QuEST and High Performance Simulation of Quantum Computers

TL;DR

QuEST is an open-source, GPU-accelerated quantum circuit simulator that scales efficiently on supercomputers, enabling high-performance simulation of up to 38 qubits with complex states and decoherence effects.

Contribution

This paper introduces QuEST, the first open-source hybrid CPU-GPU quantum simulator with seamless platform deployment and superior scalability for large quantum circuits.

Findings

QuEST can simulate up to 38 qubits on supercomputers.

QuEST demonstrates excellent strong and weak scaling performance.

Comparison shows QuEST outperforms ProjectQ in distributed environments.

Abstract

We introduce QuEST, the Quantum Exact Simulation Toolkit, and compare it to ProjectQ, qHipster and a recent distributed implementation of Quantum++. QuEST is the first open source, OpenMP and MPI hybridised, GPU accelerated simulator of universal quantum circuits. Embodied as a C library, it is designed so that a user's code can be deployed seamlessly to any platform from a laptop to a supercomputer. QuEST is capable of simulating generic quantum circuits of general single-qubit gates and multi-qubit controlled gates, on pure and mixed states, represented as state-vectors and density matrices, and under the presence of decoherence. Using the ARCUS Phase-B and ARCHER supercomputers, we benchmark QuEST's simulation of random circuits of up to 38 qubits, distributed over up to 2048 compute nodes, each with up to 24 cores. We directly compare QuEST's performance to ProjectQ's on single machines, and discuss the differences in distribution strategies of QuEST, qHipster and Quantum++. QuEST shows excellent scaling, both strong and weak, on multicore and distributed architectures.