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Artículo
Continuous unitary transformations in two-level boson systems
(American Physical Society, 2005-12-01)
Two-level 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 ...
Artículo
Scalar two-level boson model to study the interacting boson model phase diagram in the Casten triangle
(American Physical Society, 2006)
We introduce a simple two-level boson model with the same energy surface as the Q-consistent interacting boson model Hamiltonian. The model can be diagonalized for large number of bosons and the results used to check ...
Artículo
Disentangling phase transitions and critical points in the proton-neutron interacting boson model by catastrophe theory
(Elsevier, 2014)
We introduce the basic concepts of catastrophe theory needed to derive analytically the phase diagram of the proton–neutron interacting boson model (IBM-2). Previous studies [1–3] were based on numerical solutions. We here ...
Artículo
Intrinsic state for an extended version of the interacting boson model
(American Physical Society, 2000-03-01)
An intrinsic-state formalism for the interacting boson model IBM-4 is presented. A basis of deformed bosons is introduced which allows the construction of a general trial wave function that has Wigner’s spin-isospin SU(4) ...
Artículo
An extended Agassi model: Algebraic structure, phase diagram, and large size limit
(Institute of Physics Publishing, 2019)
The Agassi model (Agassi 1968 Nucl. Phys. A 116 49) is a schematic two-level model that involves pairing and monopole-monopole interactions. It is, therefore, an extension of the well known Lipkin-Meshkov-Glick model (Lipkin ...
Artículo
Excited-state phase transition and onset of chaos in quantum optical models
(American Physical Society, 2011)
We study the 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 excited-state quantum phase ...
Artículo
Number conserving particle-hole RPA for superfluid nuclei
(Elsevier, 2019-08)
We present a number conserving particle-hole 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 ...
Artículo
Quantum phase transitions in the interacting boson model: Integrability, level repulsion, and level crossing
(American Physical Review, 2003-10-17)
We study the quantum phase transition mechanisms that arise in the interacting boson model. We show that the second-order nature of the phase transition from U(5) to O(6) may be attributed to quantum integrability, whereas ...
Artículo
Decoherence due to an excited-state quantum phase transition in a two-level boson model
(American Physical Society, 2009)
The decoherence induced on a single qubit by its interaction with the environment is studied. The environment is modeled as a scalar two-level boson system that can go through either first-order or continuous-excited-state ...
Artículo
β4 potential at the U(5)–O(6) critical point of the interacting boson model
(American Physical Society, 2005)
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 ...