Postdoc with some awesome Canadian quantum researchers:
Quantum Information Processing Program
JUNIOR (POSTDOCTORAL) FELLOWSHIPS
The Canadian Institute for Advanced Research (CIFAR) is a private not-for-profit research institute. It is a catalyst for discovery, incubating ideas that revolutionize the international research community. CIFAR identifies emerging fundamental research questions concerning society, technology and the very nature of humanity and the universe, and creates interdisciplinary networks of leading scholars from around the world to explore them in a way that is unparalleled elsewhere.
CIFAR's Quantum Information Processing Program is seeking outstanding researchers to fill two Junior Fellow positions (i.e., postdoctoral fellowships). One position will begin as soon as is convenient for the successful candidate and will run through summer 2010. The other position will begin in fall 2009 and will last two years.
The Quantum Information Processing Program studies a wide range of topics relating to quantum information, an interdisciplinary field combining quantum mechanics with computation and information theory. The program includes researchers investigating experimental and theoretical physics, theoretical computer science, and mathematical aspects of quantum information. Program members in Canada are listed below.
CIFAR's new Junior Fellow Academy is an initiative designed to cultivate new generations of research leaders. This program is targeted to individuals who have demonstrated outstanding scholarship and research potential and have recently completed a Ph.D. degree. Junior Fellows will be fully integrated into an appropriate CIFAR research program, and will also participate in a virtual 'Academy', bringing them together with their peers from across all of the Institute's programs. In this setting, they will enjoy opportunities for peer networking, mentorship and career development through specially organized activities and events.
Interested candidates should apply on-line at http://www.iqc.ca/positions/postdoc-cifar/application.php?t=1. The application should include a CV (including list of publications), a research statement, and names of up to 3 potential supervisors. Eligible supervisors must be members of the CIFAR QIP program and should normally be located in Canada, although other arrangements will be considered in exceptional cases. Applicants should also provide names and e-mail addresses of 3-4 referees (at least 3 must not be CIFAR program members). Acceptable formats for submitted documents are .doc, .pdf, .odt, .html and .txt.
To receive full consideration, applications must be received by Wednesday, December 10th, 2008, although later applications will be accepted until the positions are filled.
It's great to have research institutions still devoted to fundamental questions in physics but also the relation to society. Let me put in a pitch here for my pals over at Backreaction, affiliated with the Perimeter and Lightcone Institutes (the former mentioned post just below.) Read any of "Bee's" fabulous essays and you see this woman has a mind and interdisciplinary vision like CP Snow or Carl Sagan.
Well, speaking of quantum mechanics and "fundamental questions", I have one about as fundamental as it gets. (Similar wording at Uncertain Principles on Zeilinger.) Leaving aside debate about how to interpret "collapse of the wave function" etc., I wonder: Given a case of a beam splitter, like MZ interferometer etc, why doesn't the first beam splitter "collapse" the WF? I mean, what is special about "detectors" versus "half-silvered mirrors"? If we have black spots at the other end of the MZ, we figure the light finally "hit" as photons. But the wave didn't just go one way versus the other at the BS (because we can get interference later.) And like I said, the distinction between the two sorts of interaction is not to be confused with what you think collapse ultimately is. Also, and given a BS versus "black patches," this is not directly about "observers" in the sentient sense.
More ruminations at my blog.
@Neil B: since the photon is not absorbed by the beam splitter*, the only way it interacts with the beam splitter is by imparting momentum dp upon reflection. However, the beam splitter (plus the optical table it is bolted to) is so heavy that the dp does not put the beam splitter in an orthogonal quantum state. Therefore, to excellent approximation, the beam splitter remains in a separable state with respect to the photon.
*If it is, we don't care about this event because there is no detector click.
Actually, Pieter, it's not quite that simple because we could use a very light BS if we wanted - I am not trying to get interference later in this case, just "imagining" whether the photon splits. But since I couldn't get interference then to prove the splitting of the WF, maybe that's why it would get split in such a case. But how would we tell the difference? Now we have to say, we don't know if the WF "really" split or not? (Abstraction upon abstraction ....)
Neil, I am not quite sure what you're getting at. If the beam splitter is light enough, indeed you get entanglement between the photon and the beam spliter, and the single-photon interference will be reduced (or disappears altogether). The photon will be correctly described by a mixed state (resulting from tracing out the state of the beam splitter). The "wavefunction" is still split, but now it is a statistical mixture of reflection and transmission.
As for how to tell the difference, you have to specify a measurement procedure. If quantum information has taught us anything about the interpretation of quantum mechanics, it is that we need to be very careful to only make statements that have an operational meaning.