Experiment
drorzel | July 6, 2011Today's Links Dump came late because I was at the meeting of the APS's Committee on Informing the Public. We apologize for the inconvenience, but I was too busy acquiring this critically important scientific data:
What is that, you ask? It's this:
That's the Superman roller coaster at the Six Flags America park outside of DC, which is where we're meeting this time. Lots of amusement parks do Physics Days as outreach programs, so we did the Physics Day thing ourselves, wearing ugly blue vests holding accelerometers on the major rides. Of course, the vest-mounted accelerometer I was wearing…
drorzel | July 5, 2011The fourth content area from my whirlwind overview of DAMOP is "traditional" AMO physics. This was the hardest to talk about in my talk, because I know it the least well, but ironically, that makes it really easy to write up here, because I don't have much to say about it.
Where the other areas were largely about using atomic, molecular, and optical physics to do stuff (simulating condensed matter systems, generating coherent x-rays, demonstrating cool quantum effects), this sub-sub-field is concerned with directly investigating the properties of atoms and molecules, usually by bouncing other…
drorzel | July 1, 2011Third of the five research categories within DAMOP that I talked about is Quantum Phenomena. This is a little bit of a catch-all, as there are a few different things going on in this area. They are all unified, though, by the fact that they end up making quantum mechanical effects manifest in some way, either as a means to an end, or just for the sake of showing that quantum mechanics is really weird.
What do I mean "making quantum mechanical effects manifest?" Basically, demonstrating one of the essential elements that I talked about last year: showing the wave nature of matter,…
drorzel | June 30, 2011The second in the DAMOP research categories I talked about is "Extreme Lasers," a name I was somewhat hesitant to use, as every time I see "Extreme [noun]," I get a flash of Stephen Colbert doing air guitar. It is, however, the appropriate term, because these laser systems push the limits of what's possible both in terms of the pulse duration (attosecond pulses are common, with 1as = 0.000000000000000001 s) and the pulse intensity (1014 W/cm2 is a typical order-of-magnitude, and some systems get much higher than that).
One of the main tricks for generating these ultra-short pulses is to do…
drorzel | June 29, 2011The first of the five categories of active research at DAMOP that I described in yesterday's post is "Ultracold Matter." The starting point for this category of research is laser cooling to get a gas of atoms down to microkelvin temperatures (that is, a few millionths of a degree above absolute zero. Evaporative cooling can then be used to bring the atoms down to nanokelvin temperatures, reaching the regime of "quantum degeneracy." This is, very roughly speaking, the point where the quantum wavelength of the atoms becomes comparable to the spacing between atoms in the gas, at which point the…
drorzel | June 28, 2011That's the title of my slightly insane talk at the DAMOP (Division of Atomic, Molecular, and Optical Physics of the American Physical Society) conference a couple of weeks ago, summarizing current topics of interest in Atomic, Molecular, and Optical Physics. I'll re-embed the slides at the end of this post, for anyone who missed my earlier discussion.
I put a ton of work into that talk, and had a huge amount of material that I didn't have time to include. I'd hate for that to go to waste, so I'm going to repurpose it for blog content over the next week or so. It'll probably be about a half-…
drorzel | June 17, 2011Alternate, More-Interesting Post Title: Attack of the Vampire Physicists.
I realized today that the only time I have been outside during daylight hours on this trip to Atlanta was during the brief walk down the platform to the airport entrance. This is only a little unusual for a DAMOP-- the Marriott Marquis is connected to a small mall by an enclosed walkway, so it was possible to leave the hotel and grab lunch in the food court without having to set foot outside. Other than that, I only left the hotel to go to dinner Tuesday and Wednesday, and that was on the late side, and hardly counts.…
drorzel | June 16, 2011One of the odd things about going to conferences is the unpredictable difference between talks and papers. Sometimes, when you go to a talk, you just get an exact repetition of what's in the paper; other times, you get a new angle on it, or some different visual representations that make something that previously seemed dry and abstract really click. And, of course, sometimes you get new hot-off-the-apparatus results that haven't made it into print yet.
Maddeningly, there doesn't seem to be any way to know in advance which of these things you're going to get from the title and abstract. It…
drorzel | June 14, 2011That's the title of my talk this morning at DAMOP, where I attempt the slightly insane feat of summarizing a meeting with over 1000 presentations in a single 30-minute talk. This will necessarily involve talking a little bit like the person reading the legal notices at the end of a car commercial, and a few of the guide-to-the-meeting slides will have to flash by pretty quickly. Thus, for the benefit of those who have smartphones and care about my categorization of talks, I have put the slides on SlideShare in advance, and will embed them here:
What's So Interesting About AMO Phyiscs?…
drorzel | June 13, 2011You may or may not have noticed that I've been making a concerted effort to do more ResearchBlogging posts explaining notable recent results. I've been trying to get at least one per week posted, and coming fairly close to that. I've been pretty happy with the fake Q&A format that I've settled into, and while they're time-consuming to write, they're also kind of fun.
