2026-06-28T10:34:41Zhttps://docta.ucm.es/rest/oai/request

oai:docta.ucm.es:20.500.14352/729452023-08-25T12:36:55Zcom_20.500.14352_14col_20.500.14352_15

Dynamical and excited-state quantum phase transitions in collective systems Corps, Angel L. Relaño Pérez, Armando We study dynamical phase transitions (DPTs) in quantum many-body systems with infinite-range interaction, and present a theory connecting the two kinds of known DPTs (sometimes referred to as DPTs-I and DPTs-II) with the concept of excited-state quantum phase transition (ESQPT), traditionally found in collective models. We show that DPTs-I appear as a manifestation of symmetry restoration after a quench from the broken-symmetry phase, the limits between these two phases being demarcated precisely by an ESQPT. We describe the order parameters of DPTs-I with a generalization of the standard microcanonical ensemble incorporating the infor-mation of two additional conserved charges identifying the corresponding phase. We also show that DPTs-I are linked to a mechanism of information erasure brought about by the ESQPT, and quantify this information loss with the statistical ensemble that we propose. Finally, we show analytically the main mechanism for DPTs-II is forbidden in these systems for quenches leading a broken-symmetry initial state to the same broken-symmetry phase, on one side of the ESQPT, and we provide a formulation of DPTs-II depending on the side of the ESQPT where the quench ends. We analyze the connections between various indicators of DPTs-II. Our results are numerically illustrated in the infinite-range transverse-field Ising model and are applicable to a large class of collective quantum systems satisfying a set of conditions. 2023-06-22T12:37:25Z 2023-06-22T12:37:25Z 2023-06-22T12:37:25Z 2022-07-28 journal article https://hdl.handle.net/20.500.14352/72945 2469-9950 10.1103/PhysRevB.106.024311 eng PGC-2018-094180-B-I00 100010434 LCF/BQ/DR21/11880024 open access American Physical Society