Hey everyone - just a bit of a conceptual question regarding the sudden approximation for a particle in an infinite square well. In theory, if we were to suddenly decrease the width of the potential from say L, to L' << L, in a very quick period of time - wouldn't this in some sense constitute a...
So I've been reading Cohen-Tannoudji's "Quantum mechanics vol 1" and have understood the part that proves that the hilbert space of a 3-dimensional particle can be described/decomposed as a tensor product of hilbert spaces using position vectors (or analogously momentum vectors) in the x, y and...
Need help with this - just had this on a test and this is driving me crazy - PLEASE HELP!
Let {f_{n}} be a sequence of MEASURABLE real valued functions. Prove that there exists a sequence of positive real numbers {c_{n}} such that \sum c_{n}f_{n} converges for almost every x \in \Re
How is it...