Experiment
drorzel | July 23, 2010This week's big story in physics is this Science paper by a group out of Austria Canada (edited to fix my misreading of the author affiliations), on a triple-slit interference effect. This has drawn both the usual news stories and also some complaining about badly-worded news stories. So, what's the deal?
What did they do in this paper? The paper reports on an experiment in which they looked at the interference of light sent through a set of three small slits, and verified that the resulting pattern agrees with the predictions of the Born rule for quantum probabilities.
What does Matt Damon…
drorzel | July 21, 2010Here's a picture of the ornamental pond we have in our back yard, showing the fountain that we run to keep the water circulating so it's not just a mosquito ranch:
You can see the brick that we have sitting on top of the pump housing to keep it submerged (it tends to tip over otherwise-- the filter box is a little top-heavy), and also the spray of water shooting up into the air.
You can't tell without some reference, but the pond level is actually a little lower than I like it at the moment. The lining leaks slowly, and every so often I need to put more water in. How do I judge the level,…
drorzel | July 20, 2010Yesterday's post about how nobody cares about condensed matter physics produced a surprising number of comments of the form "I was really hoping you would post about topological insulators," which surprised me a bit. Anyway, since people asked for it, I'll give it a shot. The important caveats here are that 1) this isn't my field, and 2) I have not read a great deal of the primary literature on this, so my understanding is not that deep.
We'll do this in Q&A format, as that's been working well for ResearchBlogging posts lately.
So, what's a "topological insulator," anyway? You make a…
drorzel | July 15, 2010In the comments following the silly accelerator poll, onymous wrote:
[T]he point of the LHC isn't to discover the Higgs. No one in their right minds would build a 14 TeV pp collider if their only goal was to discover the Higgs.
While it's true that the ultimate goal of the LHC is to discover more exotic particles that may or may not exist (blah, blah, supersymmetry, blah) most of the hype has focussed on the Higgs, which is the one thing they're pretty sure they'll find (comments later in that thread notwithstanding). This is one of the potential problems with the way the machine has been…
drorzel | July 14, 2010With the rumors of a Higgs Boson detected at Fermilab now getting the sort of official denial that in politics would mean the rumors were about to be confirmed in spectacular fashion, it's looking like we'll have to wait a little while longer before the next "Holy Grail" of physics gets discovered.
Strictly speaking, the only thing I recall being officially dubbed a "Holy Grail" that's been discovered was Bose-Einstein Condensation (BEC), first produced by eventual Nobelists Carl Wieman and Eric Cornell in 1995. Somebody, I think it was Keith Burnett of Oxford, was quoted in the media calling…
drorzel | July 12, 2010Rumors that the Tevatron at Fermilab may have discovered the Higgs boson have escaped blogdom to the mainstream media. This originates in a blog post by Tommaso Dorigo, which I can't read because it doesn't display properly in Firefox, but I'm sure is very interesting.
Anyway, this is a good excuse for a dorky poll:
If the Tevatron were to discover the Higgs boson before the LHC does, that would be:Market Research
There's a 99.7% probability that this poll is completely meaningless. That doesn't mean it's not entertaining, though.
drorzel | July 9, 2010The big physics story at the moment is probably the new measurement of the size of the proton, which is reported in this Nature paper (which does not seem to be on the arxiv, alas). This is kind of a hybrid of nuclear and atomic physics, as it's a spectroscopic measurement of a quasi-atom involving an exotic particle produced in an accelerator. In a technical sense, it's a really impressive piece of work, and as a bonus, the result is surprising.
This is worth a little explanation, in the usual Q&A format.
So, what did they do to measure the size of a proton? Can you get rulers that small…
drorzel | June 29, 2010A couple of significant news items from the world of particle physics:
There was a conference on neutrino physics recently, and the big news from there is that two experiments measure something funny with neutrino oscillations, namely that the oscillations seem to proceed at different rates for neutrinos and antineutrinos. This is a really surprising sort of asymmetry, and would be awfully hard to explain. These are, however, preliminary results that are being released now because there was a conference on neutrino physics, not because the people doing the experiments have rock-solid proof…
drorzel | June 28, 2010Last week, Dmitry Budker's group at Berkeley published a paper in Physical Review Letters (also free on the arxiv) with the somewhat drab title "Spectroscopic Test of Bose-Einsten Statistics for Photons." Honestly, I probably wouldn't've noticed it, even though this is the sort of precision AMO test of physics that I love, had it not been for the awesome press release Berkeley put together, and this image in particular (grabbed with its caption):
This is a nifty paper, and deserves a little explanation in Q&A format:
Is this another New Scientist style "Einstein was wrong" paper? No. If…
drorzel | June 24, 2010Next in line of questions from readers, we have tbell with:
Since science is a self-correcting process (maybe only at a statistical level, not necessarily an individual level), it would be cool if you would relate the last time you were seriously wrong about some aspect of science or research, and how you altered your thinking as a consequence.
This is kind of a tough one to answer, because I'm an experimentalist. Most of the mistakes I make in the process of research are problems of a technical nature, like "I totally thought that would work, but the impedance of the vacuum feed-throughs…
drorzel | June 22, 2010A press release from Harvard caught my eye last week, announcing results from Markus Greiner's group that were, according to the release, published in Science. The press release seems to have gotten the date wrong, though-- the article didn't appear in Science last week. It is, however, available on the arxiv, so you get the ResearchBlogging for the free version a few days before you can pay an exorbitant amount to read it in the journal.
