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Autor Relaño Pérez, Armando |
Documentos disponibles escritos por este autor (48)
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The decoherence interpretation of quantum measurements is applied to Wigner's-friend experiments. A framework in which all the experimental outcomes arise from unitary evolutions is proposed. Within it, a measurement is not completed until an un[...]texto impreso
Decoherence induced by an interacting spin environment in the transition from integrability to chaos
We investigate the decoherence properties of a central system composed of two spins 1/2 in contact with a spin bath. The dynamical regime of the bath ranges from a fully integrable limit to complete chaoticity. We show that the dynamical regime [...]texto impreso
Theoretical expressions for the distribution of the ratio of consecutive level spacings for quantum systems with transiting dynamics remain unknown. We propose a family of one-parameter distributions P(r) P(r; beta), where beta is an element of [...]texto impreso
We study nonequilibrium processes in an isolated quantum system-the Dicke model-focusing on the role played by the transition from integrability to chaos and the presence of excited-state quantum phase transitions. We show that both diagonal and[...]texto impreso
Pérez Fernández, P. ; Relaño Pérez, Armando ; Arias, J. M. ; Cejnar, P. ; Dukelsky, J. ; García Ramos, J. E. | American Physical Society | 2011-04-15We 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 transitions demarcating the u[...]texto impreso
Puebla, Ricardo ; Relaño Pérez, Armando ; Retamosa Granado, Joaquín | American Physical Society | 2013-02-19We study the phase diagram of the Dicke model in terms of the excitation energy and the radiation-matter coupling constant lambda. Below a certain critical value lambda(c), all the energy levels have a well-defined parity. For lambda > lambda(c[...]texto impreso
Pérez Fernández, P. ; Relaño Pérez, Armando ; Cejnar, P. ; Arias, J. M. ; Dukelsky, J. ; García Ramos, J. E. | American Institute of Physics (AIP) | 2012In 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 non-integrable. For comparison, the same problem is studied for th[...]texto impreso
We study the integrability of the two-spin elliptic Gaudin model for arbitrary values of the Hamiltonian parameters. The limit of a very large spin coupled to a small one is well described by a semiclassical approximation with just one degree of[...]texto impreso
We present a theory that accurately describes the counting of excited states of a noninteracting fermionic gas. At high excitation energies the results reproduce Bethe's theory. At low energies oscillatory corrections to the many-body density of[...]texto impreso
We study the thermodynamics of the full version of the Dicke model, including all the possible values of the total angular momentum j, with bothmicrocanonical and canonical ensembles. We focus on both the excited-state quantum phase transition, [...]texto impreso
For a certain class of isolated quantum systems, we report the existence of irreversible processes in which the energy is not dissipated. After a closed cycle in which the initial energy distribution is fully recovered, the expectation value of [...]texto impreso
Gómez Gómez, José María ; Molina, R. A. ; Relaño Pérez, Armando ; Retamosa Granado, Joaquín | American Physical Society | 2002-09The main signature of chaos in a quantum system is provided by spectral statistical analysis of the nearest-neighbor spacing distribution P(s) and the spectral rigidity given by the Delta(3)(L) statistic. It is shown that some standard unfolding[...]texto impreso
Pachón, Leonardo A. ; Relaño Pérez, Armando ; Peropadre, Borja ; Aspuru-Guzik, Alán | Amer Physical Soc | 2018-10-19Based on the connection between the spectral form factor and the probability to return, the origin of the energy level fluctuation 1/f(alpha) noise in fully chaotic and fully integrable systems is traced to the quantum interference between invar[...]texto impreso
Relaño Pérez, Armando ; Molina, R. A. ; Retamosa Granado, Joaquín ; Muñoz, L. ; Faleiro, E. ; Gómez Gómez, José María | IOP publishing ltd | 2010The power spectrum of the ?_(n) statistic of quantum spectra presents 1/ƒ^(?) noise. For chaotic systems ? = 1 while for regular systems ? = 2. Although the transition from regularity to chaos is non universal, for a wide variety of systems wi[...]texto impreso
Relaño Pérez, Armando ; Muñoz, L. ; Retamosa Granado, Joaquín ; Faleiro, E. ; Molina, R. A. | American Physical Society | 2008-03The continuous Gaussian ensemble, also known as the nu-Gaussian or nu-Hermite ensemble, is a natural extension of the classical Gaussian ensembles of real (nu= 1), complex (nu= 2), or quaternion (nu=4) matrices, where nu is allowed to take any p[...]