Quantum Optics
drorzel | June 29, 2006Matt Leifer, whose blog I hadn't previously encountered, has a long and fascinating post on evaluation criteria for quantum interpretations. "Interpretation" here means the stuff of countless "Isn't Quantum Mechanics weird?" books-- Copenhagen, Many-Worlds, Bohmian hidden variable theories, all that stuff. These are the "meta-theories" that are used to explain how you get from all that weird and messy wavefunction stuff up to the reality that we see and observe in our experiments.
The list is explicitly modeled after the well-known DiVincenzo Criteria for quantum computing (see also Quantum…
drorzel | June 7, 2006My Quantum Optics class this term is a junior/ senior level elective, one of a set of four or five such classes that we rotate through, offering one or two a year. We require physics majors to take one of these classes in order to graduate, and encourage grad-school-bound students to take as many as they can fit in their schedule.
Students in all majors are also required to take five "Writing Across the Curriculum" classes, which are intended to be courses with a strong writing component that should build their writing skills both in their discipline and out. As you might imagine, the bulk of…
drorzel | May 24, 2006Dave Bacon asks, I answer. Well, OK, Dave was asking how one would go about teaching quantum computing to CS undergrads, while what I provide here is a set of lectures on presenting quantum computing ideas to undergrad physics majors in my Quantum Optics class. But, really, isn't that almost the same thing (don't answer that).
The notes:
Lecture 17: Computing theory, logic gates, quantum gates, entangling operations.
Lecture 18: Quantum algorithms, the Deutsch-Josza algorithm.
Lecture 19: Physical implementations of quantum computing, the DiVincenzo Criteria.
This more or less concludes the…
drorzel | May 3, 2006Another set of Quantum Optics notes, dealing with entanglement, superposition, EPR paradoxes, and quantum cryptography. A whole bunch of really weird stuff...
Lecture 11: Superposition and entanglement.
Lecture 12: EPR "paradox," introduction to Local Hidden Variables.
Lecture 13: Local Hidden Variable theories, Bell's Theorem/ Bell's Inequalities.
Lecture 14: Bell's Inequality experiments.
Lecture 15: Cryptography, quantum key distribution.
Also, don't forget to suggest people to fill the Teddy Roosevelt spot on the Mount Rushmore of Science...
drorzel | April 17, 2006For those following along with my Quantum Optics class, here's a bunch of lectures about photons:
Lecture 7: Commutators, simple harmonic oscillators, creation and annihilation operators, photons.
Lecture 8: Coherent states of the electromagnetic field.
Lecture 9: Number-phase uncertainty, squeezed states, interferometry.
Lecture 10: Photon anti-correlation revisited, beamsplitters and vacuum states.
This material, unsurprisingly, produced the most panicked looks from students to this point. One of the homework problems was also to recapticulate a couple of calculations from a Phys. Rev. A (…
drorzel | April 8, 2006Since the previous batch of lecture notes were surprisingly popular, here's the next couple of classes worth:
Lecture 5: Stellar Interferometry, coherence, intensity correlation functions, Hanbury Brown and Twiss experiment.
Lecture 6: Non-classical light, photon anti-bunching, single-photon interference.
Sadly, this exhausts the notes I had written in advance (what with one thing and another, I haven't written any new lectures this past week), which means I need to write at least three lectures this weekend, on the mathematical description of quantized light, coherent states of the…
drorzel | April 3, 2006If 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…
drorzel | March 30, 2006I realize that I've been pretty bad about posting articles with explanatory physics content (even neglecting a couple of things that I promised to post a while back), but I have a good reason. All of my explanatory physics effort these days has been going into lecture writing, such as the two hours I spent Tuesday night writing up a lecture on the Hanbury Brown and Twiss experiment.
This Quantum Optics class is turning out to be a really interesting experience. It's a truism that you don't really find out what you know about a subject until you have to teach it to someone else. That's…
drorzel | March 8, 2006Next term, I'm slated to offer one of our "Advanced Topics in Physics" upper-level elective classes. I was originally asked to do atomic physics, but looking at the syllabus and available texts, I decided I'd rather take a different tack, and agreed to develop a new course instead.
I call myself an atomic physicist, and I go to the annual meetings of the Division of Atomic, Molecular, and Optical Physics (this year in Knoxville, whee!), but most of what falls under that heading these days is not what old-school guys would call atomic physics-- spectroscopy, atomic structure, etc. Most of what…
drorzel | February 27, 2006OK, let's say you want to explain something really difficult, like counterfactual computation with quantum interrogation, but you don't want to actually sit down and do all that typing (let's say you have a big stack of lab reports to grade, or something). There's a way to pull this off.
What you do is, you put yourself in a superposition of states in which you explain and don't explain this phenomenon, and then don't touch your blogging software (that would constitute an observation, and collapse your wavefunction) for a day or two. When you come back, you'll find that an explanation has…
drorzel | February 24, 2006A Dramatic Presentation of a Classical Analogue to the Quantum Zeno Effect
A Play in One Act:
John Boy: Good night, Mary Ellen.
Mary Ellen: Good night John Boy.
JB: Are you asleep?
ME: No.
JB: Are you asleep?
ME: No.
JB: Are you asleep?
ME: No.
Repeat several more times
Exeunt, pursued by a bear.
drorzel | February 22, 2006Buried beneath some unseemly but justified squee-ing, Scalzi links to an article about "counterfactal computation", an experiment in which the group of Paul Kwiat group at Illinois managed to find the results of a quantum computation without running the computer at all. Really, there's not much to say to that other than "Whoa."
The article describing the experiment is slated to be published in Nature, so I don't have access to it yet, but I'll try to put together an explanation when I get a copy. The experiment involves a phenomenon know as the "Quantum Zeno Effect," though, which deserves a…
drorzel | January 19, 2006In the ongoing string theory comment thread (which, by the way, I'm really happy to see), "Who" steps off first to ask an interesting question:One way to give operational meaning to a theory being predictive in the sense of being empirically testable is to ask
What future experimental result would cause you to reject the theory?
I think what worries a lot of people about string thinking is that it seems so amorphous that it might be able to accomodate any future experimental measurement. In fact I am not aware of any string theorist's answer to this basic question.
It's an interesting…