1,355,487 research outputs found
Dynamics of massive point vortices in a binary mixture of Bose-Einstein condensates
No full textWe study the massive point-vortex model introduced in Richaud et al. [A. Richaud, V. Penna, R. Mayol, and M. Guilleumas, Phys. Rev. A 101, 013630 (2020)], which describes two-dimensional point vortices of one species that have small cores of a different species. We derive the relevant Lagrangian itself, based on the time-dependent variational method with a two-component Gross-Pitaevskii (GP) trial function. The resulting Lagrangian resembles that of charged particles in a static electromagnetic field, where the canonical momentum includes an electromagnetic term. The simplest example is a single vortex with a rigid circular boundary, where a massless vortex can only precess uniformly. In contrast, the presence of a sufficiently large filled vortex core renders such precession unstable. A small core mass can also lead to small radial oscillations, which are, in turn, clear evidence of the associated inertial effect. Detailed numerical analysis of coupled two-component GP equations with a single vortex and small second-component core confirms the presence of such radial oscillations, implying that this more realistic GP vortex also acts as if it has a small massive core
Two-species boson mixture on a ring: A group-theoretic approach to the quantum dynamics of low-energy excitations
No full textWe investigate the weak excitations of a system made up of two condensates trapped in a Bose-Hubbard ring and coupled by an interspecies repulsive interaction. Our approach, based on the Bogoliubov approximation scheme, shows that one can reduce the problem Hamiltonian to the sum of sub-Hamiltonians ˆ H k , each one associated to momentum modes ± k . Each ˆ H k is then recognized to be an element of a dynamical algebra. This uncommon and remarkable property allows us to present a straightforward diagonalization scheme, to find constants of motion, to highlight the significant microscopic processes, and to compute their time evolution. The proposed solution scheme is applied to a simple but nontrivial closed circuit, the trimer. The dynamics of low-energy excitations, corresponding to weakly populated vortices, is investigated considering different choices of the initial conditions and the angular-momentum transfer between the two condensates is evidenced. Finally, the condition for which the spectral collapse and dynamical instability are observed is derived analytically
Pathway toward the formation of supermixed states in ultracold boson mixtures loaded in ring lattices
No full textWe investigate the mechanism of formation of supermixed solitonlike states in bosonic binary mixtures loaded in ring lattices. We evidence the presence of a common pathway which, irrespective of the number of lattice sites and upon variation of the interspecies attraction, leads the system from a mixed and delocalized phase to a supermixed and localized one, passing through an intermediate phase where the supermixed soliton progressively emerges. The degrees of mixing, localization, and quantum correlation of the two condensed species, quantified by means of suitable indicators commonly used in statistical thermodynamics and quantum information theory, allow one to reconstruct a bidimensional mixing-supermixing phase diagram featuring two characteristic critical lines. Our analysis is developed both within a semiclassical approach capable of capturing the essential features of the two-step mixing-demixing transition and with a fully quantum approach
The phase-separation mechanism of a binary mixture in a ring trimer
No full textWe show that, depending on the ratio between the inter- and the intra-species interactions, a binary mixture trapped in a three-well potential with periodic boundary conditions exhibits three macroscopic ground-state configurations which differ in the degree of mixing. Accordingly, the corresponding quantum states feature either delocalization or a Schrödinger cat-like structure. The two-step phase separation occurring in the system, which is smoothed by the activation of tunnelling
processes, is confirmed by the analysis of the energy spectrum that collapses and rearranges at the two critical points. In such points, we show that also Entanglement Entropy, a quantity borrowed from quantum-information theory, features singularities, thus demonstrating its ability to witness the double mixining-demixing phase transition. The developed analysis, which is of interest to both the experimental and theoretical communities, opens the door to the study of the demixing mechanism in complex lattice geometries
Spatial Phase Separation of a Binary Mixture in a Ring Trimer
No full textWe investigate the phase separation mechanism of bosonic binary mixtures in spatially-fragmented traps, evidencing the emergence of phases featuring a different degree of mixing. The analysis is initially carried out by means of a semiclassical approach which
transparently shows the occurrence of critical phenomena. These predictions are actually corroborated by the study of genuinely quantum indicators, including, but not limited to, the energy levels’ structure and the entanglement between the species. The scope of our work goes also beyond the ground state’s properties, as it comprises excited states and the dynamical evolution thereof. In particular, after introducing an indicator to monitor the degree of mixing, we show that several dynamical regimes feature persistent demixing in spite of their remarkably chaotic character
Décret, motivé par la motion de Richaud, accordant un secours provisoire de 200 livres au citoyen Colard, caporal de la 3e compagnie du 13e bataillon d'infanterie légère, qui a perdu un bras en bataille, lors de la séance du 29 germinal an II (18 avril 1794)
