A higher radix architecture for quantum carry-lookahead adder

• Main Authors: Wang, Siyi, Baksi, Anubhab, Chattopadhyay, Anupam
• Other Authors: School of Computer Science and Engineering
• Format: Article
• Language: English
• Published: 2024
• Subjects: Computer and Information Science; Quantum carry-lookahead adder; Higher radix structure
• Online Access: https://hdl.handle.net/10356/173882
• Institution: Nanyang Technological University

In this paper, we propose an efficient quantum carry-lookahead adder based on the higher radix structure. For the addition of two n-bit numbers, our adder uses [Formula: see text] qubits and [Formula: see text] T gates to get the correct answer in T-depth [Formula: see text], where r is the radix. Quantum carry-lookahead adder has already attracted some attention because of its low T-depth. Our work further reduces the overall cost by introducing a higher radix layer. By analyzing the performance in T-depth, T-count, and qubit count, it is shown that the proposed adder is superior to existing quantum carry-lookahead adders. Even compared to the Draper out-of-place adder which is very compact and efficient, our adder is still better in terms of T-count.