Once upon a time (when I wasn't being paid for my job, and there may be a correlation), part of my job description was to look at arXiv and see if anything cool was up there. Although my weekly reports thereon were, frankly, incompetent, and would have led to a change of assignment even if our lab didn't start having actual work to do, it was really fun. So, I thought, why not continue doing this and relate what's on there to this blog (yes, I know I'm the only person who reads it, and sometimes not even. "кто ищет смысл..." as Гражданская Оборона says).
So, here are two cool things:
(I) One paper (Gintautas and Huebler) makes an angular motion data logger using a ball mouse with the ball taken out (the paper includes a link to code which converts the movement of the cursor on a screen to angular position data for measuring a pendulum). This is pretty cool, because it seems obvious once you're told that it can be done. Then again, I don't know that nobody came up with this before. Also, my mouse is all-optical.
(II) I have no idea how new this idea is either, but another paper (Hudson) proposes a DC Stark decelerator (for decelerating molecules to become ultra-cold). Stark decelerators work something like this: a molecule is going at some speed, but you turn on a spatially sinusoidal electric field so that some of its kinetic energy is transferred to electric potential energy. This happens because of the Stark effect - say the molecule is in a J-state whose potential increases with increasing electric field. Then, as it is going along, it experiences a stronger and stronger field, thus slowing it down. But just as the molecule is reaching the peak of the spatial sinewave, you flip the field, so now it's at the bottom, and the electric field is again increasing in the direction it is going. This way, your molecule is always travelling into a region of higher electric field, and so is gradually slows down, and all without having to have a really huge electric field.
Trouble is, normal Stark decelerators suck (okay, m'n oud-collegas Rick and Ruth zullen waarschijnlijk niet 't zelfde mening hebben), well I mean, they are inefficient, because they rely on switching electric fields at precisely the right time (ie, exactly when the molecule is in the middle of traversing a region of high field). The idea in this paper is what if, instead of switching the field, we switch the property of the molecule. Again, seems obvious once you're told, which is nice. Since the switching of molecular properties is done by laser-stimulating some transition, you can just have lasers set up perpendicular to the molecule at the spatial peaks of your electric field. Probably hard in practise, but easy in concept!
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