 Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2021/iii/paper-302/3/iv/solution

From

A σ_{b} A^{†} = R^{a}_{b} σ_{a}

and

tr (σ_{a} σ_{b}) = 2 δ_{ab}

R^{a}_{b} = \frac{1}{2} tr (σ_{a} A σ_{b} A^{†}) .

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