Notes from first day of REU

Published on: Tue Jun 07 2011

The first day was arrival and an AMO seminar. The AMO seminars are usually every Monday so this time the new REU group went to listen. The seminar was on laser cooling of molecules. The speaker opened up with noting how laser cooling of molecules was thought to be experimentally impossible, but that once they tried it they where able to do it. There were two different methods for cooling molecules. The first one was indirect, it used cooled atoms that where then collided together forming a cold molecule. The second method was to directly cool a molecule. The speaker's group had chosen to use SrF, and by choosing SrF they made it easier to cool the molecules. I thought it was an interesting point how part of the reason their technique worked was because they selected to cool SrF.

There where photo's of their lab in the presentation and one of the devices was labeled as an "Homebuilt EOM" for electro-optic modulator. This photo sparked a discussion about the beam width of the laser sent through the EOM. The smaller the beam width the better, but if the beam width is too small it heats up the crystal component of the EOM and ruins the crystal.

The speaker was trying to cool the atom's to around 4 nanokelvins, and at first I thought this sounded great, but as the presentation progressed I started to wonder how exactly they knew the molecules where at 4 nanokelvins. Afterwards I asked about this an Dr Noe pointed out they knew the kinetic energy because the molecules are traveling in a beam. I remember from chemistry that KE is dependent on temperature. The speaker pointed out that this is why they tend to talk about ultracold molecules is terms of velocity distributions.

I think they were measuring the velocity based on the fluorescence, but I can't quite remember how exactly that was working.

Besides REU I was playing around with an iPad and note taking software with a stylus. This was very fun and reminded me of my eventual goal of replacing the keyboard on my Air with a touch surface. While I was thinking of this I thought it might be nice if I could just plug my iphone into my computer as use it as a mini graphics tablet on the go. Most of the time for taking notes I don't need it to draw terribly much, but it would be great if I could take notes on Air and then just sketch in pictures from time to time.