Category Archives: Experiments

Plasmas Can Be Cool

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Molecular Plasma is Cooler Than You Think

Plasma inside the sun blazes at millions of degrees, but much of the matter between the stars is also plasma, in a colder form. In the lab, cold plasmas have always been made from ionized atoms, but a team reports in the 14 November Physical Review Letters that molecules can also be turned into an ultracold plasma. They created the molecular plasma by cooling a beam of nitric oxide molecules and then hitting it with lasers. They say the technique can work for any molecule that can be vaporized. Ultracold molecular plasmas probably don’t exist in nature, yet they share characteristics with very dense plasmas in the centers of some stars and gaseous planets. On Earth they may be used to explore more complex plasma dynamics, or help researchers create even colder atomic plasmas.

That's a FIB

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As in Focused Ion Beam

Cold Atoms Could Replace Hot Gallium In Focused Ion Beams

Because of the versatility of their approach—it can be used with a wide range of ions tailored to the task at hand—it is expected to have broad application in nanotechnology both for carving smaller features on semiconductors than now are possible and for nondestructive imaging of nanoscale structures with finer resolution than currently possible with electron microscopes.

I ran something on this a few months ago. MOTIS Operandi

Try to Set the Night on Fire

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Light My Photonic Crystal

[R]esearchers describe a method for adding light-emitting elements in a precise way to a future photonic circuit. They filled a small hole in a silicon wafer with a liquid containing tiny chunks of fluorescent semiconductor and imaged the pattern of light that was generated. The technique permits easy removal and replacement of the fluorescent particles and offers a way of creating photonic structures that include light emitters set out in some desired pattern.

Bartender, Gimme a Pan-Galactic Gargleblaster

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Exploring Liquids: An Experiment

Fun, and physics, with fluids

Here’s a fun experiment you can try using the contents of your kitchen cupboard. Explore the effects of different densities and learn about refraction, viscosity and the planet Jupiter. You’ll need five different liquids; I used golden syrup, dishwashing liquid, water, alcohol and vegetable oil. I also used some food colouring to make it easier to see what was going on (and because the alcohol I use is Tequila which looks just like water). If you have a chopstick around that will also be handy – but any stirring implement will do.

Belated Conference Greetings

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I’ve been seemingly running in quicksand ever since returning from the 7th Symposium on Frequency Standards and Metrology, what with the pileup of work while I was away (and everything seemingly breaking during that period of time) and getting ready for our clocks to leave the nest. But now, as I’m burning up my comp time from all that, I’ve had a chance to look back.

The conference was really good, as conferences go. A little over 100 people attended, from labs around the world. I knew perhaps a third of them already (though a few probably did not remember me) and met a few more. I didn’t see any glitches except for one or two instances of technical difficulties, which speaks volumes for the organizers and support staff, because you just know there were issues, and since they didn’t become visible it means they were solved quickly. The accommodations were very nice and the food was decent as far as dining hall food goes. The whole thing came in under the government-rate per diem, and the government is actually pretty stingy about such things.

Many of the talks encompassed the recent push into optical transitions for timekeeping; the microwave transitions used in the established clocks of today run at something a little less than 1010 cycles per second, but an optical transition will be about 4 orders of magnitude higher in frequency. Even if your detection can’t be done to the same level of precision, owing to lower light levels and fewer atoms, the higher frequency represents 2 or 3 orders of magnitude improvement in the overall measurement. The enabling technology for this has been the octave-spanning optical frequency comb, made by pulsed lasers in some nonlinear medium. If you consider the time width of the pulses Fourier-transformed in the frequency domain, you see a whole bunch of laser frequencies separated by the pulse repetition rate, so it looks like a comb. As I’ve mentioned before, you can use these individual frequencies to interrogate atoms, meaning you can measure some narrow clock transition. This becomes really useful when the comb spans an octave, so the low-frequency end can be frequency-doubled and referenced to the high-frequency end, making the comb stable. The repetition rate can be tied into some stable RF or microwave source, and now you know what each frequency is to a very high level of precision. A lot of labs are now doing this.
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Nanograffiti

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More atomic force microscope writing. (Like spelling out ‘IBM’)

‘Atomic pen’ writes with individual atoms

An Osaka University research team has demonstrated an “atomic pen” that can inscribe nano-sized text on metal by manipulating individual atoms on the surface.

According to the researchers, whose results appear in the October 17 edition of Science magazine, the atomic pen is built on a previous discovery that silicon atoms at the tip of an atomic force microscope probe will interchange with the tin atoms in the surface of a semiconductor sample when in close proximity.

Zombie Water

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Mysterious ‘dead water’ effect caught on film

Research has already shown that dead water occurs when an area of water consists of two or more layers of water with different salinity, and hence density – for example, when fresh water from a melting glacier forms a relatively thin layer on top of denser seawater. Waves that form in the hidden layer can slow the boat with no visible trace.

Now French scientists recreating that scenario in a lab tank have revealed new detail of the phenomenon and even captured the effect on video. The work will help scientists to better understand dead water and the behaviour of stratified sea patches.

Smells Like … a Keyboard

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Compromising your keyboard by sniffing the EM radiation signature.

We found 4 different ways (including the Kuhn attack) to fully or partially recover keystrokes from wired keyboards at a distance up to 20 meters, even through walls. We tested 11 different wired keyboard models bought between 2001 and 2008 (PS/2, USB and laptop). They are all vulnerable to at least one of our 4 attacks.

Neal Stephenson did this in Cryptonomicon. Of course, fictional events are trumped by actual results.