Divergent Nonlinear Response from Quasiparticle Interactions

Michele Fava, Sarang Gopalakrishnan, Romain Vasseur, Fabian Essler, S. A. Parameswaran

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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 a physically transparent semiclassical picture of this singular behavior. While the semiclassical picture applies to a broad class of systems we benchmark it in two simple models: in the Ising chain using a form-factor expansion, and in a nonintegrable model - the spin-1 Affleck-Kennedy-Lieb-Tasaki chain - using time-dependent density matrix renormalization group simulations. We comment on extensions of these results to finite temperatures.

Original languageEnglish (US)
Article number256505
JournalPhysical review letters
Volume131
Issue number25
DOIs
StatePublished - Dec 22 2023

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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