المؤلفون: Santalla, Silvia N., Domenech, Iván Álvarez, Villarrubia, Daniel, Cuerno, Rodolfo, Rodríguez-Laguna, Javier

مصطلحات موضوعية: Condensed Matter - Statistical Mechanics

الوصف: We characterize universal features of the sample-to-sample fluctuations of global geometrical observables, such as the area, width, length, and center-of-mass position, in random growing planar clusters. Our examples are taken from simulations of both continuous and discrete models of kinetically rough interfaces, including several universality classes, such as Kardar-Parisi-Zhang. We mostly focus on the scaling behavior with time of the sample-to-sample deviation for those global magnitudes, but we have also characterized their histograms and correlations.

الوصول الحر: http://arxiv.org/abs/2311.15275Test

المؤلفون: Domenech, Iván Álvarez, Rodríguez-Laguna, Javier, Cuerno, Rodolfo, Córdoba-Torres, Pedro, Santalla, Silvia N.

مصطلحات موضوعية: Condensed Matter - Statistical Mechanics, Mathematics - Probability

الوصف: We consider the isochrone curves in first-passage percolation on a 2D square lattice, i.e. the boundary of the set of points which can be reached in less than a given time from a certain origin. The occurrence of an instantaneous average shape is described in terms of its Fourier components, highlighting a crossover between a diamond and a circular geometry as the noise level is increased. Generally, these isochrones can be understood as fluctuating interfaces with an inhomogeneous local width which reveals the underlying lattice structure. We show that once these inhomogeneities have been taken into account, the fluctuations fall into the Kardar-Parisi-Zhang (KPZ) universality class with very good accuracy, where they reproduce the Family-Vicsek Ansatz with the expected exponents and the Tracy-Widom histogram for the local radial fluctuations.

الوصول الحر: http://arxiv.org/abs/2311.01400Test

المؤلفون: Vinaixa, José, Mula, Begoña, Deaño, Alfredo, Santalla, Silvia N., Rodríguez-Laguna, Javier

المصدر: JSTAT 013105 (2024)

مصطلحات موضوعية: Quantum Physics, Condensed Matter - Statistical Mechanics

الوصف: We characterize the long-term state of the 1D Dirac vacuum stirred by an impenetrable object, modeled as the ground state of a finite free-fermionic chain dynamically perturbed by a moving classical obstacle which suppresses the local hopping amplitudes. We find two different regimes, depending on the velocity of the obstacle. For a slow motion, the effective Floquet Hamiltonian presents features which are typical of the Gaussian orthogonal ensemble, and the occupation of the Floquet modes becomes roughly homogeneous. Moreover, the long term entanglement entropy of a contiguous block follows a Gaussian analogue of Page's law, i.e. a volumetric behavior. Indeed, the statistical properties of the reduced density matrices correspond to those of a random Slater determinant, which can be described using the Jacobi ensemble from random matrix theory. On the other hand, if the obstacle moves fast enough, the effective Floquet Hamiltonian presents a Poissonian behavior. The nature of the transition is clarified by the entanglement links, which determine the effective geometry underlying the entanglement structure, showing that the one-dimensionality of the physical Hamiltonian dissolves into a random adjacency matrix as we slow down the obstacle motion.

الوصول الحر: http://arxiv.org/abs/2310.16693Test

المؤلفون: Ortega, Diego, Rodríguez-Laguna, Javier, Korutcheva, Elka

المصدر: Physica A 608, 128267 (2022)

مصطلحات موضوعية: Physics - Physics and Society, Condensed Matter - Statistical Mechanics

الوصف: Half of the world population resides in cities and urban segregation is becoming a global issue. One of the best known attempts to understand it is the Schelling model, which considers two types of agents that relocate whenever a transfer rule depending on the neighbor distribution is verified. The main aim of the present study is to broaden our understanding of segregated neighborhoods in the city, i.e. ghettos, extending the Schelling model to consider economic aspects and their spatial distribution. To this end we have considered a monetary gap between the two social groups and five types of urban structures, defined by the house pricing city map. The results show that ghetto sizes tend to follow a power law distribution in all the considered cases. For each city framework the interplay between economical aspects and the geometrical features determine the location where ghettos reach their maximum size. The system first steps shape greatly the city's final appearance. Moreover, the segregated population ratios depends largely on the monetary gap and not on the city type, implying that ghettos are able to adapt to different urban frameworks.
Comment: 16 pages, 8 figures

الوصول الحر: http://arxiv.org/abs/2211.02726Test

المؤلفون: Mula, Begoña, de Buruaga, Nadir Samos Sáenz, Sierra, Germán, Santalla, Silvia N., Rodríguez-Laguna, Javier

المصدر: Phys. Rev. B 106, 224204 (2022)

مصطلحات موضوعية: Quantum Physics, Condensed Matter - Strongly Correlated Electrons

الوصف: The ground state of a free-fermionic chain with inhomogeneous hoppings at half-filling can be mapped into the Dirac vacuum on a static curved space-time, which presents exactly homogeneous occupations due to particle-hole symmetry. Yet, far from half-filling we observe density modulations and depletion effects. The system can be described by a 1D Schr\"odinger equation on a different static space-time, with an effective potential which accounts for the depleted regions. We provide a semiclassical expression for the single-particle modes and the density profiles associated to different hopping patterns and filling fractions. Moreover, we show that the depletion effects can be compensated for all filling fractions by adding a chemical potential proportional to the hoppings. Interestingly, we can obtain exactly the same density profiles on a homogeneous chain if we introduce a chemical potential which is inverse to the hopping intensities, even though the ground state is different from the original one.

