning will stop this effect from cascading. It might still be worth thinking abut when considering asynchronous systems.

These are mostly physical curiosities, rather than real attacks likely to happen in the wild (or even the lab), but it is an interesting implication of the fact that information is physical.

Merry Christmas!

2007-12-25T01:20:00.000Z

Finally made it back to Ireland a little after 2 am. I've spent most of the day doing last minute shopping and various family/house related chores. Finally getting to bed now. Now doubt my little brother will be in to wake me about 5 am. He's nearly 16, but that doesn't stop him from waking us all at some ridiculous time every Christmas. Oh well! Let the madness commence.

Delayed even longer

2007-12-23T22:08:00.000Z

My flight seems to have been pushed back another hour. I haven't slept in two days, and we'll be entering the third before I get my head down. Things are starting to get a little weird.

Delayed

2007-12-23T19:30:00.001Z

I'm stuck in Heathrow airport due to fog. The place is packed, and flights are being cancelled left right and centre, so I'm glad mine only appears to be delayed at the moment. All going well, I should reach Dublin by midnight.

QEC highlights so far

2007-12-19T20:40:00.000Z

I've been sitting here for the last three days watching talk after talk on quantum error correction and fault-tolerance. I don't think I've ever been to a conference before where the material was so consistently interesting (to me at least).

I gave my talk yesterday, but laptop problems the night before meant that I missed four of the morning talks while trying to reconstruct my slides.

There have been a couple of talks which really caught my attention over the last few days, and I thought I'd mention them here.

On Monday there was a set of four, hour long, tutorials, given by Daniel Gottesman, Lorenza Viola, Dave Bacon and Ray Laflamme. I really enjoyed each of these, and I think they worked well to put everybody on the same page before the invited talks and contributed talks.

Debbie Leung gave a talk on measurement errors in the cluster state model, and showed that they are trivially equivalent to Pauli errors in the circuit model if we choose a specific interpretation of what happens in MBQC. While the trick is very simple, I really like it, and enjoyed the talk.

The other talk which caught my attention that day was given by Mohammad Amin from DWave Systems. In the talk he argued that their adiabatic quantum computer was robust against multiqubit dephasing (assuming this is in the energy basis, I have no problem with this) but also that it is not limited by single qubit decoherence times. This strikes me as highly unlikely. Actually, I think it must be impossible. He argued that we only need to consider the lower lying energy levels when talking about decoherence in AQC, and proposed a two state model. My problem with this is that because of the non-local nature of the energy eigenstates near the anti-crossing, local errors should affect all energy levels. The slides from his talk are available online here. I haven't seen him around at coffee, but I'll try to ask him why he doesn't consider this to be a problem if I see him.

The talk the next day which has stirred up the most controversy was given by Robert Alicki arguing the impossibility of fault-tolerant quantum computing. There was quite a lot in the talk that I found strange, and actually thought a lot of the arguements were orthogonal to the way we actually go about quantum error correction. That said, there were a few parts where I didn't follow his argument, so I'm probably not in such a good position to comment.

Dave Bacon is also blogging about the conference and has mentioned the latter two talks here and here. The second link is an open thread on the conference.

Also, yesterday I gave my talk on globally controlled fault-tolerant quantum computation. It seemed to go down pretty well, but I got a little rushed at the end when I saw the session chair holding up a 1 minute sign. The poster session contained some very interesting results too, and maybe I'll get around to talking about those in another post. Michael Bremner's poster on noise in globally controlled schemes certainly caught my attention, since it relates so closely to my work. Actually I think we've seen the effects of it in some recent NMR experiments. I'll write something about that later too if I get the chance.

Todays highlight, for me at least, was Panos Aliferis's talk on error correcting the IBM superconducting qubit. It seems that IBM are now below the threshold for fault-tolerance, which really is big news. It seems that they are just under the limit, so the overhead will likely be large, but even so, this really is a major achievement. The talk was very clear and easy to follow, but unfortunately, there were a lot of numbers for the error rates which I didn't manage to scribble down. Hopefully the slides will be available on line after the conference. Anyway, the over all message to take away from his talk is that asymmetry in noise can be a very good thing, and that we shouldn't obsess over CNOT fidelities if we have good controlled phase gates (even if we don't have good Hadamard gates).

Anyway, there is still half the conference left to go. I'm looking forward to hearing more results. There are a few talks I am particularly interested in, but more than that I'm looking forward to hearing results that I hadn't expected. It's always good to be pleasantly surprised by the state of the field.

