Precisely knowing an interaction Hamiltonian is crucial to realize quantum
information tasks, especially to experimentally demonstrate a quantum computer
and a quantum memory. We propose a scheme to experimentally evaluate the
spin-spin interaction for a two-qubit system by the weak measurement technique
initiated by Yakir Aharonov and his colleagues. Furthermore, we numerically
confirm our proposed scheme in a specific system of a nitrogen vacancy center
in diamond. This means that the weak measurement can also be taken as a
concrete example of the quantum process tomography.Comment: 4 pages, 1 table, 2 figures, to appear in Europhysics Letter
