21,868 research outputs found
Entanglement for rank-2 mixed states
In a recent paper, Rungta et. al. [Phys. Rev. A, 64, 042315, 2001] introduced
a measure of mixed-state entanglement called the I-concurrence for arbitrary
pairs of qudits. We find an exact formula for an entanglement measure closely
related to the I-concurrence, the I-tangle, for all mixed states of two qudits
having no more than two nonzero eigenvalues. We use this formula to provide a
tight upper bound for the entanglement of formation for rank-2 mixed states of
a qubit and a qudit.Comment: 5 pages, uses amsthm and mathrsf
Creation and Manipulation of Anyons in the Kitaev Model
We analyze the effect of local spin operators in the Kitaev model on the
honeycomb lattice. We show, in perturbation around the isolated-dimer limit,
that they create Abelian anyons together with fermionic excitations which are
likely to play a role in experiments. We derive the explicit form of the
operators creating and moving Abelian anyons without creating fermions and show
that it involves multi-spin operations. Finally, the important experimental
constraints stemming from our results are discussed.Comment: 4 pages, 3 figures, published versio
p120 catenin is required for the stress response in Drosophila
p120ctn is a ubiquitously expressed core component of cadherin junctions and essential for vertebrate development. Surprisingly, Drosophila p120ctn (dp120ctn) is dispensable for adherens junctions and development, which has discouraged Drosophila researchers from further pursuing the biological role of dp120ctn. Here we demonstrate that dp120ctn loss results in increased heat shock sensitivity and reduced animal lifespan, which are completely rescued by ectopic expression of a dp120ctn-GFP transgene. Transcriptomic analysis revealed multiple relish/NF-κB target genes differentially expressed upon loss of dp120ctn. Importantly, this aberrant gene expression was rescued by overexpression of dp120ctn-GFP or heterozygosity for relish. Our results uncover a novel role for dp120ctn in the regulation of animal stress response and immune signalling. This may represent an ancient role of p120ctn and can influence further studies in Drosophila and mammals
Geometric Phase and Quantum Phase Transition in the Lipkin-Meshkov-Glick model
The relation between the geometric phase and quantum phase transition has
been discussed in the Lipkin-Meshkov-Glick model. Our calculation shows the
ability of geometric phase of the ground state to mark quantum phase transition
in this model. The possibility of the geometric phase or its derivatives as the
universal order parameter of characterizing quantum phase transitions has been
also discussed.Comment: 6 pages and to be published in Phys.Lett.
Global Entanglement for Multipartite Quantum States
Based on the residual entanglement [9] (Phys. Rev. A \textbf{71}, 044301
(2005)), we present the global entanglement for a multipartite quantum state.
The measure is shown to be also obtained by the bipartite partitions of the
multipartite state. The distinct characteristic of the global entanglement is
that it consists of the sum of different entanglement contributions. The
measure can provide sufficient and necessary condition of fully separability
for pure states and be conveniently extended to mixed states by minimizing the
convex hull. To test the sufficiency of the measure for mixed states, we
evaluate the global entanglement of bound entangled states. The properties of
the measure discussed finally show the global entanglement is an entanglement
monotone.Comment: 6 page
Entanglement cost of mixed states
We compute the entanglement cost of several families of bipartite mixed
states, including arbitrary mixtures of two Bell states. This is achieved by
developing a technique that allows us to ascertain the additivity of the
entanglement of formation for any state supported on specific subspaces. As a
side result, the proof of the irreversibility in asymptotic local manipulations
of entanglement is extended to two-qubit systems.Comment: 4 pages, no figures, (v4) new results, including a new method to
determine E_c for more general mixed states, presentation changed
significantl
Transformed epithelia trigger non-tissue-autonomous tumor suppressor response by adipocytes via activation of toll and Eiger/TNF signaling
High tumor burden is associated with increased levels of circulating inflammatory cytokines that influence the pathophysiology of the tumor and its environment. The cellular and molecular events mediating the organismal response to a growing tumor are poorly understood. Here, we report a bidirectional crosstalk between epithelial tumors and the fat body—a peripheral immune tissue—in Drosophila. Tumors trigger a systemic immune response through activation of Eiger/TNF signaling, which leads to Toll pathway upregulation in adipocytes. Reciprocally, Toll elicits a non-tissue-autonomous program in adipocytes, which drives tumor cell death. Hemocytes play a critical role in this system by producing the ligands Spätzle and Eiger, which are required for Toll activation in the fat body and tumor cell death. Altogether, our results provide a paradigm for a long-range tumor suppression function of adipocytes in Drosophila, which may represent an evolutionarily conserved mechanism in the organismal response to solid tumors
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