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Browsing by Author "Dukelsky, J."
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An extended Agassi model: algebraic structure, phase diagram, and large size limit
García Ramos, José Enrique; Dukelsky, J.; Pérez Fernández, Pedro (IOP Publishing, 2019)The Agassi model (Agassi 1968 Nucl. Phys. A 116 49) is a schematic twolevel model that involves pairing and monopole–monopole interactions. It is, therefore, an extension of the well known Lipkin–Meshkov–Glick model (Lipkin ... 
Continuous unitary transformations in twolevel boson systems
Dusuel, Sébastien; Vidal, Julien; Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique (American Physical Society, 20051230)Twolevel boson systems displaying a quantum phase transition from a spherical (symmetric) to a deformed (broken) phase are studied. A formalism to diagonalize Hamiltonians with O(2L + 1) symmetry for large number of ... 
Decoherence and quantum quench: their relationship with excited state quantum phase transitions
García Ramos, José Enrique; Arias Carrasco, José Miguel; Cejnar, P.; Dukelsky, J.; Pérez Fernández, Pedro; Relaño Pérez, Armando (American Institute of Physics, 201205)We study the similarities and differences between the phenomena of Quantum Decoherence and Quantum Quench in presence of an Excited State Quantum Phase Transition (ESQPT).We analyze, on one hand, the decoherence induced ... 
Decoherence as a signature of an excited state quantum phase transition
Relaño Pérez, Armando; Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique; Pérez Fernández, Pedro (American Physical Society, 20081216)We analyze the decoherence induced on a single qubit by the interaction with a twolevel boson system with critical internal dynamics. We explore how the decoherence process is affected by the presence of quantum phase ... 
Decoherence due to an excited state quantum phase transition in a twolevel boson model
Pérez Fernández, Pedro; Relaño Pérez, Armando; Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique (American Physical Society, 20090917)The decoherence induced on a single qubit by its interaction with the environment is studied. The environment is modeled as a scalar twolevel boson system that can go through either firstorder or continuousexcitedstate ... 
Disentangling phase transitions and critical points in the proton–neutron interacting boson model by catastrophe theory
García Ramos, José Enrique; Arias Carrasco, José Miguel; Dukelsky, J. (Elsevier, 2014)We introduce the basic concepts of catastrophe theory needed to derive analytically the phase diagram of the protonneutron interacting boson model (IBM2). Previous studies [1,2,3] were based on numerical solutions. We ... 
Exactly solvable pairing Hamiltonian for heavy nuclei
Dukelsky, J.; Lerma, S.; Robledo, L. M.; Rodríguez Guzmán, R.; Rombouts, S. M. A. (American Physical Society, 2011)We present a new exactly solvable Hamiltonian with a separable pairing interaction and nondegenerate singleparticle energies. It is derived from the hyperbolic family of RichardsonGaudin models and possesses two free ... 
Exceptional spectral phase in a dissipative collective spin model
RubioGarcía, Álvaro; Relaño Pérez, Armando; Corps, Ángel L.; Molina, Rafael A.; Pérez Bernal, Francisco; García Ramos, José Enrique; Dukelsky, J. (American Physical Society, 2022)We study a model of a quantum collective spin weakly coupled to a spinpolarized Markovian environment and find that the spectrum is divided into two regions that we name normal and exceptional Liouvillian spectral phases. ... 
Excited state quantum phase transitions and chaos in the Dicke model
Pérez Fernández, Pedro; Relaño Pérez, Armando; Cejnar, P.; Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique (American Institute of Physics, 2012)In this contribution, the critical behavior of excited state quantum phase transitions (ESQPT’s) and its relation to order and chaos in the Dicke model are studied. This model is nonintegrable. For comparison, the same ... 
