Archive for the ‘Meetings’ category

von Neumann celebrations

6th October 2007

I think I might have mentioned before that von Neumann is a bit of a hero of mine.  I transferred my affections from Feynman as soon as I was old enough to realize how much exaggeration must be involved in the “Surely you’re joking” stories.  Sure, von Neumann may have made a mistake about hidden variable theories, but we are talking about a guy who gave us the first rigorous formulation of quantum theory, made major contributions to game theory and invented the modern computer architecture, so I’m willing to cut him some slack on that point.

Anyway, I thought I’d just mention the workshop at Princeton to mark 50 years since von Neumann’s death and 75 years since the publication of his book on quantum theory.  Looks like there were many interesting talks.

Foundations Summer School: Apply Now!

12th March 2007

Just a short note to let you know that the application form for the Perimeter Institute Quantum Foundations Summer School is now available online from here. The application deadline is 20th May.

Update: I should have mentioned that for successful applicants who are grad students all expenses will be paid by Perimeter. That should make it easier to persuade your advisor to let you go. You don’t have to be an expert on foundations and we are hoping that students studying a wide variety of areas of Physics will attend.

Update 2: Whether non-students, e.g. postdocs, will be allowed to attend is still an open question. I’m waiting to hear more about this from the organizers. Clearly, the priority for a summer school has to be grad students, so I would speculate that it will depend on the number and quality of applications that we get. I’m just guessing at the moment though and I’ll post another update once I hear the official word.

Update 3: I have just heard that there will be up to 10 places will be made available at the summer school for postdocs and junior faculty.

Foundations at APS, take 2

6th March 2007

It doesn’t seem that a year has gone by since I wrote about the first sessions on quantum foundations organized by the topical group on quantum information, concepts and computation at the APS March meeting. Nevertheless it has, and I am here in Denver after possibly the longest day of continuous sitting through talks in my life. I arrived at 8am to chair the session on Quantum Limited Measurements, which was interesting, but readers of this blog won’t want to hear about such practical matters, so instead I’ll spill the beans on the two foundations sessions that followed.

In the first foundations session, things got off to a good start with Rob Spekkens as the invited speaker explaining to us once again why quantum states are states of knowledge. OK, I’m biased because he’s a collaborator, but he did throw us a new tidbit on how to make an analog of the Elitzur Vaidman bomb experiment in his toy theory by constructing a version for field theory.

Next, there was a talk by some complete crackpot called Matt Leifer. He talked about this.

Frank Schroeck gave an overview of his formulation of quantum mechanics on phase space, which did pique my interest, but 10 minutes was really too short to do it justice. Someday I’ll read his book.

Chris Fuchs gave a talk which was surprisingly not the same as his usual quantum Bayesian propaganda speech. It contained some new results about Symmetric Informationally Complete POVMs, including the fact that the states the POVM elements are proportional to are minimum uncertainty states with respect to mutually unbiased bases. This should be hitting an arXiv near you very soon.

Caslav Brukner talked about his recent work on the emergence of classicality via coarse graining. I’ve mentioned it before on this blog, and it’s definitely a topic I’m becoming much more interested in.

Later on, Jeff Tollaksen talked about generalizing a theorem proved by Rob Spekkens and myself about pre- and post-selected quantum systems to the case of weak measurements. I’m not sure I agree with the particular spin he gives on it, especially his idea of “quantum contextuality”, but you can decide for yourself by reading this.

Jan-Ake Larrson gave a very comprehensible talk about a “loophole” (he prefers the term “experimental problem”) in Bell inequality tests to do with coincidence times of photon detection. You can deal with it by having a detection efficiency just a few percent higher than that needed to overcome the detection loophole. Read all about it here.

Most of the rest of the talks in this session were more quantum information oriented, but I suppose you can argue they were at the foundational end of quantum information. Animesh Datta talked about the role of entanglement in the Knill-Laflamme model of quantum computation with one pure qubit, Anil Shaji talked about using easily computable entanglement measures to put bounds on those that aren’t so easy to compute and finally Ian Durham made some interesting observations about the connections between entropy, information and Bell inequalities.

The second foundations session was more of a mixed bag, but let me just mention a couple of the talks that appealed to me. Marcello Sarandy Alioscia Hamma talked about generalizing the quantum adiabatic theorem to open systems, where you don’t necessarily have a Hamiltonian with well-defined eigenstates to talk about and Kicheon Kang talked about a proposal for a quantum eraser experiment with electrons.

On Tuesday, Bill Wootters won a prize for best research at an undergraduate teaching college. He gave a great talk about his discrete Wigner functions, which included some new stuff about minumum uncertainty states and analogs of coherent states.

