Physics News Backlog

Every day, a handful of physics news items pass through my RSS feeds, and every few days, one of them looks interesting enough that I check the little box to keep it unread, so I can comment on it later (I don't blog from work if I can avoid it). Of course, most of the time, I don't get around to commenting, so these press releases and news squibs tend to pile up.

It's starting to get a little silly, so I'm going to clear them out, and post a brief comment about each one, and why I thought it looked interesting here. This probably tells you something about the state of the field, but mostly, it tells you what sort of stuff catches my eye when I'm not writing silly things about the dog.

Optical lattices could give insight into QCD. One of the standard applications mentioned for quantum computers is "simulation of other quantum systems," and this is sort of in the same spirit. Qunatum Chromo-Dynamics is the theory of interactions between quarks, and is notoriously difficult to work with. The idea described here is to simulate the interactions between quarks using cold neutral atoms in an optical lattice (a collection of lasers arranged so as to trap atoms in a regular array of little interconnected traps). By adjusting the internal states of the atoms and the properties of the lasers, you can apparently arrange to have effective interactions between atoms that look like QCD.

Of course, nobody has actually done this, but it looks like a cool idea. Also, I've done some experiments with atoms in optical lattices, so I always like to see clever applications of that idea.

Entanglement dies a sudden death. One of the major roadblocks in the way of making a working quantum computer is the fact that quantum algorithms rely on superpositions of the possible states of the "bits" in the computer, and those superpositions are extremely fragile. There are things you can do to correct for the errors introduced by the collapse of these superpositions, but the best solution would be to not have the collapse happen in the first place, which requires an understanding of what, exactly, leads to the collapse.

This story describes an experiment in Brazil that looked at entanglement between pairs of photons by subjecting them to interactions designed to preferentially affect vertically polarized photons. They then looked at correlations between the polarization states of the two photons, and found that the correlations went away faster when there was more vertical polarization, more or less as they expected. It's not going to produce a quantum computer in the next year, but correlated photon experiments are always cool.

Laser-trapping of rare element gets unexpected assist. This story describes an experiment at Argonne National Lab to laser cool and trap atomic radium, which is noteworthy because radium is famously unstable. It's also the heaviest element ever trapped (edging out its neighbor on the periodic table, francium).

The goal here is to find out more about the atomic structure of radium, which is incredibly difficult to calculate and measure, and thus not that well known. These measurements may be useful for precision tests of symmetry violation, which are another one of those laboratory tests of physics beyond the Standard Model that I'm always going on about.

This is also interesting because I know the guys who did the experiment. This is the research group of Zheng-Tian Lu, who developed the single-atom trapping background measurement technique that I'm trying to get running in my lab.

Chilling out with polaritons. This describes a porposal for a way to laser cool semiconductors. Unfortunately, it relies on something to do with "polaritons," which are one of those quasi-particle excitations that solid state physicists are always dealing with, and I've never completely understood that stuff. It's interesting because, hey, laser cooling a solid object, but I don't understand the details well enough to work through the implications.

Fermions pair up without superfluidity. Probably the hottest topic in AMO physics in the past few years has been the study of BEC/ BCS physics, in which fermionic atoms are induced to pair up, and the pairs (which now look like bosons) form a Bose-Einstein condensate. This is analgous to what happens with electrons in a superconductor, and is of obvious interest to condensed matter theorists.

This story describes an experiment from the Ketterle group at MIT that found something really weird. People had thought that the pairing and the condensing were very tightly linked, and you couldn't get one without the other, but the Ketterle group found that in a particular mixture of spin states, they got atoms pairing up without a condensate forming (they can measure the two effects independently). This is... odd.

This is a cool experiment because it comes out of the Ketterle Empire, and they always do impressive work. Also, anything that surprises theorists is Good.

The longest carbon nanotubes you've ever seen. The headline pretty much says it all: a group at the University of Cincinnati has created carbon nanotubes that are 900,000 times longer than they are wide. Of course, that still only adds up to a couple of centimeters, but that's a single molecule two centimeters in length.

Really, if I have to explain why that's cool, you should be reading some other blog.

Pitt researchers create new form of matter. How many is that, now?

This is another paper that involves "polaritons." I just flagged it because I'm always amused by claims of new forms of matter.

Physicists exploit ultra-cold gases to measure ultra-small magnetic fields. This describes work from Berkeley in which Dan Stamper-Kurn's research group used a rubidium BEC as a magnetic field sensor, analogous to a SQUID (Superconducting Quantum Interference Device-- not a cephalopod). They managed to measure a tiny magnetic field with extremely high spatial resolution, which is of interest to all sorts of people. (Though Dan is quoted as saying "This finally delivers on the promise of using Bose-Einstein condensed atoms for precision measurement," which might be pushing things a little...).

This is another paper that's of interest largely because I know the people involved. Dan got his Ph.D. at about the same time I did, in the Ketterle group at MIT, and he's a good guy with a really deadpan sense of humor. Also, he's scary smart.

And that's the past month's worth of flagged articles that I didn't get around to commenting on. In an ideal world, this wouldn't be a recurring feature, but odds are good that you'll see a similar press release dump in a month or two...