UPDATE: It seems the numbers for the IBM qubit were estimates and do not relate to the actual experimental fidelities currently being achieved. This makes a lot more sense to me. Basically I didn't pay to much attention to the first few minutes of the talk (and hence missed the fact that they were estimates) and only really paid attention when the fault-tolerance discussion started. There have been a lot of very interesting talks, and so occasionally my attention drifts.

Anyone arrive in LA early for QEC?

2007-12-15T06:45:00.000Z

Just arrived in LA for the Quantum Error Correction conference being held in USC. I've arrived a little early, so I'll likely spend the next two days wondering around LA. I should also probaby write my talk at some point. Anyone else in the same boat?

So much for the First Amendment....

2007-12-06T18:43:00.000Z

Freedom requires religion, just as religion requires freedom. Freedom opens the windows of the soul so that man can discover his most profound beliefs and commune with God. Freedom and religion endure together, or perish alone

Thus spoke Mitt Romney today. He continued:

It is as if they are intent on establishing a new religion in America -- the religion of secularism. They are wrong.

Unfortunately the First Amendment of the constitution of the united states reads

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.

Anyone see the conflict between Romney's declaration about secularism and the text of the amendment? Reading between the lines it would appear that he is suggesting that the First Amendment protects only the rights of the religious. And this is from someone running for president!
Selective interpretation of the constitution can lead you down a very dangerous path...

The photons are coming, the photons are coming...

2007-11-30T13:20:00.000Z

I've just recieved a google news alert telling me there has been a break through in quantum computing. I get these at least 3-4 times a week, so I'm usually quite dubious. I have the news alerts set up for the phrase 'quantum computer' so I tend to get a lot of crap and press releases.

This one is a little different. It's reporting that two groups have managed to factor 15 with optical quantum computers.

Chao-Yang Lu, Daniel E. Browne, Tao Yang, and Jian-Wei Pan Physical Review Letters (forthcoming) and B. P. Lanyon, T. J. Weinhold, N. K. Langford, M. Barbieri, D. F. V. James , A. Gilchrist, and A. G. White
Physical Review Letters (forthcoming)

Two research groups have independently managed to experimentally solve a mathematical problem with light-based quantum computers. The simultaneous achievements appear to be the first experimental demonstrations of true (though rudimentary) quantum mechanical computations. Both groups manipulated quantum mechanically entangled photons to calculate the prime factors of the number 15.

The preprints have been available for a few months here and here, but it's still big news.

I'm a bad bad person ....

2007-11-29T23:41:00.000Z

I've been neglecting my blogging duties! I could say that I've been incredibly busy, moving from Waterloo back to Oxford, starting a new job, giving talks and traveling. All of which is true, but I don't think it's the real reason. I suspect that I never recovered my blogging skills after puting them into hibernation to finish my DPhil.

Oh well, I guess I'll have to remedy that over the next few days and weeks.

Collapsing the polynomial hierarchy

2007-09-10T08:38:00.000+01:00

Myself, Anne Broadbent and Carlos Perez-Delgado have just published a new peer-reviewed comment on the polynomial hierarchy. What was it, and where was it published?

We submitted

"Bruce Schneier can collapse the polynomial hierarchy, with a roundhouse kick to
the face."

to the Bruce Schneier facts list. It's now been published here. Please cite as A. Broadbent, J. Fitzsimons and C. Perez-Delgado, Bruce Schneier Fact 829 (2007).

New facts are reviewed before they are added to the list. What's particularly funny about this is that it legitimately reduces Carlos's Erdos number.

Internet People (with references)

2007-09-10T05:53:00.000+01:00

I came across the 'Internet People' song a few days ago. Is it bad that I get virtually all of it?

I was planning on compiling a list of all the references in it, but it turns out someone (calling themselves Hans v) already did in the comments at Channel Frededator. It wasn't hyperlinked, so I'll reproduce it here with the links fixed. There is bound to be something in there thats not safe for work (Goatse only links to the wikipedia page), so proceed with caution.

Canada

2007-07-27T22:18:00.000+01:00

I suppose I should have posted some update to say that I have arrived safely in Canada before now, but I'm not a very diligent blogger. I've just finished my second week as a postdoc in the Institute for Quantum Computing, in Waterloo, and have eventually found somewhere to live for the duration of my stay.

I submitted my thesis last Saturday week about twenty minutes before getting the bus to Gatwick airport. Officially, that'll make the time from the start of my DPhil until submission 1 year 9 months 14 days and about 3 hours. The university don't seem to count the year I spent in NUI Maynooth before coming to Oxford, which brings the total up to about 2 years 10 months. Either way, I'm done, unless of course I fail my viva, which is not a possibility I'm willing to think about.

