What I Do to Earn a Living

If you’re wondering about the slow posting hereabouts, it’s because I’m spending a lot of time on my classes. Having a day job sucks that way.

I’ve mentioned before that I’m doing a senior-level elective class on Quantum Optics. This is very much an idiot experimentalist’s approach to the material, but if you’d like a look at what I’m doing, here are my notes from the first four lectures (scanned into large PDF files, which I’m posting to the class Blackboard site, but will upload here as well, at least for a couple of classes):

  • Lecture 1: Dirac notation, state vectors, operators as matrices.
  • Lecture 2: Using state vectors to look at transitions, Fermi Golden Rule.
  • Lecture 3: More transitions, Rabi oscillations.
  • Lecture 4: Einstein A & B coefficients, photons, semi-classical approach to the photoelectric effect.

Their utility as a study aid for my students is perhaps compromised by my bad habit of ad-libbing new material during class (mostly adding connective material between topics, but sometimes, I change the order of some topics). I don’t know if they’ll be at all interesting to people reading this (and I won’t promise that I’m going to post the notes for all my lectures), but if you’d like a glimpse into what I do for my day job, and how I do it, here you go.

8 comments

  1. Having a day job sucks that way.

    Sing it, brother!

    I got through 2 of my 3 pressing stacks of papers to be graded (so one more still to go, but not tonight — thrashed from soccer practice in the rain and mud). Lecturing tomorrow, of course (variously, on human subjects research in the developing world and on sociological approaches to scientific knowledge). Plus a couple papers that need writing and three (!!!) books I need to read and write reviews of.

    But what I really want to do is curl up with those quantum optics notes!

  2. Chad, I’ve just read the first lecture.

    Maybe I am picky but I didn’t like what you wrote about the infinite square well. The wavefunction which is zero everywhere (n = 0), which you include on your drawing, is unphysical because it’s not normalizable. Expect students to be confused.

    Also, normalizability and orthogonality are not equally general properties: every wavefunction is normalizable, while only eigenstates are orthogonal to each other.

    I’ve also found the discussion of the interaction and Schroedinger picture confusing and erroneous. Time dependence is moved totally to the operators in the Heisenberg picture, the interaction picture has it in both operators and the wavefunction (so the wavefunction is NOT constant). Expect students to be confused.

    If you still can bear my picking my nose into your class notes, I can go through the rest and say what I like and dislike about them 😀

  3. Aaron: Have they already taken some quantum?

    Yes.
    Most of them haven’t had formal quantum mechanics (the phrase “Hilbert space” isn’t going to mean anything to them), but they’ve all had at least my introductory modern physics course, which included basic wavefunctions and solutions of the Schroedinger equation, and they’ve all ahd or are currently taking the intermediate modern class (though at the moment, they’re probably doing relativity with four-vectors).

    John Wilkins: Dude! use TeX!

    My command of TeX isn’t quite what it used to be, so typing up the notes takes much longer than writing them by hand. And I find it easier to sort of brainstorm this stuff together with pen and paper.

    I may someday transcribe the notes into TeX. It depends on whether I’m ever asked to teach this class again.

    Roman: As I said, this is very much an idiot experimentalist’s guide to what’s going on. I’m sacrificing a lot of formality in order to pitch it at the right level, hence things like the infinite square well (that’s not an “n=0” state, by the way, it’s just a horizontal line to indicate the energy level for n=1), and dealing only with eigenstates. The goal is just to get the basics of the notation and the main ideas across in one lecture, so I can use it to talk about interesting physics without causing mass panic.

    Also, the stuff about different pictures didn’t make it into the actual lecture. I don’t think that’ll actually get used at any point this term, but it shows up in the grad school notes I was cribbing from, so I wrote it down just in case.

    The later ones are a better guide to the sort of thing I really want to do than that first lecture, which is just stage-setting.

  4. Just looking at Lecture 1 brought back (some) memories of my 500-level QM class, um, 20 years ago. Since I teach high school science, I rarely if ever use this stuff anymore, but it was fun learning it at the time. Then I took QM 600-something, without first having Mathematical Physics as a prereq (my advisor goofed there). Big mistake. I didn’t have the background to comprehend what was going on and had to drop the class after the first semester.

    As I recall, we never got to experimental applications, we stuck to theory. The prof, one of the newer ones on the U of L campus, spurned using the text, introducing his own spin on things. It worked. He knew how to explain the topic well. One of these days I’m going to take that 600-level class over …

  5. Suppose you placed a single chiral molecule into a Rabi vacuum oscillation cavity. Would it be chiral inside the cavity? After you removed it, what is the probability it retained its initial chirality? Consider Hund’s paradox.

  6. Can I cast a vote for uploading the rest of your class notes to this site as well? Looking through them, you have these nice compact derivations of some stuff, and explain some things very transparently, and you put together material I’ve learned in grad school with material that I learned as an undergrad (which was taught very differently, and which it took me a long time to connect up in my head) in a neat, clear way. I’d actually like to print some of this out and store it with my old notes, for reference.

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