Hello,
From what I can see:
_ The first line is almost correct but you missed a factor $\frac{1}{\sqrt2}$ (and also in general the coefficient $\frac{1}{(1+\delta^2)^\frac12}$)
From what I can see:
_ The first line is almost correct but you missed a factor $\frac{1}{\sqrt2}$ (and also in general the coefficient $\frac{1}{(1+\delta^2)^\frac12}$)
_ The second line is confusing because the $\otimes I$ has disappeared
_ Accounting for the missing factors, the third line ending with a question mark seems to be the same solution as in the solution file
_ For the fourth line it seems you are switching to another representation, it is fine but it would be helpful if you would put additional parenthesis because for instance, I would be tempted to see a matrix vector-multiplication in the middle at first otherwise. Also it seems that $e^{i \gamma}$ became $e$ and there is still the above missing factors.
_ the last line follows from the previous one, nothing more to say.
Also in general, one has to be careful as the final state has norm 1. The solution clearly mentions that "Bob gets a state proportional to ..." but ideally, the correct coefficient should be calculated and appended to the result (some students did it accurately).
