This is one in a series of posts working through the exercises in the Quantum Country online introduction to quantum computing and related topics. The exercises in the original document are not numbered; I have added my own numbers for convenience in referring to them.
Exercise 11. Find single-qubit states and such that applying the CNOT gate to the combined state changes the first qubit, i.e., the control qubit.
Answer: This is a placeholder for when I get around to looking at this problem in depth.