RT Journal Article
T1 Excited-state quantum phase transitions in a two-fluid Lipkin model
A1 García Ramos, José Enrique
A1 Pérez Fernández, Pedro
A1 Arias Carrasco, José Miguel
AB [Background:] Composed systems have became of great interest in  the framework of the ground state quantum phase transitions (QPTs) and  many of their properties have been studied in detail. However, in  these systems the study of the so called excited-state quantum phase  transitions (ESQPTs) have not received so much attention.[Purpose:] A quantum analysis of the ESQPTs   in the two-fluid Lipkin model is presented in this  work. The study is performed through the Hamiltonian diagonalization  for selected values of the control parameters in order to cover the  most interesting regions of the system phase diagram. [Method:] A Hamiltonian that resembles the consistent-Q  Hamiltonian of the interacting boson model (IBM) is diagonalized for  selected values of the parameters and properties such as the density  of states, the Peres lattices, the nearest-neighbor spacing  distribution, and the participation ratio are analyzed.[Results:] An overview of the spectrum of the two-fluid Lipkin  model for selected positions in the phase diagram has been obtained.  The location of the excited-state quantum phase transition can be  easily singled out with the Peres lattice, with the  nearest-neighbor spacing distribution, with Poincar\'e    sections or with the participation ratio.[Conclusions:] This study completes the analysis of QPTs for the  two-fluid Lipkin model, extending the previous study to excited  states. The ESQPT signatures in composed systems behave in the same  way as in single ones, although the evidences of their presence can  be sometimes blurred. The Peres lattice turns out to be a convenient  tool to look into the position of the ESQPT and to define the concept  of phase in the excited states realm.
PB American Physical Society
YR 2017
FD 2017
LK http://hdl.handle.net/10272/14113
UL http://hdl.handle.net/10272/14113
LA eng
NO García Ramos,J.E., Pérez Fernández, P., Arias Carrasco, J.M.: "Excited-state quantum phase transitions in a two-fluid Lipkin model". Physical Review C - Nuclear Physics, 95 (5), 054326-1-054326-15. DOI: 10.1103/PhysRevC.95.054326
NO This work has been supported by the Spanish Ministerio de Econom ́ıa y Competitividadand the European regional development fund (FEDER) under Project No.  FIS2014-53448-C2-1-P and FIS2014-53448-C2-2-P
DS Repositorio Institucional de la Universidad de Huelva
RD 1 jun 2026