Near the transverse-field induced quantum critical point of the Ising chain, an exotic dynamic spectrum consisting of exactly eight particles was predicted, which is uniquely described by an emergent quantum integrable field theory with the symmetry of the E8 Lie algebra, but rarely explored experimentally. Here we use high-resolution terahertz spectroscopy to resolve quantum spin dynamics of the quasi-one-dimensional Ising antiferromagnet BaCo2V2O8 in an applied transverse field. By comparing to an analytical calculation of the dynamical spin correlations, we identify E8 particles as well as their two-particle excitations.
Cite
@article{arxiv.2005.13772,
title = {Observation of E8 Particles in an Ising Chain Antiferromagnet},
author = {Zhao Zhang and Kirill Amelin and Xiao Wang and Haiyuan Zou and Jiahao Yang and Urmas Nagel and Toomas Rõõm and Tusharkanti Dey and Agustinus Agung Nugroho and Thomas Lorenz and Jianda Wu and Zhe Wang},
journal= {arXiv preprint arXiv:2005.13772},
year = {2020}
}