This past week, alas, was kind of brutal, as I was doing a ton of reading in preparation for my DAMOP talk tomorrow, which, in retrospect, is kind of insane, and SteelyKid's day care being closed for two days didn't help (…
drorzel | June 7, 2011I have to admit, I'm writing this one up partly because it lets me use the title reference. It's a cool little paper, though, demonstrating the lengths that physicists will go to in pursuit of precision measurements.
I'm just going to pretend I didn't see that dorky post title, and ask what this is about. Well, it's about the trapping and laser cooling of thorium ions. They managed to load thorium ions into an ion trap, and use lasers to lower their temperature into the millikelvin range. At such low temperatures, the ions in the trap "crystallize."
So, they've demonstrated that if you get…
drorzel | June 3, 2011It's been a long and brutally busy week here, so I really ought to just take a day off from blogging. But there's a new paper in Science on quantum physics that's just too good to pass up, so here's a ReasearchBlogging post to close out the week.
Aw, c'mon, dude, I'm tired. What's so cool about this paper that it can't wait until next week? Well, the title kind of says it all: they measured the average trajectories of single photons passing through a double-slit apparatus. By making lots of repeated weak measurements at different positions behind the slits, they could reconstruct the average…
drorzel | May 27, 2011The big physics story of the week is undoubtedly the new limit on the electric dipole moment (EDM) of the electron from Ed Hinds's group at Imperial College in the UK. As this is something I wrote a long article on for Physics World, I'm pretty psyched to see this getting lots of media attention, and not just from physics outlets.
My extremely hectic end-of-term schedule and general laziness almost make me want to just point to my earlier article and have done with it. But really, it's a big story, and one I've been following for a while, so how can I pass up the chance for a ResearchBlogging…
drorzel | May 26, 2011As I've mentioned before, I'm schedule to teach a class on "A Brief History of Timekeeping" next winter term as part of the Scholars Research Seminar program. Even though I have a hundred other things to do, I continue to think about this a lot.
One of the goals of the course is to introduce students to the idea of doing research. This was primarily conceived as a humanities/ social sciences sort of thing, so most of the discussion I've seen about these has been in terms of library research. Of course, as a physicist, I very rarely need to look things up in the library. when I think about…
drorzel | May 24, 2011I'm teaching our upper-level lab course this term, where I do a two-part experiment on laser spectroscopy. The first part is to calibrate the free spectral range of a homemade Fabry-Perot interferometer, and the second part is to use that Fabry-Perot as a frequency marker to calibrate a diode laser scan across the rubidium hyperfine spectrum, allowing a measurement of the Rb ground-state hyperfine splitting.
That's a bunch of jargon, the details of which don't really matter. What matters is that this is a lab that involves scanning the frequency of a particular laser through some range of…
drorzel | May 16, 2011Several years ago, now, a group at Penn State announced a weird finding in helium at extremely low temperatures and high pressures (which is what you need to make helium solidify): when they made a pendulum out of a cylindrical container with a thin shell of solid He toward the outside edge, twisting about its axis, they saw a small but dramatic change in the oscillation frequency as they cooled the system below a particular temperature. They interpreted this as a "supersolid" phase of helium, with a quantum phase transition taking place that caused the "supersolid" to stop rotating with the…
drorzel | May 5, 2011NASA held a big press conference yesterday to announce that the Gravity Probe B experiment had confirmed a prediction of General Relativity that spacetime near Earth should be "twisted" by the Earth's rotation. A lot of the coverage has focused on the troubled history of the mission (as did the press conference, apparently), but scientifically it's very impressive.
The shift measured is very, very small-- 0.04 arcseconds over the course of a year, or 0.000011 degrees-- but agrees nicely with the predictions of relativity. I'm not sure whether to try to work this into the book-in-progress as I…
drorzel | May 4, 2011It's been a hectic day here, so I haven't had time to do any substantive blogging. I did want to quickly note a couple of stories presenting marked improvements in experiments I've written up here in the past:
1) In the "self-evident title" category, there's Confinement of antihydrogen for 1000 seconds, which extends last year's antihydrogen trapping to times a factor of 6000 longer than the previous record. That's very good, and a good sign for plans to do precision spectroscopy and other such experiments. As always, Physics World offers a nice write-up.
2) As noted in the comments of Monday…
drorzel | May 2, 2011Last summer, there was a fair bit of hype about a paper from Mark Raizen's group at Texas which was mostly reported with an "Einstein proven wrong" slant, probably due to this press release. While it is technically true that they measured something Einstein said would be impossible to measure, that framing is a little unfair to Einstein. It does draw media attention, though...
The experiment in question involves Brownian motion, and since I had to read up on that anyway for something else, I thought I might as well look up this paper, and write it up for the blog.
OK, so what did they do that…
drorzel | April 26, 2011This paper made a big splash back in November, with lots of news stories talking about it; it even made the #6 spot on Physics World's list of breakthroughs of the year. I didn't write it up then because I was hellishly busy, and couldn't take time away from working on the book-in-progress to figure out exactly what they did and why it mattered. I've got a little space now between handing the manuscript in last week and starting to revise it (probably next week), so while it's a bit late, here's an attempt at an explanation of what all the excitement was about.
So, what's this about, anyway?…