Faster Schr\"odinger-style simulation of quantum circuits

TL;DR

This paper introduces optimized Schr"odinger-style simulation techniques for quantum circuits, enabling faster and more efficient classical simulation of quantum algorithms, supporting up to 64 qubits and benchmarking against industry leaders.

Contribution

It presents novel simulation algorithms that improve efficiency by parallelizing gate operations, avoiding floating-point multiplies, and optimizing circuit gate reordering.

Findings

Supported high-performance distributed simulations up to 64 qubits

Achieved faster simulation times compared to existing industry simulators

Demonstrated effectiveness on complex circuits from Google

Abstract

Recent demonstrations of superconducting quantum computers by Google and IBM and trapped-ion computers from IonQ fueled new research in quantum algorithms, compilation into quantum circuits, and empirical algorithmics. While online access to quantum hardware remains too limited to meet the demand, simulating quantum circuits on conventional computers satisfies many needs. We advance Schr\"odinger-style simulation of quantum circuits that is useful standalone and as a building block in layered simulation algorithms, both cases are illustrated in our results. Our algorithmic contributions show how to simulate multiple quantum gates at once, how to avoid floating-point multiplies, how to best use instruction-level and thread-level parallelism as well as CPU cache, and how to leverage these optimizations by reordering circuit gates. While not described previously, these techniques implemented by us supported published high-performance distributed simulations up to 64 qubits. To show additional impact, we benchmark our simulator against Microsoft, IBM and Google simulators on hard circuits from Google.