This is one of the problems from Assignment 2 from CS191x at edx.org, so please do not post explicit answers.
We have two qubits in the state |0+⟩ and we want to entangle them by performing a partial measurement on the first qubit. Which of the following measurements should we perform on the first qubit?
(I am not including possible answers as I want to understand it in general, not only this specific case)
I am not sure how to determine the state after measuring one of the qubits. For the standard basis my reasoning goes like this: if we measure the first qubit in this base, its resulting state will be |0⟩ with the probability of 1. Because the state of two qubits is |0+⟩, we know for sure that the second qubit will then be in the state |+⟩ and therefore there is no entanglement.
Firstly, I do not know if my reasoning above is correct at all. Secondly, how to determine the resulting state in a more general case, e.g. in the sign basis? (|+⟩, |-⟩).