Benchmarking quantum simulation with neutron-scattering experiments

TL;DR

This paper demonstrates that a 50-qubit superconducting quantum processor can perform meaningful quantum simulations of material spectra, matching neutron-scattering experiments and extending to complex models with strong correlations.

Contribution

It introduces a quantum-classical workflow for computing dynamical structure factors, benchmarking quantum simulations against experimental data for the first time at this scale.

Findings

Quantum processor achieves quantitative agreement with neutron-scattering data for KCuF3.

Simulation accuracy depends on circuit depth and fidelity.

Extended simulations to a gapped XXZ model with NNN interactions.

Abstract

Realistic simulation of quantum materials is a central goal of quantum computation. Although quantum processors have advanced rapidly in scale and fidelity, it has remained unclear whether pre-fault-tolerant devices can perform quantitatively reliable material simulations. We demonstrate that a superconducting quantum processor operating on up to 50 qubits can already produce meaningful, quantitative comparisons with inelastic neutron-scattering measurements of KCuF$_3$, a canonical realization of a gapless Luttinger liquid system with a strongly correlated ground state and a spectrum of emergent spinons. The quantum simulation is enabled by a quantum-classical workflow for computing dynamical structure factors (DSFs). The resulting spectra are benchmarked against experimental measurements using multiple metrics, highlighting the impact of circuit depth and circuit fidelity on simulation accuracy. Finally, we extend our simulations to a 1D XXZ Heisenberg model with next-nearest-neighbor (NNN) interactions and a strong anisotropy, producing a gapped excitation spectrum, which could be used to describe the CsCoX$_3$ compounds above the N\'eel temperature. Our results establish a framework for computing DSFs for quantum materials in classically challenging regimes of strong entanglement and long-range interactions, enabling quantum simulations that are directly testable against laboratory measurements.