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We propose a protocol to prepare thermalized states storing relevant amounts of information about their past, and we study their resilience and the conditions under which we can profit from them. This protocol is based on the existence of an integrable stage in the preparation process, which makes it possible to record these amounts of information in the expected value of the corresponding integral of motion. By means of numerical calculations on the paradigmatic Dicke model, we show that it is possible to lead a quantum system onto a highly chaotic region, in which the eigenstate thermalization hypothesis is fulfilled and hence we find thermalization, without erasing this information. Notwithstanding, we also propose the existence of a quantum mechanism that mimics the high sensitivity to the initial conditions, the trademark of classical chaos, and thus constitutes a powerful tool for information erasure. Its efficiency is rapidly increased with the number of particles, and hence the proposed protocol is only applicable to small quantum systems. It is induced by avoided level crossings in the transition from integrability to chaos, and it is switched on when the system goes through this transition with finite rapidity. We also show that the same mechanism contributes to hide this information from equilibrium measurements when the system follows the same path in the adiabatic limit.

GHαFaS, a new Fabry-Perot system, is now available at the William Herschel Telescope (WHT). It was mounted, for the first time, at the Nasmyth focus of the 4.2-m WHT on La Palma in 2007 July. Using modern technology, with a spectral resolution of the order R ~ 15,000, and with a seeing-limited spatial resolution, GHαFaS will provide a new look at the Hα-emitting gas over a 4.8' circular field in the nearby universe. Many science programs can be done on a 4.2-m class telescope in world-class seeing conditions with a scanning Fabry-Perot. Not only galaxies but H II regions, planetary nebulae, supernova remnants, and the diffuse interstellar medium are subjects for which unique data can be aquired rapidly. Astronomers from the Laboratoire d'Astrophysique Experimentale (LAE) in Montreal, the Laboratoire d'Astrophysique de Marseille (LAM-OAMP), and the Instituto de Astrofisica de Canarias (IAC), have inaugurated GHαFaS by studying in detail the dynamics of some nearby spiral galaxies. A robust set of state-of-the-art tools for reducing and analyzing the data cubes obtained with GHαFaS has also been developed.

We analyze the emission line profiles of the region populations in three disc spiral galaxies and find evidence of wing features at 40-90 from the central peak in a significant fraction of regions. We explain the wing features as due to a shell expanding inside the region, quantify the energy involved and present two possible mechanisms to drive the expanding shell.

6 pags., 5 figs., 1 tab. -- Rutherford Centennial Conference on Nuclear Physics 8–12 August 2011, Manchester, UK, In the last decade quantum chaos has become a well established discipline with outreach to different fields, from condensed-matter to nuclear physics. The most important signature of quantum chaos is the statistical analysis of the energy spectrum, which distinguishes between systems with integrable and chaotic classical analogues. In recent years, spectral statistical techniques inherited from quantum chaos have been applied successfully to the baryon spectrum revealing its likely chaotic behaviour even at the lowest energies. However, the theoretical spectra present a behaviour closer to the statistics of integrable systems which makes theory and experiment statistically incompatible. The usual statement of missing resonances in the experimental spectrum when compared to the theoretical ones cannot account for the discrepancies. In this communication we report an improved analysis of the baryon spectrum, taking into account the low statistics and the error bars associated with each resonance. Our findings give a major support to the previous conclusions. Besides, analogue analyses are performed in the experimental meson spectrum, with comparison to theoretical models.

6 pags., 2 figs. -- XXXIII Symposium on Nuclear Physics 5–8 January 2010, Hacienda Cocoyoc, Morelos, Mexico, The power spectrum of the 5 statistic of quantum spectra presents 1/f(alpha) noise. For chaotic systems alpha = 1 while for regular systems alpha = 2. Although the transition from regularity to chaos is non universal, for a wide variety of systems with a mixed phase space the value of a is intermediate between 1 and 2 and can be related to the fraction of regular or chaotic orbits in the total phase space. This statistic can be a very useful tool for the analysis of experimental spectra, specially in the case of missing levels or spectral sequences with mixed symmetries., This research has been supported in part by Spanish Government grant No. FIS2009- 07277 and No. FIS2006-12783-C03-02, CSPD-2007-00042-Ingenio2010, and by the Universidad Complutense de Madrid grant UCM-910059. A.R. is supported by the CPAN-Consolider program.

We present the simulations of two relevant hydrodynamical problems related to astrophysical phenomena performed by three different codes. The numerical results from these codes will be compared in order to test both the numerical method implemented inside them and the influence of the physical phenomena simulated by the codes. Under some conditions laser produced plasmas could be scaled to the typical conditions prevailing in astrophysical plasmas. Therefore, such similarity allows to use existing laser facilities and numerical codes suitable to a laser plasma regime, for studying astrophysical proccesses. The codes are the radiation fluid dynamic 2D ARWEN code and the 3D HERACLES, and, without radiation energy transport, a Smoothed-Particle Hydrodynamics (SPH) code. These codes use diferent numerical techniques and have overlapping range of application, from laser produced plasmas to astrophysical plasmas. We also present the first laser experiments obtaining cumulative jets with a velocity higher than 100 km/s.

We report a kind of phase transition which takes place in isolated quantum systems with a discrete symmetry. Different phases are separated by a critical energy and recognized by means of an order parameter, which can be experimentally measured. Below the critical energy, the symmetry is broken and the equilibrium state is non-thermal, keeping large amounts of memory of the initial condition. Above, the symmetry is restored and a thermal equilibrium state is reached. We identify two universality classes, one showing a second-order phase transition and represented by the Lipkin-Meshkov-Glick model, and another showing a first-order phase transition and represented by the Dicke model.This work is dedicated to the memory of Joaquin Retamosa.

A stringent analysis of nonequilibrium dynamics and thermalization in a complex interacting spin system, which transits from integrability to chaos, is performed. The applicability of both standard thermodynamical ensembles—canonical and microcanonical—and the generalized Gibbs ensemble is tested. The role of constants of motion is studied, and a critical analysis of the usual definition of quantum integrability is performed. Different possible thermalization mechanisms are also analyzed. We find significant discrepancies between the time averages of some observables and the prediction from the thermodynamical ensembles within the ergodic region, so we conclude that quantum chaos does not guarantee thermalization. We also find that quantum integrable dynamics keeps more memory concerning the initial state, which is in part stored in a set of constants of motion that can be explicitly obtained.

We present the simulations of two relevant hydrodynamical problems related to astrophysical phenomena performed by three different codes. The numerical results from these codes will be compared in order to test both the numerical method implemented inside them and the influence of the physical phenomena simulated by the codes. Under some conditions laser produced plasmas could be scaled to the typical conditions prevailing in astrophysical plasmas. Therefore, such similarity allows to use existing laser facilities and numerical codes suitable to a laser plasma regime, for studying astrophysical proccesses. The codes are the radiation fluid dynamic 2D ARWEN code and the 3D HERACLES, and, without radiation energy transport, a Smoothed-Particle Hydrodynamics (SPH) code. These codes use different numerical techniques and have overlapping range of application, from laser produced plasmas to astrophysical plasmas. We also present the first laser experiments obtaining cumulative jets with a velocity higher than 100 km/s.