Abstract: Reversible Numerical Comparator is the most important part of numerous arithmetic devices in reversible computer. The reversible comparator circuit was optimized further in order to improve the universality of reversible comparator .The logical relationship of input and output in comparator was analyzed. A one-bit reversible comparator (OBC) and a one-bit reversible complete comparator (OBCC) were presented and designed. And on the basis of that, using these two devices, it could be cascaded and rapidly generated into a reversible circuit of universal reversible comparator. Compared with the related literatures, the cascaded method efficiently decreases the quantity of constant inputs and garbage outputs, meanwhile it has the lower quantum cost, which is prone to the comparison with two multi-bit numerical values in reversible circuit.

Key words: quantum information; reversible logic; reversible comparator; reversible cascaded circuit; quantum cost