This semester I am the luckiest prof. on campus. In addition to all the obvious reasons, including the finally melting snow, I get to teach the perfect course. The stars align for this one: it is an elective course for senior undergraduate students, so the students tend to be bright and well-motivated. Unlike so many other courses, this one is coherent, with well-defined and feasible objective and a focused target audience. And, best of all, it is a course in quantum mechanics.
Back in the days when I was an undergraduate student, learning quantum mechanics changed the course of my studies. Up to that point I immersed myself in down to earth topics such as set theory, mathematical logic, model theory, and all this good stuff. Luckily, I discovered quantum mechanics before things got too abstract, which led me more or less directly to my current concrete and hands on occupation. Since then, quantum mechanics has been close to my heart, I am really happy to be able to teach it.
The course it titled “Applications of quantum mechanics”, and is covering the second half of the text by David Griffiths, whose textbooks I find to be uniformly excellent. A more accurate description of the material would be approximation methods for solving the Schrodinger equation. Not uncommonly in the physics curriculum, when the math becomes more demanding the physics tends to take a back seat, so we are going to spend quite a bit of the time on what is essentially a course in differential equations, using WKB approximations and perturbation theory and what not. To counter that, I am looking for short and sweet applications of quantum mechanics. Short topics which can be taught in an hour or less, and involve some cool concepts in addition to practicing the new mathematical techniques.
So, this is the first audience participation question of the year, what is your favorite application of quantum mechanics?