That’s pretty much it for the foundations talks at APS this year. It’s all quantum information from here on in. That is unless you count Zeilinger, who is talking on Thursday. He’s supposed to be talking about quantum cryptography, but perhaps he will say something about the more foundationy experiments going on in his lab as well.

Dates for your diary

20th February 2007

Update: I am informed that the Oxford Everett meeting will be in the summer rather than in September and is invitation only.  Also, there will be a Symposium on the Foundations of Modern Physics in Vienna 7th-10th June.  Registration for that is open until the end of March.

I haven’t been contemplating too many quantum quandaries recently because I was away at a workshop on Operator Structures in Quantum Information in Banff (a very interesting meeting and a highly recommended location) and am currently visiting Caltech. My brain is mostly full of mathematics and non-foundations oriented physics. In the meantime, here are some interesting foundations events coming up this summer.

Firstly, Perimeter Institute is organising its first Summer School on Quantum Foundations August 27th-31st. There have been several summer schools in other locations in the past, which have mostly been philosophy/interpretations oriented. The PI School will have a distinctly “physics” flavor, e.g. it will include lectures on experiments amongst other things. I’ve seen the list of speakers and it looks like it’s going to be really interesting. For grad students and postdocs interested in foundations, summer schools are highly recommended because of the sparsity of experts in the subject at most institutions. It’s how I became reasonably competent in the subject at any rate. Please don’t write to me requesting further details because I can’t help you. All the information is going to be posted on your favorite quantum websites/mailing lists very soon. Alternatively, you’ll be able to get to the school website via this link once it is up and running.

Secondly, the Institute for Quantum Computing and Perimeter are jointly running a series of quantum oriented workshops this summer under the banner Taming the Quantum World. There’s lots of interesting events for quantum information folks, so check out the website, but the workshop on Operational Quantum Physics and the Quantum-Classical Contrast, June 4th-7th, organized by Paul Busch and Lucien Hardy will be of special interest to readers of this blog.

Since I’m plugging foundations meetings at my own institutions, I should also mention Many Worlds at 50, organized by Jonathan Barrett, Adrian Kent and David Wallace, taking place September 21st-24th.

Given the number of meetings in Waterloo this year, it is somewhat surprising that the foundations community has also found time to organise some events at other locations. Here’s the rundown of the rest:

– March 5th-9th: APS March Meeting, Denver – Two focus sessions on quantum foundations have been organised.

– March 29th-31st: 15th UK and European Meeting on the Foundations of Physics, Leeds.

– April 13th-15th: New Directions in the Foundations of Physics, Maryland. It’s invitation only (and full) I’m afraid.

– June 11th-16th: Quantum Theory: Reconsideration of Foundations 4, Vaxjo.

– July 2nd-13th: Operational probabilistic theories as foils to quantum theory, Cambridge. It’s invitation only (and full).

– Sometime in September: Everett at 50, Oxford.

If I’ve missed any meetings or you have any new info on any of these then please leave a comment.


24th September 2006

Here’s what this year’s foundational conference calendar looks like at the moment:

  • November 2-5: PSA 2006, Vancouver, Canada. This is the Biennial meeting of the Philosophy of Science Association and there are a few sessions on quantum theory.
  • November 28 – December 3: QCMC 2006, Tsukuba, Japan.  This is really a quantum information, computation and optics meeting, but there are often a few talks relevant to foundations.
  • March 5-9: APS March Meeting 2007, Denver, Colorado.  The Topical Group in Quantum Information organized special sessions on the foundations of quantum theory last year, so I imagine it won’t be a major focus this time round.  However, I haven’t seen the list of sessions for this year yet, it’s a good opportunity to find out what’s going on in the rest of physics, and at least there will be some quantum information.
  • March 26-28: Quantum Interaction, Stanford, USA.  This is a bit of an oddball meeting aimed at applying ideas from QM to Artificial Intelligence.
  • March 29-31: 15th UK and European Meeting on the Foundations of Physics, Leeds, UK.  With a special session on quantum information.
  • April: Operational Probabilistic Theories as Foils to Quantum Theory, Cambridge, UK.  This one is an invitation only 2-week event, so please don’t write to the organizers asking to come or they will get very annoyed with me.
  • June 11-16: Quantum Theory: reconsideration of foundations-4: The 80 years of the Copenhagen Interpretation, Vaxjo, Sweden.  This will be the last in this conference series.  Apparently, you can only reconsider the foundations so many times.  No info on the website yet, but it will probably appear soon.
  • I haven’t seen any official announcements yet, but apparently there will be TWO meetings in celebration of 50 years since the publication of Everett’s paper on the relative state interpretation of QM, better known as many-worlds, one at Perimeter Institute and one at Oxford University.

If anyone knows of any other relevant meetings then please let me know and I’ll post an update.

