Classical simulations are essential for the development of quantum computing, and their exponential scaling can easily fill any modern supercomputer. In this paper we consider the performance and energy consumption of large Quantum Fourier Transform (QFT) simulations run on ARCHER2, the UK's National Supercomputing Service, with QuEST toolkit. We take into account CPU clock frequency and node memory size, and use cache-blocking to rearrange the circuit, which minimises communications. We find that using 2.00GHz instead of 2.25GHz can save as much as 25% of energy at 5% increase in runtime. Higher node memory also has the potential to be more efficient, and cost the user fewer CUs, but at higher runtime penalty. Finally, we present a cache-blocking QFT circuit, which halves the required communication. All our optimisations combined result in 40% faster simulations and 35% energy savings in 44 qubit simulations on 4,096 ARCHER2 nodes.

翻译：经典模拟对量子计算的发展至关重要，但其指数级扩展性很容易填满任何现代超级计算机。本文以英国国家超级计算服务ARCHER2为平台，使用QuEST工具包对大规模量子傅里叶变换（QFT）模拟的性能与能耗进行研究。我们考虑了CPU时钟频率与节点内存大小，并采用缓存阻塞技术重构电路以最小化通信开销。研究发现，使用2.00GHz频率替代2.25GHz可在运行时增加5%的情况下节省多达25%的能耗。更高节点内存虽能提升能效并减少用户计算单元（CU）消耗，但会导致更大的运行时损耗。最终，我们提出一种缓存阻塞型QFT电路，可将所需通信量减半。综合所有优化措施，在4,096个ARCHER2节点上对44量子比特模拟实现了40%的计算加速与35%的能耗降低。