1,134 research outputs found
Entanglement properties of spin models in triangular lattices
The different quantum phases appearing in strongly correlated systems as well
as their transitions are closely related to the entanglement shared between
their constituents. In 1D systems, it is well established that the entanglement
spectrum is linked to the symmetries that protect the different quantum phases.
This relation extends even further at the phase transitions where a direct link
associates the entanglement spectrum to the conformal field theory describing
the former. For 2D systems much less is known. The lattice geometry becomes a
crucial aspect to consider when studying entanglement and phase transitions.
Here, we analyze the entanglement properties of triangular spin lattice models
by considering also concepts borrowed from quantum information theory such as
geometric entanglement.Comment: 19 pages, 8 figure
A case study of spin- Heisenberg model in a triangular lattice
We study the spin- model in a triangular lattice in presence of a uniaxial
anisotropy field using a Cluster Mean-Field approach (CMF). The interplay
between antiferromagnetic exchange, lattice geometry and anisotropy forces
Gutzwiller mean-field approaches to fail in a certain region of the phase
diagram. There, the CMF yields two supersolid (SS) phases compatible with those
present in the spin- XXZ model onto which the spin- system maps.
Between these two SS phases, the three-sublattice order is broken and the
results of the CMF depend heavily on the geometry and size of the cluster. We
discuss the possible presence of a spin liquid in this region.Comment: 7 pages, 4 figures, RevTeX 4. The abstract and conclusions have been
modified and the manuscript has been extende
Insights from a Case of Good’s Syndrome (Immunodeficiency with Thymoma)
Immunodeficiency with thymoma was described by R.A. Good in 1954 and is also named after him. The syndrome is characterized by hypogammaglobulinemia associated with thymoma and recurrent infections, bacterial but also viral, fungal and parasitic. Autoimmune diseases, mainly pure red cell aplasia, other hematological disorders and erosive lichen planus are a common finding. We describe here a typical case exhibiting all these clinical features and report a detailed immunophenotypic assessment, as well as the positivity for autoantibodies against three cytokines (IFN-alpha, IL-6 and GM-CSF), which may add to known immune abnormalities. A review of the published literature, based on case series and immunological studies, offers some hints on the still unsolved issues of this rare condition
Mesoscopic continuous and discrete channels for quantum information transfer
We study the possibility of realizing perfect quantum state transfer in
mesoscopic devices. We discuss the case of the Fano-Anderson model extended to
two impurities. For a channel with an infinite number of degrees of freedom, we
obtain coherent behavior in the case of strong coupling or in weak coupling
off-resonance. For a finite number of degrees of freedom, coherent behavior is
associated to weak coupling and resonance conditions
Spin-driven spatial symmetry breaking of spinor condensates in a double-well
The properties of an F=1 spinor Bose-Einstein condensate trapped in a
double-well potential are discussed using both a mean-field two-mode approach
and a simplified two-site Bose-Hubbard Hamiltonian. We focus in the region of
phase space in which spin effects lead to a symmetry breaking of the system,
favoring the spatial localization of the condensate in one well. To model this
transition we derive, using perturbation theory, an effective Hamiltonian that
describes N/2 spin singlets confined in a double-well potential.Comment: 12 pages, 5 figure
Analyzing How BERT Performs Entity Matching
State-of-the-art Entity Matching (EM) approaches rely on transformer architectures, such as BERT, for generating highly contextualized embeddings of terms. The embeddings are then used to predict whether pairs of entity descriptions refer to the same real-world entity. BERT-based EM models demonstrated to be effective, but act as black-boxes for the users, who have limited insight into the motivations behind their decisions. In this paper, we perform a multi-facet analysis of the components of pre-trained and fine-tuned BERT architectures applied to an EM task. The main findings resulting from our extensive experimental evaluation are (1) the fine-tuning process applied to the EM task mainly modifies the last layers of the BERT components, but in a different way on tokens belonging to descriptions of matching / non-matching entities; (2) the special structure of the EM datasets, where records are pairs of entity descriptions is recognized by BERT; (3) the pair-wise semantic similarity of tokens is not a key knowledge exploited by BERT-based EM models
Double dot chain as a macroscopic quantum bit
We consider an array of N quantum dot pairs interacting via Coulomb
interaction between adjacent dots and hopping inside each pair. We show that at
the first order in the ratio of hopping and interaction amplitudes, the array
maps in an effective two level system with energy separation becoming
exponentially small in the macroscopic (large N) limit. Decoherence at zero
temperature is studied in the limit of weak coupling with phonons. In this case
the macroscopic limit is robust with respect to decoherence. Some possible
applications in quantum information processing are discussed.Comment: Phys. Rev. A (in press
Generation of donor-specific Tr1 cells to be used after kidney transplantation and definition of the timing of their in vivo infusion in the presence of immunosuppression
Background: Operational tolerance is an alternative to lifelong immunosuppression after transplantation. One strategy to achieve tolerance is by T regulatory cells. Safety and feasibility of a T regulatory type 1 (Tr1)-cell-based therapy to prevent graft versus host disease in patients with hematological malignancies has been already proven. We are now planning to perform a Tr1-cell-based therapy after kidney transplantation. Methods: Upon tailoring the lab-grade protocol to patients on dialysis, aims of the current work were to develop a clinical-grade compatible protocol to generate a donor-specific Tr1-cell-enriched medicinal product (named T10 cells) and to test the Tr1-cell sensitivity to standard immunosuppression in vivo to define the best timing of cell infusion. Results: We developed a medicinal product that was enriched in Tr1 cells, anergic to donor-cell stimulation, able to suppress proliferation upon donor- but not third-party stimulation in vitro, and stable upon cryopreservation. The protocol was reproducible upon up scaling to leukapheresis from patients on dialysis and was effective in yielding the expected number of T10 cells necessary for the planned infusions. The tolerogenic gene signature of circulating Tr1 cells was minimally compromised in kidney transplant recipients under standard immunosuppression and it eventually started to recover 36weeks post-transplantation, providing rationale for selecting the timings of the cell infusions. Conclusions: These data provide solid ground for proceeding with the trial and establish robust rationale for defining the correct timing of cell infusion during concomitant immunosuppressive treatment
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