Emergence and Frustration of Magnetic Order with Variable-Range Interactions in a Trapped Ion Quantum Simulator

TL;DR

This study uses a trapped ion quantum simulator to explore how variable-range interactions induce and influence magnetic order and frustration in a quantum Ising model, revealing the dependence of magnetic phases on frustration levels.

Contribution

It demonstrates the controlled simulation of long-range antiferromagnetic interactions and measures their effects on magnetic order and quantum coherence in a system of up to 16 ions.

Findings

Magnetic order varies significantly with interaction range.

Signatures of quantum coherence are observed in frustrated phases.

Direct measurement of spin correlations confirms theoretical predictions.

Abstract

Frustration, or the competition between interacting components of a network, is often responsible for the complexity of many body systems, from social and neural networks to protein folding and magnetism. In quantum magnetic systems, frustration arises naturally from competing spin-spin interactions given by the geometry of the spin lattice or by the presence of long-range antiferromagnetic couplings. Frustrated magnetism is a hallmark of poorly understood systems such as quantum spin liquids, spin glasses and spin ices, whose ground states are massively degenerate and can carry high degrees of quantum entanglement. The controlled study of frustrated magnetism in materials is hampered by short dynamical time scales and the presence of impurities, while numerical modeling is generally intractable when dealing with dynamics beyond N~30 particles. Alternatively, a quantum simulator can be exploited to directly engineer prescribed frustrated interactions between controlled quantum systems, and several small-scale experiments have moved in this direction. In this article, we perform a quantum simulation of a long-range antiferromagnetic quantum Ising model with a transverse field, on a crystal of up to N = 16 trapped Yb+ atoms. We directly control the amount of frustration by continuously tuning the range of interaction and directly measure spin correlation functions and their dynamics through spatially-resolved spin detection. We find a pronounced dependence of the magnetic order on the amount of frustration, and extract signatures of quantum coherence in the resulting phases.