I flew over on Zoom airways, which are cheap, but it took me well over an hour to check in, so I wouldn't recommend them. I stayed a night in the Suites at 1 King West, in Toronto, which I would recommend. The hotel is fantastic, and is pretty central. The views from my suite were fantastic, and it all cost lest then a night at a crumby B&B in Oxford. So, if you're going to Toronto, I'd certainly recommend staying there.

I spent quite much of my first week here getting setup within the University, and in Waterloo in general. I was amazed at how easy it was to open a bank account (although surprised to learn that there are monthly banking charges). All I needed was my passport and my letter containing the job offer, unlike my banking experience in Oxford. In fact, I managed to setup a bank account without actually knowing the address of where I was staying. I bought a mobile phone, and even managed to get a social security number. None of these required proof of address! It seems that the bureaucracy I encountered in England isn't a necessary fact of life after all.

As of last night I've managed to move out of the student accomodation I had temporarily rented (there is a rant about that, but maybe I'll leave it for another time). I've moved into a room in really nice three bedroom house, pretty close to the centre of Waterloo. The woman with whom I'm sharing the house is very friendly, and we're pretty close in age, so we seem to be getting on quite well.

Anyway, life here is good, and the cost of living here is very low compared to Oxford or Dublin, so my salary goes a long way. I'm kicking myself for not taking the fulltime job here, since by choosing Oxford I've condemned myself to renting (well, sort of) and cycling everywhere, where as here I could actually buy a nice place and a decent car.

The physics is good here too...

Steorn: Putting on a brave face

2007-07-10T21:11:00.000+01:00

Below is a video of Steorn's Sean McCarthy trying to explain why their perpetual motion machine didn't work this time, but trying to convince us that it is only a minor hiccup and that free energy is on the way. He's a lot more coy about the time frame now though. Looks like the laws of thermodynamics aren't quite as elastic as he would have us believe.

This episode has muddied the waters for me. Not about whether perpetual motion machines are possible (they aren't), but about whether Steorn have managed to delude themselves or whether their out to con us. As Sean says in the video, if Steorn were out to con us, then why would they so publicly fail? Wouldn't they have had a plan to rig up something that looked like it was a perpetual motion machine? Well, maybe. On the other hand, they may have simply been incompetent, or they may have prevented from implementing their plan due to some unforeseen circumstance.

I'd rather give them the benefit of the doubt though, and assume that they are suffering from some sort of mass delusion. This would seem to fit, if for example they had been inadvertently drawing energy from the magnetic field of some nearby high voltage lines in their lab. If this was the case, coming to the museum and away from the power lines would prevent the device from working. That's what I'd like to think.

Unfortunately Steorn aren't making it very easy for me to thrust them. Sean's explanation for the failure of the device in the above clip is hardly confidence inspiring. Five bearings (which had caused no trouble before) wore down instantaneously, possible because of slightly warmer conditions due to camera lights. Pull the other one! If they are deluded, then they are certainly stretching for excuses, and would appear to be somewhat lax with respect to intellectual honesty.

Steorn's Pertually Stationary Machine

2007-07-06T02:41:00.001+01:00

In a rather odd circle, via Chad Orzel, it seems that Steorn's perpetual motion machine isn't moving. In fact, you can watch a live video stream of the device not moving.

IQC here I come

2007-07-06T00:48:00.000+01:00

Just received my work permit for Canada! I'll be a visiting research associate in the Institute for Quantum Computing and the Department of Combinatorics and Optimization in the University of Waterloo for the rest of the summer, then it's back to Oxford to take up a JRF at Merton College.

Half-Slashdotted

2007-07-04T23:54:00.000+01:00

I get mentioned in the comment section on a slashdot post and my traffic increases tenfold. I can only imagine what would happen if it was in the original post!

Well, if you came here from slashdot, stick around! Rant about Steorn (and soon DWave). Or whatever ...

Update: Looks like I was wrong. I got ten times my daily trafic in 3 hours, making it an 80-fold increase in traffic.

Putting Oxford on the map

2007-06-25T02:21:00.000+01:00

Looks like Google has finally added decent satellite photos of Oxford to Google maps. Now if only Facebook would add Oxford as a city in England, so we don't have to claim all our events are happening in Oxford, Alabama.

Anyway, here's a map with my college marked in, along with all the film set lights from 'The Golden Compass' that are keeping me awake.

Bet you can't guess where I live! And no, I don't live in Oriel.

