Digital Quantum Simulation of the Statistical Mechanics of a Frustrated Magnet

TL;DR

This paper demonstrates the first digital quantum simulation of a thermal state of a frustrated magnet using NMR, enabling exploration of phase diagrams at various temperatures and fields, advancing quantum simulation of open systems.

Contribution

It introduces a novel digital quantum simulation method for thermal states of a frustrated magnet, overcoming limitations of adiabatic approaches.

Findings

Successfully simulated a three-spin frustrated magnet at different temperatures.

Explored the phase diagram of the system at various external fields.

Identified challenges for future large-scale quantum simulations of open systems.

Abstract

Many interesting problems in physics, chemistry, and computer science are equivalent to problems of interacting spins. However, most of these problems require computational resources that are out of reach by classical computers. A promising solution to overcome this challenge is to exploit the laws of quantum mechanics to perform simulation. Several "analog" quantum simulations of interacting spin systems have been realized experimentally. However, relying on adiabatic techniques, these simulations are limited to preparing ground states only. Here we report the first experimental results on a "digital" quantum simulation on thermal states; we simulated a three-spin frustrated magnet, a building block of spin ice, with an NMR quantum information processor, and we are able to explore the phase diagram of the system at any simulated temperature and external field. These results serve as a guide for identifying the challenges for performing quantum simulation on physical systems at finite temperatures, and pave the way towards large scale experimental simulations of open quantum systems in condensed matter physics and chemistry.