LightSABRE: A Lightweight and Enhanced SABRE Algorithm

TL;DR

LightSABRE is a significantly faster and more scalable enhancement of the SABRE quantum circuit routing algorithm, improving runtime efficiency and circuit quality for large quantum circuits on modern hardware.

Contribution

It introduces LightSABRE, a novel version of SABRE that is approximately 200 times faster and achieves better circuit optimization compared to previous implementations.

Findings

200x faster runtime than previous Qiskit implementation

18.9% average reduction in SWAP gate count

Consistently high-quality routing for large quantum circuits

Abstract

We introduce LightSABRE, a significant enhancement of the SABRE algorithm that advances both runtime efficiency and circuit quality. LightSABRE addresses the increasing demands of modern quantum hardware, which can now accommodate complex scenarios, and circuits with millions of gates. Through iterative development within Qiskit, primarily using the Rust programming language, we have achieved a version of the algorithm in Qiskit 1.2.0 that is approximately 200 times faster than the implementation in Qiskit 0.20.1, which already introduced key improvements like the release valve mechanism. Additionally, when compared to the SABRE algorithm presented in Li et al., LightSABRE delivers an average decrease of 18.9\% in SWAP gate count across the same benchmark circuits. Unlike SABRE, which struggles with scalability and convergence on large circuits, LightSABRE delivers consistently high-quality routing solutions, enabling the efficient execution of large quantum circuits on near-term and future quantum devices. LightSABRE's improvements in speed, scalability, and quality position it as a critical tool for optimizing quantum circuits in the context of evolving quantum hardware and error correction techniques.