An optimized design of binary comparator circuit in quantum computing

Reversible logic; transforms logic signal in a way that allows the original input signals to be recovered from the produced outputs, has attracted great attention because of its application in diverse areas such as quantum computing, low power computing, nanotechnology, DNA computing, quantum dot cellular automata, optical computing. In this paper, we design low power binary comparators using reversible logic gates. Firstly, single bit binary reversible comparator circuits are designed using different reversible gates along with proposed gate named Newly Proposed Gate. Then, these procedures are generalized for constructing binary n-bit reversible comparator circuit. The design synthesis consists of two parts: Comparator Cell and Propagator Cell. An algorithm, based on our proposed design, shows that proposed circuit reduces overall cost and it outperforms than existing sequential comparator circuits. Also, comparing with existing tree-based comparator circuit, proposed design reduces quantum cost, garbage output and gate count in a significance level which means better improvement as cost of any quantum circuit is directly associated with quantum cost, garbage output and gate count.