Density matrix quantum circuit simulation via the BSP machine on modern GPU clusters

As quantum computers evolve, simulations of quantum programs on classical computers will be essential in validating quantum algorithms, understanding the effect of system noise, and designing applications for future quantum computers. In this paper, we first propose a new multi-GPU programming methodology called MG-BSP which constructs a virtual BSP machine on top of modern multi-GPU platforms, and apply this methodology to build a multi-GPU density matrix quantum simulator called DM-Sim. We propose a new formulation that can significantly reduce communication overhead, and show that this formula transformation can conserve the semantics despite noise being introduced. We build the tool-chain for the simulator to run open standard quantum assembly code, execute synthesized quantum circuits, and perform ultra-deep and largescale simulations. We evaluated DM-Sim on several state-of-the-art multi-GPU platforms including NVIDIA's PascaUVolta DGX1, DGX-2, and ORNL's Summit supercomputer. In particular, we have demonstrated the simulation of one million general gates in 94 minutes on DGX-2, far deeper circuits than has been demonstrated in prior works. Our simulator is more than 10x faster with respect to the corresponding state-vector quantum simulators on GPUs and other platforms. The DM-Sim simulator is released at: http:llgithub.comlpnnllDM-Sim.