Experiment
drorzel | November 15, 2008As mentioned briefly the other day, I recorded a Bloggingheads.tv Science Saturday conversation with Jennifer Ouellette on Thursday. The full diavlog has now been posted, and I can embed it here:
This was the first time I've done one of these, and it was an interesting experience.
I'm rocking the handset in this because of the aforementioned cell phone service problems, and because the whole thing was very hastily arranged, and I wasn't able to obtain a headset for the landline. If they ask me back again, I'm definitely getting one.
On the other hand, being tied to the handset did restrain…
drorzel | November 10, 2008SteelyKid has recently begun to figure out her hands. As I noted last week, within the last couple of weeks, she's started to be able to reliably grab things near her. Just within the last few days, she's discovered that she has two hands, and they can interact with each other:
She's started grabbing one hand with the other, and exploring them. I've also seen her start to use both hands in concert, holding a hanging toy steady with one hand, while manipulating bits of it with the other, like a good little scientist.
Hands are, of course, critical to science. You can't be a good scientist…
drorzel | November 6, 2008Getting back to science, at least for the moment, I was puzzled by a press release from RPI, with the eye-catching headline Solar power game-changer: 'Near perfect' absorption of sunlight, from all angles. The article describes work published in Optics Letters (that I haven't been able to put my hands on yet), developing new anti-reflection coatings to enhance the absorption of light by silicon solar panels:
An untreated silicon solar cell only absorbs 67.4 percent of sunlight shone upon it -- meaning that nearly one-third of that sunlight is reflected away and thus unharvestable. From an…
drorzel | November 3, 2008Continuing the series of descriptions of candidate technologies for making a quantum computer (previous entries covered optical lattices and ion traps), we come to one that's a little controversial. It's the only remaining candidate I can describe off the top of my head without doing some more background reading, though, so I will plunge ahead boldly...
Liquid state Nuclear Magnetic Resonance (NMR) was first suggested as a technology for quantum information processing in 1997, and some demonstration experiments followed very quickly, as there's relatively little infrastructure required. The…
drorzel | October 29, 2008Last week, I wrote about ion traps as a possible quantum computing platform, which are probably the best established of the candidate technologies. This week, I'll talk about something more speculative, but closer to my own areas of research: neutral atoms in optical lattices.
This is a newer area, which pretty much starts with a proposal in 1999. There are a bunch of different variants of the idea, and what follows will be pretty general.
What's the system? Optical lattices use the interaction between atoms and a standing wave of light to produce a periodic array of wells in which individual…
drorzel | October 23, 2008Doug Natelson is thinking about fortuitous physics, inspired by some solid state examples:
Every now and then you stumble across a piece of physics, some detail about how the universe works, that is extremely lucky in some sense. For example, it's very convenient that Si is a great semiconductor, and at the same time SiO2 is an incredibly good insulator - in terms of the electric field that it can sustain before breakdown, SiO2 is about as good as it gets.
From my own field of physics, I would suggest the rubidium atom. Rubidium isn't a substance you run across every day, and that's a Good…
drorzel | October 22, 2008Some time back, I wrote about what you need to make a quantum computer. Given that it's election season, I thought I'd revisit the topic by looking in detail at the candidate technologies for quantum computing.
The first up is Ion Trap Quantum Computing, probably the most well-established of any of the candidates. The field really starts with Dave Wineland's group at NIST, though there is outstanding stuff being done by Chris Monroe at Maryland, and a host of others.
So, how do they stack up? Here are the facts about ion traps as a quantum computing system:
What's the system? Ion traps are,…
drorzel | October 15, 2008Today, we have the first claimant of a donation incentive, from Sarah, who asks:
If you could go back in time to any lab and be there as X discovery was being made, which lab/when/where would you go? I figure this could be spun a couple of ways, either to talk about some really cool science or some really interesting personalities/history of science stuff, or both.
She suggests either the modern discovery of BEC, or the Michelson-Morley experiment for a historical entry. Both of these are excellent choices-- I was on the periphery of a group chasing BEC in 1995, and it was an exciting time,…
drorzel | October 4, 2008Over the past several weeks, I've written up ResearchBlogging posts on each of the papers I helped write in graduate school. Each paper write-up was accompanied by a "Making of" article, giving a bit more detail about how the experiments came to be, what my role in them was, and whatever funny anecdotes I can think of about the experiment.
If you haven't been following the series, or would just like a convenient index of the posts, here's the complete set:
Introduction and explanation of metastable xenon.
Experiment 1: Optical Control of Ultracold Collisions and the making thereof.…
drorzel | October 2, 2008As mentioned in the previous post, the cold plasma experiment was the last of the metastable xenon papers that I'm an author on. My role in these experiments was pretty limited, as I was wrapping things up and writing my thesis when the experiments were going on.
