Divergent nonlinear response from quasiparticle interactions
Abstract
We demonstrate that nonlinear response functions in many-body systems carry a sharp signature of interactions between gapped low-energy quasiparticles. Such interactions are challenging to deduce from linear response measurements. The signature takes the form of a divergent-in-time contribution to the response -- linear in time in the case when quasiparticles propagate ballistically -- that is absent for free bosonic excitations. We give an intuitive semiclassical picture of this singular behaviour, validated against exact results from a form-factor expansion of the Ising chain and tDMRG simulations in a non-integrable model -- the spin-1 AKLT chain. We comment on extensions of these results to more general settings, finite temperature, and higher dimensions.
Cite
@article{arxiv.2208.09490,
title = {Divergent nonlinear response from quasiparticle interactions},
author = {Michele Fava and Sarang Gopalakrishnan and Romain Vasseur and Fabian H. L. Essler and S. A. Parameswaran},
journal= {arXiv preprint arXiv:2208.09490},
year = {2024}
}
Comments
Updated version with additional numerical data. 6 pages, 3 figures (+7 pages of supplementary material)