FindHow can I find a $2 \times 2$ Hamiltonian $\mathcal H_H$ such that $e^{i\mathcal H_H}$ equals the Hadamard matrix and?
On a similar note, how to find a $4 \times 4$ Hamiltonian $\mathcal H_{CNOT}$ such that $e^{-i\mathcal H_{CNOT}}$ equals the matrix of the CNOT gate.?
I have been trying to solve this but couldn't come to any conclusion. Any help would be really appreciated.