Physics News Round-Up

I've been collecting a bunch of little news squibs from the IoP and the APS over the last week or so, and I keep saying that I'm going to do a nice long post explaining each of the experiments. And my actual job keeps eating my life, what with candidate interviews, committee meetings, class prep, and lab set-up. And, of course, those news items are becoming less current with every passing day...

In lieu of a lengthy and detailed explanation of each, then, here's a short list of physics stories that have caught my eye. If there's a great clamor for a more detailed explanation of any of these, I'll try to put one together over the weekend. For the moment, I have to go do a lab about the boring old photo-electric effect, while you can click through to read about single photon data storage, new advances in quantum computing, and signals travelling backwards in time (maybe)...

• We'll start with a slightly garbled press release and a much clearer news story regarding an experiment at Rochester using "slow light" to store image information with single photons. The description is a little confusing, because the images shown are actually the sum of many single-photon detections-- a single photon does not make the "U" pattern shown in the picture. At least, I don't think it does...
• Coherence* has links to two interesting experiments, the first of which is a new development in linear optics quantum computation. The idea here is that they've run some quantum algorithms in a system using nothing but beamsplitters, polarizers, and waveplates, and they've implemented a "feed-forward" system to speed up the results. It sounds cool, but I'll need to take a look at the actual paper (in Nature, who are bastards about online access) for this one, because the press summary is hopeless.
• Also via that Coherence* post, a proposed experiment to look for "retrocausailty" by sending correlated photons through two double-slit set-ups at different times. The idea is to have one photon of an entangled pair hit a detector that will either show a particle pattern or a wave pattern, depending on its position, and show that the other particle of the pair produces the same result. The twist is that the second particle hits first-- the plan is to delay the measurement that makes the particle/ wave determination until after the measurement of the correlated photon, and see what happens. According to the "Transactional Interpretation" favored by John Cramer, there should be a signal travelling backwards in time to determine the result of the earlier measurement, and this might be a way to test that.
• Just for completeness, let me note a Physics Web news story about an experiment I mentioned here a while back, looking at the quantum statistics of atoms. This is great stuff.