Lies, damned lies and …

SciRate stats.

A few days back Dave did some analysis on papers that were highly scited on SciRate in the past 12 months. He examined papers that had more than 10 scitations and tried to group them by region.

Papers that had multiple co-authors were split between regions and if an author had multiple affiliations between different regions it was split again. He found, somewhat interestingly, that the US beat out Europe and Canada for the number of highly scited papers. This is interesting mostly because the US spends comparatively less than Canada and Europe on Quantum Information theory research.

Somewhat foolishly I decided that it would be interesting to see what the outcome of a similar calculation would be if we did the same analysis by institution instead of geographic region. Well, after an hour or so of downloading papers and checking affiliations I cobbled together the calculation.

I decided to basically use the same scoring mechanism as Dave. Each paper with more than 10 scitations, ie 11 or more, was worth 1 point. If there were multiple co-authors they each received a fraction of that point. Again, if an author had more than 1 affiliation I split their allocation accordingly.

Oh, and I did the calculation taking into account papers from 365 days prior to the 3rd of November. Clearly, the choice of time-period over which this calculation is done makes a big difference.

Now, before presenting a summary of these results I should point out that this was all done on the back of an envelope (actually, the reverse side of a printout of a paper) and isn’t necessarily accurate. While I was happy to waste my time to do this once, it wasn’t really worth checking the stats too thoroughly. Mostly, I was only interested in the broad trends that emerged and I think I counted accurately enough to establish those. But, please, don’t take any of this too seriously. I’m only publishing these stats as a discussion starter!!!

Of the 46 papers that I counted, 37 separate institutions were listed by authors as affiliations. Only 10 of those institutions received a score of 1 or more papers (remember if there were multiple co-authors the score for a paper would be fractional). The top 10 institutions were:

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So long and thanks for all the chips!

It’s been a really long time since I last posted here. Mostly, that’s because in the last few months I’ve been leading a rather nutzoid existence.

Some time back I posted that my contract in Bristol was ending and I was looking for work. Well, I went grant and postdoc hunting and eventually I decided to take an offer of a postdoc in Hannover in Reinhard Werner’s group.

Even since I made that decision I’ve been applying for visas, packing, throwing away loads of stuff, re-packing, throwing away more stuff, finding homes for various pieces of furniture and sending big boxes of stuff to various places. Oh, and there’s been leaving drinks like 15 billion times (or at least it feels like it).

Now I’m on my way to Germany (I’m actually writing this on the plane, I guess I’ll post it later) and it’s all suddenly much less about organizing and much more about doing. Doing is always a lot more exciting.

Somewhat weirdly the Lufthansa in-flight magazine has a feature on Bristol in it! They describe it as a "crazy, laid back" city. I think that somewhat paradoxical description fits pretty well. I doubt this needs to be said, most people that know me know that I’m going to really miss Bristol. I’ve made loads of really great friends and done so many wonderful things. I’ve been trying to think what I’ll miss most: Maybe bugging the guys in the office all the time with my incessant prattling? Having drinks with friends in ultra-hip or ultra-un-hip surrounds? The music and art? Good pie (and ale)?

Now, away from the reflective and back to the exciting. I’m (hopefully if the paperwork is sorted) starting my new job next week! It’s going to be interesting to adjust to another group’s style of working, hopefully I manage to do it quickly! I’m a little concerned that my skill set is very different to that of a lot of the people in the group, but I guess that just means that I’m gonna have to learn more (and hopefully I can teach the others some new tricks as well). Oh, and I’m gonna have to get a lot better at German!

In any case, the next few months are going to be very interesting. There’s going to be loads of challenges but there are also going to be heaps of opportunity to experience new things.

Oh, and at some point I might have to change the name of this blog. I need to think more about that.

Congratulations Dr Will

Yay! Will Matthews is now Dr Will Matthews. Congratulations Will!

A random new paper

Well, seeing as I work in the Bristol QI thoeory group I guess it was only a matter of time before I was an author on a paper which uses tricks involving random quantum states.

Below is the abstract for this new paper that I’ve written together with Caterina Mora and Andreas Winter.

