Adding binary numbers with discrete solitons in waveguide arrays

We present a design and protocol to add binary numbers using discrete solitons in waveguide arrays. We show that the nonlinear interaction between discrete solitons in waveguide arrays can be exploited to design half and full adders. By modulating the separation between waveguides and introducing control solitons, we achieve the performance of an XOR gate. We construct the half and full adders using the XOR gate together with the previously- designed OR and AND gates. To facilitate the experimental realization, we calculate the profile of separations between the waveguides that will lead to the performance of the XOR gate.