Experiment
drorzel | May 4, 2009I'm an experimentalists through and through, and have always known better than to attempt real theory. On two occasions, though, I've been forced to do a little bit of computer simulation work in order to interpret my results. One of these was for the time-resolved collisions experiment, and worked out well. The other was when I was a post-doc, and was... less useful.
The situation we were dealing with in my post-doc work was a Bose-Einstein condensate of rubidium that we chopped into several pieces with an optical lattice. Whenever you do this, there is necessarily some uncertainty in the…
drorzel | May 1, 2009Like Sauron creeping into Dol Guldur, Quantum Diaries has returned to darken the blogosphere once more, driving Tommaso Dorigo before it--
Oh, wait. More good science blogs is a good thing, not a creeping menace. Even if they are particle physicists.
Anyway, in a move that is unrelated to the return of Quantum Diaries, and, in fact, happened two weeks ago, Tommaso Dorigo, a survivor of the original Quantum Diaries, has closed up shop and moved to ScientificBlogging.com. Had I known he was thinking of moving, I would've pushed the Corporate Masters to invite him to ScienceBlogs so we could…
drorzel | April 20, 2009A couple of physics stories in the last few days have caught my attention for reasons that can be lumped together under the Vizzini Effect-- that is, they say things that involve unconventional uses of common words. Take, for example, the Physics World story Physicists distinguish between the indistinguishable, which starts off:
Spurred on by their work on building one of the world's most accurate atomic clocks from strontium-87 atoms, researchers in the US have now discovered that "forbidden" collisions can occur between these atoms.
Strontium-87 atoms belong to a class of objects known as…
drorzel | April 17, 2009Via the arxiv Blog, a review article has been posted by the Haensch group with the title"Testing the Stability of the Fine Structure Constant in the Laboratory." The fine structure constant, usually referred to by the symbol α is a ratio of fundamental constants-- the electron charge squared divded by Planck's Contant times the speed of light (e2/hc)-- and usually assumed to be constant. Some beyond-the-Standard-Model theories of physics, though, include effects that could cause this ratio to change over time.
For this reason, people have been looking to see if the fine structure constant is…
drorzel | April 16, 2009Physics World has a nice news article about a new experimental development in quantum computing, based on a forthcoming paper from the Wineland group at NIST in Boulder. I'd write this up for ResearchBlogging, but it's still just on the arxiv, and I don't think they've started accepting arxiv papers yet.
The Physics World piece summarizes the key results nicely:
Now, Brad Blakestad and colleagues at the National Institute of Standards and Technology (NIST) in Boulder, Colorado have created a junction in an ion trap in which there is practically no heating. Constructed from laser-machined…
drorzel | April 3, 2009Shhhh! Stop reading so loudly! You'll wake the baby:
It's been a while since we had a sleeping baby picture of the week, and conveniently enough, SteelyKid slept late this morning. So there you go.
drorzel | March 24, 2009Steve calls me out for not commenting on new stories about "cold fusion":
Becky and I have been having much more regular access to the internet since the power was fixed. We check e-mail just about everyday and can even skim yahoo news. Or Professor Orzel's blog. I heard on BBC radio yesterday that there are people who have claimed to have evidence of cold fusion - which made me immediately think of a physics graduate who worked on sonoluminescence (bubble fusion) and of a talk given at Union last year about bubble fusion. Which made me immediately think of Professor Orzel and his skepticism…
drorzel | March 17, 2009I was busy with other stuff when this hit the blogs, but I did want to at least comment in passing on Fermilab's announcement that it still hasn't found the Higgs Boson. Detailed commentary is available from Tommaso Dorigo and John Conway.
If you're not a physicist, or even just not a particle physicist, it might seem a little surprising that "We still haven't found the Higgs" is worthy of a press release, let alone actual excitement. The important thing about the result is that they have been able to say (relatively) definitively that the Higgs boson does not exist in a certain range of…
drorzel | March 11, 2009Most people's first exposure to the ideas of modern atomic physics comes through the Bohr model of hydrogen, which treats the atom as something like a little solar system, with the positively charged nucleus as the sun, and negatively charged electrons orbiting in well-defined circular orbits. It's a very compelling picture, and works well for hydrogen (provided you make a couple of really odd assumptions), but it's completely wrong on the details. Electrons do not move in well-defined orbits, but rather exists as fuzzy wavefunctions spread over the space near the nucleus.
It turns out,…
drorzel | March 5, 2009EurekAlert had a press release yesterday titled Quantum paradox directly observed -- a milestone in quantum mechanics, which sounds like it ought to be great. The actual release, though....
For one thing, the description of the actual experiment is so vague as to be completely useless. It's not easy to quote without copying the whole thing, but it's short, so go read it yourself. Do you have any idea what's going on?
