Let $A: \ell^2 \rightarrow \ell^2$ be a bounded operator given by \begin{equation} (Au)(\alpha) = \sum_{\beta}A(\alpha,\beta)u(\beta) \end{equation} where $\left|A(\alpha,\beta) \right|\le Ce^{-|\alpha-\beta|}.$
Now assume that $B=UAU^*$ and $U$ is unitary on $\ell^2$ with $(Bu)(\alpha) = \sum_{\beta}B(\alpha,\beta)u(\beta).$
I would like to know if there is also exponential decay of the coefficients $B(\alpha,\beta)$ under these assumptions?