Chemically decisive benchmarks on the path to quantum utility

TL;DR

This paper introduces a set of chemically meaningful benchmark problems spanning diverse electronic correlation regimes to evaluate quantum algorithms in chemistry, highlighting their strengths and limitations.

Contribution

It presents a curated hierarchy of challenging chemical benchmark systems and demonstrates the application of an adaptive quantum algorithm, ADAPT-GCIM, for accurate electronic structure calculations.

Findings

ADAPT-GCIM achieves high accuracy across diverse chemical problems.

Benchmarks reveal common failure modes and constraints of quantum algorithms.

Openly available Hamiltonians facilitate reproducible benchmarking.

Abstract

Progress towards quantum utility in chemistry requires not only algorithmic advances, but also the identification of chemically meaningful problems whose electronic structure fundamentally challenges classical methods. Here, we introduce a curated hierarchy of chemically decisive benchmark systems designed to probe distinct regimes of electronic correlation relevant to molecular, bioinorganic, and heavy-element chemistry. Moving beyond minimal toy models, our benchmark set spans multireference bond breaking (N$_2$), high-spin transition-metal chemistry (FeS), biologically relevant iron-sulfur clusters ([2Fe-2S]), and actinide-actinide bonding (U$_2$), which exhibits extreme sensitivity to active-space choice, relativistic treatment, and correlation hierarchy even within advanced multireference frameworks. As a concrete realization, we benchmark a recently developed automated and adaptive quantum algorithm based on generator-coordinate-inspired subspace expansion,ADAPT-GCIM, using a black-box workflow that integrates entropy-based active-space selection via the ActiveSpaceFinder tool. Across this chemically diverse problem set, ADAPT-GCIM achieves high accuracy in challenging correlation regimes. Equally importantly, these benchmarks expose general failure modes and design constraints-independent of any specific algorithm-highlighting the necessity of problem-aware and correlation-specific strategies for treating strongly correlated chemistry on quantum computers. To support systematic benchmarking and reproducible comparisons, the Hamiltonians for all systems studied are made openly available.