Aspects of entanglement, chaos and complexity: from many-body to high energy systems

• Autor(a) principal: Júnior, Daniel Lombelo Teixeira
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/43/43134/tde-08042021-094350/
• topic: Quantum phase transitions; Quantum complexity; Quantum chaos; Entanglement dynamics; Emergent geometries; Transições de fase quânticas; Complexidade quântica; Caos quântico; Dinâmica do emaranhamento; Geometrias emergentes

The determination of structures that can emerge out of the interactions among the constituents of a quantum many-body system is a foundational task of condensed matter physics. One of the most advanced proposals within this paradigm is the holographic generation of spacetime in some strongly coupled chaotic systems with particular patterns of entanglement and quantum complexity, which is historically motivated by the holographic principle and by the AdS/CFT correspondence. As a part of this scenario, this thesis is dedicated to the analysis of some concepts that are relevant to such proposal, where they are separately applied to some lattice models. Concretely, the matter is divided into three main studies: first, the calculation of the time-dependent circuit complexity in the Ising model with a periodically driven transverse field, where we establish the effectiveness of this quantity for the detection of nonequilibrium quantum phase transitions. Our results provide hints for understanding how universal features out of equilibrium are captured by the complexity of quantum states. Second, the derivation of a bound on the maximal rate of entanglement entropy production for a class of one-dimensional quantum circuits with periodic dynamics. An example of a circuit that saturates the bound is composed by parallel SWAP gates acting on entangled pairs. Out of inequalities obeyed by the entropy, in addition to considerations on multipartite entanglement, we indicate that the effect of a chaotic dynamics cannot result in the increase on the rate of entanglement production. Third, the construction of a class of supersymmetric many-body systems using symmetric inverse semigroups. For particular toy models built out of this structure, we study some questions regarding supersymmetric phases, integrability, disorder, spreading of quantum information and many-body localization. Finally, besides those three works, we include an essay addressing the problem of emergent holographic spaces out of two-dimensional conformal field theories, where the mediation between the two parts is performed by means of a Riemannian structure defined in the Hilbert space of the field theory.