Hierarchical system mapping for large-scale fault-tolerant quantum computing

With respect to large-scale quantum computing, it is important to know precisely and quickly how much quantum computational resources are necessary to study components and the whole system. If such quantum resources are provided, how much performance a quantum computer provides is also a critical issue. Unfortunately, it is practically infeasible to deal with such problems with conventional methods based on a non-structured description about quantum algorithm. To overcome the problems, we propose a fast method by using a hierarchically structured description about quantum algorithm which is much more compact than the conventional method. During the process, the dedicated computing regions and their interconnection are dynamically mapped onto a structured quantum computing system architecture. In our study, the proposed method works very faster such as 1 h than 1500 days for Shor algorithm to factorize a 512-bit integer. Meanwhile, since the combination of structured code and architecture provides a high degree of locality, it requires less SWAP chains, and hence, it does not increase the quantum computation depth more than expected.