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TT: Fachverband Tiefe Temperaturen

TT 15: Many-Body Quantum Dynamics II (joint session DY/TT)

TT 15.3: Vortrag

Donnerstag, 30. September 2021, 10:30–10:45, H2

Disorder-Free Localization in an Interacting 2D Lattice Gauge Theory — •Peter Karpov^1,2, Roberto Verdel¹, Yi-Ping Huang³, Markus Schmitt⁴, and Markus Heyl¹ — ¹Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — ²National Univesity of Science and Technology “MISiS”, Moscow, Russia — ³National Tsing Hua University, Hsinchu, Taiwan — ⁴University of Cologne, Cologne, Germany

Disorder-free localization has been recently introduced as a mechanism for ergodicity breaking in low-dimensional homogeneous lattice gauge theories caused by local constraints. We show that also genuinely interacting systems in two spatial dimensions can become nonergodic due to this mechanism. This is all the more surprising since the conventional many-body localization is conjectured to be unstable in two dimensions; hence the gauge constraints represent an alternative robust localization mechanism for interacting models in higher dimensions.

Specifically, we demonstrate nonergodic behavior in the quantum link model by obtaining a bound on the localization-delocalization transition through a unconventional percolation problem implying a fragmentation of Hilbert space. We study the quantum dynamics in this system by introducing the method of “variational classical networks”, an efficient representation of the wave function in terms of a network of classical spins. We show that propagation of line defects has different light cone structures in the localized and ergodic phases.

[1] P. Karpov et al, Phys. Rev. Lett. 126, 130401 (2021).

[2] R. Verdel et al, Phys. Rev. B 103, 165103 (2021).