The title of the paper is "Probing the Superfluid to Mott Insulator Transition at the Single Atom Level," which is kind of a lot of jargon. The key image is…
drorzel | June 21, 2010An experiment in Germany has generated a good deal of publicity by dropping their Bose-Einstein Cendensate (BEC) apparatus from a 146 meter tower. This wasn't an act of frustration by an enraged graduate student (anybody who has worked with BEC has probably fantasized about throwing at least part of their apparatus down a deep hole), but a deliberate act of science: They built a BEC apparatus that is entirely contained within a two-meter long capsule inside the evacuated drop tower at the Center of Applied Space Technology and Microgravity (which in German leads to the acronym ZARM, which…
drorzel | June 21, 2010The Virtuosi has quickly become a staple of the daily Links Dumps here, but the recent series of posts on experimental physics deserve greater prominence, so here they are:
Life as an Experimenter- Day One
Life as an Experimenter- Day Two
Life as an Experimenter- Day Three
Life as an Experimenter- Reflections
The individual day posts provide an inside look at what it's like to do experimental condensed matter physics, specifically using beam time on an accelerator to do diffraction studies of materials. It's got everything you would like to see in such a story-- equipment failures, sleep…
drorzel | June 7, 2010In my write-up about the Hidden Dimensions panel, I mentioned in passing that:
I also would've liked to see an experimental physicist up there, to provide a little more grounding about what the actual problems are, and how you might hope to look for something. But then, I always think there should be more experimental physicists involved in everything.
I'm going to be traveling today, so I thought I would throw up a filler post offering a list of things that would be improved by the inclusion of an experimental physicist. Then I realized that that would be kind of difficult, as everything is…
drorzel | June 2, 2010I mentioned in a previous post that one of the cool talks I saw at DAMOP had to do with generation of coherent X-Ray beams using ultra-fast lasers. What's particualrly cool about this work is that it doesn't require gigantic accelerators or nuclear explosions to produce a laser-like beam of x-rays-- it's all done with lasers that fit on a normal-size optical table in an ordinary lab room.
The specific talk I saw was by Margaret Murnane of JILA, who co-leads their ultra-fast laser group, and dealt with a new technique for producing soft-x-rays (~500 eV photons) with ultrafast lasers. We'll do…
drorzel | June 1, 2010While I mostly restricted myself to watching invited talks at DAMOP last week, I did check out a few ten-minute talks, one of which ended up being just about the coolest thing I saw at the meeting. Specifically, the Friday afternoon talk on observing relativity with atomic clocks by Chin-Wen Chou of the Time and Frequency Division at NIST in Boulder.
The real technical advance is in a recent paper in Physical Review Letters (available for free via the Time and Frequency Publications Database, because government research isn't subject to copyright): they have made improvements to their atomic…
drorzel | May 27, 2010Since I sort of implied a series in the previous post, and I have no better ideas, here's a look at Thursday's DAMOP program:
Thursday Morning, 8am (yes, they start having talks at 8am. It's a great trial.)
Session J1 Novel Probes of Ultracold Atom Gases
Chair: David Weiss, Pennsylvania State University Room: Imperial East Invited Speakers: Cheng Chin, Markus Greiner, Kaden Hazzard, Tin-Lun Ho
Session J2 Coherent Control with Optical Frequency Combs
Chair: Linda Young, Argonne National Laboratory Room: Imperial Center Invited Speakers: J. Ye, Moshe Shapiro, W. Campbell, …
drorzel | May 27, 2010I was pretty sedentary on Wednesday, going to only two sessions, and staying for most of the talks in each. I spent most of the initial prize session getting my bearings in the conference areas, and talking to people I know from my NIST days.
In the 10:30 block, I went to the session on Alkaline Earth Quantum Fluids and Quantum Computation. Tom Killian of Rice opened with a nice talk on work his group has done on trapping and Bose condensing several isotopes of strontium; somebody near me pooh-poohed it as just a technical talk on evaporative cooling issues, but I thought Tom did a nice job…
drorzel | May 26, 2010The conference I'm at this week is the annual meeting of the Division of Atomic, Molecular, and Optical Physics of the American Physical Society (which this year is joint with the Canadian version, the Division of Atomic and Molecular Physics and Photon Interactions, or "DAMPΦ." The Greek letter is a recent addition-- as recently as 2001, they were just DAMP.). As the name suggests, this is a meeting covering a wide range of topics, and in some ways is like two or three meetings running in parallel in the same space.
You can see the different threads very clearly if you look at the different…
drorzel | May 18, 2010It's been a very long day, so I'm lying on the couch watching
"Pardon the Interruption" on ESPN. They're having a boring
conversation about baseball, and I'm just drifting off into a pleasant
doze when:
"Fear! Fire! Foes! Awake! Fear! Fire! Foes! Awake!"
I jolt awake. "What are you barking at?!?" I yell at the dog, who
is standing in the middle of the living room, baying at nothing. She
stops.
"Scary things!"
The room is empty. "There's nothing here," I say, and then hear a
car door slam. I look outside, and see the mathematician next door
heading into his house. "Were you barking at Bill? He…