Non-equilibrium dynamics of ultra cold lattice gases with inter-site interactions

• Applicant: Professor Dr. Luis Santos
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2018 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 395724503

• Final Report Year: 2023

Final Report Abstract

Ultracold gases in optical lattices provide an excellent platform for the quantum simulation of many-body systems. Recent experiments with magnetic atoms, polar molecules, and Rydberg atoms are opening exciting perspectives for the study of spin and Hubbard models with strong inter-site dipole-dipole interactions. The present project has analyzed how these inter-site interactions affect the non-equilibrium dynamics of dipolar extended-Hubbard models. We have shown in particular, that strong-enough dipolar interactions result in quasi-localization induced by the formation of clusters of dynamically-bound dimers, as well as in self-bound lattice droplets, which may be readily observed in on-going or near-future experiments. Moreover, our results have shown that dynamically-bound dipolar dimers in two-dimensional lattices experience an effective lattice geometry that differs from that experienced by individual particles. This is particularly relevant in triangular lattices, where dipolar dimers move resonantly in an effective kagome lattice, presenting a peculiar bimodal dynamics that results from the appearance of an emerging flat band. As a major result, we have shown that polar lattice gases constitute an excellent scenario for the study of Hilbert-space fragmentation and disorder-free localization, an issue of major recent interest. We have analyzed the role of interactions beyond nearest-neighbors, showing that they result in Hilbertspace shattering and strong localization for dipole strengths that may be soon available in experiments. Finally, although the bulk of the project dealt with Hubbard models, we have investigated as well nonequlibrium dynamics in spin models with dipolar and more general power-law interactions, analyzing the many-body localization transition and the creation of correlated excitations in bilayer experiments.

Publications

• Disorderless Quasi-localization of Polar Gases in One-Dimensional Lattices. Physical Review Letters, 124(1).
  Li, W.; Dhar, A.; Deng, X.; Kasamatsu, K.; Barbiero, L. & Santos, L.
  
• Universal Algebraic Growth of Entanglement Entropy in Many-Body Localized Systems with Power-Law Interactions. Physical Review Letters, 125(1).
  Deng, Xiaolong; Masella, Guido; Pupillo, Guido & Santos, Luis
  
• Cluster dynamics in two-dimensional lattice gases with intersite interactions. Physical Review A, 103(4).
  Li, Wei-Han; Dhar, Arya; Deng, Xiaolong & Santos, Luis
  
• Hilbert Space Shattering and Disorder-Free Localization in Polar Lattice Gases. Physical Review Letters, 127(26).
  Li, Wei-Han; Deng, Xiaolong & Santos, Luis
  
• Transversal effects on the ground state of hard-core dipolar bosons in one-dimensional optical lattices. Physical Review A, 107(6).
  Korbmacher, Henning; Domínguez-Castro, Gustavo A.; Li, Wei-Han; Zakrzewski, Jakub & Santos, Luis
  
• Tunable momentum pair creation of spin excitations in dipolar bilayers. Physical Review A, 108(1).
  Bilitewski, Thomas; Domínguez-Castro, G. A.; Wellnitz, David; Rey, Ana Maria & Santos, Luis