Simulating Neutron Scattering on an Analog Quantum Processor

TL;DR

This paper demonstrates the simulation of neutron scattering on an analog quantum processor, specifically measuring the dynamic structure factor of a quantum spin chain, and confirms entanglement using experimental data.

Contribution

It introduces a novel method for simulating neutron scattering on an analog quantum processor and validates it with experimental results on a 25-spin chain.

Findings

Successful measurement of the dynamic structure factor on hardware

Experimental confirmation of bipartite entanglement via QFI

Error mitigation techniques improve simulation accuracy

Abstract

Neutron scattering characterization of materials allows for the study of entanglement and microscopic structure, but is inefficient to simulate classically for comparison to theoretical models and predictions. However, quantum processors, notably analog quantum simulators, have the potential to offer an unprecedented, efficient method of Hamiltonian simulation by evolving a state in real time to compute phase transitions, dynamical properties, and entanglement witnesses. Here, we present a method for simulating neutron scattering on QuEra's Aquila processor by measuring the dynamic structure factor (DSF) for the prototypical example of the critical transverse field Ising chain, and propose a method for error mitigation. We provide numerical simulations and experimental results for the performance of the procedure on the hardware, up to a chain of length $L=25$. Additionally, the DSF result is used to compute the quantum Fisher information (QFI) density, where we confirm bipartite entanglement in the system experimentally.