Quantum annealing simulation of out-of-equilibrium magnetization in a spin-chain compound

TL;DR

This paper demonstrates how a superconducting quantum annealing processor can simulate out-of-equilibrium magnetization in a frustrated spin-chain, revealing quantum effects on metastability and phase transitions.

Contribution

It introduces a method to simulate frustrated magnetism dynamics using quantum annealing, highlighting quantum fluctuations' role in reducing metastability and promoting order.

Findings

Quantum fluctuations reduce metastable trapping.

Quantum effects promote long-range ferrimagnetic order.

Finite-temperature features are influenced by quantum fluctuations.

Abstract

Geometrically frustrated spin-chain compounds such as Ca3Co2O6 exhibit extremely slow relaxation under a changing magnetic field. Consequently, both low-temperature laboratory experiments and Monte Carlo simulations have shown peculiar out-of-equilibrium magnetization curves, which arise from trapping in metastable configurations. In this work we simulate this phenomenon in a superconducting quantum annealing processor, allowing us to probe the impact of quantum fluctuations on both equilibrium and dynamics of the system. Increasing the quantum fluctuations with a transverse field reduces the impact of metastable traps in out-of-equilibrium samples, and aids the development of three-sublattice ferrimagnetic (up-up-down) long-range order. At equilibrium we identify a finite-temperature shoulder in the 1/3-to-saturated phase transition, promoted by quantum fluctuations but with entropic origin. This work demonstrates the viability of dynamical as well as equilibrium studies of frustrated magnetism using large-scale programmable quantum systems, and is therefore an important step toward programmable simulation of dynamics in materials using quantum hardware.