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DY: Fachverband Dynamik und Statistische Physik
DY 9: Quantum Dynamics, Decoherence and Quantum Information
DY 9.1: Talk
Monday, March 27, 2023, 14:00–14:15, MOL 213
From Dual Unitarity to Generic Quantum Operator Spreading — •Michael A. Rampp, Roderich Moessner, and Pieter W. Claeys — Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
Dual-unitary circuits are paradigmatic examples of exactly solvable yet chaotic quantum many- body systems, but solvability naturally goes along with a degree of non-generic behaviour. By investigating the effect of weakly broken dual-unitarity on the spreading of local operators we study whether, and how, small deviations from dual-unitarity recover fully generic many-body dynamics. We present a discrete path-integral formula for the out-of-time-order correlator and use it to recover a butterfly velocity smaller than the light-cone velocity, vB < vLC , and a diffusively broadening operator front, two generic features of ergodic quantum spin chains absent in dual-unitary circuit dynamics. We find that the butterfly velocity and diffusion constant are determined by a small set of microscopic quantities and that the operator entanglement of the gates plays a crucial role.