Quantum computation of magnon spectra

TL;DR

This paper demonstrates the use of IBM quantum computers to compute magnon spectra in a Heisenberg spin chain, showing promising results for small systems despite noise issues in larger ones.

Contribution

It introduces a method for quantum computation of correlation functions in spin chains and evaluates its effectiveness on current quantum hardware.

Findings

Exact correlation functions for two sites

Noisy but spectrally accurate results for four sites

Successful extraction of magnon energies from spectral peaks

Abstract

We demonstrate quantum computation of two-point correlation functions for a Heisenberg spin chain. Using the IBM Q 20 quantum machines, we find that for two sites the correlation functions produce the exact results reliably. For four sites, results from the IBM Q 20 Tokyo quantum computer are noisy due to read out errors and decoherence. Nevertheless, the correlation functions retain the correct spectral information. This is illustrated in the frequency domain by accurately extracting the magnon energies from peaks in the spectral function.