Hierarchical System Mapping for Large-Scale Fault-Tolerant Quantum Computing

TL;DR

This paper introduces a hierarchical system mapping approach for large-scale fault-tolerant quantum computing, significantly reducing mapping time and resource overhead compared to previous methods.

Contribution

It proposes a fast, hierarchical assembly code-based mapping method that supports dynamic module interconnection, enabling practical large-scale quantum resource analysis.

Findings

Mapping time reduced from 1500 days to 1 hour for Shor's algorithm

Hierarchical assembly code improves locality and reduces SWAP chains

Method supports dynamic module interconnection with communication bus

Abstract

Considering the large-scale quantum computer, it is important to know how much quantum computational resources is necessary precisely and quickly. Unfortunately the previous methods so far cannot support a large-scale quantum computing practically and therefore the analysis because they usually use a non-structured code. To overcome this problem, we propose a fast mapping by using the hierarchical assembly code which is much more compact than the non-structured code. During the mapping process, the necessary modules and their interconnection can be dynamically mapped by using the communication bus at the cost of additional qubits. In our study, the proposed method works very fast such as 1 hour than 1500 days for Shor algorithm to factorize 512-bit integer. Meanwhile, since the hierarchical assembly code has high degree of locality, it has shorter SWAP chains and hence it does not increase the quantum computation time than expected.