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2008-08-28 18:01:40
by Chad Orzel in Uncertain Principles
Astronomy
This 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 frequenc...more
- Rolston S. (1998) Time-Resolved Studies of Ultracold Ionizing Collisions. Physical Review Letters, 80(23), 5093-5096. DOI: 10.1103/PhysRevLett.80.5093
- He Y. (2007) Climate Change and War Frequency in Eastern China over the Last Millennium. Human Ecology, 35(4), 403-414. DOI: 10.1007/s10745-007-9115-8
2008-08-21 12:02:14
by Chad Orzel in Uncertain Principles
Astronomy
I 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 ...more
- Rolston S. (1998) Suppression and Enhancement of Collisions in Optical Lattices. Physical Review Letters, 80(3), 480-483. DOI: 10.1103/PhysRevLett.80.480
- Billon P. L. (2001) The political ecology of war: natural resources and armed conflicts. Political Geography, 20(5), 561-584. DOI: 10.1016/S0962-6298(01)00015-4
2008-08-05 10:01:30
by Chad Orzel in Uncertain Principles
Astronomy
(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 mic...more
- Rolston S. (1995) Optical Control of Ultracold Collisions in Metastable Xenon. Physical Review Letters, 74(4), 506-509. DOI: 10.1103/PhysRevLett.74.506
2008-07-30 11:02:03
by Chad Orzel in Uncertain Principles
Astronomy
Over at Backreaction, Bee has a nice post about uncertainty, in the technical sense, not the quantum sense. The context is news stories about science, which typically do a terrible job of handling the uncertainties and caveats that are an essential part of science.
Properly dealing with uncertainty is one of the hardest parts of science. Which is why I'm particularly impressed by people who spend their whole careers measuring nothing but uncertainties-- looking for an electric dipole moment for the electron, or parity non-conservation, or Lorentz violation, or any of a bunch of othe...more
- Kapitulnik A. (2008) Improved constraints on non-Newtonian forces at 10 microns. Physical Review D, 78(2), DOI: 10.1103/PhysRevD.78.022002
2008-04-22 11:02:56
by Chad Orzel in Uncertain Principles
Astronomy
Two weeks ago, now, I promised some peer=reviewed physics blogging, to compensate for the "screechy monkey" nonsense. Of course, I got distracted by other things, but I've been sitting on this paper for a while now, and I really need to get it off my desk.
The paper in question is "Quantum Register Based on Individual Electronic and Nuclear Spin Qubits in Diamond," by the group of Misha Lukin at Harvard, published in Science last June. It's a clever idea for a way to do quantum computing using individual nuclear spins in a diamond matrix. I really like this idea, not least because i...more
- Lukin M. D. (2007) Quantum Register Based on Individual Electronic and Nuclear Spin Qubits in Diamond. Science, 316(5829), 1312-1316. DOI: 10.1126/science.1139831
2008-04-15 20:06:23
by Angry Astronomer in Angry Astronomer
Astronomy
The development of telescope technology has been a long process. In recent years, most large single mirrors for telescopes have been based on the traditional design of a glass base, shaped into a concave parabola, coated with a reflecting surface (typically aluminum) deposited in a evacuated vaporization chamber. The parabolic shape is often obtained by beginning with a liquid glass which is placed into a mold and spun as the glass is allowed to cool. The balance of the centrifugal and gravitational forces creates a parabola, the depth of which (and hence the focal length of the telescope) can...more
- Worden S. P. (2007) Deposition of metal films on an ionic liquid as a basis for a lunar telescope. Nature, 447(7147), 979-981. DOI: 10.1038/nature05909
2008-03-18 16:17:12
by Angry Astronomer in Angry Astronomer
Astronomy
In my attempt to determine whether or not close in planets can induce super flares on stellar type stars, one of the approaches I was taking was to attempt to determine whether or not close in planets could even perturb the stellar atmospheres. The reasoning behind this was that if they can't even do that much, then there's no real chance that they could do enough to cause these mega flares.
In looking over the titles in the most recent Astrophysical Journal, one jumped out at me: The On/Off Nature Of Star-Planet Interactions.
I figured that was worth a read. So what did ...more
- Bohlender D. (2003) Evidence for Planet‐induced Chromospheric Activity on HD 179949. The Astrophysical Journal, 597(2), 1092-1096. DOI: 10.1086/378583
2008-03-14 11:06:54
by Chad Orzel in Uncertain Principles
Astronomy
The next lab visit experiments I want to talk about are really the epitome of what I called the "NIST Paradigm" in an earlier post. These are experiments on "four-wave mixing" done by Colin McCormick (who I TA'd in freshman physics, back in the day), a post-doc in Paul Lett's lab at NIST. As Paul said when I visited, if they had had a better idea of the field they were dabbling in, they would've thought that what they were trying was impossible; thanks to their relative ignorance, though, they just plowed ahead, and accomplished something pretty impressive.
The basic scheme is laid ...more
- Lett P. D. (2007) Strong relative intensity squeezing by four-wave mixing in rubidium vapor. Optics Letters, 32(2), 178-180.
2008-03-13 11:07:20
by Chad Orzel in Uncertain Principles
Astronomy
As I mentioned a few days ago, I visited Luis Orozco's lab during our trip to DC last week. I already talked about his cavity QED stuff, but that's only one of the projects under development. He's also working on a next-generation apparatus for the laser cooling and trapping of francium, to be done at the TRIUMF accelerator in Vancouver-- francium is an element with no stable isotopes, and at most a few grams of it exist on the earth at any given moment. Luis and his students demonstrated the laser cooling of francium a few years back, using atoms made in an accelerator at Stony Brook out o...more
- DeMille D. (2007) Measurement method for the nuclear anapole moment of laser-trapped alkali-metal atoms. Physical Review A, 75(3), DOI: 10.1103/PhysRevA.75.033418
2008-03-12 11:09:13
by Chad Orzel in Uncertain Principles
Astronomy
One of the many very cool things going on in the Laser Cooling Empire at NIST is a series of experiments using optical tweezers to study various biological systems. I used to share an office with the biochemist in the group, who was there to handle the wet chemistry that physicists are notoriously bad at.
I've toyed with the idea of setting up an optical tweezers apparatus at Union-- the optical set-up is very simple-- so I spent a little while talking about it with Kris Helmerson, the PI on that project. He mentioned some cool things they were doing, one of which is explained very ...more