A Higher Radix Architecture for Quantum Carry-lookahead Adder

Siyi Wang; Anubhab Baksi; Anupam Chattopadhyay

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arXiv · 2304.02921

A Higher Radix Architecture for Quantum Carry-lookahead Adder

Siyi Wang·Anubhab Baksi·Anupam Chattopadhyay

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Abstract

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 $O(n)-O(\frac{n}{r})$ qubits and $O(n)+O(\frac{n}{r})$ T gates to get the correct answer in T-depth $O(r)+O(\log{\frac{n}{r}})$, 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.

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Siyi Wang, Anubhab Baksi, Anupam Chattopadhyay. 2023-04-06. A Higher Radix Architecture for Quantum Carry-lookahead Adder. https://arxiv.org/abs/2304.02921

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