Double the fun.

Last Friday I was attempting to squeeze more power out of the Raman BBO, and proceeded to lose all the power.  So I spent this past weekend fixing it.  Fun.  But I managed to accomplish what I had set out to do.  All is well and good.

Or so I thought.  Turns out, when I turned on the Microwaves for the EO (phase modulator), the power dropped significantly.  Apparently, the free-spectral-range of the cavity wasn’t matched to the microwave sidebands, and hence weren’t building up.

Some explanation:

To double the frequency of our laser light (change color from infrared to blue, or blue to ultraviolet), we shine the light into a cavity with the nonlinear crystal (this crystal changes the color).  A cavity basically is a set of mirrors aligned such that the light makes a complete circuit and ends up exactly where it started, heading in the same direction, and building up inside the cavity.

For an optical cavity, there are a discrete set of colors that will build up in the cavity.  The spacing between these adjacent colors is called the free-spectral-range.  So here’s the problem I had:  without the phase modulator on, I only had one color in the cavity, and it built up just fine.  Got a decent amount of power out of it.  Turning on the phase modulator creates additional colors of the light.  And these different colors were not in the set of colors that build up in the cavity. 

So, basically, I had to re-align the cavity such that these additional colors build up.  And that is why I’m posting this at 3am. 

Maryland impressions

This past week the lab went down to the University of Maryland to see where we will be spending the next few years of our life.  First impressions:  The campus is quite pretty—the buildings have a red-brick southern-style architecture.  I liked that.  Unfortunately, the interior of the buildings leave much to be desired.  Also, there wasn’t much in the way of food nearby or a collegetown.  As Dan told me, College Park is a strip-mall with a university attatched.  Perhaps it is because DC is nearby.

Unfortunately, I haven’t found a place to live yet.  The cost of living is higher than in Ann Arbor, so I’m looking for a cheap place.  I guess that means I’ll have to take another trip down there before moving.

Now back to the 13+ hour workdays. 

Stupid mistakes

I’ve been quite non-existent the past couple weeks.  Undoubtedly because of two things.  (1)  I have no internet at home.  The person whose wifi I’ve been using must have left for the summer.  Hence, I have no signal at home.  With three months left in Michigan(!), I don’t care.  It’s obvious that I’ve become a product of the ‘information age.’  What did I do before the internet?  Ah yes.  Read.    (2)  Because I only have a couple months left, I’ve been working ridiculous hours, hoping to finish this experiment before leaving.  12+ hours for the past few weeks is not fun.  (sometimes, it’s 15 or 16 hours).  Additionally, Dan—the senior grad student on my project—just defended his thesis, and will be leaving the lab shortly.  That means I’ll be in charge of this project, and I don’t know what I’m doing.

And things are not peachy in the lab.  We have a new student on my project, and I have to explain everything all over again.  We have very little power in our Raman laser, and Yisa just chipped the BBO crystal today (which is extremely expensive).  He’s too cavalier with optics.  But I figured out why I was only getting ~90% qubit detection fidelity—apparently some idiot turned off the RF generator for the doppler cooling beam.  Thus, we weren’t cooling the ions.  Alas, the initialization beam got mis-aligned.  The fun never ends.