The main authors on this were Tom Killian, now running his own cold plasma lab at Rice and Scott Bergeson, now running his own cold plasma lab at BYU. Scott was a pulsed-laser expert with a remarkably cavalier attitude toward things like anti-reflection coatings on vacuum windows, and Tom came from Dan Kleppner's hydrogen BEC project…
drorzel | October 2, 2008This is the last of the papers I was an author on while I was in grad school, and in some ways, it's the coolest. It's rare that you get to be one of the first people to do an entirely new class of experiment, but that's what this was. It kicked off a new sub-field (or sub-sub-field...), the history and status of which was written up in Physics a little while back.
The ultracold plasma experiment may be the ultimate version of what we jokingly called the "NIST Paradigm" of cold-atoms physics research, which could be summarized as "I wonder what will happen if we stick this other laser in?" It…
drorzel | September 24, 2008So, the LHC has been shut down until next year, after a major helium leak in on section. This means it will be March or April of next year before collisions in the ATLAS detector create dragons that will eat us all.
Now you know why I didn't make a big deal of the "start-up" a couple of weeks ago. (Well, also, I was in Canada at a conference...)
If you're worried that this will delay the march of progress, though, fear not:
The failure occurred as the accelerator's two proton beams were being ramped up for a test run at 5 TeV. CERN had then planned to use the winter shutdown to make final…
drorzel | September 23, 2008Derek Lowe has posted an article about X-ray lasers in chemistry, which amused me because of the following bit:
Enter the femtosecond X-ray laser. A laser will put out the cleanest X-ray beam that anyone's ever seen, a completely coherent one at an exact (and short) wavelength which should give wonderful reflection data.
This is funny to somebody in my end of the science business, because we usually think of femtosecond lasers as have an extremely broad spectrum, not an "exact wavelength." It's a striking example of something I see all the time with chemists-- what chemists think of as "…
drorzel | September 2, 2008 This is the last of the five papers that were part of my Ph.D. thesis, and at ten journal pages in length, it's the longest thing I wrote. It was also the longest-running experiment of any of the things I did, with the data being taken over a period of about three years, between and around other experiments. As usual for this series of posts, I can sum up the key result in one graph:
(No spiffy color figure this time, as the experiment never made it onto the old web page, and my original figures are three or four computers ago.)
What we found was that when we prepared samples of metastable…
drorzel | August 28, 2008As I said in the introduction to the previous post, this was the first paper on which I was the lead author, and it may be my favorite paper of my career to date. I had a terrific time with it, and it led to enough good stories that I'm going to split the making-of part into two posts.
The experiment itself was based on an earlier paper by Phil Gould at UConn. Phil was a post-doc at NIST back in the day, and used to visit our group fairly regularly. On one of these visits, he stopped by the xenon lab, and gave me a pre-print of their time-resolved collision paper, saying "You guys really…
drorzel | August 28, 2008This paper is the third of the articles I wrote when I was a grad student, and the first one where I was the lead author. It's also probably my favorite of the lot, not just because of the role it played in my career, but because it packs a lot of science into four pages.
The whole thing is summarized in this figure from the old NIST web page, which is a simplified version of Figure 2 from the paper itself:
This shows the collision rate as a function of time after we hit a cold sample of atoms with a 40ns pulse of laser light tuned near the atomic resonance frequency. As discussed in the…
drorzel | August 21, 2008The experiment described in the previous post was published in early 1998, but the work was done in 1997. This was the year when things really turned around for me in grad school-- the optical control paper was done in the summer 0f '94, and '95 and '96 were just a carnival of pain. Everything in the lab broke, was repaired, and then broke again.
The lead guy on the lattice collision experiment was a post-doc named John Lawall, who really took charge. He completely re-vamped the lock system for the laser, and spent a huge amount of time re-doing the laser alignment for the trap and the…
drorzel | August 21, 2008I announced my intention to do some research blogging a little while ago, and managed one pair of posts before the arrival of SteelyKid kind of distracted me. I'm still planning to complete the Metastable Xenon Project blog, though (despite the utter lack of response to the first two), and the second real paper I was an author on is "Suppression and Enhancement of Collisions in Optical Lattices," a PRL from 1998, with a preprint version available here.
So, this is another paper about collisions, obviously, but what's an optical lattice? An optical lattice is an arrangement of laser beams--…
drorzel | August 5, 2008One of the things I'd like to accomplish with the current series of posts is to give a little insight into what it's like to do science. This should probably seem familiar to those readers who are experimental scientists, but might be new to those who aren't. I think that this is one of the most useful things that science blogs can do-- to help make clear that science is a human activity like anything else, with its ups and downs, good days and bad.
To that end, I'm going to follow the detailed technical explanation of each of these papers with a post relating whatever anecdotes I can think…
drorzel | August 5, 2008(This is the first in a planned series of posts writing up each of the scientific papers on which I am an author. A short description and a link to a PDF of the paper can be found at the archived Optical Control page.)
The essence of the optical control paper is contained in this one figure:
"Very pretty," you're thinking, "But what does it mean?"
The graph shows the increase or decrease in the ionizing collision rate for a sample of xenon atoms (well, two different samples, of different isotopes, but they behave exactly the same) at a temperature of 100 microkelvin or so due to the…