1,721,245 research outputs found
Subsystem complexity after a global quantum quench
Full text linkWe study the temporal evolution of the circuit complexity for a subsystem in harmonic lattices after a global quantum quench of the mass parameter, choosing the initial reduced density matrix as the reference state. Upper and lower bounds are derived for the temporal evolution of the complexity for the entire system. The subsystem complexity is evaluated by employing the Fisher information geometry for the covariance matrices. We discuss numerical results for the temporal evolutions of the subsystem complexity for a block of consecutive sites in harmonic chains with either periodic or Dirichlet boundary conditions, comparing them with the temporal evolutions of the entanglement entropy. For infinite harmonic chains, the asymptotic value of the subsystem complexity is studied through the generalised Gibbs ensemble
Complexity of mixed Gaussian states from Fisher information geometry
Full text linkWe study the circuit complexity for mixed bosonic Gaussian states in harmonic lattices in any number of dimensions. By employing the Fisher information geometry for the covariance matrices, we consider the optimal circuit connecting two states with vanishing first moments, whose length is identified with the complexity to create a target state from a reference state through the optimal circuit. Explicit proposals to quantify the spectrum complexity and the basis complexity are discussed. The purification of the mixed states is also analysed. In the special case of harmonic chains on the circle or on the infinite line, we report numerical results for thermal states and reduced density matrices
Entanglement and symmetry resolution in two dimensional free quantum field theories
Full text linkWe present a thorough analysis of the entanglement entropies related to different symmetry sectors of free quantum field theories (QFT) with an internal U(1) symmetry. We provide explicit analytic computations for the charged moments of Dirac and complex scalar fields in two spacetime dimensions, both in the massive and massless cases, using two different approaches. The first one is based on the replica trick, the computation of the partition function on Riemann surfaces with the insertion of a flux α, and the introduction of properly modified twist fields, whose two-point function directly gives the scaling limit of the charged moments. With the second method, the diagonalisation in replica space maps the problem to the computation of a partition function on a cut plane, that can be written exactly in terms of the solutions of non-linear differential equations of the Painlevé V type. Within this approach, we also derive an asymptotic expansion for the short and long distance behaviour of the charged moments. Finally, the Fourier transform provides the desired symmetry resolved entropies: at the leading order, they satisfy entanglement equipartition and we identify the subleading terms that break it. Our analytical findings are tested against exact numerical calculations in lattice models
Breast hamartoma: ultrasound, elastosonographic, and mammographic features. Mini pictorial essay
No full textHamartomas, also known as fibroadenolipomas, are rare, benign formations that can develop in various organs, including the breast. They present clinically as a soft, mobile nodular lesions and are generally asymptomatic. They may be discovered incidentally during imaging studies performed for other reasons. Owing to the increasingly widespread use of mammographic screening, the diagnosis of breast hamartomas is on the rise. The masses are associated with specific mammographic and sonographic features that reflect their diverse tissue components. They also appear to present reproducible features on elastography. This article reviews the typical features of breas
The potentials of computed tomography in the study of mechanical ileus of the small intestine [Le possibilità della Tomografia Computerizzata nello studio dell'ileo meccanico dell'intestino tenue.]
No full textSubsystem complexity after a local quantum quench
Full text linkAbstract We study the temporal evolution of the circuit complexity after the local quench where two harmonic chains are suddenly joined, choosing the initial state as the reference state. We discuss numerical results for the complexity for the entire chain and the subsystem complexity for a block of consecutive sites, obtained by exploiting the Fisher information geometry of the covariance matrices. The qualitative behaviour of the temporal evolutions of the subsystem complexity depends on whether the joining point is inside the subsystem. The revivals and a logarithmic growth observed during these temporal evolutions are discussed. When the joining point is outside the subsystem, the temporal evolutions of the subsystem complexity and of the corresponding entanglement entropy are qualitatively similar
The role of computerized tomography in the study of duodenal carcinoma [Il ruolo della tomografia computerizzata nello studio del carcinoma duodenale.]
No full text2-D Modeling of topographic effects using three basic geometries and the spectral-element method
No full textThe topographic effect was investigated selecting three basic 2-D geometries and using the feasibility of the spectral-element method (SEM; as implemented in the specfem2d code). The 2-D geometries were a triangle, an half-circle and a slope. 2-D models (P-SV waves) considering a real topography (Mount Ocre in L'Aquila district) were also performed, varying the velocities and the number of nearby topographic peaksPublishedTrieste3T. Pericolosità sismica e contributo alla definizione del rischioope
Entanglement Hamiltonians in 1D free lattice models after a global quantum quench
Full text linkWe study the temporal evolution of the entanglement Hamiltonian of an interval after a global quantum quench in free lattice models in one spatial dimension. In a harmonic chain we explore a quench of the frequency parameter. In a chain of free fermions at half filling we consider the evolution of the ground state of a fully dimerised chain through the homogeneous Hamiltonian. We focus on critical evolution Hamiltonians. The temporal evolutions of the gaps in the entanglement spectrum are analysed. The entanglement Hamiltonians in these models are characterised by matrices that provide also contours for the entanglement entropies. The temporal evolution of these contours for the entanglement entropy is studied, also by employing existing conformal field theory results for the semi-infinite line and the quasi-particle picture for the global quench
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