  Classical computers require large memory resources and computational power to
simulate quantum circuits with a large number of qubits. Even supercomputers
that can store huge amounts of data face a scalability issue in regard to
parallel quantum computing simulations because of the latency of data movements
between distributed memory spaces. Here, we apply a cache blocking technique by
inserting swap gates in quantum circuits to decrease data movements. We
implemented this technique in the open source simulation framework Qiskit Aer.
We evaluated our simulator on GPU clusters and observed good scalability.
