Domain-Specific Quantum Architecture Optimization

TL;DR

This paper introduces a framework for customizing quantum processor architectures, particularly qubit connectivity, to improve performance and fidelity for near-term quantum algorithms, integrating optimization with an optimal compiler.

Contribution

It is the first to combine architecture optimization with an optimal compiler, evaluate connectivity impacts under realistic error models, and benchmark on practical quantum circuits.

Findings

Up to 59% fidelity improvement for QAOA on heavy-hexagon architecture

Up to 14% fidelity improvement on grid architecture for QAOA

11% and 605% fidelity improvements for QCNN on heavy-hexagon and grid architectures

Abstract

With the steady progress in quantum computing over recent years, roadmaps for upscaling quantum processors have relied heavily on the targeted qubit architectures. So far, similarly to the early age of classical computing, these designs have been crafted by human experts. These general-purpose architectures, however, leave room for customization and optimization, especially when targeting popular near-term QC applications. In classical computing, customized architectures have demonstrated significant performance and energy efficiency gains over general-purpose counterparts. In this paper, we present a framework for optimizing quantum architectures, specifically through customizing qubit connectivity. It is the first work that (1) provides performance guarantees by integrating architecture optimization with an optimal compiler, (2) evaluates the impact of connectivity customization under a realistic crosstalk error model, and (3) benchmarks on realistic circuits of near-term interest, such as the quantum approximate optimization algorithm (QAOA) and quantum convolutional neural network (QCNN). We demonstrate up to 59% fidelity improvement in simulation by optimizing the heavy-hexagon architecture for QAOA circuits, and up to 14% improvement on the grid architecture. For the QCNN circuit, architecture optimization improves fidelity by 11% on the heavy-hexagon architecture and 605% on the grid architecture.