No full textRichaud Hyacinthe. Décret, motivé par la motion de Richaud, accordant un secours provisoire de 200 livres au citoyen Colard, caporal de la 3e compagnie du 13e bataillon d'infanterie légère, qui a perdu un bras en bataille, lors de la séance du 29 germinal an II (18 avril 1794). In: Tome LXXXIX - Du 29 germinal au 13 floréal an II (18 avril au 2 mai 1794) p. 35
Loneliness and Depression in Middle and Late Childhood: The Relationship to Attachment and Parental Styles
No full textIn this study, the author analyzed the relationship between (a) parenting and attachment and (b) self-competence, loneliness, and depression in children aged 8–12 years. The author administered (a) the Argentine Scale of Perception of the Relationships with Parents (M. C. Richaud de Minzi, 2004), (b) the Kerns’ Security Scale (K. A. Kerns, L. Klepac, & A. K. Cole, 1996; M. C. Richaud de Minzi, C. Sacchi, & J. E. Moreno, 2001, Argentine adaptation), (c) the Self-Perception Profile for Children (S. Harter, 1985; M. C. Richaud de Minzi et al.), (d) the Dimensions of Depression Profile for Children and Adolescents (S. Harter & M. Nowakowski, 1987), and (e) the Louvain Loneliness Scale for Children and Adolescents (A. Marcoen, L. Goossens, & P. Caes, 1987; M. C. Richaud de Minzi et al.) to 1,019 children (8–12 years of age, 483 boys, 536 girls). Results indicated that attachment and parent–child relationship styles were differentiated constructs. Parents’ acceptance promoted secure attachment and positive outcomes in children. Moreover, fathers’ lack of interest had a marked negative effect. The author found differences in the perceptions and influences of fathers and mothers, which follow the cultural patterns of gender attribution. Key words: attachment, loneliness, parenting, self-competenceFil: Richaud, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro Interdisciplinario de Investigaciones en Psicología Matemática y Experimental Dr. Horacio J. A. Rimoldi; Argentin
Relación de los estilos parentales autoritarios y permisivos con la autocrítica, la vulnerabilidad, la ansiedad y la competencia percibida por los niños
No full textLos estilos de crianza son un factor primordial para el desarrollo cognitivo, emocional y social del niño. Es conocido el rol importantísimo que juegan los padres en la socialización de sus hijos. Durante el desarrollo de los niños, los padres guían las experiencias de sus hijos de tal manera que les van transmitiendo valores, metas y aspiraciones. Durante las décadas de 1970 y 1980, las investigaciones concentraron su atención en la relación padres-hijos (especialmente madre-hijo) y su influencia sobre diferentes aspectos de la interacción de los niños con sus pares y sobre su ajuste social y académico en la escuela. Sin embargo, es importante destacar que en las últimas décadas el rol del padre en las familias esta cambiando. Las investigaciones muestran que la calidad de las relaciones que se establecen entre los padres y los hijos esta asociada a los estilos de vida que pueden observarse luego incluso de la adolescencia. Muchos estudios recientes han indicado que existe una relación entre varias formas de problemas psicológicos durante la niñez y la percepción de estilos parentales, esto es la percepción que los niños tienen de la conducta de sus padres. Es por ello que que se considera a los estilos parentales como factores de riesgo para el desarrollo individual durante la niñez y la adolescencia.Fil: Mesurado, Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro Interdisciplinario de Investigaciones en Psicología Matemática y Experimental Dr. Horacio J. A. Rimoldi; ArgentinaFil: Richaud, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro Interdisciplinario de Investigaciones en Psicología Matemática y Experimental Dr. Horacio J. A. Rimoldi; Argentin
Quantum-Granularity Effect in the Formation of Supermixed Solitons in Ring Lattices
No full textWe investigate a notable class of states peculiar to a bosonic binary mixture featuring repulsive intraspecies and attractive interspecies couplings. We evidence that, for small values of the hopping amplitudes, one can access particular regimes marked by the fact that the interwell boson transfer occurs in a jerky fashion. This property is shown to be responsible for the emergence of a staircase-like structure in the phase diagram of a mixture confined in a ring trimer and to resemble the mechanism of the superfluid-Mott insulator transition strongly. Under certain conditions, in fact, we show that it is possible to interpret the interspecies attraction as an effective chemical potential and the supermixed soliton as an effective particle reservoir. Our investigation is developed both within a fully quantum approach based on the analysis of several quantum indicators and by means of a simple analytical approximation scheme capable of capturing the essential features of this ultraquantum effect
Phase separation can be stronger than chaos
No full textWe investigate several dynamical regimes characterizing a bosonic binary mixture loaded in a ring trimer, with particular reference to the persistence of demixing. The degree of phase separation is evaluated by means of the ‘entropy of mixing’, an indicator borrowed from statistical thermodynamics. Three classes of demixed stationary configurations are identified and their energetic and linear stability carefully analyzed. An extended set of trajectories originating in the vicinity of fixed points are explicitly simulated and chaos is shown to arise according to three different mechanisms. In many dynamical regimes, we show that chaos is not able to disrupt the order imposed by phase separation, i.e. boson populations, despite evolving in a chaotic fashion, do not mix. This circumstance can be explained either with energetic considerations or in terms of dynamical
restrictions
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