1,720,979 research outputs found
Symmetry resolved entanglement entropy of excited states in a CFT
No full textWe report a throughout analysis of the entanglement entropies related to different symmetry sectors in the low-lying primary excited states of a conformal field theory (CFT) with an internal U(1) symmetry. Our findings extend recent results for the ground state. We derive a general expression for the charged moments, i.e. the generalised cumulant generating function, which can be written in terms of correlation functions of the operator that define the state through the CFT operator-state correspondence. We provide explicit analytic computations for the compact boson CFT (aka Luttinger liquid) for the vertex and derivative excitations. The Fourier transform of the charged moments gives the desired symmetry resolved entropies. At the leading order, they satisfy entanglement equipartition, as in the ground state, but we find, within CFT, subleading terms that break it. Our analytical findings are checked against free fermions calculations on a lattice, finding excellent agreement. As a byproduct, we have exact results for the full counting statistics of the U(1) charge in the considered excited states
Rényi entropy and negativity for massless complex boson at conformal interfaces and junctions
No full textWe consider the ground state of a theory composed by M species of massless complex bosons in one dimension coupled together via a conformal interface. We compute both the Renyi entropy and the negativity of a generic partition of wires, generalizing the approach developed in a recent work for free fermions. These entanglement measures show a logarithmic growth with the system size, and the universal prefactor depends both on the details of the interface and the bipartition. We test our analytical predictions against exact numerical results for the harmonic chain
U(1) symmetry resolved entanglement in free 1+1 dimensional field theories via form factor bootstrap
No full textWe generalise the form factor bootstrap approach to integrable field theories
with U(1) symmetry to derive matrix elements of composite branch-point twist
fields associated with symmetry resolved entanglement entropies. The bootstrap
equations are solved for the free massive Dirac and complex boson theories,
which are the simplest theories with U(1) symmetry. We present the exact and
complete solution for the bootstrap, including vacuum expectation values and
form factors involving any type and arbitrarily number of particles. The
non-trivial solutions are carefully cross-checked by performing various limits
and by the application of the Delta-theorem. An alternative and compact
determination of the novel form factors is also presented. Based on the form
factors of the U(1) composite branch-point twist fields, we re-derive earlier
results showing entanglement equipartition for an interval in the ground state
of the two models
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Attività estrattiva ed impatto sul territorio: tipologia di coltivazione e strumenti di tutela in Regione Liguria.
No full textG.I.S. e cartografia tematica nella zonizzazione dei comuni di "media montagna" in Liguria - G.I.S. and thematic cartography in the zoning of middle mountains borroughs in Liguria
No full textDomain wall melting across a defect
No full text- We study the melting of a domain wall in a free-fermionic chain with a localised impurity. We find that the defect enhances quantum correlations in such a way that even the smallest scatterer leads to a linear growth of the entanglement entropy contrasting the logarithmic behaviour in the clean system. Exploiting the hydrodynamic approach and the quasiparticle picture, we provide exact predictions for the evolution of the entanglement entropy for arbitrary bipartitions. In particular, the steady production of pairs at the defect gives rise to non-local correlations among distant points. We also characterise the subleading logarithmic corrections, highlighting some universal features
Spreading of a local excitation in a quantum hierarchical model
No full textWe study the dynamics of the quantum Dyson hierarchical model in its paramagnetic phase. An initial state made by a local excitation of the paramagnetic ground state is considered. We provide analytical predictions for its time evolution, solving the single-particle dynamics on a hierarchical network. A localization mechanism is found, and the excitation remains close to its initial position at arbitrary times. Furthermore, a universal scaling among space and time is found that is related to the algebraic decay of the interactions as r-1-σ. We compare our predictions to numerics, employing tensor network techniques, for large magnetic fields, discussing the robustness of the mechanism in the full many-body dynamics
Osservazioni sulla distribuzione ed evoluzione dell'uso del suolo dei comuni di "media montagna" in Liguria
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