Toward Designing High-Speed Cost-Efficient Quantum Reversible Carry Select Adders

Compared to classical computing implementations, reversible arithmetic adders offer a valuable platform for implementing quantum computation models in digital systems and specific applications, such as cryptography and natural language processing. Reversible logic efficiently prevents energy wastage through thermal dissipation. This study presents a comprehensive exploration introducing new carry-select adders (CSLA) based on quantum and reversible logic. Five reversible CSLA designs are proposed and compared, evaluating various criteria, including speed, quantum cost, and area, compared to previously published schemes. These comparative metrics are formulated for arbitrary n-bit size blocks. Each design type is described generically, capable of implementing carry-select adders of any size. As the best outcome, this study proposes an optimized reversible adder circuit that addresses quantum propagation delay, achieving an acceptable trade-off with quantum cost compared to its counterparts. This article reduces calculation delay by 66%, 73%, 82%, and 87% for 16, 32, 64, and 128 bits, respectively, while maintaining a lower quantum cost in all cases.