Teh AMO hottness

I should probably sneak in a few posts before Chad gets back. It's been a hectic week, as the time came for my current experiment (as it does for all experiments) where one stops futzing around trying to make things better, and takes the actual data, with an eye to moving on. This means that you want good, clean runs with lots of attention to detail (as opposed to the semi-qualitative exploration of parameter space, when you're first seeing an effect), and the first thing life-wise that suffers during this phase is blogging.

But the second-worst blog post in the world is the why haven't I blogged post, so I'll shut my trap. An astro friend of mine asked me to post on what I think is really cool in atomic physics these days, which is just too huge of a task to do exhaustively, but I'll throw out some stuff off the top of my head. I'm sure I'll forget some wildly important subfield, but I haven't had my coffee yet and I'm trying to beat Aaron to the next post.

First of all, atomic physics has to a large degree become dominated by the cold atom scene, and one major thrust of that scene is the study of cold atoms into optical lattices. I posted briefly about this stuff before, but the whole concept is one large bridge over to the condensed-matter world: an optical crystal with band structure and site-to-site phase coherence is yowza interdisciplinary, and not just in a use-interdisciplinary-to-get-money way. The windows lattices are giving us into quantum behaviour are simply astounding, from observing single-atom superposition in double-well lattices to quantum gates (mentioned before) and second-order tunnelling. (Full disclosure: there's some own-group-promotion there.) The traditional CM notion of the Mott insulator zero-temperature phase transition, for example, is a current hotbed of neutral atom optical lattice investigation, as is the idea of using neutrals in a lattice to simulate classically intractable quantum Hamiltonians.

Optical frequency standards and clocks are really hitting their stride now, and the idea of a part in 10^18 stability is not crazy at all. As usual the folks in Colorado are leading the way; an example of the work is here. I don't see the day approaching anytime soon when the cesium standard at 9 GHz is going to be replaced; if any field has inertia, it's fundamental unit definition. Maybe in twenty years or so. For a cool exploration of some of the consequences of such good stability, here's a cool article from Physics Today by Dan Kleppner of MIT.

There's also strong movement away from classic (10-year-old!) techniques of trapping to so-called "atom-chip" based experiments, where the trapping fields for cold atoms are generated not by big ol' coils or lasers shining into the cell, but by in-vacuum current-bearing wires combined (perhaps) with strong radiofrequency dressing. It's a great step to miniaturization and simplification (depending on how you think of simple). Doing macroscopic quantum superposition experiments, for example, becomes much more doable when you move to the chip scale.

They get a lot of publicity, so I won't say too much about the quantum-information advances in cavity QED and trapped ions, but suffice to say these subfields show no sign of slowing down.

How could I forget fermions? The other huge bridge to condensed-matter physics is a hotbed of activity these days, from people studying phase separation and superfluidity of degenerate Fermi gases (see here , here, and here) to work putting fermions in optical lattices (an example here). You can also put them on atom chips! As much of a boson fellow that I am, I suspect there's going to be a lot of insight in the next five years coming from the fermion scene, both macroscopic and lattice-based. The large fellow in the corner is high-Tc superconductivity. Please ignore him.

So what did I leave out that's also cool? Polar molecules and Rydberg atoms are hot right now, as is the cooling of mesoscopic oscillators to the quantum regime; the study of Bose gases in 2D has also seen significant flurries of work lately. And I would be remiss if I didn't mention that precision measurements, particularly the recent work further refining alpha and the electron magnetic moment, never cease to amaze me.

Please, please forgive me if I did not link to your research group or forgot to mention your subfield. This review was very off-the-cuff.