Vaxjo Meeting

13th June 2006

I returned this weekend from the meeting on Foundations of Probability and Physics at the University of Vaxjo in Sweden. There were many interesting talks, so I'll just mention a few of them that I found particularly inspiring.

Giacomo Mauro d'Ariano explained his axiomatization of quantum theory, inspired by observations from quantum state and process tomography. One of the nice features of this is that he gives an operational definition of the adjoint. Why the observables of QM should form an algebra from an operational point of view has been a topic of recent debate amongst foundational people here at Perimeter, so this could be a piece of the puzzle.

Rüdiger Schack explained what it might mean for quantum randomness to be "truly random" from a Bayesian point of view, using the concept of "inside information" that he has developed with Carlton Caves.

Philip Goyal gave another axiomatization of quantum theory. I'm not sure whether the framework he uses is that well-motivated (especially the sneaky way that complex numbers are introduced). On the other hand, one of his axioms has the flavor of an "epistemic constraint", which gels nicely with ideas that have been expressed earlier by Chris Fuchs and Rob Spekkens.

Joseph Altepeter gave another excellent talk about the state of the art Bell inequality experiments currently going on in Paul Kwiat's group.

John Smolin outlined speculative ideas that he and Jonathan Oppenheim have developed that applies the concept of locking quantum information to solve the black hole information loss problem. 

Foundations Spring/Summer 2006

19th March 2006

Here’s my list of the highlights of the conference season for foundations this year:

Personallly, I’ll definitely be at Vaxjo, Malta and Tsukuba, so I’ll see you there if you’re going.

Foundations at APS

14th March 2006

I’m currently at the APS March Meeting, where there were two sessions on Quantum Foundations on Monday. I am pleased to report that they were well attended. Hopefully, this marks the start of an increased involvement of the APS in the field.

The second session was particularly interesting, so here’s a short summary of what we heard:

  • Invited speaker Lucien Hardy outlined his Causaloid framework for general probabilistic theories without a fixed background causal structure. It is hoped that this might lead to a new path for developing a theory of quantum gravity.
  • Chris Fuchs gave a shortened version of his usual talk, focussing on the role of symmetric informationally complete POVMs in his approach to quantum foundations.
  • Terry Rudolph presented an extension of Rob Spekkens’ toy theory for dealing with continuous variable theories. This has lots of features in common with QM, but has a natural hidden variable interpretation, being a resticted version of Liouville mechanics.
  • Rob Spekkens showed how two seemingly different notions of “nonclassicallity”, nalely negativity of peseudo-probability distributions and the impossibility of a noncontextual hidden variable theory, are actually the same within the new approach to contextuality that he has developed.
  • Nicholas Harrigan outlined an approach to quantifying contextuality that he has been developing with Terry Rudolph.
  • Joseph Altepeter, from Kwiat’s group, gave an interesting presentation on their current state of the art photonic Bell inequality experiments.
  • OK, I have to admit that I was getting tired at this point and skipped out for a talk, so I have no idea about the next talk. Apologies to Giuliano Scarcelli.
  • There then followed two talks about decoherence from Diego Dalvit and Fernando Cucchietti, collaborators of Zurek and Paz respectively. This is an important topic for many interpretations of QM and the results looked solid. However, I’m not an expert on this stuff.
  • Ruth Kastner, who was due to deconstruct the now famous Ashfar experiment, was unfortunately unable to attend due to illness, but Ashfar was here to give his side of the story instead. The experiment is interesting at least because it has made quite a few physicists think about complimentarity and foundations in general a bit more deeply. Personally, I agree with Kastner’s analysis, but Ashfar disputes it.
  • Jeff Tollaksen outlined a new way of measuring the “weak values” introduced by Aharonov and collaborators. I didn’t follow the details of the construction, but look forward to reading the paper.
  • Caslav Brukner outlined his work with Zeilinger on an “information based” approach to quantum foundations. It’s not my personal favourite amongst such approaches, but gave plenty of food for thought.

Well, foundations at this meeting are pretty much finished after that. There are still a few interesting quantum information sessions before the end of the week, but I can leave other bloggeurs to deal with that.

Support the APS topical group

22nd December 2005

As you may know, the American Physical Society has recently opened a topical group on Quantum Information, Concepts and Compuation, which covers the foundations of quantum mechanics within its remit (under the “concepts” heading I suppose).  There will be a special session on the Foundations of Quantum Theory at the APS March Meeting in Baltimore this year.

Although the abstract submission deadline has passed, I’d like to encourage everyone involved in quantum foundations to attend.  The APS has not always looked favourably on foundational studies and it has been difficult to get foundations papers published in their journals in the past.  The topical group could open the way for a new era of respectability for the subject within the APS, so making sure that the special session is well attended seems like a very good idea to me.  In any case, besides the political point, the talks are bound to be interesting.