Oh, and Amy, you're not allowed to answer!

Steorn: It just keeps going and going...

2007-06-24T19:46:00.000+01:00

The claims that is, not the machine. Ok, I realize this that I'm a little late in linking to this, but I've just found video of a talk by Steorn CEO Sean McCarthy on their alleged perpetual motion technology. The talk was given at my alma mater, University College Dublin. Below are the YouTube videos. Apparently now they've solved the dark matter/dark energy problem (see the second and fifth videos).

First of all, I should say that I am now convinced that they are bat-shit crazy. They're claiming that the strength of fundamental interactions is time dependent. In particular they are claiming that the strength of magnetic interactions varies with time. In fact, they have claimed to have measured it on a millisecond timescale! The problem is they're not the first to measure magnet interaction strengths. It's done all the time. NMR and ESR spectroscopy, for instance, rely on the magnetic moments of nucleons and electrons remaining constant, and both work spectacularly well. We know beyond a shadow of a doubt that these interactions do not vary noticeably with time.

I think I now know what there problem is. I think they are basically neglecting the effect of one magnet on another. They seem to completely neglect the fact that hysteresis can and does occur in ferromagnets. Sean seems to focus on thermodynamic quantities (the magnetization curves), and then claims that some of them maybe time dependent but had previously been assumed to be constant. The problem is that he completely neglects any analysis of the microscopic system, which is where all these ensemble properties come from. We understand magnets very well at a quantum mechanical level, and his proposal for time varying interaction strengths make no sense in this context.

If magnetic interactions varied on the timescale he suggests at a sufficient level to allow for the kind of energies he is claiming, then the vast majority of quantum computing architectures simply wouldn't work, since entangling gates would give something completely different depending on when they are applied. Taking my own work as an example, the scheme described in Phys. Rev. Lett. 97, 090502 (2006) (quant-ph/0601120) would never work, since the always-on varying interactions would lead to extremely rapid decoherence. Unfortunately for Steorn, and fortunately for me, it does work (quant-ph/0606188).

It's very odd the way people with crackpot claims seem to completely ignore the effect their 'discovery' would have on other areas.

Update: Sean Carroll has an interesting alternative science respectability checklist over at Cosmic Variance from which the Steorn crowd could learn a lot.

Update (2:41am 25/06/2007): Ok, I have to ask, what is the Steorn Knowledgebase, and what is it saying about me? A lot of people seem to be coming here through it, but it requires a login, so I have no idea what the context is. Anyone care to enlighten me?

Oh, and if whoever administers the site should happen to read this, please accept some advice and disable the standard Apache Tomcat page. It's not terribly secure to leave it the way it is.

Update (10:39pm 25/06/2007): It would seem that somebody at Steorn did read this, since they have fixed the server, although not in the most elegant way.

Update (3:14 am 05/07/2007): Well, my traffic seems to have jumped massively since someone linked to this off slashdot. For those of you who got here through slashdot, here are my other Steorn related posts (in chronological order):

Free Energy
Steorn Song
Yet more Steorn

Feel free to stick around and join in the rants!

A glimpse of the golden compass

2007-06-20T15:29:00.000+01:00

It seems that a film is being made of the Philip Pullman book "The Golden Compass". I was walking to the pub the other evening with some friends, when we accidentally stumbled upon the filming in Radcliffe Square. The building in the scene is the Radcliffe Camera, and is only about 50m from my front door. Maybe I'm just not terribly observant, since I didn't notice the film crew just as I missed the filming of Battle of the Brains. D'Oh!

Just looked at the trailer, and Christ Church features pretty prominently too!

So that Rory may win a bet

2007-06-11T02:17:00.000+01:00

This is Heather McNeil. I've no idea who she is other that my friend Rory made a bet with her that he could get her picture in the top 10 on google image search for her name. Apparently they're in the same cult or something. So he's encouraging everyone to link to her photo to move it up in the rankings. There is a blog too, at http://heathermcneil.blogspot.com.

Anyway, I feel I should help him out, so this is my contribution. Feel free to ignore!

What if the Beatles were Irish?

2007-06-05T14:19:00.000+01:00

Come on, you must have asked yourself that?

There are some questions that can't be answered by google...

2007-05-10T17:46:00.000+01:00

Fortunately most of them can be reduced to the halting problem. And for those, google will turn up a hell of a lot of opinions.

