  We consider the two-step method [A. R. Kuzmak and V. M. Tkachuk, Phys. Lett.
A 378 (2014) 1469] for preparation of an arbitrary quantum gate on two spins
with anisotropic Heisenberg interaction. At the first step, the system evolves
during some period of time. At the second step, we apply pulsed magnetic field
individually to each spin. We obtain the conditions for realization of SWAP,
iSWAP, $\sqrt{SWAP}$ and entangled gates. Finally, we consider the
implementation of this method on the physical system of ultracold atoms in
optical lattice.