Second, it doesn't provide a complete citation for the article-- it gives the title, authors, and journal, but not the relevant page and volume information, which you need in…
drorzel | February 17, 2009I no longer remember the context, but the Gravity Probe B experiment came up in discussion around the department last week, and nobody could really remember what the status of it was. It came up again during the "Physics: What We Don't Understand" panel Saturday morning, where Geoff Landis was able to supply a few details from inside NASA. It came up again during a later panel on the year in physics and astronomy, and again, Geoff was able to supply some details.
I'm not sure what the deal is, but there's evidently something in the air at the moment making people think about Gravity Probe B,…
drorzel | February 10, 2009Like a lot of physics departments, we offer an upper-level lab class, aimed at juniors and seniors. There are a lot of ways to approach this sort of course, but one sensible way to think about it is in terms of giving students essential skills and experiences. That is, i's a course in which they learn to do the things that no physics major should graduate without doing.
I'm sure that other disciplines do something similar, so I thought I might throw this out there as a general question:
What are the essential skills and experiences a student ought to have before graduating with a degree in…
drorzel | February 6, 2009There's a new paper from the PAMELA dark matter search out that's written up in Physics, including a link to a free version of the PDF. This paper is considerably less dramatic than one that appeared last year, leading Physics World to suggest that they're backing off the earlier claim.
What's the deal? Sean Carroll has you covered, with a detailed explanation of what's in both papers, and why the findings have been published and reported the way they have:
What happened is that the PAMELA collaboration submitted their second paper (anomalous positrons) to Nature, and their first paper (well-…
drorzel | January 28, 2009Physics World's news aggregator had a story yesterday with the headline Chilly solution to neutrino mass problem, and the one-sentence teaser
Ultracold atoms could be used to measure the mass of the neutrino.
This creates a wonderful image of somehow turning a magneto-optical trap or a Bose-Einstein Condensate into a neutrino detector, which is a nice thought, but highly improbable. Even a BEC has a density a million times less than the density of air, and a volume that's way too small to catch any neutrinos.
So what's going on? The answer is cool in its own right, and the path from the…
drorzel | January 22, 2009My graduate alma mater made some news this week, with a new quantum teleportation experiment in which they "teleport" the state of one ytterbium ion to another ytterbium ion about a meter away. That may not sound like much, but it's the first time anybody has done this with ions in two completely separate traps, in different vacuum systems. It's also written up in Physics World, though they spell Chris Monroe's name wrong throughout.
The paper is coming out in Science, and I may try to write it up for a ResearchBlogging post over the weekend. I may also need to add it to the quantum…
drorzel | January 12, 2009 There's been a fair bit of press for the article Subtracting photons from arbitrary light fields: experimental test of coherent state invariance by single-photon annihilation, published last month in the New Journal of Physics, much of it in roughly the same form as the news story in Physics World (which is published by the same organization that runs the journal), which leads with:
A property of laser light first predicted in 1963 by the future Nobel laureate Roy Glauber has been verified by physicists in Italy.
These stories can be a little puzzling, though. After all, Glauber got his…
drorzel | December 19, 2008When I saw ZapperZ's post about this paper (arxiv version, expensive journal version) from the group of Serge Haroche in Paris, I thought it might be something I would need to incorporate into Chapter 5 of the book-in-progress. Happily, it's much too technical to require extensive re-writing. Having taken the time to read it, though, I might as well make a ResearchBlogging post of it... (My comments will be based on the arxiv version, because it's freely downloadable.)
So, "Freezing Coherent Field Growth in a Cavity by the Quantum Zeno Effect." That's quite a mouthful. What does it really…
drorzel | December 7, 2008I spent most of yesterday helping out with an on-campus workshop for high school teachers and students. Seven high school physics teachers and seventeen high school students spent the day doing a half-dozen experiments to measure various physical constants.
I was in charge of having them measure Plack's constant using the photoelectric effect. The actual measurement (made using a PASCO apparatus) takes about fifteen minutes, so I gave each group a quick explanation of the history: Einstein proposed the particle model of light as an explanation for the photoelectric effect in 1905, and nobody…
drorzel | December 1, 2008I got email last week from the Institute of Physics pointing me to a pair of video interviews with Anton Zeilinger of the University of Vienna. Zeilinger has built an impressive career out of doing fundamental tests of quantum mechanics-- he's not only got the accent and the hair to be a brilliant physicist, he's got a long list of amazing experimental papers to back it up.
They've gone the Locus route, and not included any of the questions he was responding to, which is always a little weird. Zeilinger provides enough context that everything makes sense, though, and he says some really…
drorzel | November 17, 2008There's a link in today's links dump to a post from Pictures of Numbers, a rarely-updated blog on the visual presentation of data (via Swans On Tea, I think). There's some really good stuff there about how to make graphs that are easy to read and interpret.
I would like to dissent mildly from one of their points, in the Better Axes post, specifically the advice about not starting at zero. In many cases, this is good advice, but like most rules of thumb, it shouldn't be followed too closely.
Take, for example, this post from one of my metastable xenon papers:
A strict application of the…