Excitedstate phase transition and onset of chaos in quantum optical models
Pérez Fernández, Pedro; Relaño Pérez, Armando; Arias Carrasco, José Miguel; Cejnar, P.; Dukelsky, J.; García Ramos, José Enrique (American Physical Society, 20110415)We study critical behavior of excited states and its relation to order and chaos in the Jaynes Cummings and Dicke models of quantum optics. We show that both models exhibit a chain of excitedstate quantum phase transitions ... 
Number conserving particlehole RPA for superfluid nuclei
Dukelsky, J.; García Ramos, José Enrique; Arias, J.M.; Pérez Fernández, Pedro; Schuck, P. (Elsevier, 201907)We present a number conserving particlehole RPA theory for collective excitations in the transition from normal to superfluid nuclei. The method derives from an RPA theory developed long ago in quantum chemistry using ... 
Phase diagram of an extended Agassi model
García Ramos, José Enrique; Dukelsky, J.; Pérez Fernández, Pedro; Arias Carrasco, José Miguel (American Physical Society, 2018)Background: The Agassi model [D. Agassi, Nucl. Phys. A 116, 49 (1968)] is an extension of the LipkinMeshkovGlick (LMG) model [H. J. Lipkin, N. Meshkov, and A. J. Glick, Nucl. Phys. 62, 188 (1965)] that incorporates the ... 
Phase Diagram of the ProtonNeutron Interacting Boson Model
Arias Carrasco, José Miguel; García Ramos, José Enrique; Dukelsky, J. (American Physical Society, 2004)We study the phase diagram of the protonneutron interacting boson model with special emphasis on the phase transitions leading to triaxial phases. The existence of a new critical point between spherical and triaxial shapes ... 
Quantum Phase Transitions in the Interacting Boson Model : Integrability, level repulsion and level crossing
Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique (American Physical Society, 20031014)We study the quantum phase transition mechanisms that arise in the Interacting Boson Model. We show that the secondorder nature of the phase transition from U(5) to O(6) may be attributed to quantum integrability, whereas ... 
Quantum quench influenced by an excitedstate phase transition
Pérez Fernández, Pedro; Cejnar, P.; Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique; Relaño Pérez, Armando (American Physical Society, 20110303)We analyze excitedstate quantum phase transitions (ESQPTs) in three schematic (integrable and nonintegrable) models describing a singlemode bosonic field coupled to a collection of atoms. It is shown that the presence ... 
A scalar twolevel boson model to study the IBM phase diagram in the Casten triangle
Vidal, Julien; Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique (American Physical Society, 20060505)We introduce a simple twolevel boson model with the same energy surface as the Qconsistent Interacting Boson Model Hamiltonian. The model can be diagonalized for large number of bosons and the results used to check ... 
Twolevel interacting boson models beyond the mean field
Arias Carrasco, José Miguel; Dukelsky, J.; García Ramos, José Enrique; Vidal, Julien (American Physical Society, 20070102)The phase diagram of twolevel boson Hamiltonians, including the Interacting Boson Model (IBM), is studied beyond the standard mean field approximation using the HolsteinPrimakoff mapping. The limitations of the usual ... 
The U(5)–O(6) transition in the Interacting Boson Model and the E(5) critical point symmetry
Arias Carrasco, José Miguel; Alonso Alonso, Clara Eugenia; Vitturi, A.; García Ramos, José Enrique; Dukelsky, J.; Frank, A. (American Physical Society, 20031024)The relation of the recently proposed E(5) critical point symmetry with the interacting boson model is investigated. The largeN limit of the interacting boson model at the critical point in the transition from U(5) to ... 
The β 4 potential at the U(5)–O(6) critical point of the Interacting Boson Model
García Ramos, José Enrique; Dukelsky, J.; Arias Carrasco, José Miguel (American Physical Society, 20050908)Exact numerical results of the interacting boson model Hamiltonian along the integrable line from U(5) to O(6) are obtained by diagonalization within boson seniority subspaces. The matrix Hamiltonian reduces to a block ...