Abstract

Several optical Fredkin gate [Fig. 1] implementations have recently been proposed¹ as building blocks for optical computers. It is shown that such conditional-routing devices can in fact be cascaded to compute the function f(x₁,…,x_n,y₁,…, y_n)=[(x₁…x_n)+(y₁…y_n)]mod2. This is accomplished through the design of a Fredkin-based minimal full adder circuit [Fig. 2] with carry-out feedback possessing the property that its control signals never interchange with data signals. Computation is performed by inserting the variable arguments initially into various control lines, while constant values are inserted into the initial data lines. The circuit is thus 'programmed' by scratchpad constants entered into its first-level data lines.

© 1987 Optical Society of America