Persona: Rodríguez Laguna, Javier
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jrlaguna@fisfun.uned.es
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0000-0003-2218-7980
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Rodríguez Laguna
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Javier
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16 resultados
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Publicación Engineering large end-to-end correlations in finite fermionic chains(American Physical Society., 2018-12-14) Santos, Hernán; Alvarellos Bermejo, José Enrique; Rodríguez Laguna, JavierWe explore deformations of finite chains of noninteracting fermions at half-filling which give rise to large correlations between their extremes. After a detailed study of the Su-Schrieffer-Heeger model, the tradeoff curve between end-to-end correlations and the energy gap of the chains is obtained using machine-learning techniques, paying special attention to the scaling behavior with the chain length.We find that edge-dimerized chains, where the second and penultimate hoppings are reinforced, are very often close to the optimal configurations. Our results allow us to conjecture that, given a fixed gap, the maximal attainable correlation falls exponentially with the system size. Study of the entanglement entropy and contour of the optimal configurations suggest that the bulk entanglement pattern is minimally modified from the clean case.Publicación Semblanzas de los Premios Nobel 2016 en Física(Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias, 2016-01-01) Rodríguez Laguna, JavierPublicación Entanglement as geometry and flow(American Physical Society, 2020-05-20) Singha Roy, Sudipto; Santalla, Silvia N.; Sierra, Germán; Rodríguez Laguna, JavierWe explore the connection between the area law for entanglement and geometry by representing the entanglement entropies corresponding to all 2 N bipartitions of an N -party pure quantum system by means of a (generalized) adjacency matrix. In the cases where the representation is exact, the elements of that matrix coincide with the mutual information between pairs of sites. In others, it provides a very good approximation, and in all the cases it yields a natural entanglement contour which is similar to previous proposals. Moreover, for one-dimensional conformal invariant systems, the generalized adjacency matrix is given by the two-point correlator of an entanglement current operator. We conjecture how this entanglement current may give rise to a metric entirely built from entanglement.Publicación Semblanzas de científicas y científicos españoles: Juan Ignacio Cirac Sasturain(Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias, 2018-01-01) Fernández González, Carlos; Rodríguez Laguna, JavierPublicación A New Thermodynamic Model to Approximate Properties of Subcritical Liquids(MDPI, 2023-06-29) Sánchez Orgaz, Susana; González Fernández, M. Celina; Varela Díez, Fernando; Rodríguez Laguna, JavierIn order to obtain the thermodynamic properties of compressed liquids, it is usual to consider them as incompressible systems, since liquids and solids are well represented by this thermodynamic model. Within this model, there are two usual hypotheses that can be derived in two different submodels: the strictly incompressible (SI) model, which supposes a constant specific volume 𝑣=𝑣0, and a more general model, called temperature-dependent incompressible (TDI) model, which relates a specific volume to temperature, 𝑣=𝑣(𝑇). But, usually, this difference ends here in the thermal equation of state, and only the SI model was developed for caloric and entropic equations. The aim of this work is to provide a complete formulation for the TDI model and show where it can be advantageously used rather than the SI model. The study concludes that the proposed model outperforms the traditional model in the study of subcritical liquid. One conceivable utilization of this model is its integration into certain thermodynamic calculation software packages (e.g., EES), which integrate the more elementary SI model into its code for certain incompressible substances.Publicación Novedades científicas en 2017 en Física(Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias, 2017-01-01) Rodríguez Laguna, JavierPublicación Ergotropy and entanglement in critical spin chains(American Physical Society, 2023-02-08) Mula, Begoña; Fernández, Julio J.; Santalla, Silvia N.; Alvarellos Bermejo, José Enrique; García Aldea, David; Rodríguez Laguna, Javier; Fernández Sánchez, Eva MaríaA subsystem of an entangled ground state (GS) 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 GS, 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 one-dimensional critical states.Publicación Entanglement detachment in fermionic systems(Springer, 2018-11-27) Santos, Hernán; Alvarellos Bermejo, José Enrique; Rodríguez Laguna, JavierThis article introduces and discusses the concept of entanglement detachment. Under some circumstances, enlarging a few couplings of a Hamiltonian can effectively detach a (possibly disjoint) block within the ground state. This detachment is characterized by a sharp decrease in the entanglement entropy between block and environment, and leads to an increase of the internal correlations between the (possibly distant) sites of the block. We provide some examples of this detachment in free fermionic systems. The first example is an edge-dimerized chain, where the second and penultimate hoppings are increased. In that case, the two extreme sites constitute a block which disentangles from the rest of the chain. Further examples are given by (a) a superlattice which can be detached from a 1D chain, and (b) a star-graph, where the extreme sites can be detached or not depending on the presence of an external magnetic field, in analogy with the Aharonov-Bohm effect. We characterize these detached blocks by their reduced matrices, specially through their entanglement spectrum and entanglement Hamiltonian.Publicación Nonuniversality of front fluctuations for compact colonies of nonmotile bacteria(American Physical Society, 2018-07-10) Santalla, Silvia N.; Abad, José P.; Marín, Irma; Muñoz García, Javier; Vázquez, Luis; Cuerno, Rodolfo; Rodríguez Laguna, Javier; Espinosa Escudero, María del MarThe front of a compact bacterial colony growing on a Petri dish is a paradigmatic instance of non-equilibrium fluctuations in the celebrated Eden, or Kardar-Parisi-Zhang (KPZ), universality class. While in many experiments the scaling exponents crucially differ from the expected KPZ values, the source of this disagreement has remained poorly understood. We have performed growth experiments with B. subtilis 168 and E. coli ATCC 25922 under conditions leading to compact colonies in the classically alleged Eden regime, where individual motility is suppressed. Non-KPZ scaling is indeed observed for all accessible times, KPZ asymptotics being ruled out for our experiments due to the monotonic increase of front branching with time. Simulations of an effective model suggest the occurrence of transient nonuniversal scaling due to diffusive morphological instabilities, agreeing with expectations from detailed models of the relevant biological reaction-diffusion processes.Publicación Recensiones: Cine en ciencias: El enigma Agustina(Universidad Nacional de Educación a Distancia (España). Facultad de Ciencias, 2019-01-01) Fernández, Eva María; Rodríguez Laguna, Javier