الوصول الحر: http://arxiv.org/abs/2209.10624Test

المؤلفون: Santalla, Silvia N., Ramírez, Giovanni, Roy, Sudipto Singha, Sierra, Germán, Rodríguez-Laguna, Javier

المصدر: Physical Review B 107, L121114 (2023)

مصطلحات موضوعية: Quantum Physics, Condensed Matter - Strongly Correlated Electrons

الوصف: The time evolution of a quantum state with short-range correlations after a quench to a one-dimensional critical Hamiltonian can be understood using the quasi-particle picture, which states that local entanglement spreads as if it was carried by quasi-particles which separate at a fixed speed. We extend the quasi-particle picture using the recently introduced link representation of entanglement, allowing us to apply it to initial states presenting long-range correlations. The entanglement links are current correlators, and therefore follow a wave equation on the appropriate configurational space which allows us to predict the time evolution of the entanglement entropies. Our results are checked numerically for free fermionic chains with different initial entanglement patterns.
Comment: 7 pages, 7 figures, close to the published version

الوصول الحر: http://arxiv.org/abs/2208.03766Test

المؤلفون: Mula, Begoña, Fernández, Eva M., Alvarellos, José E., Fernández, Julio J., García-Aldea, David, Santalla, Silvia N., Rodríguez-Laguna, Javier

المصدر: Physical Review B 107, 075116 (2023)

مصطلحات موضوعية: Quantum Physics, Condensed Matter - Statistical Mechanics

الوصف: A subsystem of an entangled ground state is in a mixed state. Thus, if we isolate this subsystem from its surroundings we may be able to extract work applying unitary transformations, up to a maximal amount which is called ergotropy. Once this work has been extracted, the subsystem will still contain some bound energy above its local ground state, which can provide valuable information about the entanglement structure. We show that the bound energy for half a free fermionic chain decays as the square of the entanglement entropy divided by the chain length, thus approaching zero for large system sizes, and we conjecture that this relation holds for all 1D critical states.

الوصول الحر: http://arxiv.org/abs/2207.13998Test

المؤلفون: Roy, Sudipto Singha, Ramírez, Giovanni, Santalla, Silvia N., Sierra, Germán, Rodríguez-Laguna, Javier

المصدر: Physical Review B 105, 214306 (2022)

مصطلحات موضوعية: Quantum Physics, Condensed Matter - Strongly Correlated Electrons

الوصف: We describe a relation between the light-cone velocities after a quantum quench and the internal structure of the initial state, in the particular case of free fermions on a chain at half filling. The considered states include short-range valence bond solids, i.e., dimerized states, and long-range states such as the rainbow. In all the considered cases the correlations spread into one or a few well-defined light cones, each of them presenting an effective velocity which can be read from the form factor. Interestingly, we find that the observed velocities range from zero to the Fermi velocity and may not always be obtained from the dispersion relation for valid momenta.
Comment: 14 pages, 9 figures

الوصول الحر: http://arxiv.org/abs/2112.13382Test

المؤلفون: de Buruaga, Nadir Samos Sáenz, Santalla, Silvia N., Rodríguez-Laguna, Javier, Sierra, Germán

المصدر: Phys. Rev. B 104, 195147 (2021)

مصطلحات موضوعية: Condensed Matter - Strongly Correlated Electrons

الوصف: We study an inhomogeneous critical Ising chain in a transverse field whose couplings decay exponentially from the center. In the strong inhomogeneity limit we apply Fisher's renormalization group to show that the ground state is formed by concentric singlets similar to those of the rainbow state of the XX model. In the weak inhomogeneity limit we map the model to a massless Majorana fermion living in a hyperbolic spacetime, where, using CFT techniques, we derive the entanglement entropy that is violated linearly. We also study an inhomogeneous non-critical Ising model that for weak inhomogeneity is mapped to a massive Majorana fermion, while for strong inhomogeneity regime it exhibits trivial and non-trivial topological phases and a separation between regions with high and low entanglement. We also present the entanglement Hamiltonian of the model.
Comment: 18 pages, 11 figures, 6 appendices

الوصول الحر: http://arxiv.org/abs/2107.12113Test

المؤلفون: Ortega, Diego, Rodríguez-Laguna, Javier, Korutcheva, Elka

المصدر: Physica A 574, 1260110 (2021)

مصطلحات موضوعية: Physics - Physics and Society, Condensed Matter - Statistical Mechanics

الوصف: Residential segregation is analyzed via the Schelling model, in which two types of agents attempt to optimize their situation according to certain preferences and tolerance levels. Several variants of this work are focused on urban or social aspects. Whereas these models consider fixed values for wealth or tolerance, here we consider how sudden changes in the tolerance level affect the urban structure in the closed city model. In this framework, when tolerance decreases continuously, the change rate is a key parameter for the final state reached by the system. On the other hand, sudden drops in tolerance tend to group agents into clusters whose boundary can be characterized using tools from kinetic roughening. This frontier can be categorized into the Edward-Wilkinson (EW) universality class. Likewise, the understanding of these processes and how society adapts to tolerance variations are of the utmost importance in a world where migratory movements and pro-segregational attitudes are commonplace.
Comment: arXiv admin note: substantial text overlap with arXiv:2007.10767

الوصول الحر: http://arxiv.org/abs/2104.08924Test