# Tag Info

After several days of thinking and researching, I decided to answer my own question. N.B. The tensor product symbol $\otimes$ are omitted when there is no risk in confusion, especially when the index is different. In symbol, $$A_iB_j = A_i \otimes B_j (i \neq j).$$ Firstly, for case $$e^{i \beta B} Z_i Z_j e^{-i \beta B},$$ we only consider qubit $j$, in ...