Are random pure states useful for quantum computation?

We show the following: a randomly chosen pure state as a resource for measurement-based quantum computation, is – with overwhelming probability – of no greater help to a polynomially bounded classical control computer, than a string of random bits. Thus, unlike the familiar “cluster states”, the computing power of a classical control device is not increased from P to BQP, but only to BPP. The same holds if the task is to sample from a distribution rather than to perform a bounded-error computation. Furthermore, we show that our results can be extended to states with significantly less entanglement than random states.

For those of you who will be going to QIP in January you will see these results discussed alongside the results from this great paper by David Gross, Steve Flammia and Jens Eisert.

Where can I watch the election count bleg

Help! Are there any pubs in Bristol following the US election count tomorrow night?

Alternatively is anyone having a party that will have wifi and cable news?

Final day of the Spring School and Spring has sprung

As I mentioned in the Weakly Abstract post yesterday I’m currently attending the Quantum Information Processing Spring School here in Bristol.

One of the cool things about this meeting has been the venue. See that photo in the header of my blog? Well, the school is being hosted at the Burwall’s Centre for Continuing Education which is on the left hand side of the suspension bridge in the photo. The Burwall’s Centre is basically an old mansion overlooking the Avon Gorge which Bristol University has converted into a conference centre.

The view from up here is pretty spectacular especially today as Spring has finally decided to happen. Unfortunately I’ve left my camera at home but hopefully I can harass one of the students here to take a photo today so I can post it later…

Weakly Abstract: February 11 – February 15

It’s time for the second installment of the Weakly Abstract and I can already tell that this is going to be a hell of a job to get through every week. The last week saw some fantastic papers hit the quant-ph arXiv, here’s the Weakly Abstract shortlist:

  1. Stephen Jordan and Edward Farhi, Perturbative Gadgets at Arbitrary Orders.
  2. Julia Kempe, Oded Regev, Falk Unger, and Ronald de Wolf, Upper Bounds on the Noise Threshold for Fault-tolerant Quantum Computing.
  3. Ronald de Wolf, A note on quantum algorithms and the minimal degree of $\eps$-error polynomials for symmetric functions.

The world however is a harsh and cruel place so there can only be one Weakly Abstract per week, and because nepotism is such a powerful force (and also because this paper got the most scites on SciRate this week) I’ve chosen "Random Quantum Circuits are Approximate 2-designs" by Richard Low¬† and Aram Harrow:

Random Quantum Circuits are Approximate 2-designs
Authors: Aram Harrow, Richard Low

Given a universal gate set on two qubits, it is well known that applying random gates from the set to random pairs of qubits will eventually yield an approximately Haar-distributed unitary. However, this requires exponential time. We show that random circuits of only polynomial length will approximate the first and second moments of the Haar distribution, thus forming approximate 1- and 2-designs. Previous constructions required longer circuits and worked only for specific gate sets. As a corollary of our main result, we also improve previous bounds on the convergence rate of random walks on the Clifford group.

This paper is Richard (Rich) Low’s arXiv debut which is a massive achievement seeing as he has the misfortune of sharing an office with me. Now, because of this I get to try something that I’ve never really done before, I’m going to do an interview with Rich about the paper…

mick: Hi Rich.

Rich: Hello.

mick: Your paper is really long. Let’s say, hypothetically, that I couldn’t be assed reading the whole thing, and possibly couldn’t even be bothered to read my way through the abstract. What would you say is the take home message of your paper?

Rich: The title. Presumably you’ve read that.

mick: OK then, what is a quantum 2-design?

Rich: A state 2-design is an ensemble of states that looks uniformly random when you are only given two copies of the state.

mick: What is a unitary 2-design?

Rich: It’s an ensemble of unitaries that looks uniformly random given two copies of a unitary from the ensemble.

mick: OK, so what did you do again?

Rich: We showed that random circuits constructed from a 2-qubit universal gate set give approximate unitary 2-designs efficiently.

mick: So that really took 36 pages? I guess that at least this paper is shorter than Toby’s paper last week. So should we end this now and just drink our beer?

Rich: Yes.