Misleading IQ tests

2007-04-30T18:23:00.000+01:00

After watching "Battle of the Brains" I went to have a look at the website for the BBC program Horizon, which produced it. There wasn't much information on the site, but there was a link to the International High IQ society, the founder of which took part in the documentary (not doing particularly well either!). So, bored with thesis writing, I decided to take their tests. It seems they have two tests, a score of 125 or higher qualifies you to join the society. I passed the test straight off, after a few worrying questions at the start. The main problem with the test is that it asks you only six questions of each type with no explanation. I answered a few before I realised the simple tricks they were using (they essentially XOR visual shaped for one part, and in another they rotate dots on rings). My problem with this is that once you've realised how these tricks work, the next time you take a similar test, you are going to get an extremely high score. It seems to be a massive design flaw that someone could tell you how to answer these tests without ever knowing what questions were going to be asked. In fact, it would be relatively trivial to write a computer program to answer at least some of the standard questions. The reason I say some is that others involved freehand drawings which would be hard to deal with automatically.

But that's not the problem that has me annoyed. What really has me annoyed is the mathematics section. In this section it asks such gems as "How many sides has a hexagon?" and "What type of triangle has all sides different length and all angles different?". These aren't maths questions, they're questions on definitions. They have absolutely no meaning beyond testing how much you remember from primary school!

But the real kicker was when I was asked "Which conjecture states that every even number can be written as the sum of two primes?" and "What is the anti-symmeterized tensor product?". So, yes I can answer these, but only because I'm a theoretical physicist. The maths section doesn't test basic mathematical aptitude, but rather ask specifically "Do you have a degree in Mathematics?". They may as well ask "Which of the following is the twice contracted Bianchi identity?".

And don't even get me started on the general knowledge section.

To end on a high note I would just like to mention that I retook the test randomly clicking on answers as fast as I could 3 times in a row. Here are the results: 1st attempt: IQ =110, second attempt IQ=92, third time IQ=95, for an average IQ of 99. An IQ of 99 is essentially average. How the hell can I get an average score by simply clicking randomly? It would imply that people who score less than 100 would be better off simply picking what they think is the correct answer and then clicking on one of the other answers, since if they consistently score below 99 or so they must be actively seeking out the wrong answer. Not clicking on that, and picking randomly from the others automatically increases the chances of getting a correct answer, and would give them an above average IQ score.

What rubbish!

Signs it's time to finish my thesis

2007-04-30T02:16:00.000+01:00

Over the last month or two I've had a series of events occur to me which I'm taking to be a sign it's time to get my thesis finished and submitted.

I've received my very first email from a crackpot. I've had a couple of comments from crackpots before now, but that is to be expected on a blog with the word Quantum in the title.
I've been asked for advice on constructing an exhibition on nanotechnology for some museum in the US.
I've been asked to review a paper for a well respected Neurology journal. What's new here is not that I've been asked to review a paper, as I already review PRL and PRA papers, but rather that I've been asked to review a neurology paper! I'm not a neurologist, and don't know the first thing about neurology.
Someone emailed me asking if I would be their supervisor (actually this was more than a month ago). I guess they missed the Mr. in front of my name.
I've realised I have more words in papers and a lit review than I am allowed put in my thesis.
I now have the lowest Erdos number in my group.
My h-index has risen.
My students baked me cookies. (Thanks, they were really tasty!)
I have a job starting soon.
I've been elected a fellow of an Oxford college.

Now if only I could find some way to make my thesis write itself.

Battle of the Brains

2007-04-30T02:00:00.000+01:00

A recent programme on BBC pitted 7 people from different disciplines against each other in a series of intelligence tests. These tests consisted of everything from the standard IQ tests to more controversial tests of kinesthic ability and emotional intelligence. Much of the programme was filmed in Oxford (actually most of it seems to have been filmed about 150m from my front door!), but it seems to have passed me by, so I didn't catch it when it played on TV. Luckily it has been immortalised by google.

Of the seven people involved one was an artist, one a musician, one a dramatist, one an airforce fast-jet pilot, one an ex-trader and now 'high IQ specialist (whatever that means), one a chess grand master and one was Seth Lloyd.

At this point I was going to say 'You'll never guess who won...', but if you've ever met him, then you'll probably guess it was Seth ... and you'd be right! He came joint first with dramatist Bonnie Greer. Well done Seth, you've done all us quantum physicists proud!

Quantum computing with grass

2007-04-14T11:17:00.000+01:00

According to an article in Nature this month, there is evidence that photosynthesis might involve some quantum computation!

If biological systems can truely achieve some quantum speedup for unstructured searchs, then perhaps there is a lot we can learn from them about fault-tolerance. Oh how I would love to sell someone a box of grass as the worlds most advanced quantum computer!