Design of Fault-Tolerant Quantum Ripple Carry Adder

Abstract

The performance of existing technology for implementing digital circuits based on irreversible logic is closely reaching its limit. Conventional logic circuits result in heat dissipation whenever there is an information loss. Hence reversible logic is attaining major consideration in the perspective of evolving technologies such as quantum computing as there isno information loss and there is a unique mapping between the input vectors and output vectors. A reversible gate is supposed to be parity preserving if there existsimilarity between input parityand the outputparity.To construct reliable fault-tolerant reversible systems elements should be of fault-tolerant reversiblestructures.Adder circuits are studied extensively since their performance can directly affect the entire digital system. This paper presents a Toffoli gate (TG) based fulladderwhich serves as a fundamental component in constructing a ripple carry adder. Further a parity preserving Toffoligate based full adder is presented which was utilized to develop a fault-tolerant Ripple Carry Adder without compromising on its performance.The proposed designs have been simulated using IBM Quantum Simulator and have been verified for their correctness. The proposed adders will serve as vital design components in developing fault-tolerant reversible arithmetic and logic unit.